In order for a robot to accurately repeat a sequence of motions each time the system is powered up, the position of the each motor relative to a fixed reference must consistently be reestablished. If a motor is equipped with an absolute encoder, the encoder provides the position reference information. However, many motors are equipped with an incremental encoder. Incremental devices can provide very accurate data on the relative position of a motor but no fixed reference. For incremental position sensors, a motion sequence must be performed after the controller is powered up to determine the motor position relative to a reference (home) location.
For both absolute positioning devices and relative positioning devices, the process of establishing the motor position with respect to a fixed reference is called a "homing" sequence or method. All axes must be homed each time that the controller is restarted. For some axes, homing is as straight forward as reading the current value of the position sensing device. For other axes, homing may be accomplished by a series of motions in combination with reading sensors.
For a more detailed explanation of the overall process, please see Overview of homing the robot.
For learning how to execute the homing sequence, please see Executing the robot homing sequence.
To better understand the homing methods supported, please see See "Introduction to the Homing Methods" on page 1.