A multi-arm robotic system for optimal sculpting

Recent research has considered robotic machining as an alternative to traditional CNC machining. However, one of the problems with serial link manipulators is that they have a low inherent stiffness due to the cantilever design of the links and low torsional stiffness of the actuators. This problem is addressed during the resolution of a Cartesian-space tool path, defined relative to the blank, into joint space using the pseudo-inverse method of redundancy resolution. The two-armed system is modeled as a single system using a relative Jacobian to relate the joint motions to the relative motion of the tool and blank. The null space of the relative Jacobian is used to optimize the joint trajectories by minimizing the system compliance factor. A min-max optimization and a null-space search are investigated in order to produce a global optimum. Simulation results show that stiff trajectories lower the level of torque consumption, which allows for an increase in productivity. The deflection of the tool relative to the blank is decreased as well.