End effector force sensor and manual actuation assistance

The positioning system 500 includes a multi-joint positioning arm 502, an end effector 504 coupled to a distal end of the positioning arm, a force-moment sensor (FMS) 506 coupled to the end effector and a controller coupled to communicate with the positioning arm and the FMS. Using signals from the FMS, at least one external force or torque applied to the end effector is determined. A drive velocity for moving the end effector is determined, based on the at least one external force or torque. One or more joint movements of the positioning arm for moving the end effector is calculated, according to the drive velocity. The positioning arm is moved according to the one or more calculated joint movements. The end effector may include a handle (512, fig 6). The system may form part of a medical navigation system also having a tracking system for tracking markers attached to the positioning arm and end effector. The end effector may be configured to support an imaging system or a medical instrument.