Compliant Contact Modeling of a Humanoid Robotic Thumb for Assisting Grasp

Abstract

In the present study, an analytical model of a four Degree of Freedom (DoF) humanoid robotic thumb with compliance during grasping has been developed. The model involves forward kinematics, inverse kinematics (IK) and the inverse dynamic model of the thumb with compliant contact at multiple points of interaction. Due to the complexity of the thumb, and in order to avoid unpredictable behavior at singularities, the Damped Least Squares (DLS) inverse of the Jacobian was carried out. Further, the inverse dynamic model of the thumb was developed with compliance at the point of contact using a non-linear spring-damper system. Numerical simulations were run in MATLAB. A link-based model was constructed and simulated using similar boundary conditions in Simulink. Thereafter, the analytical data were compared with the Simulink data and were found to be in close agreement with each other.