Example implementations may relate to a computing device configured to operate a robotic system. In particular, the device receives input data that is generated by a hand-holdable controller including a knob, where the knob includes touch sensors arranged to detect touch on surfaces of the knob. Based on the input data, the device detects that the controller is within a first threshold distance from a first component of the robotic system and responsively operates the first component of the robotic system based on the input data. The device then receives subsequent input data that is generated by the controller. Based on the subsequent input data, the device subsequently detects that the controller is within a second threshold distance from a second component of the robotic system and responsively operates the second component of the robotic system based on the subsequent input data.