System Identification and Sliding Mode Control of the Force Sensitive Resistor Calibration Device

Force sensitive resistors (FSRs), commonly utilized in various pressure measurement applications, exhibit distinct characteristics like hysteresis and creep. Accurate calibration, tailored to their specific use, is therefore crucial. To this end, a calibration device capable of delivering precise and repeatable dynamic loads was developed. The essential functionality of this device is its force control, which ensures the accurate application of target loads. However, controlling force with high-speed response is challenging due to the rigidity of the base on which the thin FSR sensors are mounted and compressed by the device's end-effector. To address this challenge, a stable and robust sliding mode force controller was implemented. The dynamic model of the calibration device was established for designing this controller, and its parameters were determined through parameter identification. The system model's performance was enhanced using a four-piece piecewise Hammerstein linear model. The efficacy of the designed controller was validated through force control applications on both static and dynamic loads. Additionally, experiments were conducted to assess the impact of variations in control parameters.