Conveying system, method for controlling conveying system, and linear motor

Abstract

A conveying system includes a guide constituting a conveying path, a carrier configured to move along the conveying path, a magnetic member provided on one of the guide and the carrier so as to be arranged along the conveying path, a plurality of coils provided on the other one of the guide and the carrier and configured to generate thrust along the conveying path by generating a moving magnetic field acting on the magnetic member in accordance with supply of power, a magnetic sensor configured to detect magnetism varying with a movement of the carrier, and a controller which is configured to execute position detection of a first method of obtaining a position of the carrier based on inductance variation of the coil and execute position detection of a second method of obtaining a position of the carrier based on an output of the magnetic sensor.

What is claimed is: 
     
         1 . A conveying system comprising:
 a guide constituting a conveying path;   a carrier configured to move along the conveying path;   a magnetic member provided on one of the guide and the carrier, so as to be arranged along the conveying path;   a plurality of coils provided on the other one of the guide and the carrier and configured to generate thrust along the conveying path by generating a moving magnetic field acting on the magnetic member in accordance with supply of power;   a magnetic sensor configured to detect magnetism varying with a movement of the carrier; and   a controller,   wherein the controller is configured to execute:   position detection of a first method of obtaining a position of the carrier based on inductance variation of the coil; and   position detection of a second method of obtaining a position of the carrier based on an output of the magnetic sensor.   
     
     
         2 . The conveying system according to  claim 1 ,
 wherein the magnetic member is provided in the guide, and   the plurality of coils and the magnetic sensor are provided in the carrier.   
     
     
         3 . The conveying system according to  claim 2 ,
 wherein the magnetic member is formed of a soft magnetic material and includes a plurality of salient poles aligned in a direction along the conveying path, and   the controller obtains the position of the carrier based on signal variation due to the salient poles in any of the first method and the second method.   
     
     
         4 . The conveying system according to  claim 1 ,
 wherein the controller is configured to execute:   position detection of the first method when power is supplied to the plurality of coils; and   position detection of the second method when power is not supplied to the plurality of coils.   
     
     
         5 . The conveying system according to  claim 1 ,
 wherein the controller is configured to execute position detection of both the first method and the second method in a case where power is supplied to the plurality of coils, and configure to further execute:   calculation of a difference between a position detection result of the first method and a position detection result of the second method;   adopting the position detection result of the first method in a case where the difference is within an allowable range; and adopting the position detection result of the second method in a case where the difference is outside the allowable range.   
     
     
         6 . The conveying system according to  claim 1 ,
 wherein the guide further includes a scale configured to hold position information,   the carrier further includes a position sensor configured to detect position information held by the scale, and   the controller further executes position detection of a third method for obtaining a position of the carrier based on an output of the position sensor when the position sensor passes through a position at which the scale is arranged.   
     
     
         7 . The conveying system according to  claim 1 , wherein the guide is dividable into a plurality of guide units. 
     
     
         8 . A method for controlling a conveying system using the conveying system comprising: a guide constituting a conveying path; a carrier configured to move along the conveying path; a magnetic member provided on one of the guide and the carrier, so as to be arranged along the conveying path; a plurality of coils provided on the other one of the guide and the carrier and configured to generate thrust along the conveying path by generating a moving magnetic field acting on the magnetic member in accordance with supply of power; and a magnetic sensor configured to detect magnetism varying with a movement of the carrier, the method comprising:
 obtaining a position of the carrier based on inductance variation of the coil; and   obtaining a position of the carrier based on an output of the magnetic sensor.   
     
     
         9 . A linear motor comprising:
 a stator provided along a linear movement path;   a mover configured to move along the movement path;   a magnetic member provided on one of the guide and the carrier along the movement path;   a plurality of coils provided on the other one of the guide and the carrier and configured to generate thrust along the movement path by generating a moving magnetic field acting on the magnetic member in accordance with supply of power;   a magnetic sensor configured to detect magnetism varying with a movement of the mover; and   a controller,   wherein the controller is configured to execute:   position detection of a first method of obtaining a position of the mover based on inductance variation of the coil; and   position detection of a second method of obtaining a position of the mover based on an output of the magnetic sensor.