A Virtual Sensor For Needle Deflection Estimation During Soft-Tissue Needle Insertion
A tissue-independent model to estimate needle deflection during insertion in soft tissue is presented in this paper. A force/torque sensor is connected to the needle base in order to measure forces and moments during insertion due to needle deflection. A static mechanical model, which is based on the Euler-Bernoulli beam equation and the balance of forces applied by the tissue onto the needle takes these force and moment measurements as input. The needle tip deflection can then be calculated based on the beam model undergoing these forces. Three different needle-tissue interaction models are presented. Their estimation performance is evaluated and experimentally compared by carrying out insertion experiments into phantom tissue. The experimental results show a precise estimate of needle tip deflection for a novel virtual sensor introduced in this work. The main advantage of this virtual sensor approach is that measurements obtained from the force/torque sensor are the only necessary model inputs. Furthermore, the approach does not rely on ultrasound or other image-based needle observation techniques. This makes the virtual sensor suitable for real-time feedback of needle tip deflection.