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High-Speed Carriage Design for Light Payload XY Motion

IP.com Disclosure Number: IPCOM000036143D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 4 page(s) / 99K

Publishing Venue

IBM

Related People

Pappen, FM: AUTHOR [+2]

Abstract

This article describes a high-speed carriage mechanism that can move light payloads in an XY plane faster than conventional methods.

This text was extracted from a PDF file.
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High-Speed Carriage Design for Light Payload XY Motion

This article describes a high-speed carriage mechanism that can move light payloads in an XY plane faster than conventional methods.

The carriage mechanism of this disclosure is shown in Fig. 1. It includes an air bearing 1, two pivoted sliding rods 2 and 3 and a payload. For purposes of this disclosure the payload is shown as a probe actuator payload assembly 4.

The air bearing 1 floats upon a flat surface. It is translated and rotated by the pair of sliding rods 2 and 3. Both rods are attached to the air bearing pivot joints. Rod 3 is constrained to translate only, while the other rod 2 both translates and is free to rotate slightly about sliding rotating contact 5. Motors 6 and 7 drive the rods 2 and 3, respectively, providing a push/pull action.

Starting at the position shown in Fig. 1, a pure X direction move is achieved by moving both rods 2 and 3 the same amount. A Y direction move is achieved by pushing one rod while pulling the other. The mechanism can locate a point of its cantilevered payload 4 anywhere within its workspace. For example, carriage positions locating the tip of the payload 4 are shown in Figs. 2, 3, 4 and 5.

Each position within the workspace of the tool can be equated to a unique pair of rod lengths. The equations necessary to perform this calculation are presented below under Kinematic Equations.

(Image Omitted)

The key to this system is accurate positioning of the rods 2 and 3. Each motor needs to be controlled separately and the relative distance each rod has extended must be sensed and controlled. This requires a drive system with position feedback. Many combinations can be implemented. Among them are: - Servo motor with a linear encoder on each of the rods. Stepper motor with a linear encoder on each of the

rods.

Servo motor with a rotary encoder on each of the

rods.

Stepper motor with a rotary encoder on each of the

rods. The implementation includes:

1) A linear encoder mounted to each rod

(Image Omitted)

2) A position control loop around each motor.

The carriage mechanism design lends itself well to i...