Method for controlling an automated work cell

• US 8,965,574 B2
• Filed: 05/13/2011
• Issued: 02/24/2015
• Est. Priority Date: 05/14/2010
• Status: Active Grant

• Current Assignee: Staubli Faverges (Stã¤Ubli Holding AG)
• Original Assignee: Staubli Faverges (Stã¤Ubli Holding AG)
• Inventors: Joly, Luc, Bonnet Des Tuves, Jean Michel, Pertin, Franois, Vogt, Grald
• Primary Examiner(s): McDieunel, Marc
• Application Number:
  US13/696,739
• Publication Number:
  US 20130116821A1
• Time in Patent Office: 1,383 Days
• Field of Search: 700/254, 422/73, 422/82.05, 422/82.08, 435/29, 435/288.7
• US Class Current: 700/254
• CPC Class Codes: B25J 9/16 Programme controls programme controls in general G05B19/00, e.g. numerical pogramme controls G05B19/18; recording or playback systems G05B19/42
• CPC Class Codes: B25J 9/161 Hardware, e.g. neural networks, fuzzy logic, interfaces, processor
• CPC Class Codes: G05B 19/4086 Coordinate conversions; Other special calculations
• CPC Class Codes: G05B 2219/33273 DCS distributed, decentralised controlsystem, multiprocessor
• CPC Class Codes: G05B 2219/39253 Virtual arm, has end effector on any joint of real manipulator
• CPC Class Codes: G05B 2219/39384 Control unit near robot, control and teaching panel in safe zone
• CPC Class Codes: G05B 2219/39408 Integrated structure and control design

Abstract

A method for controlling an automated work cell which includes at least one robot arm having at least three degrees of freedom controlled according to a plurality of control axes; a control center; a device for controlling the robot arm which includes a plurality of motor controllers each controlling operation of one motor and suitable for operating at least one portion of the robot arm; and a communication bus between the control center and the device for controlling the robot arm; wherein the method includes steps of: a) sending instructions emitted by the control center to control the control axes to a single arithmetic unit belonging to the device for controlling the robot; b) determining, within the arithmetic unit and according to instructions received from the orders for each of the motors controlled by a motor controller; and c) sending each motor controller an order, determined in step b), for the motor controlled by each motor controller.

Claims

1. A method of controlling an automated work cell including:

at least one robot arm with at least three degrees of freedom controlled according to several control axes,

a control center,

a device controlling the robot arm, including several motor controllers each controlling functioning of a motor for maneuvering at least a part of the robot arm, and

a bus for communication between the control center and the control device of the robot arm,

wherein the method comprises the steps of;

a) transmitting instructions, sent by the control center for controlling the control axes, to a single computing unit belonging to the device controlling the robot arm;

b) determining, in the computing unit and from several of the instructions received from the control center at step a), orders for each of the motors controlled by a motor controller; and

c) transmitting to each motor controller an order, determined at step b), for the motor controlled by each motor controller.

2. The control method according to claim 1, including the supplementary steps of:

d) transmitting, from each motor controller and to the computing unit, the position of the motor that it controls;

e) calculating, in the computing unit and on the basis of positions of all of the motors, the positions of each of the control axes of the robot arm; and

f) transmitting to the control center the positions calculated at step e).

3. The control method according to claim 2, including the supplementary steps of:

g) calculating, in the computing unit and on the basis of all the positions of the motors, a cartesian speed of a characteristic point;

h) comparing the calculated cartesian speed with a threshold value;

i) transmitting, from the computing unit and to the control center, an alert signal if the cartesian speed is greater than the threshold value.

4. The control method according to claim 3, wherein the computing unit takes account, in the calculation of step e), the times of measuring the positions of the motors and the time of transmission to the control center of the positions of each of the control axes of the robot arm in order to correct the positions of the movement control axes according to the presumed movement of the robot arm.

5. The control method according to claim 1, wherein, at step b), movement orders including the positions to be reached for each motor for complying with the instructions sent by the control center are calculated.

6. Control method according to claim 5, wherein, at step b), the calculation of the movement orders for each motor is accompanied by a prediction of torque to be supplied for each motor, based on the instructions sent by the control center.

7. The control method according to claim 6, wherein the instructions sent by the control center contain information on a load transported for at least one movement control axis.

8. The control method according to claim 6, wherein the positions to be reached for each motor in order to comply with the instructions sent by the control center include a compensation for deformations of the robot arm calculated from at least some of the torque predictions.

9. The control method according to claim 1, including a step consisting in:

d) transmitting to the control center a signal representing a state of powering up of the robot arm, in which the robot arm is respectively declared to be ready to function or powered down only if all the motors are powered up or powered down and braked.

10. The control method according to claim 1, including:

d) transmitting, from the computing unit and to the control center, a signal representing a state of functioning of all parts of the robot arm, in which all the parts of the robot arm are declared to be faulty if at least one of these parts is detected as not functioning.

11. The control method according to claim 1, wherein the bus supports a synchronous communication mode.

12. The control method according to claim 1, wherein the bus functions on an interface model of a serial real-time communications system.

13. The control method according to claim 12, wherein the control center communicates with the computing unit using the commands of a profile drive hardware profile.