Soft Exosuits for Walking Assistance
Prior to joining Virginia Tech, Dr. Asbeck led the development of several soft exosuits for assisting walking. Exosuits apply forces to the body in parallel with the wearer’s muscles so that walking (or other motions) results in less fatigue. These suits can be used to give healthy individuals greater endurance, or can be used to provide small corrections to an impaired individual’s gait.
One design is a multi-articular exosuit extending from the heel to the waist. The exosuit applies force on transitions between legs, which is when the body uses the most energy. The calf muscles push the body upward and forward, while the thigh muscles begin to swing the leg forward. The exosuit is able to help both of these motions since it crosses both the ankle and hip joints.
In addition to the multi-articular design, Dr. Asbeck was involved in the creation of several hip-assistance exosuits. Some, made completely of textiles, were designed to assist the hip in both directions (flexion and extension). An additional design uses a backpack frame to attach to the upper body and assists hip extension. This was made to be used by hikers, especially while walking uphill which requires a large amount of power at the hip.
Low-cost Robotic Arms
At Stanford, Dr. Asbeck developed a low-cost 7-DOF robotic arm with Morgan Quigley. Initial designs used laser-cut plywood for ease of rapid-prototyping; they also explored sheet metal and other scalable but low-cost and easily customizable manufacturing methods.
The robot was designed to be backlash-free with sub-mm resolution, with a payload of 2+ kg. To achieve this, they used stepper motors combined with low gear reductions via timing belts and cables. The stepper motors have high torque at low speeds, and also act as an electromagnetic clutch for human safety.
Microspines for Robot and Human Climbing
Dr. Asbeck’s PhD research centered on the development and application of microspines, which are small metal hooks on compliant linkages that function like the claws of a squirrel or cockroach. They do not penetrate the surface, as do the claws of cats or bears, but rest on surface asperities (bumps or pits). With large numbers of small spines, substantial loads can be supported on relatively smooth surfaces.
He developed the Spinybot robot (with Sangbae Kim) to demonstrate the use of microspines and the required forces used in climbing. The robot was able to climb a wide variety of vertical surfaces with microspines, such as stucco, brick, and sandstone. After the Spinybot robot, his work focused on using microspines on heavier platforms, which required increased numbers of spines and more robust designs. The RiSE robot was able to climb a wide variety of surfaces using microspines, and the TV show Prototype This! used large patches of spines to enable a professional climber to scale a 5-story building.