TY - JOUR T1 - A miniature pan-tilt actuator: the spherical pointing motor JF - IEEE Transactions on Robotics and Automation Y1 - 1994 A1 - Bederson, Benjamin B. A1 - Wallace,R.S. A1 - Schwartz,E.L. KW - absolute positioning device KW - active vision KW - Actuators KW - Application software KW - Assembly KW - automatic calibration KW - camera sensor KW - CAMERAS KW - CCD image sensors KW - CCD sensor chip KW - Charge coupled devices KW - Charge-coupled image sensors KW - closed-loop control strategies KW - computerised control KW - Lenses KW - Magnetic fields KW - miniature lens assembly KW - miniature pan-tilt actuator KW - open-loop control strategies KW - orthogonal motor windings KW - pan-tilt mechanism KW - Permanent magnet motors KW - position control KW - Scanning probe microscopy KW - spherical pointing motor KW - two-degree-of-freedom device AB - A pan-tilt mechanism is a computer-controlled actuator designed to point an object such as a camera sensor. For applications in active vision, a pan-tilt mechanism should be accurate, fast, small, inexpensive and have low power requirements. The authors have designed and constructed a new type of actuator meeting these requirements, which incorporates both pan and tilt into a single, two-degree-of-freedom device. The spherical pointing motor (SPM) consists of three orthogonal motor windings in a permanent magnetic field, configured to move a small camera mounted on a gimbal. It is an absolute positioning device and is run open-loop. The SPM is capable of panning and tilting a load of 15 grams, for example a CCD image sensor, at rotational velocities of several hundred degrees per second with a repeatability of .15°. The authors have also built a miniature camera consisting of a single CCD sensor chip and miniature lens assembly that fits on the rotor of this motor. In this paper, the authors discuss the theory of the SPM, which includes its basic electromagnetic principles, and derive the relationship between applied currents and resultant motor position. The authors present an automatic calibration procedure and discuss open- and closed-loop control strategies. Finally, the authors present the physical characteristics and results of their prototype VL - 10 SN - 1042-296X CP - 3 M3 - 10.1109/70.294205 ER -