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Tanks - tracked vehicles driving and handling

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To repeat my question again -

On 2.5.2018 at 9:31 PM, x3kj said:

driveOnComponents and the other driveOn thing (i forgot) is also missing

Whats the purpose of those selections for tankX? Is it still important? First time it was introduced way back when, i think it was to help with climbing ability - which now technically is not necessary (propably?) because there is fake acceleration helper force.

What can we expect from these selections in terms of function and behaviour and what do we need to keep in mind when modelling the components? Are there specific things to avoid there?

 

 

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On 9/10/2018 at 4:02 AM, scotg said:

I'm always speaking from a mod perspective, so...
Was the neutral steer rate ever updated? Specifically, is there a setting to determine how fast a vehicle can turn in place, or disable it entirely? I'm thinking this might be the first step to making better half-tracks.

You can now use UVAnimations & carX simulation for some better representation of halftrucks. IFA3 is now using such approach ;)

 

7 hours ago, x3kj said:

Whats the purpose of those selections for tankX? Is it still important? First time it was introduced way back when, i think it was to help with climbing ability - which now technically is not necessary (propably?) because there is fake acceleration helper force.

What can we expect from these selections in terms of function and behaviour and what do we need to keep in mind when modelling the components? Are there specific things to avoid there?

It's still useful for tank bellies since when vehicle is colliding from the bottom with some obstacles (be it for example famous antitank wall which can be found in large quantities across Altis or Stratis), friction can be pretty high and vehicle might not be able climb over some obvious objects. Tracks also got some components in Geo PhysX due to fact that i.e. grenades are not colliding with PhysX wheels - it was disabled last year when we noticed grenades (or in general, any collision) could go quite deep into wheels and then engine would try to push it up in violent way.

 

https://imgur.com/a/G6KOv5f

 

 

For comparison, here are friction values extracted from config (they can be changed if someone wish to do so ;) )


	class PhysXMaterials
	{
		class PhysXMaterialBase
		{
			isDefault = 0;
			isAnisotropic = 0;
			restitution = 0.05;
			staticFriction = 0.75;
			dynamicFriction = 0.55;
		};
		class Default: PhysXMaterialBase
		{
			isDefault = 1;
			restitution = 0.05;
			staticFriction = 0.75;
			dynamicFriction = 0.55;
		};
		class Terrain: PhysXMaterialBase
		{
			restitution = 0.01;
			staticFriction = 0.6;
			dynamicFriction = 0.46;
		};
		class Wheel: PhysXMaterialBase
		{
			restitution = 0.05;
			staticFriction = 0.9;
			dynamicFriction = 0.68;
		};
		class DriveOn: PhysXMaterialBase
		{
			restitution = 0;
			staticFriction = 0.01;
			dynamicFriction = 0.007;
		};

 

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While testing my mod tank's speed, I noticed it was going faster in a turn than it would in a straight line. I don't have a speed boost available on my tank. I thought it might have something to do with one of the tire slip properties, but just a random guess. To see if this is just mine or a common issue, I tested the Bobcat and Sochor the same way. The Bc was doing the same thing as mine - turning about 5kph faster top speed than going straight, as long as I didn't use speed boost/max speed. The Sochor went too fast in a straight line and then rolled over before I could observe its turning speed. I don't know if any of this is supposed to happen or not. If not, what should I start tweaking in order to fix my tank?

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On 10/12/2018 at 5:58 PM, scotg said:

While testing my mod tank's speed, I noticed it was going faster in a turn than it would in a straight line. I don't have a speed boost available on my tank. I thought it might have something to do with one of the tire slip properties, but just a random guess. To see if this is just mine or a common issue, I tested the Bobcat and Sochor the same way. The Bc was doing the same thing as mine - turning about 5kph faster top speed than going straight, as long as I didn't use speed boost/max speed. The Sochor went too fast in a straight line and then rolled over before I could observe its turning speed. I don't know if any of this is supposed to happen or not. If not, what should I start tweaking in order to fix my tank?

You can notice similar behavior on the vanilla tanks too, especially with Nyx. It's a downsides of the tankTurnForce, especially when using higher forces. Try to use lower values or limit the force to lower angular speeds. Tire parameters come into play as well.  You may try lowering the lateral stiffness or having a relatively small friction near zero slip - to let the tank turn well even with lower tankTurnForce configured.

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On 14.10.2018 at 11:04 PM, oukej said:

You can notice similar behavior on the vanilla tanks too, especially with Nyx. It's a downsides of the tankTurnForce, especially when using higher forces. Try to use lower values or limit the force to lower angular speeds. Tire parameters come into play as well.  You may try lowering the lateral stiffness or having a relatively small friction near zero slip - to let the tank turn well even with lower tankTurnForce configured.

 

Sounds weird to me. Guess it needs a tiny fix, tanks in RL tend to slow down whenever steering actions triggered, 1st because most common method is to use breaks at the track of the side one wanna turn to. 2nd because turning causes higher mechanical resistance everywhere at tracks and wheels. You consider scotg's finding as worth to fix?

 

Quote

tankTurnForce

int>0, (PhysX)

How well a tank can turn, higher = better turning ability.

This is possibly some kind of coefficient that generates turning power for a TankX vehicle. The value apparently needs to be very high, on the order of 20-30 * vehicle weight (in kg) or more<?>.

[(comment in "Samples_F\Test_Tank_01\CfgVehicles.hpp"), A]

 

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20 hours ago, The Man Without Qualities said:

Sounds weird to me. Guess it needs a tiny fix, tanks in RL tend to slow down whenever steering actions triggered, 1st because most common method is to use breaks at the track of the side one wanna turn to. 2nd because turning causes higher mechanical resistance everywhere at tracks and wheels. You consider scotg's finding as worth to fix?

During the "overhaul" we've tried to have the tanks without the artificial turning force but it wasn't possible to achieve reasonable behavior so we had to resort back to this solution. Knowing and accepting the downside that you're mentioning.

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On 10/12/2018 at 5:58 PM, scotg said:

While testing my mod tank's speed, I noticed it was going faster in a turn than it would in a straight line.

An interesting effect, something similar shows up in Kerbal Space Program of all games...

They've got a number of rover wheels that behave like normal steerable wheels on a normal wheeled vehicle, then they have 1 beefy one with "tank type" steering - or rather, differential steering, without steering the wheel (its rotation plane is fixed in relation to the vehicles). It steers to the left by turning the right wheels more than the left and vice versa.

They were meant to be the slowest wheels in the game, but are in fact the fastest because they too accelerate in turns (it seems the outer wheels speed up without the inner ones slowing down), and rapidly giving left-right-left-right... inputs allows vehicles to accelerate to "crazy" speeds in a straight line (>100 m/s, or over 360 kmh... which is only crazy fast for rovers, since that game allows you to build things that reach speeds of several/dozens of km/second)

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It's a problem with any game that does not account for where forces used for steering come from. In particular, a "magic" speed increase on one side without either slowing down on the other or putting extra load on the engine. If this was accomplished by braking a wheel/thread instead, it would be better, but the vehicle would lose a lot of speed in turns (a serious problem with IRL systems that operate in this principle).

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On 17-10-2018 at 9:26 PM, The Man Without Qualities said:

Sounds weird to me. Guess it needs a tiny fix, tanks in RL tend to slow down whenever steering actions triggered, 1st because most common method is to use breaks at the track of the side one wanna turn to. 2nd because turning causes higher mechanical resistance everywhere at tracks and wheels. You consider scotg's finding as worth to fix?

Most common method for eastern bloc tanks, not western tanks.
Western tanks (literally since the centurion) use regenerative steering, where one track goes slower and that force gets applied to the other track making it go faster, basically little speed-loss or even none depending on what speed you're travelling.

This depends in what gear the tank is in too.

As most tanks have speed governors, they can't go above ~72kph, which is good because above those speeds you can't effectively turn.
One of the easiest tanks to drive is the Leopard 2 for instance, it drives much like a car would, generally considered to be the most pleasant and "accurate" tank to drive.
Soviet tanks don't have this, they have the typical one track brakes method.

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On 27.10.2018 at 1:56 AM, dragon01 said:

It's a problem with any game that does not account for where forces used for steering come from. In particular, a "magic" speed increase on one side without either slowing down on the other or putting extra load on the engine. If this was accomplished by braking a wheel/thread instead, it would be better, but the vehicle would lose a lot of speed in turns (a serious problem with IRL systems that operate in this principle).

 

2 hours ago, scavenjer said:

Most common method for eastern bloc tanks, not western tanks.
Western tanks (literally since the centurion) use regenerative steering, where one track goes slower and that force gets applied to the other track making it go faster, basically little speed-loss or even none depending on what speed you're travelling.

This depends in what gear the tank is in too.

As most tanks have speed governors, they can't go above ~72kph, which is good because above those speeds you can't effectively turn.
One of the easiest tanks to drive is the Leopard 2 for instance, it drives much like a car would, generally considered to be the most pleasant and "accurate" tank to drive.
Soviet tanks don't have this, they have the typical one track brakes method.

 

So I concur that in any case the vehicle would loose some speed, most old Russky-Tanks a lot, Leo-2 less.

Why is this working for wheeled simulation? When I turn there I loose speed.

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On 29-10-2018 at 2:24 PM, The Man Without Qualities said:

So I concur that in any case the vehicle would loose some speed, most old Russky-Tanks a lot, Leo-2 less.

Why is this working for wheeled simulation? When I turn there I loose speed.

Different properties/config most likely, from what I can tell, turning does reduce speed on MBTs, it just "bottoms" out at a certain speed.

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