Sensors & Control Engineering
Control refers to the process of regulating or manipulating the behaviour of a system to achieve desired outcomes. In electro mechanisms, control plays a key role in managing and optimizing system performance. It aims at reducing the error of an actuator response compared to the input order.
At CTEC, the driver and the controller parts are always combined in the same single box or rack referred to as “The controller”. The controller is based on microprocessor hardware with implemented digital control laws to allow fast, accurate and reliable computations.
Integrated in the control loop, the position sensor is a key element in a control loop to get a response from the mechanism output.
Sensors
As a standard practice at CTEC, we use strain gauges on our piezoelectric mechanisms. Directly bonded to the piezoelectric ceramic, the strain gauge allows for an indirect measurement of the mechanism’s movement through the deformation of the ceramic. These sensors offer the advantage of being compact and easily integrable. However, they have a limitation when the desired dynamic performance approaches the resonance frequency of the mechanism. The mechanical amplification of the resonance introduces an error between the expansion of the ceramics and the actual movement of the mechanism.
For demanding control requirements and magnetic mechanisms, CTEC utilizes Eddy Current Sensors (ECS sensors) to achieve a direct reading of the mechanism. This technology, combined with a more advanced control, allows us to precisely control our mechanisms even up to and beyond their resonance. However, this type of sensor requires more space and imposes additional integration constraints on the mechanism.
CTEC can customise its Eddy Current Sensor technology to suit your specific application: embedded linear or angular sensors, such as flat ECS on PCB placed below the mirror in FSM and DTT mechanisms and micro switching sensing solutions for tangential and normal motion detection.
Control
Depending on the application and the aimed performances, control is customized for each specific development. The table below summarizes the error analysis needs for different applications:
Functions
Slow positioning
Fast positioning
Tracking
Rejection of vibration
Applications
Static
Dynamic
Dynamic