Sensor integration and controller design for a smart end-effector

Design, construction and testing of a controller is presented for the parallel jaw end-effector used in the Robotics Research Laboratory (RRL) of the Mechanical And Aerospace Engineering Department at the University of Tennessee, Knoxville.This parallel jaw end-effector is used by a seven degree-of-freedom RoboticsResearch Corporation (RRC) manipulator. The end-effector is equipped with proximity, crossfire, force, and ultrasonic sensors. The controller provides the operator with all the sensory information along with position and force control of the parallel jaw end-effector. Position and force control are achieved using the hardware to control the motor torque output which consists of a Digital to Analogconverter and a power amplifier. The hardware for the proximity sensors was provided with the end-effector. A similar hardware was built for the ultrasonic sensor. The control software is written in C language and is implemented on a 50MHz 486DX2 microprocessor. The program has a user interface capable of selecting the control scheme and switching between the 486DX microprocessor and the IRIS-4D/340GTX Silicon Graphics workstation which is used for higher level control of the RRC manipulator. The program allows the user to enter the desired force required to hold a certain object and the desired position depending on the chosen control scheme. The proportional and integral gains can also be modified through the user interface. The status of the proximity sensors is available at the user's request. The operator chooses between force and position control of the end-effector for object manipulation, and ultrasonic sensor and proximity sensors for object location and obstacle avoidance.