A robotic surgery method for cutting a bone of a patient includes characterizing the geometry and positioning of the bone and manually moving a handheld manipulator, the handheld manipulator operatively coupled to a bone cutting tool having an end effector portion, to cut a portion of the bone with the end effector portion. The handheld manipulator further comprises a manipulator housing and an actuator assembly movably coupled between the manipulator housing and the bone cutting tool. The method further includes causing the actuator assembly to automatically move relative to the manipulator housing to maintain the end effector portion of the tool within a desired bone cutting envelope in response to movement of the manipulator housing relative to the bone.