External Joint Torque-Based Estimation of Contact Information

Abstract

In the paper, a method for the estimation of the contact force and contact location is proposed. Contact can occur at any point on the body of the robot manipulator. The contact force estimation algorithm is based on the measurement of the part of the joint torques caused by the external force. As this is a complex nonlinear problem, the proposed method is based on nonlinear constrained optimization. Using certain assumptions, the complexity of the problem is reduced. In this paper, only robots with cylindrically-shaped links are considered. The simulation and experimental results show that the proposed approach allows the estimation of the contact forces by using only the joint torque sensors, without any additional external sensory systems for the detection of contacts along the robot body-structure.

Force sensing in continuum manipulators using fiber Bragg grating sensors

“…In rigid link robots contact forces/torques at the endeffector are estimated using joint forces/torques [20] [21]. The continuum manipulator is modeled as a rigid link robot with revolute joints [22].…”

Model-based sensorless robot collision detection under model uncertainties with a fast dynamics identification

“…In the transformed expression (19), the regressorH r no longer contains the information specified by system mechanical structure, which otherwise has to be provided in equation (16) with cautious and tedious symbolic computation, making the dynamic parameter identification procedure more convenient. Compared to the original parameter set defined in equation 16, the converted parameter setp r mapping from p r is identified separately for each joint and has sparse feature due to the conversion, while the burden of symbolic computation is significantly reduced.…”

Designing a virtual whole body tactile sensor suit for a simulated humanoid robot using inverse dynamics

“…For the second part, we propose a similar algorithm used in [19], though computationally more efficient. Searching over all links of the robot basically requires exact geometries of the surfaces.…”

“…Searching over all links of the robot basically requires exact geometries of the surfaces. Likar approximates link shapes of an ABB manipulation arm by cylinders [19] and then sets up constrained optimization problems to find the force application point on all cylinders. In our method however, due to the complexity of our humanoid robot in terms of the number of links, we approximate link shapes by ellipsoids which look realistic and propose an alternative exact solution of similar optimization problems.…”

“…6) Pick the link with minimal error e1 + e2. This procedure is in fact very fast compared to optimization based approaches proposed in [19]. All the stages together can run in real-time (100µs) on a moderate Core i5 CPU.…”