Estimation of contact information using nonlinear optimization

The paper presents an algorithm for estimating the contact information i.e. the contact force and the contact location. The estimation algorithm is based on the measurement of the part of joint torques which are caused by the external force. This torques may arise from a wide variety of contact situations, which makes this a complex nonlinear problem. Using some approximations, the complexity of the estimation problem is reduced and solved by the proposed algorithm based on nonlinear constrained optimization. In this paper only the robots with cylindrically shaped links are considered. The simulation and experimental results show that the proposed approach allows estimation of contact forces by using only joint torque sensors without any additional external sensory systems for detection of contacts along the robot body structure.