Storage and retrieval machine having improved real-time responsiveness and improved noise immunity

• US 5,815,085 A
• Filed: 11/16/1995
• Issued: 09/29/1998
• Est. Priority Date: 11/16/1995
• Status: Expired due to Fees

• Current Assignee: HK Systems Incorporated (KION GROUP AG)
• Original Assignee: HK Systems Incorporated (KION GROUP AG)
• Inventors: Schneider, Randall M., Crucius, Wesley
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Asongwed, Anthony A.
• Application Number:
  US08/558,426
• Time in Patent Office: 1,048 Days
• Field of Search: 340/825.5, 340/825.35, 414/270, 414/273, 414/276, 414/272, 300/825.06
• US Class Current: 340/3.31
• CPC Class Codes: B66F 9/07 Floor-to-roof stacking devices, e.g. "stacker cranes", "retrievers"
• CPC Class Codes: B66F 9/24 Electrical devices or systems
• CPC Class Codes: H04L 25/4917 using multilevel codes
• CPC Class Codes: H04L 27/32 Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26

Abstract

A communication system for a storage and retrieval machine comprises a conductor bar, base and carriage electrical devices, a sliding brush, first and second transmitters, and first and second receivers. The sliding brush is mounted to the carriage and is in slidable electrical contact with the conductor bar. The transmitters and receivers are coupled to the conductor bar or the sliding brush, depending on the direction of transmission. The first and second transmitters transmit positive half-waves and negative half-waves, respectively, across the conductor bar in response to inputs. Hence, two one-bit intra SRM communication links are provided between the SRM carriage and base. A communication system for communicating high priority and low priority messages between a base and carriage of an SRM comprises base and carriage electrical devices, and first and second communication links. Specifically, the first communication link includes a conductor bar, a sliding brush, and a first transmitter and first receiver which are coupled to either the conductor bar or the sliding brush, depending on the direction of transmission. The first communication link communicates high priority messages. The second communication link, which includes first and second optical modems on the carriage and base, respectively, communicates the low priority messages. The present invention advantageously permits increased real-time responsiveness of the SRM control system, enjoys increased noise immunity, and uses low maintenance components.

Claims

1. A communication system for a storage and retrieval machine having a mast, a base and a carriage, said carriage being vertically movable along said mast, said communication system comprising:

a signal generator supplying a signal having positive and negative half-waves;

a conductor bar extending along said mast of said storage and retrieval machine to said carriage;

a base electrical device mounted to said base of said storage and retrieval machine;

a sliding brush, said sliding brush being mounted to said carriage, and said sliding brush being in slidable electrical contact with said conductor bar;

a carriage electrical device mounted to said carriage of said storage and retrieval machine;

a first transmitter and a first receiver, one of said first transmitter and said first receiver being coupled to said base electrical device and to said conductor bar, the other of said first transmitter and said first receiver being coupled to said carriage electrical device and to said sliding brush, said first transmitter being further coupled to said signal generator, and said first transmitter defining means for transmitting said positive half-waves across said conductor bar to said first receiver in response to an input of said first transmitter and thereby defining a first one-bit intra storage and retrieval machine communication link between said carriage electrical device and said base electrical device; and

a second transmitter and a second receiver, one of said second transmitter and said second receiver being coupled to said base electrical device and to said conductor bar, the other of said second transmitter and said second receiver being coupled to said carriage electrical device and to said sliding brush, said second transmitter being further coupled to said signal generator, and said second transmitter defining means for transmitting said negative half-waves across said conductor bar to said second receiver in response to an input of said second transmitter and thereby defining a second one-bit intra storage and retrieval machine communication link between said carriage electrical device and said base electrical device.

2. A communication system for a storage and retrieval machine according to claim 1, wherein said first transmitter comprises

a first transmitter relay, said first transmitter relay closing in response to said transmitter input, said closure of said first transmitter relay permitting said positive half-waves of said signal generator to be transmitted on said conductor bar;

and

a first receiver relay, said first receiver relay closing in response to said positive half-waves transmitted on said conductor bar, said first receiver relay forming an output of said first receiver;

and wherein said transmitter and receiver relays further define means for filtering noise in said first one-bit intra storage and retrieval machine communication link.

3. A communication system for a storage and retrieval machine according to claim 1, wherein said base electrical device is a computer implementing a supervisory control.

4. A communication system for a storage and retrieval machine according to claim 3, wherein said carriage electrical device includes first and second sensors and a shuttle controller, said first and second sensors being coupled to said shuttle controller, said shuttle controller being coupled to said first and second transmitters, and said first and second transmitters being coupled to said sliding brush.

5. A communication system for a storage and retrieval machine according to claim 4;

wherein said shuttle controller and said supervisory control define means for altering the meaning of bits transmitted over said first and second one-bit intra storage and retrieval machine communication links.

6. A communication system for a storage and retrieval machine according to claim 1, further comprising

a first optical modem, said first optical modem being mounted on said carriage of said storage and retrieval machine;

a second optical modem, said second optical modem cooperating with said first optical modem to provide a third intra storage and retrieval machine communication link between said carriage electrical device and said base electrical device;

and wherein said first and second communication links communicate high priority messages, and said third communication link communicates low priority messages.

7. A communication system for communicating high priority messages and low priority messages, said communication system comprising:

a first electrical device;

a second electrical device, said second electrical device being mounted to a carriage, said carriage being movable along an axis of motion;

a first communication link, said first communication link including

a conductor bar extending along said axis of motion of said carriage,

a sliding brush, said sliding brush being mounted to said carriage and being in slidable electrical contact with said conductor bar,

a first transmitter, said first transmitter being coupled to one of (1) said conductor bar and said first electrical device and (2) said sliding brush and said second electrical device,

a first receiver, said first receiver being coupled to the other of (1) said conductor bar and said first electrical device and (2) said sliding brush and said second electrical device,

and wherein said first transmitter and said first receiver cooperate so as to define a one-bit communication link that communicates said high priority messages between said first electrical device and said second electrical device; and

a second communication link, said second communication link including

a first modem, said first modem being coupled to said first electrical device,

a second modem, said second modem being mounted on said carriage and being coupled to said second electrical device,

and wherein said first modem and said second modem cooperate so as to define a serial communication link that communicates said low priority messages between said first electrical device and said second electrical device.

8. A communication system according to claim 7, further comprising

a signal generator supplying a signal having positive and negative half-waves, said first transmitter transmitting said positive half-waves of said sine wave across said conductor bar;

a second transmitter, said second transmitter being coupled to one of (1) said conductor bar and said first electrical device and (2) said sliding brush and said second electrical device, and said second transmitter transmitting said negative half-waves across said conductor bar;

a second receiver, said second receiver being coupled to the other of (1) said conductor bar and said first electrical device and (2) said sliding brush and said second electrical device, said second receiver cooperating with said second transmitter to communicate said high priority messages between said carriage electrical device and said base electrical device.

9. A communication system according to claim 8, wherein said first electrical device and said second electrical device define means for altering the meaning of bits transmitted from said first transmitter to said first receiver and from said second transmitter to said second receiver.

10. A communication system according to claim 7, wherein said first transmitter comprises

a first transmitter relay, said first transmitter relay closing in response to a transmitter input, said closure of said first transmitter relay permitting positive half-waves of a signal generator to be transmitted on said conductor bar;

and

a first receiver relay, said first receiver relay closing in response to said positive half-waves transmitted on said conductor bar, said first receiver relay forming an output of said first receiver;

and wherein said transmitter and receiver relays define means for filtering noise on said conductor bar.

11. A communication system according to claim 7, wherein said high priority messages and said low priority messages are communicated between a base and carriage of a storage and retrieval machine.

12. A communication system for communicating high priority messages and low priority messages within a storage and retrieval machine, said storage and retrieval machine having a mast, a base and a carriage, said carriage being vertically movable along said mast, said communication system comprising:

a carriage electrical device mounted to said carriage of said storage and retrieval machine;

a base electrical device mounted to said base of said storage and retrieval machine;

a first communication link, said first communication link including

a conductor bar extending along a mast of said storage and retrieval machine,

a sliding brush, said sliding brush being mounted to said carriage and being in slidable electrical contact with said conductor bar,

a first transmitter, said first transmitter being coupled to one of (1) said conductor bar and said base electrical device and (2) said sliding brush and said carriage electrical device,

a first receiver, said first receiver being coupled to the other of (1) said conductor bar and said base electrical device and (2) said sliding brush and said carriage electrical device, said first receiver and said first transmitter defining means for communicating said high priority messages between said carriage electrical device and said base electrical device; and

a second communication link, said second communication link including

a first optical modem, said first optical modem being mounted on said carriage of said storage and retrieval machine and being coupled to said carriage electrical device,

a second optical modem, said second optical modem being coupled to said base electrical device, and said second optical modem and said first optical modem defining means for communicating said low priority messages between said carriage electrical device and said base electrical device.

13. A communication system according to claim 12, further comprising

a signal generator supplying a signal having positive and negative half-waves, said first transmitter transmitting said positive half-waves across said conductor bar;

a second transmitter, said second transmitter being coupled to one of (1) said conductor bar and said base electrical device and (2) said sliding brush and said carriage electrical device, and said second transmitter transmitting said negative half-waves across said conductor bar;

a second receiver, said second receiver being coupled to the other of (1) said conductor bar and said base electrical device and (2) said sliding brush and said carriage electrical device, said second receiver cooperating with said second transmitter to communicate said high priority messages between said carriage electrical device and said base electrical device.

14. A communication system according to claim 13, wherein said first transmitter and said first receiver define a first one-bit intra storage and retrieval machine communication link, wherein said second transmitter and said second receiver define a second one-bit intra storage and retrieval machine communication link.

15. A communication system according to claim 14, wherein said base electrical device and said carriage electrical device define means for altering the meaning of bits transmitted over said first and second one-bit intra storage and retrieval machine communication links.

16. A communication system according to claim 13, wherein said second optical modem is mounted to said base of said storage and retrieval machine.

17. A communication system according to claim 12, wherein said first transmitter comprises

a first transmitter relay, said first transmitter relay closing in response to a transmitter input, said closure of said first transmitter relay permitting positive half-waves of a signal generator to be transmitted on said conductor bar;

and

a first receiver relay, said first receiver relay closing in response to said positive half-waves transmitted on said conductor bar, said first receiver relay forming an output of said first receiver;

and wherein said transmitter and receiver relays define means for filtering noise on said conductor bar.

18. A method of communicating high priority messages and low priority messages between a base and a carriage of a storage and retrieval machine, the method comprising:

A. establishing a low priority communication link between said base and said carriage, said low priority communication link comprising a first modem which is associated with said base and a second modem which is associated with said carriage;

B. establishing a high priority communication link, said high priority communication link comprising a first transmitter, a first receiver, a second transmitter, and a second receiver, said first transmitter being adapted for transmitting positive half-waves to said first receiver and said second transmitter being adapted for transmitting negative half-waves to said second receiver, and two of said first transmitter, said first receiver, said second transmitter, and said second receiver being associated with one of said base and said carriage and the other two being associated with the other of said base and said carriage;

C. generating a low priority message;

D. transmitting said low priority message over said low priority communication link;

E. generating a high priority message; and

F. transmitting said high priority message over said high priority communication link, including the step of transmitting one bit of information by transmitting either said positive half-waves or said negative half-waves using either said first transmitter or said second transmitter;

wherein steps (C), (D), (E) and (F) occur regularly during operation of said storage and retrieval machine; and

wherein an amount of time which separates performances of step (E) and corresponding performances of step (F) is insubstantial as compared to an amount of time which separates performances of step (C) and corresponding performances of step (D), such that said high priority messages are transmitted substantially without delay.

19. A method of communicating between a base and a carriage of a storage and retrieval machine, the method comprising:

providing a conductor bar, said conductor bar electrically coupling said base to said carriage by way of (1) a first receiver and a first transmitter which are disposed on electrically opposite sides of said conductor bar, and (2) a second receiver and a second transmitter which are disposed on electrically opposite sides of the conductor bar;

generating a signal having positive and negative half-waves;

transmitting a first bit of information across said conductor bar, including the step of transmitting said positive half-waves across said conductor bar to said first receiver in response to an input of said first transmitter; and

transmitting a second bit of information across said conductor bar, including the step of transmitting said negative half-waves across said conductor bar to said second receiver in response to an input of said second transmitter.

20. A communication system for communicating between a base and a carriage of a storage and retrieval machine, said communication system comprising:

A. a first electrical device;

B. a second electrical device, said second electrical device being mounted to a carriage, said carriage being movable along an axis of motion;

C. a first communication link, said first communication link including

1. a conductor bar extending along said axis of motion of said carriage,

2. a sliding brush, said sliding brush being mounted to said carriage and being in slidable electrical contact with said conductor bar,

3. a first transmitter, said first transmitter being coupled to one of (1) said conductor bar and said first electrical device and (2) said sliding brush and said second electrical device, and

4. a first receiver, said first receiver being coupled to the other of (1) said conductor bar and said first electrical device and (2) said sliding brush and said second electrical device; and

D. a second communication link, said second communication link including

1. a first modem, said first modem being associated with said base and being coupled to said first electrical device, and

2. a second modem, said second modem being associated with said carriage and being coupled to said second electrical device.