Communication interface for multi-microprocessor servo control in a multi-axis robot control system

A digital control for a robot operating at a predetermined control sampling rate and having a plurality of joints with each joint being driven by an electric motor, said control comprising:

• a power amplifier operable to supply drive current to each joint driving motor;
• respective feedback control loop means for respectively controlling said power amplifier for each of said joint driving motors;
• each of said feedback control loop means including at least one control loop operable to control the associated power amplifier and thereby control at least one control variable selected from position, velocity and torque;
• at least first servo control means for performing control support tasks and calculation tasks for said control loop for all of the joint driving motors;
• said first servo control means including a first microprocessor for performing calculation tasks including computing output control commands from stored algorithms for said one control loop for each joint driving motor;
• said first microprocessor having a relatively high computing performance capability and a relatively low data processing interface capability;
• said first servo control means further including a second microprocessor for supervising the operation of said first servo control means and performing servo control support tasks in said one control loop for each joint driving motor including the routing of control command, status and feedback data to and from said first microprocessor;
• communication means for interfacing said first and second microprocessors relative to each other and relative to higher and lower level control circuitry so as to enable siad first servo control means to operate said one control loop for each joint driving motor and control the at least one control variable for said one control loop;
• said communication interfacing means including a first memory bank and a second memory bank;
• means for concurrently cross-coupling said first microprocessor to one of said banks, to write command and feedback data thereto and to read calculated control data therefrom, and for concurrently cross-coupling said second microprocessor to the other of said banks to read command and feedback data therefrom and to write calculated control data thereto;
• and
• means for cyclically cross-switching said microprocessors and said banks at the control sampling rate, without impacting the control processing performance of either microprocessor, so that said first microprocessor can supply new control calculations cosynchronously with the execution of said second microprocessors' supervisory tasks for control loop operation based on new control commands and feedback data in each control cycle.