Continuous Collision Detection for a Robotic Arm Mounted on a Cable-Driven Parallel Robot

Abstract

A continuous collision checking method for a cable-driven parallel robot with an embarked robotic arm is proposed in this paper. The method aims at validating paths by checking for collisions between any pair of robot bodies (mobile platform, cables, and arm links). For a pair of bodies, an upper bound on their relative velocity and a lower bound on the distance between the bodies are computed and used to validate a portion of the path. These computations are done repeatedly until a collision is found or the path is validated. The method is integrated within the Humanoid Path Planner (HPP) software, tested with the cable-driven parallel robot CoGiRo, and compared to a discretized validation method.

Continuous Tension Validation for Cable-Driven Parallel Robots

“…The path illustrated in Fig. 1 was tested using the proposed continuous cable tension validation method combined with the continuous cable collision validation method proposed previously in [16].…”

“…While a discretized method may produce false positives, the presented method never does. Used with the continuous collision checking method presented in [16], it constitutes a complete continuous validation method for CDPRs integrated within the open source software HPP and can be used for automatic path planning.…”

“…We consider the general continuous validation algorithm presented in [16]. The algorithm can determine if a straight path is valid or not regarding a list of validation elements.…”

“…Moreover, if a path is found non-valid, it means that there is absolutely no feasible tension distribution. The method proposed in this paper complements the continuous cable collision checking approach proposed in our previous work [16], aiming at a complete continuous path validation method for CDPRs. Moreover, its implementation in HPP makes it easy to use with other CDPR configurations and/or payloads, provided that the number of cables is at least equal to the number of mobile platform DOFs.…”

“…Then, given the distance -or a lower bound on the distancebetween two bodies at a given parameter value, the method computes a time interval over which no collision can occur between the bodies. Our previous paper [16] extended this method to cable collisions (with the environment, with the mobile platform, and among them). In this paper, a similar approach is taken to validate the feasability of the cable tensions of a CDPR, by reasoning in the wrench space using the hyperplane shifting method [18].…”