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Robot Position and Orientation Sensor

IP.com Disclosure Number: IPCOM000041485D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 4 page(s) / 71K

Publishing Venue

IBM

Related People

Brennemann, AE: AUTHOR [+3]

Abstract

Linear diodes, optical imaging and fiber-optic bundles coact to make a crash-resistant detector for the motions and forces common to robot-positioning arms and finger assemblies. This article presents a sensing system which is more convenient, less critical to adjust and possibly less costly than those known. The system described uses linear diodes (also known as lateral diodes), optical imaging and a light source (either infrared or small light sources as fiber-optic bundles.) The use of such linear diodes is shown in the IBM Technical Disclosure Bulletin 22, 1881-1882 (October 1979). Fig. 1 shows a force-sensing system for a finger force-sending device 11 which consists of the light source and diode combination. Detailed in Fig. 1 is a light-emitting diode (LED) 30 and two square linear diodes 34 and 36 mounted as a cube.

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Robot Position and Orientation Sensor

Linear diodes, optical imaging and fiber-optic bundles coact to make a crash- resistant detector for the motions and forces common to robot-positioning arms and finger assemblies. This article presents a sensing system which is more convenient, less critical to adjust and possibly less costly than those known. The system described uses linear diodes (also known as lateral diodes), optical imaging and a light source (either infrared or small light sources as fiber-optic bundles.) The use of such linear diodes is shown in the IBM Technical Disclosure Bulletin 22, 1881-1882 (October 1979). Fig. 1 shows a force-sensing system for a finger force-sending device 11 which consists of the light source and diode combination. Detailed in Fig. 1 is a light-emitting diode (LED) 30 and two square linear diodes 34 and 36 mounted as a cube. Deflection probe 12 has a beam splitter and mask attached to its end. Light from LED 30 passes through mask 32 where the mask image is split by beam splitter 38. The images impinge on diodes 34 and 36; thus as forces move probe 12, the light images move on the surface of the linear diodes 34 and 36. The output voltages from the diodes can be conditioned to indicate the position of the light spot on the diode, which is a measure of the deflection of probe 12 which in turn is a measure of force applied to the robot finger. To detect motion in three dimensions, one of the diodes should be a two-dimensional linear cell while the remaining one could be a linear diode. This combination would then provide motion detection for three orthogonal movements of member 12. For example, motions of member 12 in the Y and Z directions are detected by a two-dimensional ("square") diode at 36. Motions along the X axis are detected by a linear diode 34. However, the alignment of the light beam from the optical image via beam splitter 38 on a linear diode at 34 becomes more critical than if both diodes are square. Also, if both diodes 34 and 36 are square (two-dimensional) diodes, then rotation of member 12 about its axis can be measured. This is a measure of torque about an axis through member 12. For example, when member 12 is rotated about the Y axis, motion is detected at the Z output on diode 36 but not on diode 34. This would indicate torque along the Y axis. For linear Z motion this would be seen at the Z output of diode 34 and diode 36. Note that the torque output would be an approximate linear measurement for small angles of rotation whereas the orthogonal motions of X, Y and Z would be linear. Although the light-diode system is shown as a means to detect forces in a robot gripper, it should not be restricted to that use. An extension of the same idea could be configured as a general position and orientation sensor. One such arrangement (Figs. 2A-2B) shows three lateral cells 34, 36 and 42 placed orthogonally on the faces of a cube-shaped cavity 45. A cube-shaped device replaces the b...