UBC Theses and Dissertations
Sensorless plunger position control and differential plunger position self-sensing using constant air gap solenoids Reinholz, Bradley
Industry 4.0 cyber-physical systems will require innovative new technologies including smart sensors that can monitor their own health and smart actuators that can be controlled without a dedicated position sensor. A novel constant air gap solenoid (CAS) is presented that is configurable as a smart actuator or a smart sensor. The novel CAS actuator and CAS sensor have the unique ability to simultaneously produce two distinct self-sensed plunger position measurements unlike other electromagnetic actuators or inductive differential position sensors. These measurements can then be fused to produce a single wide-bandwidth position measurement that performs more robustly than the individual self-sensed measurements. The CAS actuator is first studied by deriving equations to describe and predict its behavior. Next, finite element analysis is utilized to investigate a basic CAS actuator geometry and predict its force and inductance characteristics. The finite element analysis results are then imported into a lumped-parameter simulation built within Simulink to predict CAS actuator performance characteristics. Afterwards, a physical prototype of the simulated geometry is fabricated and experimentally validated. The experimental results demonstrate that the prototype is capable of 40Hz sensorless plunger control for 1mm ramp and step trajectories. The CAS sensor is developed by configuring two CASs to pull against each other to allow differential measurements to be obtained. The derived analytical equations prove that the differential measurements are immune to factors, such as resistance changes due to temperature. The CAS sensor, like the CAS actuator is first studied using finite element analysis, then a Simulink simulation and is finally experimentally validated with a physical prototype. The experimental results show accurate noise-cancelling measurements that can maintain less than 1% nonlinearity. If a current sensor is removed, the CAS sensor can still achieve approximately 3% nonlinearity over its 3mm stroke, proving that it has inherent failure redundancy. The results of this work demonstrate the CAS actuator and CAS sensor have distinct advantages over comparable actuation and sensing technologies. Furthermore, this work experimentally demonstrates a CAS can be configured to be a smart actuator or a smart sensor and therefore is applicable to cyber-physical systems and other practical applications.
Item Citations and Data
Attribution-NonCommercial-NoDerivatives 4.0 International