Design and evaluation of pint-sized gyroscopic actuators

One important aspect of gait stability is the control of whole-body centroidal angular momentum H. We recently showed that if sensory-motor impairments affect a person's balance control, control of H can be assisted by control moment gyroscopes (CMGs). However, the effect of CMG technology inherently depends on the size and weight of these actuators, and on the speed of the flywheels they contain. These factors all pose challenges for wearable applications. Here, we show that it is possible to design CMGs light enough for wearable applications, while generating meaningful output torques. Our CMG, weighing 1.187 kg, can exert a peak torque of 15 N m with a torque-tracking bandwidth of 18 Hz. These results are partly due to an integrated model of components and partly to advancements in flywheel velocity control, allowing the speed to safely reach 20 000 rpm. These actuators open up new pathways of building wearable assistive devices for clinical applications.