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initial version

As suspected it was due to the rear wheel surface config. Removing the specification of <slip1> and <slip2> probably had no effect, but on the rear wheels only, reduction of <mu2> to a lower value of around 0.1 allowed the inside rear wheel to slide sideways as required. This reduced transient forces that seemed to be producing pressure upwards.

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Changing geometry to stop reaction forces

As suspected it was due to the rear wheel surface config. Removing the specification of <slip1> and <slip2> probably had no effect, but on the rear wheels only, reduction of <mu2> to a lower value of around 0.1 allowed the inside rear wheel to slide sideways as required. This reduced transient forces that seemed to be producing pressure upwards.

Additionally and possibly more importantly, the wheel's collision shape was modelled as a cylinder. as the rear suspension joints were free only one direction (z direction), when the body of the vehicle tilted during turning, this caused the wheels to tilt resulting in a collision with the edges of the cylinder which represented the wheel. It was these collisions the was causing the observed behaviour. Changing the shape of the wheel's collision geometry to a sphere stopped the collisions the reaction forces, thus removing this jumping force due to the collision reaction forces.

As suspected it was due to the rear wheel surface config. Removing the specification of <slip1> and <slip2> probably had no effect, but on the rear wheels only, reduction of <mu2> to a lower value of around 0.1 allowed the inside rear wheel to slide sideways as required. This reduced transient forces that seemed to be producing pressure upwards.

Additionally and possibly more importantly, the wheel's collision shape was modelled as a cylinder. as the rear suspension joints were free only one direction (z direction), when the body of the vehicle tilted during turning, this caused the wheels to tilt resulting in a collision with the edges of the cylinder which represented the wheel. wheel and the ground plane.

It was the rectification forces from these collisions the that was causing the observed behaviour. Changing the shape of the wheel's collision geometry to a sphere stopped the collisions the reaction forces, thus removing this jumping force due to the collision reaction forces.

As suspected it was due to the rear wheel surface config. Removing the specification of <slip1> and <slip2> probably had no effect, but on the rear wheels only, reduction of <mu2> to a lower value of around 0.1 allowed the inside rear wheel to slide sideways as required. This reduced transient forces that seemed to be producing pressure upwards.

Additionally and possibly more importantly, the wheel's collision shape was modelled as a cylinder. as the rear suspension joints were free only one direction (z direction), when the body of the vehicle tilted during turning, this caused the wheels to tilt resulting in a collision with the edges of the cylinder which represented the wheel and the ground plane.

It was the rectification reaction forces from these collisions that was causing the observed behaviour. Changing the shape of the wheel's collision geometry to a sphere stopped the collisions and the subsequent reaction forces, thus removing this jumping force due to the collision reaction forces.forces

click to hide/show revision 5
Effect of canting the wheels to improve low speed steering.

As suspected it was due to the rear wheel surface config. Removing the specification of <slip1> and <slip2> probably had no effect, but on the rear wheels only, reduction of <mu2> to a lower value of around 0.1 allowed the inside rear wheel to slide sideways as required. This reduced transient forces that seemed to be producing pressure upwards.

Additionally and possibly more importantly, the wheel's collision shape was modelled as a cylinder. as the rear suspension joints were free only one direction (z direction), when the body of the vehicle tilted during turning, this caused the wheels to tilt resulting in a collision with the edges of the cylinder which represented the wheel and the ground plane.

It was the reaction forces from these collisions that was causing the observed behaviour. Changing the shape of the wheel's collision geometry to a sphere stopped the collisions and the subsequent reaction forces

Finally, the number of contact of the wheels and where they were is important, as I also had a problem with the steering working intermittently at low speeds. This resulted in the front wheels sliding across the surface. Looking at the EV Ranger model, I noticed that the cylinders forming the wheels were slightly canted so that they ran on the inside edge of the cylinder modelling the wheel. This was done by specifiying the joint axis for the wheel to be <xyz 0="" 1="" 0.05=""/> for the left side and <xyz 0="" 1="" -0.05=""/> for the right. Implementing this in my own model improved low speed steering.