referencesensor

A reference sensor is a sensor that provides a known, stable reference value used as a basis for comparison in measurement and control tasks. In control systems, the reference sensor supplies a reference signal or position that the controller uses to compute an error signal and drive actuators toward a target state. In robotics, CNC machines, and metrology, reference sensors are instrumental for establishing a coordinate origin, calibrating instruments, or aligning components before operation.

Common forms of reference sensors include mechanical endstops or limit switches, home switches that indicate a machine’s zero position, optical sensors that detect a fixed reference mark, and magnetic or capacitive/inductive sensors that sense a dedicated reference feature. The choice of sensor depends on factors such as required repeatability, environmental conditions, speed, and lifecycle.

In practice, the reference sensor is often part of a homing or calibration sequence. During homing, triggering the reference sensor fixes a known origin, and all subsequent measurements or actuator positions are described relative to that origin. The sensor can provide digital on/off signals or analog measurements, and it may connect via various interfaces such as digital I/O, PWM, SPI, I2C, CAN, or analog voltage/current schemes.

Key considerations for reference sensors include repeatability and drift, reliability under operating conditions, resistance to noise and false triggers, and ease of maintenance. Redundancy may be employed in critical systems to improve safety and robustness.

See also: reference signal, homing, endstop, calibration, metrology.