Diagnostic system for cranes
View Patent ↗A hoist system for critical loads incorporates improved safety technology to monitor various possible fault conditions. For example, a command-not-operated function causes braking of the hoist when an encoder detects one of a group of conditions including a lack of load movement when a movement command is issued by the operating system, failure of encoder feedback, or failure of a control circuit. An uncommanded motion function also causes braking of the hoist when an encoder detects one of a group of conditions including load movement without a movement command issued by the operating system, or reverse directional movement of the load from a directional movement command input by the operating system.
1. A hoisting system comprising:
a hoist for lifting a load;
brakes connected to said hoist;
an operating system for operating said hoist; and
a controller for providing single failure proof operation comprising a command-not-operated function that causes braking of said hoist when an encoder detects one of a group of conditions consisting essentially of: (1) a lack of load movement when a movement command is issued by said operating system, (2) failure of encoder feedback, or (3) failure of a control circuit.
2. The hoisting system of claim 1 , wherein said command-not-operated function further comprises a programmed time delay.
3. The hoisting system of claim 2 , wherein said programmed time delay compensates for a time delay caused by at least one of backlash and, hoist drive torque proof testing.
4. The hoisting system of claim 1 , wherein said controller further comprises an overspeed function that causes braking of said hoist when an encoder detects one of a group of conditions consisting of; (1) a load movement exceeding a predetermined threshold speed in an upward direction, or (2) a load movement exceeding a predetermined threshold speed in a downward direction.
5. The hoisting system of claim 4 , wherein said controller further comprises a differential motion function that causes braking of said hoist when a direction and speed of a load movement does not match a direction and speed of a load movement command issued by said operating system.
6. The hoisting system of claim 5 , further comprising;
a high speed driveline and a low speed driveline; and
wherein said controller further comprises a drive train discontinuity function that causes braking of said hoist when a predetermined ratio difference between said high speed driveline speed and said low speed driveline speed is exceeded.
7. The hoisting system of claim 1 , wherein said controller further comprises a differential motion function that causes braking of said hoist when a direction and speed of a load movement does not match a direction and speed of a movement command issued by said operating system.
8. The hoisting system of claim 1 , further comprising:
a high speed driveline and a low speed driveline; and
wherein said controller further comprises a drive train discontinuity function that causes braking of said hoist when a predetermined ratio difference between said high speed driveline speed and said low speed driveline speed is exceeded.
9. The hoisting system of claim 1 , wherein said encoder is a quadrature encoder.
10. A hoisting system comprising:
a hoist for lifting a load;
brakes connected to said hoist;
an operating system for operating said hoist; and
a controller for providing single failure proof operation comprising:
an uncommanded motion function that causes braking of said hoist when an encoder detects one of a group of conditions consisting of; (1) load movement without a movement command issued by said operating system, or (2) reverse directional movement of said load from a directional movement command input by said operating system.
11. The hoisting system of claim 10 , wherein said controller further comprises an overspeed function that causes braking of said hoist when an encoder detects one of a group of conditions consisting of: (1) a load movement exceeding a predetermined threshold speed in an upward direction, or (2) a load movement exceeding a predetermined threshold speed in a downward direction.
12. The hoisting system of claim 11 , wherein said controller further comprises a differential motion function that causes braking of said hoist when a direction and speed of a load movement does not match a direction and speed of a movement command issued by said operating system.
13. The hoisting system of claim 12 , further comprising;
a high speed driveline and a low speed driveline;
wherein said controller further comprises a drive train discontinuity function that causes braking of said hoist when a predetermined ratio difference between said high speed driveline speed and said low speed driveline speed is exceeded.
14. The hoisting system of claim 13 , wherein said controller further comprises a command-not-operated function that causes braking of said hoist when an encoder detects one of a group of conditions consisting of (1) a lack of load movement when a movement command is issued by said operating system, (2) failure of encoder feedback, or (3) failure of a control circuit.
15. The hoisting system of claim 14 , further comprising a programmed time delay before a function is triggered.
16. The hoisting system of claim 15 , wherein said programmed time delay compensates for at least one of hoist drive deceleration and, operator reverse plugging.
17. The hoisting system of claim 15 , wherein said programmed time delay compensates for at least one of hoist drive deceleration and, operator reverse plugging.
18. The hoisting system of claim 10 , wherein said uncommanded motion function further comprises a programmed time delay.
19. The hoisting system of claim 18 , wherein said programmed time delay compensates for at least one of hoist drive deceleration and, operator reverse plugging.
20. The hoisting system of claim 10 , wherein said encoder is a quadrature encoder.
21. A method of retrofitting a crane assembly with an improved controller, comprising the steps of:
providing a controller providing a single failure proof operation comprising a command-not-operated function that causes braking of a hoist when an encoder detects one of a group of conditions consisting off: (1) a lack of load movement when a movement command is issued by said operating system, (2) failure of encoder feedback, or (3) failure of a control circuit.
22. A method of retrofitting a crane assembly with an improved controller, comprising the steps of:
providing a controller providing a single failure proof operation comprising an uncommanded motion function that causes braking of a hoist when an encoder detects one of a group of conditions consisting of: (1) load movement without a movement command issued by said operating system, or (2) reverse directional movement of a load from a directional movement command input by said operating system.
23. A method of providing a lift hoisting diagnostic system comprising the steps of:
operating an operating system for moving a crane;
issuing a command to move a load with said operating system;
detecting non-movement of said load with an encoder;
transmitting a signal from said encoder to a controller;
comparing said command to move with said signal from said encoder;
transmitting from said controller a command to a braking system; and
braking said crane.
24. The method of providing a lift hoisting diagnostic system of claim 23 , further comprising the step of: compensating for a time delay caused by at least one of backlash and, hoist drive torque proof testing.
25. A method for providing a hoisting diagnostic system comprising steps of:
detecting movement of a load with an encoder:
transmitting a signal from said encoder to a controller;
transmitting a signal from an operating system for commanding movement of said load to said controller;
comparing said signal from said encoder with said signal from said operating system;
transmitting from said controller a command to a braking system; and
braking said crane.
26. The method of providing a hoisting diagnostic system of claim 25 , further comprising the step of compensating for a time delay due to at least one of hoist drive deceleration and, operator reverse plugging.
27. A hoisting diagnostic apparatus comprising;
a controller for providing single failure proof operation comprising;
a command-not-operated function that causes braking of a hoist when an encoder detects one of a group of conditions consisting of: (1) a lack of load movement when a movement command is issued by a operating system, (2) failure of encoder feedback, or (3) failure of a control circuit.
28. A hoisting diagnostic apparatus comprising;
a controller for providing single failure proof operation comprising:
an uncommanded motion function that causes braking of a hoist when an encoder detects one of a group of conditions consisting of: (1) load movement without a movement command issued by an operating system, or (2) reverse directional movement of a load from a directional movement command input by said operating system.
29. A hoisting diagnostic apparatus comprising:
a controller for operating a crane comprising:
a complex programmable logic device for receiving signals;
a processor for interfacing with said complex programmable logic device; and
wherein said complex programmable logic device is programmed with encoder counter logic.
30. The hoisting diagnostic apparatus of claim 29 , wherein said complex programmable logic device further comprises encoder signal filters.
31. The hoisting diagnostic apparatus of claim 29 , wherein said complex programmable logic device further comprises encoder edge decoders.
32. The hoisting diagnostic apparatus of claim 29 , wherein said complex programmable logic device further comprises encoder counter control logic.