Force and pose control of a hemispherical ultrasonic probe in contact with viscoelastic gelatine

Abstract

Ultrasound probes are widely employed for internal sonification, to detect anomalies and assess mechanical properties. Achieving precise contact and orientation control is crucial for optimizing the transmission of acoustic energy into the test material. This study investigates the contact control of a hemispherical probe against a viscoelastic gelatin (tissue-like) test object. For small applied loads, the signals from the force sensor are often contaminated with noise. To enhance contact measurements, an ultrasound hemispherical probe was designed for Hertzian contact with gelatin. The transmitted/reflected acoustic energy is known to be a function of the contact area, which can be related to the applied force. The transmitted and reflected acoustic energy, which depends on the contact area, is related to the applied force. The goal is to develop an adaptive, model-free algorithm to control the contact force and orientation of the probe to maximize energy transfer. This algorithm integrates reflected acoustic energy at the contact interface with force data as feedback. A multi-input fuzzy controller scheme that is robust to noise and operates in real time is proposed. Numerical and experimental results demonstrate the controller’s stability and its ability to rapidly converge to the desired force and orientation conditions.