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EP-4741952-A1 - REDUNDANT SAFETY CONTROL FOR A LINEAR MOTOR CONVEYOR

EP4741952A1EP 4741952 A1EP4741952 A1EP 4741952A1EP-4741952-A1

Abstract

Safe torque-off (STO) functionality can be used to ensure the driving power to at least a section of a linear motor is de-energized. The STO may use a plurality of safety mechanisms for redundantly de-energizing the coils of the linear motor. The safety mechanisms may include disconnecting the motor power supply from power circuitry, shorting the motor power supply to ground, and/or disconnecting an operating supply from control circuitry.

Inventors

  • WOBLICK, Frank

Assignees

  • ATS Corporation

Dates

Publication Date
20260513
Application Date
20251107

Claims (15)

  1. A redundant safety control system for a linear motor conveyor comprising: safety control inputs comprising first and second inputs for receiving respective first and second safety signals indicating a condition requiring de-energizing driving power of at least a section of the linear motor conveyor; a first safety circuit controlled by the safety control inputs, the first safety circuit controllably disconnecting power supplied to a power circuit based on the control inputs, the power circuit providing power to drive at least one coil of the at least one section of the linear motor conveyor; and a second safety circuit controlled by the safety control inputs, the second safety circuit shorting the power supplied to the power circuit to ground based on the second input control signal.
  2. The redundant safety control system of claim 1, further comprising a third safety circuit controlled by the safety control inputs, the third safety circuit disconnecting operating power supplied to control circuitry controlling the power circuit.
  3. The redundant safety control system of claim 1 or 2, wherein the second safety circuit comprises an input signal delay to delay the shorting of the power relative to the disconnecting of the power supplied to the power circuit.
  4. The redundant safety control system of claim 3, wherein the input signal delay provides a sufficient delay after disconnecting of the power supplied to the power circuit to avoid current transients when shorting of the power.
  5. The redundant safety control system of any one of claims 1 to 4, wherein the first safety circuit comprises a controllable eFuse.
  6. The redundant safety control system of any one of claims 1 to 5, wherein the power circuit comprises an H-bridge circuit.
  7. The redundant safety control system of any one of claims 1 to 6, wherein the second safety circuit shorts the power supplied to the power circuit through a MOSFET.
  8. The redundant safety control system of any one of claims 1 to 7, wherein the power circuit provides power to linear motor components for providing a motive force to the shuttles on the section of the linear motor conveyor.
  9. The redundant safety control system of claim 8, wherein the track section comprises a plurality of coil drivers each for driving one or more respective coils of the linear motor conveyor.
  10. The redundant safety control system of any one of claims 1 to 9, wherein the first and second safety signals are set in response to one or more of: opening of a guarding door; detected presence of an operator in a controlled area; activation of an emergency stop switch; detection of an error at the conveyor; and a manually provided indication of a desire to stop movement of shuttles.
  11. The redundant safety control system of any one of claims 1 to 10, further comprising one or more feedback signals providing an indication that no power is supplied to the power circuit.
  12. A method of redundantly stopping movement of a shuttle on a track section of a linear motor conveyor, the method comprising: setting both a first safety signal and a second safety signal, the first and second safety signals indicating a condition requiring stoppage of shuttles moving on at least a section of the linear motor conveyor; disconnecting power supplied to a power circuit used to drive one or more coils of the linear motor conveyor in response to the safety signals; and disconnecting power supplied to the power circuit and shorting the power input of the power circuit to ground in response to the safety signals.
  13. The method of claim 12, wherein disconnecting the power supplied to the power circuit uses a controllable eFuse.
  14. The method of claim 12 or 13, wherein shorting the power supplied to the power circuit uses a MOSFET.
  15. A non-transitory computer readable medium storing instructions which when executed by a processor perform a method according to any one of claims 12 to 14.

Description

RELATED APPLICATIONS The current application claims priority to U.S. Provisional Application 63/718,374, filed November 8th, 2024 and entitled "Redundant Safety Control For A Linear Motor Conveyor," the entire contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD The current application relates to redundant safety control for a linear motor conveyor system and in particular to de-energizing driving power for at least a portion of the linear motor conveyor. BACKGROUND Linear motor conveyor systems use electromagnetics to controllably move shuttles along a track. The shuttles can convey parts, components or other tooling through different manufacturing and/or packaging processes. Track sections include a number of individually controllable coils that can provide a motive force to the shuttles. In an operating environment, it is desirable, and potentially necessary, to protect individuals from potential contact with moving components such as the shuttles. Such protection may be provided by enclosing the conveyor system and other tooling within an enclosure. However, it may be necessary for an individual to enter the enclosed area, for example, to fix a problem, replace, refill or empty components etc. It is desirable to ensure that the shuttles cannot move during such operations, or in other scenarios where an individual or object may be in a position that could be hit by a moving shuttle. One way to ensure that a shuttle cannot move is to turn off the driving power to the conveyor system. While such functionality, often referred to as Safe Torque-Off (STO), is effective at preventing unintended movement of a shuttle, they can be complex to implement for linear motor conveyors due at least in part to the linear arrangement of the large number of driving coils. Existing STO functionality may turn off the supply power to entire large sections of a linear motor conveyor. Additional, alternative and/or improved STO functionality for linear motor conveyor systems is desired. BRIEF DESCRIPTION OF THE DRAWINGS Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which: FIG. 1 depicts an illustrative linear motor conveyor system;FIG. 2 depicts an illustrative implementation of the safe torque-off (STO) functionality;FIG. 3 depicts a further illustrative implementation of the STO functionality;FIG. 4 depicts an illustrative track section of a linear motor conveyor system using STO functionality;FIG. 5 depicts a further track section of a linear motor conveyor system using STO functionality;FIG. 6 depicts a further track section of a linear motor conveyor system using STO functionality with feedback signals;FIG. 7 depicts a method of implementing the STO functionality;FIG. 8 depicts a further implementation of the STO functionality on at least a portion of a track section;FIG. 9 depicts a further illustrative implementation of the STO functionality;FIG. 10 depicts a further illustrative implementation of the STO functionality; andFIG. 11 depicts a method of implementing the STO functionality. DETAILED DESCRIPTION In accordance with the present disclosure there is provided a redundant safety control system for a linear motor conveyor comprising: safety control inputs comprising first and second inputs for receiving respective first and second safety signals indicating a condition requiring de-energizing driving power of at least a section of the linear motor conveyor; a first safety circuit controlled by the safety control inputs, the first safety circuit controllably disconnecting power supplied to a power circuit based on the control inputs, the power circuit providing power to drive at least one coil of the at least one section of the linear motor conveyor; and a second safety circuit controlled by the safety control inputs, the second safety circuit shorting the power supplied to the power circuit to ground based on the second input control signal. In a further embodiment of the redundant safety control system, the redundant safety control system further comprises a third safety circuit controlled by the safety control inputs, the third safety circuit disconnecting operating power supplied to control circuitry controlling the power circuit. In a further embodiment of the redundant safety control system, the second safety circuit comprises an input signal delay to delay the shorting of the power relative to the disconnecting of the power supplied to the power circuit. In a further embodiment of the redundant safety control system, the input signal delay provides a sufficient delay after disconnecting of the power supplied to the power circuit to avoid current transients when shorting of the power. In a further embodiment of the redundant safety control system, the delay is at least 5ms. In a further embodiment of the redundant safety control system, the delay is pro