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Contact Sense Rotary and Tool Calibrator

IP.com Disclosure Number: IPCOM000046814D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 33K

Publishing Venue

IBM

Related People

Kaftan, RL: AUTHOR [+2]

Abstract

This arrangement measures the relationship for a manipulator between the linear and wrist motions and between the wrist center and tool tip. The calibration device consists of a block of aluminum 10 with 3 mutually orthogonal dowel pins D1, D2 and D3, extending from 3 faces of the block. The device is used in conjunction with a 5-axis manipulator consisting of 3 linear (X, Y, Z) axes (pitch, yaw) wrist. The block 10 is mounted such that the 3 dowel pins are aligned with the 3 linear axes of the manipulator. The block is electrically isolated from the machine ground and is connected to a contact sense digital input (DI) point on the manipulator. Attached to the 2-axis manipulator wrist is another dowel pin (not shown) which is used as a probe to contact the dowel pins D1, D2 and D3 in the block 10.

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Contact Sense Rotary and Tool Calibrator

This arrangement measures the relationship for a manipulator between the linear and wrist motions and between the wrist center and tool tip. The calibration device consists of a block of aluminum 10 with 3 mutually orthogonal dowel pins D1, D2 and D3, extending from 3 faces of the block. The device is used in conjunction with a 5-axis manipulator consisting of 3 linear (X, Y, Z) axes (pitch, yaw) wrist.

The block 10 is mounted such that the 3 dowel pins are aligned with the 3 linear axes of the manipulator. The block is electrically isolated from the machine ground and is connected to a contact sense digital input (DI) point on the manipulator. Attached to the 2-axis manipulator wrist is another dowel pin (not shown) which is used as a probe to contact the dowel pins D1, D2 and D3 in the block 10. Since the manipulator itself is grounded, when the machine probe contacts the pin in the block, the DI point changes state and can be detected by the system. The rotary calibration for a 2-axis manipulator wrist is obtained by aligning the tool probe parallel to an axis of motion for the manipulator and measuring the angle required to do this.

This procedure is explained by the following example: To align the tool probe parallel to the motion of the Z-axis, the following steps must be performed: 1 - Position the manipulator such that the tool probe is nominally parallel to the Z-axis and the axis of rotation for the pitch is parallel to the Y-axis (pitch = 0, yaw = 0). 2 - Position the tool probe behind (-X direction) the dowel D2 in the figure. (This is the dowel which is parallel to the axis of rotation for the wrist axis being calibrated.) 3 - Approach the dowel D2 by moving the manipulator in the +X direction, and record the X-axis value for the point of contact (P1). 4 - Withdraw the manipulator in the -X direction and then move a known distance (Q) in the Z direction such that the tool probe remains behind dowel D2. 5 - Approach D2 in the +X direction, and record the point of contact (P2)...