The cool muscle motor is capable of performing an origin search and home itself automatically, or on command. Homing can be performed to an origin switch or to a hard stop. There are six different K parameters that define the operation of the origin search:

The origin search can be performed in either the clockwise or counter clockwise directions, on power up or on command, as well as to a home sensor or hard stop. 

Home to Hard Stop

When the motor homes to a hard stop, it will move in the direction specified in K45 until it encounters a resistance where the motor torque rises above the value specified in K47. When the motor stops, it will then travel a small amount in the opposite direction to the nearest tooth top dead center on the magnetic encoder, and then one full tooth more. This is to reduce any variability in the home location. Any small variance in the origin location is eliminated because it will always move to that tooth. The magnetic encoder has 50 teeth, so the maximum amount this move could be is 1/50th of a rotation.

When the motor hits the hard stop, it will send out a message indicating how far between teeth the hard stop was encountered. This number could be anywhere from 0-1000. The motor will report this as "Origin.1=xxx" where xxx is the number of pulses between teeth that the origin was encountered. For improved repeatability, it is best if this number is as close as possible to the mid point, 500.

If there is an offset programmed in K48, the motor will then move this distance after the mechanical origin is found.

Home to Origin Sensor

When the motor is set to home to an origin sensor, it will proceed again in the direction indicated by K45. The torque for this move can also be set in K47, however, if the torque is exceeded it will not register this as home. The origin location will be set when an input programmed as 'origin sensor' in K27 or K30 is triggered. The motor will rotate until the rising edge of the input is detected, and then back off until the falling edge is detected so that the origin becomes the very edge of when the sensor is detected. 

If the origin search is started and the origin sensor input is already triggered, the motor will rotate in the opposite direction of K45 until the input turns off. The motor will then begin the regular home procedure as described above.  

Homing Methods

Two distinct methods are available when executing a home routine.

1. Hardstop detect - the motor moves towards a hardstop. When the hardstop is reached the driver reads the position of the magnetic encoder. It then moves back 2 teeth of the encoder gear to set the absolute position. Moving back the two teeth allows for high repeatability as fatigue and variance in the hardstop detect can be accounted for automatically.
2. Sensor detect - the motor moves towards a home sensor. When the sensor is triggered the driver interrupt captures the motor position. The motor decelerates and moves back to the captured position.
   1. If the sensor is detect when the home routine is first initiated the motor will move off the sensor first in the opposite direction to the defined origin search direction. 

Hardstop CW -

1. Motor runs CW towards a hardstop. 
2. The driver monitors the motor current and detects when a hardstop has been reached. 
3. Motor backs up CCW to the 2nd previous encoder tooth (improved repeatability) and sets the position to 0.
4. If an offset is set the motor moves the offset distance
   1. Care should be taken not to set a +ve offset as this will move the load into the hardstop
5. Sets the final position to 0.

Hardstop CCW -

1. Motor runs CCW towards a hardstop. 
2. The driver monitors the motor current and detects when a hardstop has been reached. 
3. Motor backs CW up to the 2nd previous encoder tooth (improved repeatability) and sets the position to 0.
4. If an offset is set the motor moves the offset distance.
   1. Care should be taken not to set a -ve offset as this will drive the load into the hardstop
5. Sets the final position to 0.

Sensor CW - 

• Diagram shown with motor connected to linear actuator.
  • CW rotation moves the load left to right
• Sensor is connected directly on IN2 or IN3

1. Motor runs CW waiting for sensor input
2. Sensor rising edge triggers the input, motor captures encoder position, decelerates and reverses direction
3. Motor stops on captured position and sets position to 0
4. If an offset is defined the motor continues to the defined offset and sets the final target position to 0.
   1. Offset could be +ve or -ve. The above diagram shows a -ve offset

Sensor CCW - 

• Diagram shown with motor connected to linear actuator.
  • CCW rotation moves the load right to left
• Sensor is connected directly on IN2 or IN3