Multi-axis DSP-based parallel processing servo controller for machine tools and robots

• US 4,878,002 A
• Filed: 10/27/1988
• Issued: 10/31/1989
• Est. Priority Date: 10/27/1988
• Status: Expired due to Fees

• Current Assignee: Advanced Engineering Systems Operations & Products Incorporated 1 Maple Street Concord NH
• Original Assignee: Advanced Engineering Systems, Operations & Products Inc.
• Inventors: Slocum, Alexander, Heatzig, Eric, Thurston-Slocum, Debra
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Bergmann, Saul M.
• Application Number:
  US07/263,503
• Time in Patent Office: 369 Days
• Field of Search: 318/568.2, 318/568.13, 364/132, 364/148
• US Class Current: 318/568.2
• CPC Class Codes: G05B 19/4141 characterised by a controller or microprocessor per axis
• CPC Class Codes: G05B 2219/33156 Communication between two processors over shared, dualport ram
• CPC Class Codes: G05B 2219/33337 For each axis a processor, microprocessor
• CPC Class Codes: G05B 2219/34047 Dsp digital signal processor
• CPC Class Codes: G05B 2219/34076 Shared, common or dual port memory, ram
• CPC Class Codes: G05B 2219/34157 Synchronize interpolation of different axis boards, simultaneous start
• CPC Class Codes: G05B 2219/34225 Interface board for measuring system, for resolver, encoder or interferometer
• CPC Class Codes: G05B 2219/41195 Cross coupled feedback, position change one axis effects control of other
• CPC Class Codes: G05B 2219/41248 Adapting characteristics of servo
• CPC Class Codes: G05B 2219/42152 Learn, self, auto tuning, calibrating, environment adaptation, repetition

Abstract

A multi-axis Digital Signal Processor based servo controller system in which all servo and sensor interface boards are connected to a common backplane bus system enabling inter-board communication, with parallel processing using dual port memory and multiple DSP chips, and with each servo board having access to position data from other axis feedback sensors as well as their own, and a self-tuning control software architecture that uses the hardware architecture high speed to allow it to self-tune control constants to optimize performance.

Claims

1. A multi-axis DSP-based servo controller system for positioning motor-driven carriages and similar devices in response to multi-axis position-sensing readings as by optical encoders, laser interferometers, and analog position sensors, the system having, in combination, three types of sensor interface boards consisting of an A quad B incremental position sensor reading board, a multi-axis positioning-sensing reader board, an analog-to-digital (A/D) conversion board, and a plurality of multi-axis DSP based servo boards for executing digital control algorithms and outputting analog control voltages, one DSP servo board for each motor associated with one axis, and each board having a dual port memory and a local memory;

a multiple bus backplane interconnected with the dual port memory of each of the sensor interface boards such as to enable inter-board communication and parallel processing;

means for applying the multi-axis position data read by the A quad B incremental position sensor reader board and stored in its dual port memory by way of the bus backplane to each servo board for storage in each servo board dual port memory;

means for transferring the position data thus stored in each servo board dual port memory to its own local memory;

means for feeding the analog position sensed information of the A/D board stored in its local and dual port memory from the latter by way of the bus backplane for storage in each servo board dual port memory;

each servo board having servoloop controller DSP means responsive to the position values in its local memory to perform its control loop algorithm while up-dated position data in the positionsensing board dual port memory is transferred into the dual port memory of the servo board;

each servo board having digital-to-analog (D/A) converter means connected to receive output commands from its servo-loop controllers and in turn connected to motor amplifiers means for controlling the corresponding axis motor;

each servo board being provided with a self-turning algorithm to find optimal control constants for a physical system connected to the controller.

2. A system as claimed in claim 1 and in which means is provided for connecting said bus backplane to host computer means to download programs to the DSP servo controller boards.

3. A system as claimed in claim 1 and in which motor controller means for handling interrupts and synchronization interconnects said bus backplane and display monitor means.

4. A system as claimed in claim 1 and in which each board dual port memory has access to position data from the other axis sensing, permitting the implementation of error-mapping and compensation techniques.

5. A system as claimed in claim 1 and in which each servo board D/A output means comprises multiple D/A outputs and multiple digital I/O ports to permit use of motor control systems requiring such.

6. A system as claimed in claim 1 and in which each servo board local memory is of sufficiently high speed and size to enable storing look-up tables and error maps, as well.

7. A system as claimed in claim 5 and in which the said multiple D/A outputs may be up to six and the multiple I/O ports, up to sixteen 32-bit digital ports.

8. A system as claimed in claim 1 in which an algorithm determines the response of the mechanical system and adjusts the control algorithm constants to automatically optimize performance as defined by the user.

9. A multi-axis Digital Signal Processor-based servo controller system having a plurality of multi-axis servo and sensor interface boards;

means for connecting all the servo and sensor interface boards to a common backplane bus system, enabling inter-board communications;

means for providing parallel processing using dual port memory and multiple DSP chips in each board;

means for enabling each servo board to access position data from other axis feedback sensors as well as their own; and

self-tuning control software architecture implementing the said system at high speed to allow it to self-tune control constants for optimizing performance.