Method For Control Of Linear Drive Devices For A Thread-Like Product In Particular A Textile Thread During The Start-Up Phase And Device For Carrying Out The Same

Abstract

A control method for a motor driven linear drive device is provided in which: a device control unit receives information representative of measured speed of said device; on receiving a start-up command, start-up of the motor is not initiated if the measured speed is zero; information representative of the speed of the drive devices is monitored; and a control sequence which brings about rotation of the motor in accordance with a pre-programmed acceleration profile is initiated when rotation of the device caused by an external action is detected.

1 . A method for control of linear drive devices for a thread-like product, in particular a textile thread, during a start-up phase, each of said devices being slaved to an electric motor, the motor being associated with at least one control unit capable of receiving speed and/or speed ratio set points and start/stop commands, 
 wherein:    the device control unit is subjected to a means of measuring the speed of said device;    on receiving a start-up command, start-up of the motor is not initiated if measured speed of the device is zero;    information representative of the speed of at least one of the drive devices is monitored; and    a control sequence which brings about rotation of the motor in accordance with a pre-programmed acceleration profile is initiated when rotation of the device caused by an external action is detected.    
   
   
       2 . A method as claimed in  claim 1 , wherein, when rotation of drive device caused by an external action is detected, a control sequence which brings about rotation of the motor is only initiated if a direction of said rotation matches a pre-determined direction of rotation.  
   
   
       3 . A method as claimed in  claim 2 , wherein, if the direction of the detected rotation caused by an external action is opposite to a parameterized direction of rotation, resisting torque is created.  
   
   
       4 . A method as claimed in  claim 1 , wherein when the start-up command is received, a limited torque to maintain switch-off is created.  
   
   
       5 . A method as claimed in  claim 1 , wherein the external action comprises driving the thread and/or the drive device, said driving being obtained manually by an operator or by auxiliary means.  
   
   
       6 . A method as claimed in  claim 1 , wherein a start-up process of the device comprises: 
 a period during which the motor is kept switched off;    a period during which rotation is caused by an external action;    a period during which rotation is in accordance with the pre-programmed acceleration profile; and    a period of operation at rated speed.    
   
   
       7 . A method as claimed in  claim 1 , wherein the pre-programmed acceleration profile comprises a linear ramp or ramp of any shape whatsoever.  
   
   
       8 . A method as claimed in  claim 1 , wherein: 
 the pre-programmed acceleration profile comprises a plateau of constant intermediate speed that is different from a rated speed set point; and    said intermediate speed is pre-programmed or a rotation speed created by the external action and measured briefly by the means after the external action is detected.    
   
   
       9 . A method as claimed in  claim 8 , wherein: 
 a duration of the plateau is pre-programmed; and    the speed plateau is maintained until the control unit receives an end-of “tracking” mode command or command to change to normal operating mode via an input/output or over a network.    
   
   
       10 . A method as claimed in  claim 3 , wherein the torque is limited during execution of an acceleration phase.  
   
   
       11 . A method as claimed in  claim 10 , wherein the limiting of the torque is fixed and depends on the rotation speed.  
   
   
       12 . A method as claimed in  claim 10 , wherein torque limiting is maintained for a pre-programmed time 
 until the speed reaches a speed of an intermediate speed plateau; or    until an end of the intermediate speed plateau; or    until the speed reaches a rated speed set point; or    until the control unit receives an end-of “tracking” mode command or command to change to normal operating mode via an input/output or over a network.    
   
   
       13 . Apparatus for using the method according to  claim 1 , comprising several thread drive devices, at lease one thread drive device being slaved to a motor associated with a control unit capable of receiving a speed signal, wherein the motor is a variable-reluctance or permanent-magnet motor, a power supply sequence of the motor comprises a sequence for switching power supplies of motor windings synchronized by signals representative of position of a rotor relative to a stator of the motor, said signals being sent to a processor in order to measure and detect the rotation speed of the at least one thread drive device.  
   
   
       14 . Apparatus as claimed in  claim 13 , wherein the signals representative of the position of the rotor relative to the stator are used by the processor in order to determine direction of rotation of the at least one device.  
   
   
       15 . Apparatus for using the method as claimed in  claim 12 , wherein the several drive devices cooperate with each other in order to drive a single thread.  
   
   
       16 . Apparatus as claimed in  claim 15 , wherein each drive device has an individual start-up tracking mode, sensors that output signals representative of device rotation speed and means of waiting for rotation caused by an external action in order to accelerate in accordance with a respective acceleration profile.  
   
   
       17 . Apparatus as claimed in  claim 15 , wherein only one device of the drive devices has an individual start-up tracking mode, and further comprising a control system programmed to keep speed ratios of other devices constant relative to said one device that has the tracking mode, means of measuring rotation speed of the one device, and the speed ratios being predetermined by parameter adjustment.  
   
   
       18 . A device as claimed in  claim 17 , wherein detection of the speed caused by an external action, management of acceleration profiles and, execution of the tracking sequence are performed by a program executed by a central processing unit and/or the control unit.  
   
   
       19 . The method of  claim 3 , wherein the resisting torque is parameterized and/or monitored by voltage or current limiting.