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Manipulator Runaway Safety System

IP.com Disclosure Number: IPCOM000043364D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Giattino, P: AUTHOR

Abstract

The safety system prevents a manipulator arm runaway condition upon initial hydraulic system startup and when coming out of freeze-motion mode. Freeze motion is a mode in which the manipulator arm is stopped but the hydraulics are not shut off. The safety system 13 consists of a pair of solenoid-operated valves 10 and 12 with bypasses 14 and 16, respectively. Valve 10 is located in the supply side S, and valve 12 is located in the return side R. The initial startup of the hydraulic system 20 puts the manipulator 22 in a freeze-motion mode requiring activation of the run switch not shown prior to any command or program move. Should the run switch or a motor servo valve be in an open condition, for example, stuck, when coming out of freeze motion, a runaway arm condition cannot occur with the safety system 13 in place.

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Manipulator Runaway Safety System

The safety system prevents a manipulator arm runaway condition upon initial hydraulic system startup and when coming out of freeze-motion mode. Freeze motion is a mode in which the manipulator arm is stopped but the hydraulics are not shut off. The safety system 13 consists of a pair of solenoid-operated valves 10 and 12 with bypasses 14 and 16, respectively. Valve 10 is located in the supply side S, and valve 12 is located in the return side R. The initial startup of the hydraulic system 20 puts the manipulator 22 in a freeze-motion mode requiring activation of the run switch not shown prior to any command or program move. Should the run switch or a motor servo valve be in an open condition, for example, stuck, when coming out of freeze motion, a runaway arm condition cannot occur with the safety system 13 in place. The solenoid valve 12 in the hydraulic system return line R is a normally-closed valve. The fluid bypass valve 16 in the return line R is set to allow only enough fluid flow to have movement of the arm at a velocity and force that would not be physically detrimental. When the manipulator 22 is controlled to come out of freeze motion, opening of the return solenoid valve 12 is delayed until a signal is processed by the error detection system maintaining the valve closed or opening the valve based a on safe or unsafe condition. The supply-side solenoid valve 10 is a normally-closed valve with a fixed bypass 14 which op...