Cobot implementation of virtual paths and 3D virtual surfaces

Cobots are devices for human/robot interaction, in which axes of motion are coupled to one another by computercontrolled continuously variable transmissions rather than individually driven by servomotors. We have recently built a cobot with a three-dimensional workspace and a 3-revolute parallelogram-type mechanism. Here we present the control methods for the display of virtual surfaces and for free mode in which the cobot endpoint moves as if it were unconstrained. We provide experimental results on the performance of the free, virtual path, and virtual surface controllers.