Hill-climbing & fuzzy combined control algorithm for a percussive ultrasonic drill

Abstract

Deep space exploration is research highlights at present and the percussive ultrasonic drill is one of the commonly used anchoring devices on asteroid probes. The resonant piezoelectric transducer drives the percussive ultrasonic drill to convert high-frequency electrical energy into mechanical vibration making the drilling tool break the rock. In order to realize the stable drilling of the percussive ultrasonic drill in a short time, the control algorithms for resonant frequency capturing and resonant frequency tracking are studied. The equivalent circuit model of the ultrasonic transducer was established and the impedance characteristics, load characteristics, temperature characteristics, and hysteresis characteristics of the transducer were analyzed based on the equivalent model. According to the working characteristics of the transducer, this paper studies the hill-climbing algorithm applied to capture the resonant frequency and the fuzzy control frequency tracking algorithm based on the minimum impedance and analyzes the actual control effect. The experimental results show that the proposed climbing algorithm for the frequency capturing reduces the time by 1.3 s compared to the frequency scan, and the proposed fuzzy control for frequency tracking reduces the minimum impedance by 19.5 Ω and the phase angle by 9.7° compared to PLL tracking. The proposed resonance control algorithm can realize the fast and stable frequency driving of the percussive ultrasonic drill under different temperature environments and drilling object conditions.