CA1156332A - Equipment control system with fiber optic coupled remote control - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Hydraulically operated equipment, e.g., cranes or the like, may be accurately controlled by a remote control coupled by a fiber optic link to hydraulic valve control servo circuitry at the equipment site.
Analog input voltage levels representing various functions and/or motor positions are pulse position modulated for transmission through the fiber optic link, and are reconverted into analog signals for controlling selected motors and valve actuating solenoids, Novel safety features are incorporated for stopping and delaying all control if a deadman switch is released or if a function is incorrectly selected, and a standby power pack automatically neutralizes all motors and functions in the event of failure of the main power source.

Claims (9)

1. A fiber optic linked remote control system for transmitting electrical analog data signals from a remote control unit via a fiber optic link to receiving means located at the equipment to be con-trolled, said remote control system including:
a remote control station having a manual control section containing function selecting means, output voltage varying means, and a spring-biased deadman switch;
fiber optic transmitting circuitry coupled to said remote control station, said transmitting cir-cuitry including modulating means for converting analog signals representing functions selected by said selecting means and voltage levels selected by said voltage varying means into a corresponding series of optical data output pulses, said trans-mitting circuitry further including deadman circuitry responsive to a release of said spring-biased deadman switch for cancelling the output of said modulating means;
a fiber optic link, the first end of said link being coupled to the output of said transmitting circuitry;
fiber optic receiving circuitry coupled to the second end of said fiber optic link, said receiving circuitry including demodulating means for reconvert-ing the optical data output pulses of said trans-mitting modulation means into corresponding analog signals representing functions selected by said remote station function selecting means and said output volt-age varying means; and safety circuitry within said receiving circuitry and becoming activated by the canceled optical output of said transmitting circuitry produced by operation of said deadman circuitry or breaking, within said receiving circuitry, the circuitry of said analog signal corresponding to the varying output voltage selected at said remote station, and for delaying for a predetermined delay period the restoration of said varying voltage circuitry after inactivation of said deadman circuitry and corresponding restoration of said transmitting circuitry optical output.

2. The remote control system claimed in Claim 1 wherein said safety circuitry is further activated by a broken fiber optic link.

3. The remote control system claimed in Claim 1 wherein said receiving circuitry includes servo cir-cuitry for comparing an analog position indicating signal received from external apparatus with said analog signal corresponding to varying output voltage, said servo circuitry generating from the signal com-parison error signal an output signal of a polarity necessary to reposition said external apparatus to a position whereby said comparison error signal is canceled.

4. The remote control system claimed in Claim 3 wherein said external apparatus is an electrical positioning motor having a neutral position corres-pending to a neutral positioning of said remote con-trol station output voltage varying means, said receiving circuitry including means for repositioning said motor to said neutral position, irrespective of the positioning of said remote control voltage vary-ing means, upon activation of said safety circuitry.

5. The remote control system claimed in Claim 4 wherein said receiving circuitry includes circuitry responsive to an input power failure for engaging an associated standby power source, for activating said safety circuitry, and for repositioning said motor to said neutral position.

6. The remote control system claimed in Claim 5 wherein said receiving circuitry includes function monitoring circuitry coupled to function signal con-ductors carrying each of said demodulated analog signals representing functions selected by said remote station function selecting means, said monitoring circuitry including means for monitoring the motor output signal of said servo circuitry and for activa-ting said safety circuitry when the selection of said remote station function selecting means is altered while said positioning motor is out of its neutral position.

7. The remote control system claimed in Claim 6 wherein said external apparatus includes a manually activated mechanism coupled by the excitation of a solenoid operated coupler to said positioning motor, the solenoid of said coupler being coupled to one of said receiving circuit function signal conductors in said receiving circuitry and responsive to a demodula-ted analog system therein for operation of said mecha-nism by said positioning motor.

8. The remote control system claimed in Claim 7 wherein said manually actuated mechanism is a hydraul-ic control valve, and wherein said receiving circuitry includes circuitry responsive to an input power fail-ure for opening an external hydraulic bypass valve coupled between a pressurized hydraulic line and a low pressure reservoir.

9. The remote control system claimed in Claim 7 wherein said manually actuated mechanism includes a plurality of hydraulic control valves, each valve in said plurality having a solenoid operated coupler for interconnecting its control valve to a movable valve operating mechanism, said positioning motor being coupled to said valve operating mechanism for pro-viding movement thereto.