Noisy net contact force on uneven mesh terrain

Autonomous Machines Robotics - Isaac Isaac Gym
1

Hi,

I created a simple cube object on an uneven mesh terrain (see picture below), and measure its net contact force and sensor force in CPU and GPU.

visual
visual1280×695 265 KB

The force sensor is attached to the cube.

The GPU settings are:
physx.use_gpu = True
use_gpu_pipeline = True

Both of the above parameters are set to False for the CPU settings.

I am using Isaac Gym Preview 4.

I found that the net contact force values are noisy in both CPU and GPU (see pictures below). Is this a bug?

xy-values on GPU:

xy_plot_on_gpu
xy_plot_on_gpu1280×1025 135 KB

z-values on GPU:

z_plot_on_gpu
z_plot_on_gpu1280×1025 109 KB

z-values on CPU:

z_plot_on_cpu
z_plot_on_cpu1280×1025 107 KB

I am aware of the net contact force issue with the triangle meshes described in the Isaac Gym’s documentation: docs/programming/terrain.html
Are they related?

I also found that the sensor forces are slightly off. Is this a bug too?

What is the solution?

Thanks.