This paper introduces a new algorithm to realize the on-line coordinate transformation for a 3 DOF robot. The introduced algorithm defines incremental units in joint and Cartesian spaces. Based on these units the incremental computation of the DDA integrator is used to solve the direct kinematics. The calculation of the inverse Jacobian is replaced with a look-up table. With these approach a reference pulse system for a motion control of a planar robots is established. Therefore, the algorithm removes the necessity of the floating-point arithmetic and trigonometric function call.
The algorithm considers the 3 DOF robot as the combination of two types of planar robots. By employing two CPUs the on-line coordinate transformation can be realized. A reference Cartesian path is given by a 3-axis hardware interpolator, which is widely used for NC machine tools. The interpolator is developed by using the KM3701, which is a function generator LSI chip for 2-axis interpolation. Through experiments the Cartesian path control of the 3 DOF robot is demonstrated.