Cobot Control

Cobots are a class of mechanically passive robotic devices, intended for direct physical collaboration with a human operator. The operator supplies all motive power while the cobot enforces software-defined guiding surfaces, or constraints. Cobots are intrinsically passive, safe devices. This is because, rather than employ powered actuators to produce constraint forces, cobots use “steerable ” nonholonomic joints. Constraint forces are mechanical in origin, yet software defined. The simplest possible cobot is a unicycle which is steered by a servo system acting under computer control, but which is moved by a human operator. The unicycle cobot requires essentially no consideration of kinematics. Two fundamental control modes of the unicycle cobot, “virtual caster ” and “constraint tracking”, are reviewed. More complicated cobots, such as the three-wheeled “Scooter”, require a set of kinematic transformations relating configuration space to joint space. These transformations play a role in cobot control like that of the jacobian in robot control. 1