A two-mode six-DOF motion system based on a ball-joint-like spherical motor for haptic applications

A ball-joint-like spherical motor capable of offering smooth, continuous multi-DOF motion is presented as an alternative design for haptic applications. With a two-mode configuration, this device can be operated as a joystick manipulating a target in six degrees-of-freedom (DOF), and provides realistic force/torque feedback in real-time. Utilizing the magnetic field measurements, the orientation and the torque-to-current coefficients can be computed in parallel; this novel scheme greatly improves the sampling rate as well as reduces error accumulation commonly found in multi-DOF robotic devices. Of particular interest here is to explore this two-mode design in a computer-aided virtual environment. As an intuitive illustration, the disassembly process of a snap-fit (consisting of a typical cantilever hook and a wedge-shaped end) is simulated, where the two-mode permanent magnet spherical motor haptic device is incorporated as an interfacing device that receives motion commands from a virtual design environment and delivers torque feedback to the designer/user.