In X-Y positioning applications, such as automated pick-and-place, rotary encoders provide feedback on two axis of motion in order to determine X-Y coordinates. The encoder can be attached to the shaft of a ball screw or the drive motor of an actuator. In some cases a pinion gear and rack system or measuring wheel can be used to provide position information.
Mechanically, shaft, thru-bore and even measuring wheel encoders can be applied, depending what design is most readily integrated into the system.
Electrically, variables such as resolution, output type, channels, voltage, etc, all should be specified to meet the individual application requirements. Due to the reciprocating motion, quadrature output is a must since direction must be determined. Additionally an index pulse should be specified to ensure the ability to find a home position. Both incremental and absolute encoders are suitable for X-Y positioning.
Environmentally, proximity of the encoder to potential exposure to liquids, fine particulates and extreme temperatures will dictate specification. In applications with wash down requirements, an IP66 or IP67 seal can offer protection against moisture ingress. However, consider a stainless steel or polymer composite housing or shielding the encoder to mitigate the effects of harsh cleaning chemicals and solvents.