The Problem with Giant Robots

[Alrik Vas]

How large would we put the UAR-1's contact area with the ground at, realistically? Like, the bottom of it's feet. What do you contend the surface area to be?

I feel like 7x4 9(ft) per foot unit is possibly beyond generous. That's combined for 56 sqft area (672 in), and 18 tons (36000 lbs) of weight. Simple math tells us this thing is at a standstill pounding the ground with about 53 psi. Then it lifts a foot to walk, and it goes up a silly amount on the back leg.

[eliakon]

How large would we put the UAR-1's contact area with the ground at, realistically? Like, the bottom of it's feet. What do you contend the surface area to be?

I feel like 7x4 9(ft) per foot unit is possibly beyond generous. That's combined for 56 sqft area (672 in), and 18 tons (36000 lbs) of weight. Simple math tells us this thing is at a standstill pounding the ground with about 53 psi. Then it lifts a foot to walk, and it goes up a silly amount on the back leg.

Right, it goes up to 106. Or 16PSI more than a road racing bicycle. I don't recall anyone in the Tour de France ever destroying the road though.

[Alrik Vas]

That's true. And the UAR-1 is based around packed dirt and city streets/highways. So it should be fine, and actually outmaneuver most ground vehicles with it's speed and agility.

Though get it on softer land it will slow down much more than a track vehicle, i'd think.

[say652]

What about Three Galaxy GR? Couldn't they use Contragravity tech to counter the soft terrain problems?
Also for Rifts Earth GR couldn't the Bionic flight system tech be modified to do something similar?

[Alrik Vas]

NE makes Grav Packs, listed in Wave 2. In any case, yes, you could do that. Probably expensive and you might have to remove other systems unless you want a backpack on your giant robot.

[dragonfett]

So what about the IAR-2 Abolisher which was not intended for urban combat?

[glitterboy2098]

that would depend on a lot of different factors beyond just ground pressure, really. compressibility of the soil, the depth of the soft layer, amounts of vegetation, etc.
in really soft terrain like soft mud, marshes, or deep loose snow, a robot might have a bit of an edge because where a tank's treads or truck's wheels would dig ruts into the ground (using a lot of energy to push and dig the soil out of the way), a robot's walking gait is more of a "lift, move forward, drop" movement for its legs, not having to displace quite as much of the soft ground in the course of moving. neither would be moving very fast, but the robot could probably trudge along a bit better in some terrain where tanks would be in danger of bogging down.

of course, in such terrain the better choice of vehicle would be hovercraft anyway, whether the skirted kind seen a lot today (and still seen in rifts with the New Navy's iwo jima APC) or the vectored thrust stuff more commonly seen.

though that does bring up an interesting point.. rifts robots can, and in many cases do, include thruster systems allowing limited flight or at the least boosted jumps. which would give them some degree of advantage even in ground where tanks would be able to move easier than a robot.. a tank has to roll across the ground, and either go around or wallow through overly soft ground, but more than a few rifts robots can cross that ground in a succession of short skimming flights or boosted hops. Heinlein starship trooper's Mobile infantry style.



to be honest, despite what the books claim, the main advantage girant robots have in rifts over tanks isn't about crossing soft ground, but rather the fact most giant robots are going to handle Forests better than tanks. a tank can push through underbrush and over small tree's easy enough, but it still has to go around the bigger, older growth, and even small trees can hinder it's turret traverse, making it harder to aim. a giant robot also has to go around the old growth, but the smaller guns and the use of arm mounted guns means they shouldn't be as hindered by the close confines. especially since a robot has more points of articulation and can thus adjust its posture much like a human soldier would to lean around obstacles or otherwise get aim without having to re-position as often. plus with their main guns and sensors usually mounted 12-25ft above the ground, giant robots would have better lines of sight and lines of fire in many cases, being above the worst of the underbrush and smaller trees.

with so much of north america (and the world) having reverted to old growth forest in the 3 centuries since the great cataclysm, this would be an advantage, particularly in the "domain of man" in the midwest, where there was a fair bit of forest left even before the rifts.

[Alrik Vas]

that would depend on a lot of different factors beyond just ground pressure, really. compressibility of the soil, the depth of the soft layer, amounts of vegetation, etc.

A lot of that is why rating ground pressure is a thing, so it kind of has everything to do with it. In any case, I agree with the majority of the rest of your post, so no need to quote it.

[Blue_Lion]

How large would we put the UAR-1's contact area with the ground at, realistically? Like, the bottom of it's feet. What do you contend the surface area to be?

I feel like 7x4 9(ft) per foot unit is possibly beyond generous. That's combined for 56 sqft area (672 in), and 18 tons (36000 lbs) of weight. Simple math tells us this thing is at a standstill pounding the ground with about 53 psi. Then it lifts a foot to walk, and it goes up a silly amount on the back leg.

Right, it goes up to 106. Or 16PSI more than a road racing bicycle. I don't recall anyone in the Tour de France ever destroying the road though.

Now that you have incorrectly determined ground pressure standing look at it while moving.

http://hypertextbook.com/facts/1999/SaraBirnbaum.shtml

So that would be the rear foot phase 18X3 or 54 tons of force when the heel strikes, and push off 18 X 4 =72 tons to 18x7 =126 tons on the fore foot.

Assuming the heal is 3.5X4(to me that seams rather extreme amount of heal that is 14 square feet correct? So 14 X144(note there are a 144 square inches to a square foot not 12) is 2016 square inches. tons to pounds US short method 54 x 2000 gives 108000 pounds (think I did that right) So math indicates with the heal size listed the strike has 53.5 pounds per square inch.

This sight uses scientific Kilagrams per square cm
http://civilblog.org/2015/02/23/how-to- ... l-on-site/
could bring insite on the types of soils that can be traversed.

Guide with pounds per square foot.
http://www.pole-barn.info/soil-bearing-capacity.html
http://www.concretenetwork.com/concrete ... matter.htm

Note the math above although the square inch appears low there is over 7,000 pounds per square foot in impact force. the chart does have a safety margin built in that is above the load bearing capacity of rock. Just standing on two feet has a load of almost 643 pounds per square foot so although it can stand on soft soil most terrene would not be able to withstand its movement force.


Understanding that it is just not the surface area that you touch that supports the weight but the area around it as well. That is why most charts for building are pounds per square feet.

example the M1A1 tank has a 2,160 per square foot. Just over soft soils in the soft soils it does sink a bit but can still move leaving tank track ditches. It is often said to perform poorly in soft soil conditions.

https://en.wikipedia.org/wiki/Ground_pressure
While the racing bike has 90 pounds per square inch it likely only has about 2 inches of contact spread over a distance of greater than 3 foot so each square foot is bearing an average of what 90 pounds to 180 for some one really heavy.

Although you can find pounds per square inch to break things, load bearing seams rated in pounds per square foot in the US.


Low over pressure 4 pounds per square inch can nock over most buildings at 10 pounds per square inch reinforced building fall. (This shows that low pounds per inch over a large area in a short time frame can destroy objects.) that is pressure above air pleasure of 14.7 per square inch at sea level so 24.7 pounds of impact pressure on a large surface area can collapse a building.

https://en.wikipedia.org/wiki/Overpressure

I do not think I swing a sledge hammer with over 1 ton of force for load bearing limit but the impact does chip and break stone and indent in soft soil.

[ShadowLogan]

NE makes Grav Packs, listed in Wave 2. In any case, yes, you could do that. Probably expensive and you might have to remove other systems unless you want a backpack on your giant robot.

Yes Gravity manipulation technology is viable (to reduce the weight), but if you can manipulate gravity you can probably just skip the whole issue with the legs and go with a floating legless 'bot design. You don't even need gravity manipulation tech either, you could just go with thrusters (though this probably is going to be noisy, raise issues of jet wash, debris being tossed around, etc).

in really soft terrain like soft mud, marshes, or deep loose snow, a robot might have a bit of an edge because where a tank's treads or truck's wheels would dig ruts into the ground (using a lot of energy to push and dig the soil out of the way), a robot's walking gait is more of a "lift, move forward, drop" movement for its legs, not having to displace quite as much of the soft ground in the course of moving. neither would be moving very fast, but the robot could probably trudge along a bit better in some terrain where tanks would be in danger of bogging down.

Actually it is that soft terrain that will give the giant robot the most difficulty because of its locomotion it will exert more pressure on the ground. The limb will also encounter resistance and probably be less energy efficient since the limb will be constantly going back-forth where the tread/wheels would be more efficient in that they can use their momentum. The Tread/Wheel is likely to also have better traction over the foot.

I thought one of the reasons for the tanks/armored vehicles to have tracks was to handle the soft terrain better than wheel vehicles.

though that does bring up an interesting point.. rifts robots can, and in many cases do, include thruster systems allowing limited flight or at the least boosted jumps. which would give them some degree of advantage even in ground where tanks would be able to move easier than a robot.. a tank has to roll across the ground, and either go around or wallow through overly soft ground, but more than a few rifts robots can cross that ground in a succession of short skimming flights or boosted hops. Heinlein starship trooper's Mobile infantry style.

??? Are you sure you aren't thinking of Robotech/Macross 'bots or Rifts Power Armor. The majority of Rifts Bots though don't utilize a thruster system AFAIK, and most of those are flyers IINM. I did a quick sprint through the main 'bot heavy Rifts books that I have (RMB/RUE, Japan, Triax1, CWC, Atlantis, SB1o) and found thruster systems rare unless you where also a flyer. Now Triax2, NG, SB3, SA1&2, China, Spirit West, and Underseas (or Phaseworld setting) might change the dynamic a bit, but I don't think they will heavily change the result.

to be honest, despite what the books claim, the main advantage girant robots have in rifts over tanks isn't about crossing soft ground, but rather the fact most giant robots are going to handle Forests better than tanks. a tank can push through underbrush and over small tree's easy enough, but it still has to go around the bigger, older growth, and even small trees can hinder it's turret traverse, making it harder to aim. a giant robot also has to go around the old growth, but the smaller guns and the use of arm mounted guns means they shouldn't be as hindered by the close confines. especially since a robot has more points of articulation and can thus adjust its posture much like a human soldier would to lean around obstacles or otherwise get aim without having to re-position as often. plus with their main guns and sensors usually mounted 12-25ft above the ground, giant robots would have better lines of sight and lines of fire in many cases, being above the worst of the underbrush and smaller trees.

I don't see how the giant bots are going to have an easier time navigating a forest than an armored vehicle. In many cases they are just as wide as an armored vehicle, trading their length for width might make them generally narrower than an armored vehicle, but odds are that this type of movement will be slower.

The turret traverse might be an issue, though it's questionable if it will be as much of a hindrance as you think. While a typical tank isn't going to be able to adjust its posture much, short of the giant bot going on its back/belly it is likely to present a much larger profile than the tank. It is probably also possible to retrofit/design a tank with these factors in mind to give the unit just as much flexibility as the giant robot is perceived to have (WW2's Preying Mantis Tank prototype comes to mind, or the old Centaur Tank in Robotech's now decanonized comics).

The points of articulation on a robot can also work against it. It introduces more failure points, and could potentially be more prone to Foreign Object Debris, and by RAW require advanced training to repair and maintain (Robot Mechanics, which has prerequisite of Mechanical Engineer) compared to a tank (Automechanics or Vehicle Armorer neither of which of have a prerequisite). Cleaning out/repairing damage from the FOD might be simple, but the GR could be more difficult due to its size and limb placement at the time of failure, unlike a tank/armored vehicle.

[Blue_Lion]

I think the ones that say they work better are thinking they can just step over most obstacles. In truth I do not think they could step over most obstacles in the forest as their height increases the amount of tree they come into contact with. The trees it is pushing through would also be likely to reduce ability to see ground obstacles to step over. Both units would have a similar ability to push through trees, if anything the higher surface area of a track means you can apply more force. (Basically I see it as a claim by some one that has never traveled through heavy brush.)

[eliakon]

How large would we put the UAR-1's contact area with the ground at, realistically? Like, the bottom of it's feet. What do you contend the surface area to be?

I feel like 7x4 9(ft) per foot unit is possibly beyond generous. That's combined for 56 sqft area (672 in), and 18 tons (36000 lbs) of weight. Simple math tells us this thing is at a standstill pounding the ground with about 53 psi. Then it lifts a foot to walk, and it goes up a silly amount on the back leg.

Right, it goes up to 106. Or 16PSI more than a road racing bicycle. I don't recall anyone in the Tour de France ever destroying the road though.

Now that you have incorrectly determined ground pressure standing look at it while moving.

http://hypertextbook.com/facts/1999/SaraBirnbaum.shtml

So that would be the rear foot phase 18X3 or 54 tons of force when the heel strikes, and push off 18 X 4 =72 tons to 18x7 =126 tons on the fore foot.

Assuming the heal is 3.5X4(to me that seams rather extreme amount of heal that is 14 square feet correct? So 14 X144(note there are a 144 square inches to a square foot not 12) is 2016 square inches. tons to pounds US short method 54 x 2000 gives 108000 pounds (think I did that right) So math indicates with the heal size listed the strike has 53.5 pounds per square inch.

This sight uses scientific Kilagrams per square cm
http://civilblog.org/2015/02/23/how-to- ... l-on-site/
could bring insite on the types of soils that can be traversed.

Guide with pounds per square foot.
http://www.pole-barn.info/soil-bearing-capacity.html
http://www.concretenetwork.com/concrete ... matter.htm

Note the math above although the square inch appears low there is over 7,000 pounds per square foot in impact force. the chart does have a safety margin built in that is above the load bearing capacity of rock. Just standing on two feet has a load of almost 643 pounds per square foot so although it can stand on soft soil most terrene would not be able to withstand its movement force.


Understanding that it is just not the surface area that you touch that supports the weight but the area around it as well. That is why most charts for building are pounds per square feet.

example the M1A1 tank has a 2,160 per square foot. Just over soft soils in the soft soils it does sink a bit but can still move leaving tank track ditches. It is often said to perform poorly in soft soil conditions.

https://en.wikipedia.org/wiki/Ground_pressure
While the racing bike has 90 pounds per square inch it likely only has about 2 inches of contact spread over a distance of greater than 3 foot so each square foot is bearing an average of what 90 pounds to 180 for some one really heavy.

Although you can find pounds per square inch to break things, load bearing seams rated in pounds per square foot in the US.


Low over pressure 4 pounds per square inch can nock over most buildings at 10 pounds per square inch reinforced building fall. (This shows that low pounds per inch over a large area in a short time frame can destroy objects.) that is pressure above air pleasure of 14.7 per square inch at sea level so 24.7 pounds of impact pressure on a large surface area can collapse a building.

https://en.wikipedia.org/wiki/Overpressure

I do not think I swing a sledge hammer with over 1 ton of force for load bearing limit but the impact does chip and break stone and indent in soft soil.

Not to be rude...
But the sites your linked to are between useless and irrelevant.
An unsourced, disjointed list of some maximum newtons of runners from shoe test studies, four of which were conducted by shoe companies internally, doesn't help anything since we don't know ANYTHING about their methodology, speeds, weights of runners, impact areas, credentials of performers etc.

Citing the load bearing values of soils for building codes really doesn't help us figure out what you can walk on

The ground pressure discusses the PSI issue by also giving the values in pascals. AND notes that, for example spiked shoes can get 13mPa!

Now if you have a site that allows for an accurate calculation of the energy transfer of bipedal objects by weight/speed/contact area then THAT would be something to look at.
With out that its back to the "well I don't think it can work, so I want to use stuff out of context to prove it can't"
Remember the default here is that Robots work. Claiming that they are actually impossible is an affirmative claim. The burden of proof is on the claimant to prove their claim.

[Alrik Vas]

Actually, if you're in a forest, and the trees are too thick for a tank to run over, a 'bot might move through them still because it has less surface area on it's feet. It can step between trees and move them at their weakest points (the top half) and literally bend them out of the way as they pass (depends on the type of the tree though). They'd do this just as humans can do the same thing to heavy overgrowth.

And I've moved through this kind of terrain before, without an ability to cut through, I did just that. You step to the path of least resistance and you move things aside with your hands as you go, turning sideways as needed.

Also, Blue, about your post above, you're right. i calculated for walking ground pressure, not standing. My mistake. Also about your last post, in the end, what exactly are you saying? You give a lot of information, but I don't know where you were going with it.

[Blue_Lion]

How large would we put the UAR-1's contact area with the ground at, realistically? Like, the bottom of it's feet. What do you contend the surface area to be?

I feel like 7x4 9(ft) per foot unit is possibly beyond generous. That's combined for 56 sqft area (672 in), and 18 tons (36000 lbs) of weight. Simple math tells us this thing is at a standstill pounding the ground with about 53 psi. Then it lifts a foot to walk, and it goes up a silly amount on the back leg.

Right, it goes up to 106. Or 16PSI more than a road racing bicycle. I don't recall anyone in the Tour de France ever destroying the road though.

Now that you have incorrectly determined ground pressure standing look at it while moving.

http://hypertextbook.com/facts/1999/SaraBirnbaum.shtml

So that would be the rear foot phase 18X3 or 54 tons of force when the heel strikes, and push off 18 X 4 =72 tons to 18x7 =126 tons on the fore foot.

Assuming the heal is 3.5X4(to me that seams rather extreme amount of heal that is 14 square feet correct? So 14 X144(note there are a 144 square inches to a square foot not 12) is 2016 square inches. tons to pounds US short method 54 x 2000 gives 108000 pounds (think I did that right) So math indicates with the heal size listed the strike has 53.5 pounds per square inch.

This sight uses scientific Kilagrams per square cm
http://civilblog.org/2015/02/23/how-to- ... l-on-site/
could bring insite on the types of soils that can be traversed.

Guide with pounds per square foot.
http://www.pole-barn.info/soil-bearing-capacity.html
http://www.concretenetwork.com/concrete ... matter.htm

Note the math above although the square inch appears low there is over 7,000 pounds per square foot in impact force. the chart does have a safety margin built in that is above the load bearing capacity of rock. Just standing on two feet has a load of almost 643 pounds per square foot so although it can stand on soft soil most terrene would not be able to withstand its movement force.


Understanding that it is just not the surface area that you touch that supports the weight but the area around it as well. That is why most charts for building are pounds per square feet.

example the M1A1 tank has a 2,160 per square foot. Just over soft soils in the soft soils it does sink a bit but can still move leaving tank track ditches. It is often said to perform poorly in soft soil conditions.

https://en.wikipedia.org/wiki/Ground_pressure
While the racing bike has 90 pounds per square inch it likely only has about 2 inches of contact spread over a distance of greater than 3 foot so each square foot is bearing an average of what 90 pounds to 180 for some one really heavy.

Although you can find pounds per square inch to break things, load bearing seams rated in pounds per square foot in the US.


Low over pressure 4 pounds per square inch can nock over most buildings at 10 pounds per square inch reinforced building fall. (This shows that low pounds per inch over a large area in a short time frame can destroy objects.) that is pressure above air pleasure of 14.7 per square inch at sea level so 24.7 pounds of impact pressure on a large surface area can collapse a building.

https://en.wikipedia.org/wiki/Overpressure

I do not think I swing a sledge hammer with over 1 ton of force for load bearing limit but the impact does chip and break stone and indent in soft soil.

Not to be rude...
But the sites your linked to are between useless and irrelevant.
An unsourced, disjointed list of some maximum newtons of runners from shoe test studies, four of which were conducted by shoe companies internally, doesn't help anything since we don't know ANYTHING about their methodology, speeds, weights of runners, impact areas, credentials of performers etc.

Citing the load bearing values of soils for building codes really doesn't help us figure out what you can walk on

The ground pressure discusses the PSI issue by also giving the values in pascals. AND notes that, for example spiked shoes can get 13mPa!

Now if you have a site that allows for an accurate calculation of the energy transfer of bipedal objects by weight/speed/contact area then THAT would be something to look at.
With out that its back to the "well I don't think it can work, so I want to use stuff out of context to prove it can't"
Remember the default here is that Robots work. Claiming that they are actually impossible is an affirmative claim. The burden of proof is on the claimant to prove their claim.

Not to be rude but on the first page I linked a page with the math to determine the force of impact. It is related to an article by two professors at James Madison university. That includes information on their experiment but no one bothered with the math. (In addition the first entry in the table with the rule of thumb was sourced to a study done by professors from Organ state and running speed. They had a formula for increase with running speed.)
http://mathaware.org/mam/2010/essays/To ... unWalk.pdf

I use the general rule of thumb for impact from the page I linked this time for two reasons, 1 the math was based of the subjects weight 2. it matches information from a military class on mines that I took that a 180 pound solder can set off an anti tank mine that requires 550 pounds of pressure on its plate to go off.


I the only information I can find on how much weight the ground can support is in the building codes.
Do you have any better sources to present? (knocking some ones sources when you do not provide anything better. Quite simply I have spent time looking for sources on this and it is not an easy thing to research.)

It is not like I see any one else looking for information beyond a Wiki link.

I could not find the impact load tolerance for the ground, the best I could find was the load bearing rating for building. Do things not respond better to sustained force vs sudden force.

It would seam to be reasonable that if the pounds per square foot where less than the construction tolerance the ground will hold when you go past that then you need to question if the ground will hold up. The content was can the soil bear the weight, the tables where for footing sitting on the ground. Seams fairly relent when it comes to an idea of what the ground can hold.

I find it rather insulting you come at me with such a demand of accuracy when you ignore others making a basic math mistake.

[eliakon]

Not to be rude but on the first page I linked a page with the math to determine the force of impact. It is related to an article by two professors at James Madison university. That includes information on their experiment but no one bothered with the math. (In addition the first entry in the table with the rule of thumb was sourced to a study done by professors from Organ state and running speed. They had a formula for increase with running speed.)
http://mathaware.org/mam/2010/essays/To ... unWalk.pdf

I use the general rule of thumb for impact from the page I linked this time for two reasons, 1 the math was based of the subjects weight 2. it matches information from a military class on mines that I took that a 180 pound solder can set off an anti tank mine that requires 550 pounds of pressure on its plate to go off.


I the only information I can find on how much weight the ground can support is in the building codes.
Do you have any better sources to present? (knocking some ones sources when you do not provide anything better. Quite simply I have spent time looking for sources on this and it is not an easy thing to research.)

It is not like I see any one else looking for information beyond a Wiki link.

I really don't think so. Long term construction takes into account all sorts of issues that simple transient loads don't.
but really that isn't my problem. I don't have to find proof to defend someone else's thesis. That is sort of their job.

I could not find the impact load tolerance for the ground, the best I could find was the load bearing rating for building. Do things not respond better to sustained force vs sudden force.

It would seam to be reasonable that if the pounds per square foot where less than the construction tolerance the ground will hold when you accede that then you need to question if the ground will hold up.

Except that the wiki claims that cleats can have up to 13,000,000 pascals of pressure.
And it ignores things like dinosaurs which we can, presumably, were able to walk around.

Clearly the answer seems to be 'its complicated'
I am not saying that it may not be possible. What I am saying is that proof that it is impossible is going to need to be just that. Proof. Not just some conjecture using some estimations and guess work combined with some formulas that seem to be only partially explained and that may or may not be fully directly applicable.

[Blue_Lion]

Not to be rude but on the first page I linked a page with the math to determine the force of impact. It is related to an article by two professors at James Madison university. That includes information on their experiment but no one bothered with the math. (In addition the first entry in the table with the rule of thumb was sourced to a study done by professors from Organ state and running speed. They had a formula for increase with running speed.)
http://mathaware.org/mam/2010/essays/To ... unWalk.pdf

I use the general rule of thumb for impact from the page I linked this time for two reasons, 1 the math was based of the subjects weight 2. it matches information from a military class on mines that I took that a 180 pound solder can set off an anti tank mine that requires 550 pounds of pressure on its plate to go off.


I the only information I can find on how much weight the ground can support is in the building codes.
Do you have any better sources to present? (knocking some ones sources when you do not provide anything better. Quite simply I have spent time looking for sources on this and it is not an easy thing to research.)

It is not like I see any one else looking for information beyond a Wiki link.

I really don't think so. Long term construction takes into account all sorts of issues that simple transient loads don't.
but really that isn't my problem. I don't have to find proof to defend someone else's thesis. That is sort of their job.

I could not find the impact load tolerance for the ground, the best I could find was the load bearing rating for building. Do things not respond better to sustained force vs sudden force.

It would seam to be reasonable that if the pounds per square foot where less than the construction tolerance the ground will hold when you accede that then you need to question if the ground will hold up.

Except that the wiki claims that cleats can have up to 13,000,000 pascals of pressure.
And it ignores things like dinosaurs which we can, presumably, were able to walk around.

Clearly the answer seems to be 'its complicated'
I am not saying that it may not be possible. What I am saying is that proof that it is impossible is going to need to be just that. Proof. Not just some conjecture using some estimations and guess work combined with some formulas that seem to be only partially explained and that may or may not be fully directly applicable.

Wait you want proof a negative but not proof of a positive?

How about this prove to me it is possible as that was your thesis in this. (I could have sworn the standard was to prove a something and not the prove a lack of it.)

Most people spend 0 effort looking into the force applied during movement. Just the standing force.

It is complicated and that is why you have to look at all forms of data that can be applied. If we can prove the force is less than soil bearing for long term that would be a clear it can work. It does not mater how great you calculate the force of the standing or moving object if you do not have a bench mark where you run a risk of failure. That is what I am using the construction codes for the point that we can start to consider the risk of failure.

Without a failure point all numbers have no relevance to chance of failure. So using that and then looking at the movement of a real world object in relation to it. The Abrams main battle tank-in soft soil it tends to dig in and sink a little, looking at its weight in relation to the load bearing weight I see it is over the rating threshold by less than 10%. That shows to me further you go beyond that point the bigger the chance of it not being traversable.

I have found a few sources with calculations for movement and force. But these you hold to higher standard than you do the list of force by type in the wiki. example human 1.8 meters tall medium build not a very exact weight description.

(I am not a math guru I am going to go with the easy math but if you want to see the real values plug in the number to one of the listed variables listed from either the professors listed between the sights (r=.93) or http://mathaware.org/mam/2010/essays/To ... unWalk.pdf)

[ShadowLogan]

Actually, if you're in a forest, and the trees are too thick for a tank to run over, a 'bot might move through them still because it has less surface area on it's feet. It can step between trees and move them at their weakest points (the top half) and literally bend them out of the way as they pass (depends on the type of the tree though). They'd do this just as humans can do the same thing to heavy overgrowth.

The surface area on its feet though is the weakness not a strength. Its bipedal nature is also a liability not a strength.

Yes some giant bipedal robots could turn and walk sideways, but not all of them. On the list I generated earlier (and added to a bit, but may not have updated the list) of the 21 robots length: 3 are 10ft+, 2 are non-bipedal at 40ft+ (I skipped the CS Spider walkers which would add to this), 2 more are bipedal with 40ft+, and 10 are between 6-10ft. Armored vehicles (14) had a width range of 6-13ft. So of those sample 21 'bots 17 would be stopped (80%) by the width just as easily as those 14 armored track/wheeled vehicles if they walked sidways to trade their length for width and ALL of them are stopped using their actual width just like the armored vehicles.

Sure a giant robot could bend (some types of) trees to allow easier movement, but it is also possible that the 'bot will not be tall enough to reach the weakest point. Rifts GRs tend to be in the 15-35ft range IINM, and depending on the species of tree it can grow beyond that in the wild. So any tree short enough to be manoeuvred by a giant bipedal robot is likely also manageable by an armored vehicle.

And it ignores things like dinosaurs which we can, presumably, were able to walk around.

While some dinosaurs have the size requirement down, what about the mass/weight?

I have an easily accessible sample size of 456 creatures (and RCCs) in Rifts/Phaseworld setting (though not from every book) that list their mass/weight and can look up their mass easily enough:
-heavy Dinosaurs on the list T-Rex 6 metric tons, Tri-tops at 5 metric tons, Stegosaur at 3 metric tons, Sauropod at ~33metric tons
-creatures heavier than the Sauropod: 15 (IINM most of these aren't bipedal)
-creatures between 10 and ~33 metric tons: 17 (IINM most of these aren't bipedal)
-creatures between 1 and 10 metric tons: 68 (44 of which are under 5 metric tons, and IINM most of these aren't bipedal either)
-Note due to the way the sample was originally collected I can not filter for "giant robot" size and other factors, so the raw number count is high because of that

By comparison I have an easily accessible sample size of 89 Giant Robots in Rifts/Phaseworld setting (though not every book) that provide their mass/weight. Metric mass (should be dry when possible and not their loaded mass):
-14 of them are under 10 metric tons (and 5 of them are under 5 metric tons)
-52 of them are between 10 metric tons and 33 metric tons, and 5 more that are 34-35 border range
-10 of them are over 100 metric tons and 8 of them are between 40 and 100
-note border line PA/Bots, ex Glitterboy or Ulti-max where treated as Power Armor in the sample as that is how the books considered them by description

So as anyone can see in the Rifts/Phaseworld setting the typical Giant Robot platform is more massive than the typical creature in the same setting, even if they are of giant stature and the typical creatures in the same mass range as giant robots tend to also be non-bipedal (which is the majority of the sample of GRs).

[say652]

The Horned Demon Fish weighs 600 tons is between 100-150 feet long and can move on land.

[ShadowLogan]

The Horned Demon Fish weighs 600 tons is between 100-150 feet long and can move on land.

The one in SB4: CS Navy (pg104-5)?

It might weight 600tons and be upto 150ft long (and 18-24ft wide), but:
A. it doesn't walk on land, it drags itself along as it has no legs or feet or snakes along (which seems more likely)
B. due to the way it moves it can take advantage of its large surface area to reduce its ground pressure
-assuming the width remains constant it would exert between ~2.3 and ~4.6psi, as it is more likely a triangle it would be ~4.6-9.3psi and this doesn't even consider any area the fins might add

So it really isn't comparable to a giant legged robot, especially a bipedal giant legged robot, so doesn't really support the notion that you can have a 600ton giant legged robot.

[Alrik Vas]

Most people spend 0 effort looking into the force applied during movement. Just the standing force.

Hey Blue. I didn't make a math mistake. I divided weight by surface area, that's the formula. Explain where my mistake was and then I'll be with you on it.

That aside, the Wikipedia link is actually talking about ground pressure generated by walking/movement (I figured this out as things went along, after studying the page you posted about force/weight generated by running/moving for athletic shoe tests).

I had the Enforcer at 8psi (or so) before, I looked at the page you posted. Recalculating, it came out to 56psi where the foot pushes off the ground. That's the max generated from human sprinting (x7 standing pressure).

So either I'm an idiot (totally possible), or I'm simply not understanding your posts (also possible).

Regardless, I put in the effort.

[Blue_Lion]

Most people spend 0 effort looking into the force applied during movement. Just the standing force.

Hey Blue. I didn't make a math mistake. I divided weight by surface area, that's the formula. Explain where my mistake was and then I'll be with you on it.

That aside, the Wikipedia link is actually talking about ground pressure generated by walking/movement (I figured this out as things went along, after studying the page you posted about force/weight generated by running/moving for athletic shoe tests).

I had the Enforcer at 8psi (or so) before, I looked at the page you posted. Recalculating, it came out to 56psi where the foot pushes off the ground. That's the max generated from human sprinting (x7 standing pressure).

So either I'm an idiot (totally possible), or I'm simply not understanding your posts (also possible).

Regardless, I put in the effort.

The mistake I am referring to is multiplying square feet by 12 for square inches. There are 144 square inches in a square foot. A square foot is 12 inches by 12 inches or 12X12 that gives 144.
The first post on this page has 56 square feet being 657 square inches when it should be 8064 square inches. As I said a basic math error(an error that is more in the favor of working).

[eliakon]

Not to be rude but on the first page I linked a page with the math to determine the force of impact. It is related to an article by two professors at James Madison university. That includes information on their experiment but no one bothered with the math. (In addition the first entry in the table with the rule of thumb was sourced to a study done by professors from Organ state and running speed. They had a formula for increase with running speed.)
http://mathaware.org/mam/2010/essays/To ... unWalk.pdf

I use the general rule of thumb for impact from the page I linked this time for two reasons, 1 the math was based of the subjects weight 2. it matches information from a military class on mines that I took that a 180 pound solder can set off an anti tank mine that requires 550 pounds of pressure on its plate to go off.


I the only information I can find on how much weight the ground can support is in the building codes.
Do you have any better sources to present? (knocking some ones sources when you do not provide anything better. Quite simply I have spent time looking for sources on this and it is not an easy thing to research.)

It is not like I see any one else looking for information beyond a Wiki link.

I really don't think so. Long term construction takes into account all sorts of issues that simple transient loads don't.
but really that isn't my problem. I don't have to find proof to defend someone else's thesis. That is sort of their job.

I could not find the impact load tolerance for the ground, the best I could find was the load bearing rating for building. Do things not respond better to sustained force vs sudden force.

It would seam to be reasonable that if the pounds per square foot where less than the construction tolerance the ground will hold when you accede that then you need to question if the ground will hold up.

Except that the wiki claims that cleats can have up to 13,000,000 pascals of pressure.
And it ignores things like dinosaurs which we can, presumably, were able to walk around.

Clearly the answer seems to be 'its complicated'
I am not saying that it may not be possible. What I am saying is that proof that it is impossible is going to need to be just that. Proof. Not just some conjecture using some estimations and guess work combined with some formulas that seem to be only partially explained and that may or may not be fully directly applicable.

Wait you want proof a negative but not proof of a positive?

How about this prove to me it is possible as that was your thesis in this. (I could have sworn the standard was to prove a something and not the prove a lack of it.)

I will make it simple for you
The status quo is "Robots work" we see this because the book says that they work.
If a thesis comes along and says "The book is actually wrong. None of those robots can work because the math proves that they would sink into the ground when they take a step" then
1) that claim is the affirmative thesis and thus the one that needs to provide proof. I have no burden to provide mathematical proof defending the status quo
2) that claim is not a negative claim. It is a positive claim it is saying that X will happen because of Y. Thus you need to prove that X will happen because of Y. It is not trying to prove a negative. That would be if I was asking for proof that robots do not sink. But we don't need to prove that... because that is the status quo already.
3) Demanding that I prove that robots will not sink though is in fact your logically fallacious request to prove a negative.

[say652]

Not to be rude but on the first page I linked a page with the math to determine the force of impact. It is related to an article by two professors at James Madison university. That includes information on their experiment but no one bothered with the math. (In addition the first entry in the table with the rule of thumb was sourced to a study done by professors from Organ state and running speed. They had a formula for increase with running speed.)
http://mathaware.org/mam/2010/essays/To ... unWalk.pdf

I use the general rule of thumb for impact from the page I linked this time for two reasons, 1 the math was based of the subjects weight 2. it matches information from a military class on mines that I took that a 180 pound solder can set off an anti tank mine that requires 550 pounds of pressure on its plate to go off.


I the only information I can find on how much weight the ground can support is in the building codes.
Do you have any better sources to present? (knocking some ones sources when you do not provide anything better. Quite simply I have spent time looking for sources on this and it is not an easy thing to research.)

It is not like I see any one else looking for information beyond a Wiki link.

I really don't think so. Long term construction takes into account all sorts of issues that simple transient loads don't.
but really that isn't my problem. I don't have to find proof to defend someone else's thesis. That is sort of their job.

I could not find the impact load tolerance for the ground, the best I could find was the load bearing rating for building. Do things not respond better to sustained force vs sudden force.

It would seam to be reasonable that if the pounds per square foot where less than the construction tolerance the ground will hold when you accede that then you need to question if the ground will hold up.

Except that the wiki claims that cleats can have up to 13,000,000 pascals of pressure.
And it ignores things like dinosaurs which we can, presumably, were able to walk around.

Clearly the answer seems to be 'its complicated'
I am not saying that it may not be possible. What I am saying is that proof that it is impossible is going to need to be just that. Proof. Not just some conjecture using some estimations and guess work combined with some formulas that seem to be only partially explained and that may or may not be fully directly applicable.

Wait you want proof a negative but not proof of a positive?

How about this prove to me it is possible as that was your thesis in this. (I could have sworn the standard was to prove a something and not the prove a lack of it.)

I will make it simple for you
The status quo is "Robots work" we see this because the book says that they work.
If a thesis comes along and says "The book is actually wrong. None of those robots can work because the math proves that they would sink into the ground when they take a step" then
1) that claim is the affirmative thesis and thus the one that needs to provide proof. I have no burden to provide mathematical proof defending the status quo
2) that claim is not a negative claim. It is a positive claim it is saying that X will happen because of Y. Thus you need to prove that X will happen because of Y. It is not trying to prove a negative. That would be if I was asking for proof that robots do not sink. But we don't need to prove that... because that is the status quo already.
3) Demanding that I prove that robots will not sink though is in fact your logically fallacious request to prove a negative.

Ok that's 2 times i agree with Eli. What in the Actual cheese sammich!!

[Blue_Lion]

Not to be rude but on the first page I linked a page with the math to determine the force of impact. It is related to an article by two professors at James Madison university. That includes information on their experiment but no one bothered with the math. (In addition the first entry in the table with the rule of thumb was sourced to a study done by professors from Organ state and running speed. They had a formula for increase with running speed.)
http://mathaware.org/mam/2010/essays/To ... unWalk.pdf

I use the general rule of thumb for impact from the page I linked this time for two reasons, 1 the math was based of the subjects weight 2. it matches information from a military class on mines that I took that a 180 pound solder can set off an anti tank mine that requires 550 pounds of pressure on its plate to go off.


I the only information I can find on how much weight the ground can support is in the building codes.
Do you have any better sources to present? (knocking some ones sources when you do not provide anything better. Quite simply I have spent time looking for sources on this and it is not an easy thing to research.)

It is not like I see any one else looking for information beyond a Wiki link.

I really don't think so. Long term construction takes into account all sorts of issues that simple transient loads don't.
but really that isn't my problem. I don't have to find proof to defend someone else's thesis. That is sort of their job.

I could not find the impact load tolerance for the ground, the best I could find was the load bearing rating for building. Do things not respond better to sustained force vs sudden force.

It would seam to be reasonable that if the pounds per square foot where less than the construction tolerance the ground will hold when you accede that then you need to question if the ground will hold up.

Except that the wiki claims that cleats can have up to 13,000,000 pascals of pressure.
And it ignores things like dinosaurs which we can, presumably, were able to walk around.

Clearly the answer seems to be 'its complicated'
I am not saying that it may not be possible. What I am saying is that proof that it is impossible is going to need to be just that. Proof. Not just some conjecture using some estimations and guess work combined with some formulas that seem to be only partially explained and that may or may not be fully directly applicable.

Wait you want proof a negative but not proof of a positive?

How about this prove to me it is possible as that was your thesis in this. (I could have sworn the standard was to prove a something and not the prove a lack of it.)

I will make it simple for you
The status quo is "Robots work" we see this because the book says that they work.
If a thesis comes along and says "The book is actually wrong. None of those robots can work because the math proves that they would sink into the ground when they take a step" then
1) that claim is the affirmative thesis and thus the one that needs to provide proof. I have no burden to provide mathematical proof defending the status quo
2) that claim is not a negative claim. It is a positive claim it is saying that X will happen because of Y. Thus you need to prove that X will happen because of Y. It is not trying to prove a negative. That would be if I was asking for proof that robots do not sink. But we don't need to prove that... because that is the status quo already.
3) Demanding that I prove that robots will not sink though is in fact your logically fallacious request to prove a negative.

Wait demanding evidence that something works is a request to prove a negative?

Assuming only one side in a debate needs to provide evidence is a fallaciously of logic. In a debate both sides must provide evidence for their claim. This is a debate not the scientific method, in a debate both sides must attempt to prove their stance.

In a debate saying that you do not have to prove your point but demanding the other side does wile dismissing any sources of information they can find is utter nonsense. We are debating a topic if you can not provide any support for your stance in a debate you loose the debate.

I find your statement that only one side in a debate needs to prove its point a fundamental fallacious logical standard.

(This is a debate on if a work of fiction is practical and would work in real life not if they work in a game so their is no status quo.)

[J_cobbers]

So hear is a question, how much PSI can the following terrain sustain? Here is one source for the answer: http://www.altec.com/cribbing-and-blocking-protect-yourself/

SOIL TYPE LOAD BEARING CAPACITY
Virgin Ground 22 psi
Asphalt 29 psi
Compressed Crushed Stone 36 psi
Clay/Silt Soil, Firm 43 psi
Mixed Granular Soil 51 psi
Firm Compacted Gravel 58 psi
Firm Compacted Gravel (more compacted) 72 psi
Firm Compacted Gravel (even more compacted) 109 psi
Brittle Weathered Rock 145 psi
Concrete 1000 psi

My breif reading up on the subject on Wikipedia indicates that exceeding the Load Bearing Capacity means that the ground in question will be subject to shearing, ie it will give way. But in doing so the question is "how much" and I do not the have an engineering background to answer that, but my guess is that it depends on the conditions. I don't think it means that our Giant Robots sink indefinitely into the material in question, but probably they would to some extent, or cause a lot of deformation as the ground beneath compacts (leaving big o'l foot prints) to the point where the density is enough to support the PSI in question. In real life that also probably would serve to slow down the speed of travel, and cause some slippage in the footing as the material deforms with the stride of the bots.

[Alrik Vas]

J_Clobbers, that's actually pretty helpful even though not all the information is there. Gives me enough to decide that most giant robots could walk across most solid terrain, and possibly up to half their listed speed up to asphalt. They can run across the majority of that list from Mixed Granular Soil and down. Full speed from Firm Compacted Gravel down, even.

So yeah, Giant Robots can move pretty well. They just aren't as properly armored as tanks are.

[Blue_Lion]

So hear is a question, how much PSI can the following terrain sustain? Here is one source for the answer: http://www.altec.com/cribbing-and-blocking-protect-yourself/

SOIL TYPE LOAD BEARING CAPACITY
Virgin Ground 22 psi
Asphalt 29 psi
Compressed Crushed Stone 36 psi
Clay/Silt Soil, Firm 43 psi
Mixed Granular Soil 51 psi
Firm Compacted Gravel 58 psi
Firm Compacted Gravel (more compacted) 72 psi
Firm Compacted Gravel (even more compacted) 109 psi
Brittle Weathered Rock 145 psi
Concrete 1000 psi

My breif reading up on the subject on Wikipedia indicates that exceeding the Load Bearing Capacity means that the ground in question will be subject to shearing, ie it will give way. But in doing so the question is "how much" and I do not the have an engineering background to answer that, but my guess is that it depends on the conditions. I don't think it means that our Giant Robots sink indefinitely into the material in question, but probably they would to some extent, or cause a lot of deformation as the ground beneath compacts (leaving big o'l foot prints) to the point where the density is enough to support the PSI in question. In real life that also probably would serve to slow down the speed of travel, and cause some slippage in the footing as the material deforms with the stride of the bots.

Nice what you put in the search to find that.
Been looking for something like that but could not find it.

So assuming the math i did on heel impact was correct and the estimated foot sized provided was correct (I used half the foot is in the heel strike area) a 18 ton bipedal robot at 53.5PSI should be fine on compacted gravel but would have performance issues with anything below mixed granular soil. Likely bogged down beyond any effective speed in virgin soil.

Looking at that the M1 Abrams main battle tank is effective on all soils, odd most tankers say it does poor on soft ground. That does support tanks as more practical off road vehicles.


(Note I do know they work in game but this was never about that. I would be curious to see some one do one of the math problems that had force multiplier by speed to see what the force would be at given speeds but I know I would mess it up if I did it.)

[guardiandashi]

So hear is a question, how much PSI can the following terrain sustain? Here is one source for the answer: http://www.altec.com/cribbing-and-blocking-protect-yourself/

SOIL TYPE LOAD BEARING CAPACITY
Virgin Ground 22 psi
Asphalt 29 psi
Compressed Crushed Stone 36 psi
Clay/Silt Soil, Firm 43 psi
Mixed Granular Soil 51 psi
Firm Compacted Gravel 58 psi
Firm Compacted Gravel (more compacted) 72 psi
Firm Compacted Gravel (even more compacted) 109 psi
Brittle Weathered Rock 145 psi
Concrete 1000 psi

My breif reading up on the subject on Wikipedia indicates that exceeding the Load Bearing Capacity means that the ground in question will be subject to shearing, ie it will give way. But in doing so the question is "how much" and I do not the have an engineering background to answer that, but my guess is that it depends on the conditions. I don't think it means that our Giant Robots sink indefinitely into the material in question, but probably they would to some extent, or cause a lot of deformation as the ground beneath compacts (leaving big o'l foot prints) to the point where the density is enough to support the PSI in question. In real life that also probably would serve to slow down the speed of travel, and cause some slippage in the footing as the material deforms with the stride of the bots.

Nice what you put in the search to find that.
Been looking for something like that but could not find it.

So assuming the math i did on heel impact was correct and the estimated foot sized provided was correct (I used half the foot is in the heel strike area) a 18 ton bipedal robot at 53.5PSI should be fine on compacted gravel but would have performance issues with anything below mixed granular soil. Likely bogged down beyond any effective speed in virgin soil.

Looking at that the M1 Abrams main battle tank is effective on all soils, odd most tankers say it does poor on soft ground. That does support tanks as more practical off road vehicles.


(Note I do know they work in game but this was never about that. I would be curious to see some one do one of the math problems that had force multiplier by speed to see what the force would be at given speeds but I know I would mess it up if I did it.)

its a lot more complicated to be honest.

note I am not an actual engineer, but I do have some experience with "life"
https://en.wikipedia.org/wiki/Ground_pressure
notes that most of the stated ground pressures are for standing still.

ok human male (standing) is 55kpa or 8 psi, and up to 18Mpa for spike heels

adult horse standing is ~25psi and they don't typically sink into most surfaces like normal soil while standing.

quote from the page
Pressures for Man and Horse are for standing still. A walking human will exert more than double his standing pressure. A galloping horse will exert up to 3.5 MPa (500 psi). The ground pressure for a pneumatic tire is roughly equal to its inflation pressure.

now what I have observed is that in the moving case as noted a horse can increase its EFFECTIVE force on the ground from 25psi to ~500psi when galloping and yet unless the ground is seriously fragile their hooves don't typically sink in more than 1-2 inches or less because you really have to consider the equivalent of buoyancy factors.

I know you are going to say "buoyancy factors" what do objects floating in a liquid have to do with ground pressure?
well the thing is, buoyancy has to do with how much material is being displaced by the object in question for instance the robot vehicles foot. IE when the giant robots foot hits the ground, its going to attempt to displace said ground, as it starts to dig in and damage the surface. under those circumstances that means that it is going to be compressing, and attempting to treat the surface as a psudo liquid material as it tries to "shove" it out of the way. which actually means that said displacement effects get significantly more difficult as more and more material is being displaced.

what this all boils down to is that said giant robot is likely to leave footprints in "soft" ground, but if its effective ground pressure is say 500 psi on an ~25-30ish psi resistant surface its only likely to sink in an inch or 2, on a 3psi resistant surface it might be more like 5-10 inches.

[say652]

I think on Rifts Earth (3 galaxies is to easy) you could just modify flight systems to compensate for the weight on the ground.
IRL you could also modify flight systems to counter the wrought. This generates a lot of heat and reduces battery life to hours instead of days.

[ShadowLogan]

I think on Rifts Earth (3 galaxies is to easy) you could just modify flight systems to compensate for the weight on the ground.
IRL you could also modify flight systems to counter the wrought. This generates a lot of heat and reduces battery life to hours instead of days.

At that point though it would probably just be easier to forgo the legs for the flight/hover system.

You'd also be limited in what type of flight/hover approach to use. Conventional chemical rockets are too fuel inefficient (non-chemical rockets have other issues), helicopter blades to large, even jet exhaust could lead to problems (F-35B). Noise might be another factor.

[Warmaster40k]

I am not going into any thing math heavy, but rather personal observation. As some one who has watched elephants, worked around tracked vehicles and walked in muddy terrain, I know that sinkage occurs. The real question is, despite that, can it still operate. Will it just continue on leaving behind tracks of it being there. I mean the the only thing that sucked about trudging through mud is that some times when i stepped off I would just leave a shoe behind.

[kaid]

J_Clobbers, that's actually pretty helpful even though not all the information is there. Gives me enough to decide that most giant robots could walk across most solid terrain, and possibly up to half their listed speed up to asphalt. They can run across the majority of that list from Mixed Granular Soil and down. Full speed from Firm Compacted Gravel down, even.

So yeah, Giant Robots can move pretty well. They just aren't as properly armored as tanks are.

Well they are about as heavily armored as tanks currently are in rifts the issue is they are not as properly armored as power armor or cyborgs.

Most large vehicles in rifts don't scale up in armor as much as one would expect from a personal set of body armor and power armor.

Giant robots ability to move over more varied terrain is their biggest boost. Even with some sinking they would still be capable of movement in stuff that would simply stop a tank such as swamps/bogs/lakes. Even robots not capable of swimming are capable of simply trucking along the bottom of a lake or body of water up to generous enough depths for all but the deepest lakes without to much trouble.

Having fully mobile arms and hands that are capable of delivering MDC level strikes means clearing its way through a forrest would be simple if loud. Tanks can mange it as well but more slowly as they are going to wind up having to do a lot of backing up and charging to punch through trees/obstacles. Given giant robots are capable of using the martial arts skill of their pilots is a pretty clear indication of how nimble they really are.

Also their tallness which is a detriment to some extent in combat also has advantages in an area as wild and undeveloped as rifts earth. Your line of sight means you can see farther than a tank can and over obstacles or trees a tank could not.

The main thing keeping tanks in the mix at all is simply because they are comparatively cheap and can run off a variety of fuel options and are easier to maintain. For adventurers and merc groups giant robots do have their place and advantages.

Still if I was designing something like that I think I would go either with something like the spider skull walker/bull dog or a hexapod design like the various scorpion robots. You gain the advantages of walking locomotion has on on a more dispersed surface area to mitigate the vulnerabilities. The other plus of a hexa pod design you could probably lose 2 or 3 legs and still be mobile.

[kaid]

As a side note and because it looks cool I will simply note we are already using some walking vehicles for the benefits mentioned.
https://www.youtube.com/watch?v=CD2V8GFqk_Y

[Shark_Force]

tanks with arms makes more sense if you want to benefit from arms being able to clear terrain. tanks with periscopes or a remotely controlled drone makes a lot more sense if you want height for vision, and does a lot better job of keeping the tank behind cover while doing so.

being able to move sideways is nice i guess, but once hover technology is on the table, that pretty much means much faster all-direction mobility, and also much better ability to adjust clearance with rifts tech (some hover vehicles can go as much as 200 feet up... though on a more heavily armoured vehicle, i'd be surprised if they went nearly that high).

giant robots are in the game because they're cool, therefore that's what we imagine. this isn't a hard science fiction universe, and the presence of giant robots is far from the only thing that stands out as unrealistic if you spend much time thinking about it at all.

[Axelmania]

So what about the IAR-2 Abolisher which was not intended for urban combat?

Maybe they restrict them for use on rocky terrain, like guarding mountain fortresses?

That and... there's sometimes MDC terrain out there not made by man, like the MDC grass made by biomancers or MDC ironwood.

Maybe the CS cuts down the ironwood trees that mages build and uses them to construct Abolisher platforms?

Another thing about forests, even with SDC trees, in regards to sinkage. A robot could use its hands to push straight down on the trees' trunks, using them like a cane, or ski poles, to take weight off its feet, to reduce how far its weight causes the feet to sink into the forest floor.

A forest floor isn't just soil, it would have a complex interwoven root system of many trees underneath, which would help prevent sinkage. A lot like walking on a wooden floor, except stronger, because roots have a lot of give to them and aren't that brittle while underthere. As anyone who has had to chop roots to save their lawn knows, they retain flexibility for a good bit unless you chop them out and leave them out to dry for a while.

The root system supporting a tree would also cause trees to sink less when the robot pushes down on them, compared to say, a pole that is stuck into the earth.

The robots would just have to be careful to push straight down, where the tree is strongest. If they did it diagonally then there would be horizantal force that would increase the odds of the trunk snapping.

The larger hands and the high robotic strength of the robots would allow them to grip thicker trunks than a normal human could, and their longer arms would allow them to do this with wider spacing.

Humans could do this too, if it was an issue. It might get tiring after a while (you're sort of doing a pulling motion, exhausting your lats/triceps/grip) but that wouldn't be a problem the robot would have, it could do this indefinitely.

Probably require some piloting skill rolls to locomote at full speed while doing this, otherwise you'd have to slow down or else if you fail the roll, you screw up and don't push straight down on the tree and end up snapping it or something.

Still probably a better option than the obvious skill penalties you'd get if the bot's feet were sinking down 10 feet every step, wading through soil as if it were snow.

I still think that would happen to a lesser degree in a forest compared to say, the soil of a grassy meadow, due to the roots of the trees reducing the sinkage of the soil when stepped on.

[ShadowLogan]

Something else to consider with giant robots that walk. Even if they are practical, they might show up on seismic sensors much easier and farther out than a conventional ground vehicle of similar weight or infantry.

As a side note and because it looks cool I will simply note we are already using some walking vehicles for the benefits mentioned.
https://www.youtube.com/watch?v=CD2V8GFqk_Y

I'm aware of said vehicle. However giant robots in Rifts have two things working against them for this example:
-most are bipedal, this one has six legs so it can theoretically distribute the weight more, so doesn't help prove bipedal viability
-there might also be a disconnect in terms of mass/weight for its size for similar Rifts 'bots (CS Spiderwalker is 28tons fully loaded IIRC, and it has 6 legs, how heavy is this example?).

[taalismn]

I think on Rifts Earth (3 galaxies is to easy) you could just modify flight systems to compensate for the weight on the ground.
IRL you could also modify flight systems to counter the wrought. This generates a lot of heat and reduces battery life to hours instead of days.

That's a lot of power drain...and a lot of dust/dirt kick-up for anything less than a contra-gravity system.
Forget about stealth, and hope your sensors can pick through your self-generated debris cloud.