Hybrid Force/Velocity Control with Compliance Estimation via Strain Elastography for Robot Assisted Ultrasound Screening

Ultrasound scanning provides a noninvasive solution for additional screening in breast cancer detection and could potentially be improved by utilizing a human-robot collaborative system. Alternative ultrasound modalities, such as elastography, offer promising improvements over current sonography cancer detection rates but require stability and knowledge of applied force. A human-robot scanning system could leverage the sonographer's capabilities to select transducer placement while the robot maintains stability during scanning. This paper presents a novel hybrid force velocity controller for ultrasound scanning which utilizes elastography to provide compliance feedback and improve controller performance. We explore the sensitivity of the elastography algorithm to initial elasticity assumptions and analyze the performance gains of compliance feedback. The results of our study show that our proposed controller provides a performance improvement when poor initial tissue compliance estimates are used.