System for motion control, method of using the system for motion control, and computer readable instructions for use with the system for motion control

• US 7,143,301 B2
• Filed: 05/03/2005
• Issued: 11/28/2006
• Est. Priority Date: 02/09/2001
• Status: Expired due to Fees

• Current Assignee: Motion Engineering, Inc. (Regal Rexnord Corp.)
• Original Assignee: Motion Engineering, Inc. (Regal Rexnord Corp.)
• Inventors: Pearce, Robert, Cline, David
• Primary Examiner(s): Knight, Anthony
• Assistant Examiner(s): HARTMAN JR, RONALD D
• Application Number:
  US11/120,207
• Publication Number:
  US 20050273182A1
• Time in Patent Office: 574 Days
• Field of Search: 713400-401, 327/136, 327/141, 709/248, 709251-252, 370/519, 700 71- 72
• US Class Current: 713/401
• CPC Class Codes: H04J 3/062 Synchronisation of signals having the same nominal but fluctuating bit rates, e.g. using buffers pulse-stuffing H04J3/07; asynchronous-synchronous conversion H04L5/24; speed conversion H04L25/05; speed conversion in computers G06F5/06
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 12/4035 in which slots of a TDMA packet structure are assigned based on a contention resolution carried out at a master unit TDM/TDMA multiplex systems per se H04J3/1694; hybrid switching systems H04L12/64
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing
• CPC Class Codes: H04L 12/422 Synchronisation for ring networks Time Division Multiplex ring networks, e.g. SDH/SONET H04J3/085
• CPC Class Codes: H04L 12/423 with centralised control, e.g. polling
• CPC Class Codes: H04L 2012/4026 Bus for use in automation systems
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically

Abstract

A motion control system and method that includes a central controller configured to generate first and second demand control signals to be used to define actuation motion of respective first and second actuators. The central controller is in communication with first and second nodes by way of a data network, each node including at least a respective actuator configured to implement at an actuator time a motion or force-related effort based upon the respective demand control signal. Each node also includes a memory configured to store at least one respective propagation delay parameter related to a signal propagation delay between the central controller and the node. A timing mechanism establishes timing at each node based on the respective propagation delay parameter so that the actuator time at the nodes occurs simultaneously. Strictly cyclic and/or full-duplex high-speed communication can be supported. The network can be wired in a ring or as a tree and with twisted pair cabling or fiber. The central controller issues demand signals to the nodes that are actuator, servo motor drive, and/or I/O devices. The central controller can also provide a timing message that is used by the nodes, in conjunction with local delay correction circuitry, so that the simultaneous acquisition of data and the simultaneous implementation of controlled action occur.

Claims

1. A method of autoenumerating a plurality of slaves controlled by a central controller in a system for motion control, comprising:

linking the central controller and the slaves in a network;

determining a propagation delay parameter between said central controller and each respective slave in said plurality of slaves by a timing mechanism configured to establish timing at each slave based on the respective propagation delay and to delay reception of a servo clock message at each slave by an amount of time corresponding to the propagation delay parameters for information passed from the central controller to each slave so that actuator times at each of the slaves occurs simultaneously;

transmitting a query message from the central controller along said network;

receiving said query message at a slave of said plurality of slaves in said network;

transmitting an answer message to said query message along said network from said slave to said central controller, said answer message enumerating said slave;

receiving said answer message at said central controller;

retransmitting said query message from said central controller along said network;

relaying said retransmitted query message through said enumerated slave to a further slave; and

transmitting a further answer message to said query message along said network from said further slave through said enumerated slave to said central controller, said further answer message enumerating said further slave.

2. The method according to claim 1, wherein said query message is transmitted in a first direction and said answer message is transmitted in a reverse direction.

3. A computer readable medium storing instructions for execution on a computer system, which when executed by a computer system causes the computer system to perform the method recited in claim 2.

4. The method according to claim 1, wherein said linking step comprises arranging the central controller and the slaves in a ring network.

5. The method according to claim 4, further comprising:

repeating said steps of retransmitting said query message, relaying said query message, and transmitting a further answer message until said further slave comprises a last slave in said ring network;

transmitting said query message from said central controller along said ring network;

relaying said query message through each slave in said plurality of slaves; and

receiving said query message at central controller.

6. A computer readable medium storing instructions for execution on a computer system, which when executed by a computer system causes the computer system to perform the method recited in claim 5.

7. A computer readable medium storing instructions for execution on a computer system, which when executed by a computer system causes the computer system to perform the method recited in claim 4.

8. A computer readable medium storing instructions for execution on a computer system, which when executed by a computer system causes the computer system to perform the method recited in claim 1.

9. A computer readable medium storing instructions for execution on a computer system, which when executed by a computer system, cause the computer system to perform the method recited in claim 1.

10. The method according to claim 1, wherein said linking step comprises arranging the central controller and the slaves in a full-duplex ring network, said method further comprising:

a step of reenumerating, from each of two ports of the central controller, two fragments of a ring that remains connected to the central controller when one or more links of the full-duplex ring network no longer functions or has been removed; and

a step of operating the two fragments as two networks each of a slender tree topology.

11. An autoenumerating motion control system comprising:

a network; and

a central controller and plural slaves communicating with each other via said network; and

at least one timing mechanism, wherein said timing mechanism is configured to establish timing at each slave based on a respective propagation delay parameter for each slave and to delay reception of a servo clock message at each of said plural slaves by an amount of time corresponding to each respective propagation delay parameter for information passed from the central controller to each of said plural slaves so that the actuator times at each of said plural slaves occur simultaneously,

wherein the central controller further comprises;

means for transmitting a query message from the central controller along said network, and means for receiving said answer message at said central controller, and each of said slaves further comprises means for receiving said query message carried by said means for linking, means for transmitting an answer message to said query message along said means for linking from said slave to said central controller, said answer message enumerating said slave, and means for relaying a further query message through said enumerated slave to a further slave and a further answer message to said query message along said network from said further slave through said enumerated slave to said central controller, said further answer message enumerating said further slave.