Contact-force model

An Isaac Lab tactile sensor model with a physically scaled DEX-01 fingertip on the Tesollo DG-5F hand. The fingertip is one exterior-only mesh, approximately 32.70 x 22.41 x 19.00 mm, with a 22.40 x 19.00 mm rear profile. It has 738 contact samples mapped into a 32x32 firmware frame.

The model queries the counter object’s PhysX signed distance field (SDF) and distributes the measured normal contact load across penetrating samples by depth, following TacSL. Output is normal contact force in newtons.

Each sample queries the counter-object SDF. Penetrating samples receive a share of the measured net normal contact force according to penetration depth. The frame unwraps the fingertip surface; it is not an optical contact image.

A taxel is one contact sample on the fingertip surface. The 738 samples retain the firmware pixel mapping; unoccupied frame cells contain zero. Summing all taxel values gives the sensor’s total normal load.

Use known-load validation to check simulated force balance and limitations to understand the model boundary.

Force distribution

For taxel penetration depths d_i < 0, the model computes a contact normal from the penetration-weighted surface normals and projects the filtered PhysX contact-force vector onto it. The nonnegative projected load F_n is allocated as f_i = F_n d_i / sum(d_j) over the penetrating taxels. Samples outside the counter object receive zero.

This preserves the total physical normal load while distributing it across the sampled contact patch. The known-load checker compares that sum with the independent filtered contact force, fixture weight, and momentum change.