Sensing Shear Forces During Food Manipulation: Resolving the Trade-Off Between Range and Sensitivity

Autonomous assistive feeding systems need to acquire deformable food items of varying physical characteristics to be able to feed users. However, bite acquisition of these deformable food items is challenging without force feedback of appropriate range and sensitivity. We developed custom solutions using two widely-used shear sensing fingertip tactile sensors and calibrated them to the range of forces needed for manipulating food items. We compared their performance with traditional force/torque sensors and showed the trade-off between the range and the sensitivity of the fingertip tactile sensors in detecting potential bite acquisition successes for food items with widely varying weights and compliance. We then developed a control policy, using which a robotic gripper equipped with the fingertip tactile sensors can autonomously regulate the sensing range and the sensitivity to be able to skewer food items of different compliance and detect their bite acquisition success attempts.