Computer Manipulator Control, Visual Feedback and Related Problems

Summary

The design of a six degree of freedom manipulator with high positional accuracy and approximately human reach and motion properties is discussed.

The manipulator is moved along time-coordinated space trajectories in which velocity and acceleration are controlled. In lifting and placing objects an approach normal to the support surface is used.

The manipulator isservoed by a small computer which has as input the joint positions and velocities together with other sensor signals. The outputs of the control computer are the joint motor drive levels. No analog servo is used. The servo is compensated for gravity loading and for configuration-dependent dynamic properties of the manipulator.

A set of programs for precise manipulation of simple planar bounded objects by means of visual feedback have also been developed. The image of the hand and manipulated objects is acquired by the computer through the camera. The stored image is analyzed using a corner and line finding program developed for this purpose. The precision obtained is better than.1 inch. It is limited by the resolution of the imaging system and of the arm position measuring system.