Contact Parameter Estimation With a Space Robot Verification Facility

Computer simulations play an important role in the design and verification of space robotic operations since on-orbit tests are impossible to conduct before launch. Thus, accurate computer modeling and simulation of space robotic tasks is essential. Of particular difficulty are the space manipulator operations, that involve constrained or contact tasks. Here, the contact dynamics capability in the modeling tools becomes critical for high fidelity simulations. This in turn implies a need for accurate determination of contact parameters, which are used as inputs to contact dynamics simulation. In this work, the identification of contact dynamics parameters based on sensor data obtained during robotic contact tasks is considered. In particular, the contact parameter estimation problem is addressed for simple contacting geometries using the SPDM Task Verification Facility Manipulator Testbed (SMT) at the Canadian Space Agency, where SPDM is the Special Purpose Dexterous Manipulator. The SMT is a robotic simulation facility, which also features gravity compensation algorithms to support the emulation of space robots. Single point SMT contact experiments were performed with six different payloads. Eight unique single point contact parameter estimation algorithms were used as part of the process of identifying payload stiffness from SMT experimental data.