Analysis of Wheel-Tissue Interaction for In Vivo Robotic Mobility

Providing mobility of miniature, in vivo surgical robots under a variety of changing in vivo conditions is necessary to help expand the application of minimally invasive surgery. Analytical and finite element analysis results of wheeled mobility on tissue inside abdominal cavity are presented here, as a preliminary step towards further improved mobility performance. Results indicate that the mobility of a wheeled robot on tissue is influenced by factors including wheel torque application rate and material relaxation time. While using a viscoelastic standard linear solid material tissue model, the steady state translation speed of the wheel decreases with the increase of material relaxation time given a constant torque application time. Interestingly, at a relaxation time threshold value, the wheel’s steady-state speed no longer decreases, but abruptly undergoes continuous acceleration. Results also indicate that for very small and very large relaxation times the viscoelastic material can be approximated as an elastic material.