A homing routine for a rotating object using a slotted photo sensor is explained here.

(1) Method of homing for a rotating object

Rotating objects are homed in same ways the linear motion objects are homed. There are risks of overrun errors when homing rotary to linear converted objects, but there is no overrun risks when a rotation movement itself is utilized. The configuration only contains one home position sensor. As a sensor target, slotted photo sensor cams can be used. In this case the motor pulse counts are used for the control.
In addition, multiples of photo sensor cams can be used for a various angle settings to control stop positions.

[Photo 1] shows a combination of a slotted photo sensor and a slotted target cam. The system uses two sensors and two cam targets to detect the cam's angle.

[Photo 2] is an enlarged view of the slotted cams. Here, the slot width have been modified to accommodate the motor speeds. MISUMI can provide the cams with customized slot width, shape, number of slots, and shaft bores suit the customers needs for convenience.

(2) Managing sensor wirings

Care must be given to sensor wire management since many automation equipment troubles can be attributed to sensor wire problems. [Photo 3] shows a representative wire management example. Take in consideration the following to perform wiring work.

	・	Align pull direction from terminals to avoid wire strain.
	・	Secure wire where they do not interfere with operation and maintenance work.
	・	Label the wire with numbers to improve maintainability.
	・	Allow ample wire slack for cable carrier use.