SUBJECT: M.S. Thesis Presentation
BY: Alexander Hart
TIME: Thursday, February 1, 2018, 4:00 p.m.
PLACE: Whitaker Ford Building, 2110
TITLE: Positional Estimation of Soft Actuators Through Embedded Sensing
COMMITTEE: Dr. Frank Hammond III, Chair (ME/BME)
Dr. Denis Dorozhkin (ME)
Dr. Jun Ueda (ME)


Soft robotic systems are inherently prone to deformations beyond the desired modes of actuation. The compliant nature of materials used to fabricate them is responsible for this. Kinematic model estimation from pressure is effective for coarse system control, but achieving higher degrees of precision demands integration of more robust sensing techniques. Positional precision and accuracy are necessary for the development of complex systems of soft robots composed of numerous actuators and sensors. As market options for direct soft sensing components are limited, full scope research and development of the desired sensing techniques is required. This process of sensor development involves mechanical design of components, electronic instrumentation, orientation and placement for target actuator deformations, interpretation of response for embedded control, and benchmarking performance for facilitated system integration. The documentation of these attempts at sensor development serves to expand the toolbox of techniques for soft sensing in soft robotic bodies.

Two investigations were conducted in this pursuit. To adapt an existing system for embedded sensing, conductive fluidic microchannel sensors were embedded in bi-directional pneumatic soft actuators for the purpose of driving haptic feedback. Sensors were placed to inform bend on the primary desired mode of actuation as well as undesired modes of deformation for haptic feedback of a prosthetic grasp device. This sensory information informed the user of the prosthetics grasp configuration through vibro-tactile intensity. The second investigation involved the development of an orthotic grasp mechanism. The soft actuators utilized in this system were routed with fiber optics for measuring optical reflectance against an internal diaphragm. With an EMG input, these sensor embedded actuators were employed in feedback control to independently alter grasp configuration to objects of varying shapes.