The Robot is a Two DOf manipulator, which was custom built here at RMC by Dr J. C. Piedboeuf and his students over a period of three years. The first DOF is a rotation about a vertical passing through a fixed and allows the arm to sweep in the horizontal plane. The second DOF is rotation about a rotating horizontal axis. The two DOF allows the end point of the manipulator span the surface of a dome with the length of the link as its radius.
The motors at each joint are DC servo-motors with precision anti backlash harmonic drives. The motor at the base is an RF-32-3816 motor manufactured by Hi-T Drive and uses a harmonic drive with a reduction ratio of 1:78. The motor driving the second joint is an RF-32-2315, made by the same company and uses a harmonic drive with a reduction ratio of 1:131. Each motor is equipped with an optical position encoder with a resolution of 500 steps/rev to measure the angular position of the joint and a tacho-generator with a nominal sensitivity of 7 V/1000 rpm to measure the angular velocity.
Control Computer & Interface
The control computer system is a generic PC-compatible computer with a 486DX-50 MHz CPU, 32MB of ram. The computer is equipped with two National Instrument data acquisition boards. The first board is an AT-MIO-16F-5 with 8 analog inputs and 2 analog outputs. The second board is a PC-DIO-24 which provides 24 individual digital inputs and is used to interface with the optical position encoder through an Encoder/Decoder interface card. The analog Input/Outputs are feed through a signal conditioning unit, SCXI-1000, which consists of several national instruments modules for noise filtering and strain gage calibrations. A relay control unit is used to energize the motors and for emergency shut off. The main control algorithm is written in C/C++ and the GUI is developed in MATLAB/SIMULINK.