Position encoder with limits

A method for controlling a structural member coupled to a position encoder that includes a first sensor, a second sensor, and a carrier adapted to move with respect to the first sensor and the second sensor, the carrier including encoding elements situated on the carrier to interact with the first sensor, a first limit indicator, separate from the encoding elements, situated at a first location on the carrier to interact with the second sensor at a first position of the carrier corresponding to a first limit of the position encoder, and a second limit indicator, separate from the encoding elements and the first limit indicator, situated at a second location on the carrier to interact with the second sensor at a second position of the carrier corresponding to a second limit of the position encoder, the method comprising:

• controlling an actuator to move the structural member toward a new position, movement of the structural member causing the carrier of the position encoder to move with respect to the first sensor and the second sensor of the position encoder;
• receiving incremental position information from the position encoder as the actuator moves the structural member toward the new position, the incremental position information generated by the first sensor in response to interaction of the encoding elements with the first sensor as the carrier of the position encoder moves with respect to the first sensor of the position encoder;
• receiving a limit indication from the position encoder, the limit indication generated by the position encoder in response to detection of the first limit indicator or the second limit indicator by the second sensor;
• and
• stopping or reversing the movement of the structural member by controlling the actuator in response to the receiving of the limit indication.