ROBOTIC TOOL CHANGER ALIGNMENT MODULES

• US 20160039059A1
• Filed: 08/05/2014
• Published: 02/11/2016
• Est. Priority Date: 08/05/2014
• Status: Active Grant

• Current Assignee: ATI Industrial Automation Incorporated (Novanta Inc.)
• Original Assignee: ATI Industrial Automation Incorporated (Novanta Inc.)
• Inventors: Berrocal, William G., Takla, Alfred Atef
• Granted Patent: US 9,731,392 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23Q 3/15506 the tool being inserted in a tool holder directly from a storage device (without transfer device)
• CPC Class Codes: B23Q 3/186 Aligning devices
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G05B 2219/50141 Setup tool, preset
• CPC Class Codes: G05B 2219/50264 Change tool during positioning movement
• CPC Class Codes: G05B 2219/50291 Multi-tool, several tools

Abstract

Alignment modules attached to a robotic tool changer assist spatial orientation and alignment of a robot arm relative to a robotic tool for location training. A three-axis spatial orientation sensor is first attached to an alignment module affixed to a tool unit. The sensor is “zeroed,” or calibrated to the spatial orientation of the tool unit. The sensor is transferred to a corresponding surface of an alignment module affixed to a master unit. The orientation of the robot arm is adjusted to eliminate sensor error signals indicating deviations from the zeroed orientation of the tool unit. An optical signal, such as a cross line laser beam, is then projected between the alignment modules. The x- and y-axis position of the robot arm is adjusted to align the optical signal with alignment markings. When the master and tool units are aligned, the robot arm is advanced in the z-axis direction until the master unit abuts the tool unit.

Claims

1. A method of aligning a robot arm with a robotic tool, wherein a master unit of a tool changer is affixed to the robot arm and a tool unit of the tool changer is affixed to the robotic tool, comprising:

sensing the spatial orientation of the tool unit along three orthogonal axes;

adjusting an orientation of the robot arm to align the master unit to the sensed spatial orientation of the tool unit with respect to the three axes;

projecting one or more optical indicators from one of the master and tool units to the other; and

adjusting a position of the robot arm in two orthogonal directions transverse to a coupling axis centered on the tool unit, in response to the optical indicators, so as to center the master unit on the coupling axis; and

moving the robot arm along the coupling axis until the master unit contacts the tool unit.

2. The method of claim 1 wherein sensing the spatial orientation of the tool unit along three orthogonal axes and adjusting a position of the robot arm to align the master unit to the sensed spatial orientation of the tool unit with respect to the three axes comprise:

affixing an Inertial Measurement Unit (IMU) to the tool unit in a predetermined orientation;

zeroing the IMU to capture the spatial orientation of the tool unit along three orthogonal axes;

transferring the IMU to the master unit in the same predetermined orientation;

reading error signals from the IMU indicating deviations from the sensed spatial orientation; and

adjusting the orientation of the robot arm to align the master unit to the sensed spatial orientation of the tool unit with respect to the three axes.

3. The method of claim 1 wherein projecting one or more optical indicators from one of the master and tool units to the other and adjusting the position of the robot arm in response to the optical indicators comprises projecting a laser beam from a predetermined position on one unit, and adjusting the position of the robot arm to align the incident beam with position markers on the other unit.

4. The method of claim 1 wherein the laser beam is a cross line laser beam projecting two orthogonal lines, and wherein the position markers comprise orthogonal line markers.

5. The method of claim 1 wherein adjusting the position of the robot arm in two orthogonal directions in response to the optical indicators comprises moving the robot arm until one or more optical sensors indicates an incident optical indicator.

6. The method of claim 2 wherein the IMU is part of an Attitude and Heading Reference System (AHRS).

7. A robotic tool changer, comprising:

a master unit operative to be affixed to one of a robot arm and a robotic tool;

a tool unit operative to be affixed to the other of the robot arm and the robotic tool;

a first alignment module affixed to a tool ledge of one of the master and tool units, the first alignment module including an optical source;

a second alignment module affixed to a corresponding tool ledge of the other of the master and tool units, the second alignment module including one or more optical targets on a surface facing the first alignment module; and

a spatial orientation sensor operative to be attached to corresponding surfaces of both the first and second alignment modules, the sensor operative to sense the spatial orientation, along three orthogonal axes, of the alignment module to which it is attached.

8. The robotic tool changer of claim 7 wherein one of the spatial orientation sensor and the alignment module surfaces include protrusions and the other of the sensor and surfaces include corresponding holes or detents such that the sensor is aligned in a predetermined position when attached to an alignment module surface.

9. The robotic tool changer of claim 7 wherein the spatial orientation sensor is attached to the first or second alignment module surface with a hand-actuated fastener.

10. The robotic tool changer of claim 7 wherein the spatial orientation sensor comprises an Inertial Measurement Unit (IMU).

11. The robotic tool changer of claim 7 wherein the IMU comprises a wired connection to a robot control terminal.

12. The robotic tool changer of claim 7 wherein the IMU comprises a wireless interface to a robot control terminal.

13. The robotic tool changer of claim 7 wherein the IMU is operative to

when attached to the alignment module affixed to the tool changer unit affixed to a robotic tool, zero to capture the spatial orientation of the tool unit along three orthogonal axes;

and

when attached to the alignment module affixed to the tool changer unit affixed to the robot arm, output error signals indicating deviations from the sensed spatial orientation.

14. The robotic tool changer of claim 13 wherein the IMU is further operative to output updated error signals indicating current deviations from the sensed spatial orientation, as the orientation of the robot arm is adjusted in response to the error signals.

15. The robotic tool changer of claim 13 wherein the optical source is a laser.

16. The robotic tool changer of claim 15 wherein the laser outputs a cross-line beam comprising two orthogonal lines.

17. The robotic tool changer of claim 16 wherein the optical targets of the second alignment module comprise two orthogonal lines.

18. The robotic tool changer of claim 7 wherein the IMU is part of an Attitude Heading Reference System (AHRS).

19. A non-transitory machine-readable medium storing instructions for assisting a user to aligning a robot arm with a robotic tool, said instructions operative to cause a processing circuit of a computing device to perform the steps of:

capturing the spatial orientation of a tool unit of a tool changer along three orthogonal axes by commanding a spatial orientation sensor mounted on the tool unit to sense its spatial orientation and zero outputs indicative of a deviation from the sensed spatial orientation along each axis;

directing the user to adjust an orientation of the robot arm to align the master unit to the sensed spatial orientation of the tool unit with respect to the three axes by receiving, from the same spatial orientation sensor now mounted on a master unit of the tool changer, outputs indicative of a deviation from the sensed spatial orientation along each axis, and out-putting the indications to the user.

20. The medium of claim 19 wherein the instructions are further operative to perform the steps of:

prior to capturing the spatial orientation of the tool unit, directing the user to attach the spatial orientation sensor to the tool unit; and

prior to receiving outputs from the spatial orientation sensor, directing the user to attach the spatial orientation sensor to a corresponding surface of the master unit.

21. The medium of either of claim 19 wherein the instructions are further operative to perform the step of:

after the outputs from the spatial orientation sensor indicate the spatial orientation of the master unit deviates from the sensed spatial orientation of the tool unit by less than a predetermined amount, directing the user to activate an optical source on the master unit and to adjust a position of the robot arm in two orthogonal directions transverse to a coupling axis centered on the tool unit, so as to align one or more optical indicators projected by the source and impinging on the tool unit to align with one or more corresponding indicators on the tool unit.

22. The medium of claim 19 wherein the instructions are further operative to perform the step of:

after the master unit is aligned with the tool unit in two orthogonal directions transverse to a coupling axis centered on the tool unit, directing the user to move the robot arm along the coupling axis until the master unit contacts the tool unit.