On Inverse Inertia Matrix and Contact-Force Model for Robotic Manipulators at Normal Impacts
This work addresses the problem of accurate impact modeling for robotic manipulators, which is incremental as it refines existing models for a specific scenario.
The authors tackled the lack of impact dynamics models for fixed-base robotic manipulators by revisiting contact-force models and inverse inertia matrices, finding through 150 trials that a viscoelastic contact-force model and composite-rigid body assumption best match experimental data.
State-of-the-art impact dynamics models either apply for free-flying objects or do not account that a robotic manipulator is commonly high-stiffness controlled. Thus, we lack tailor-made models for manipulators mounted on a fixed base. Focusing on orthogonal point-to-surface impacts (no tangential velocities), we revisit two main elements of an impact dynamics model: the contact-force model and the inverse inertia matrix. We collect contact-force measurements by impacting a 7 DOF Panda robot against a sensorized rigid environment with various joint configurations and velocities. Evaluating the measurements from 150 trials, the best model-to-data matching suggests a viscoelastic contact-force model and computing the inverse inertia matrix assuming the robot is a composite-rigid body.