| For a wearable assistance robot, the term "wearable" has special implications. These implications are that a wearable actuator must be lightweight, energy efficient/conservative and most importantly, safe. In contrast, a typical factory floor robot is none of these things.; As an approach to developing energy conservative actuators, the concept of structure control is created. Structure control is an indirect method of mechanical actuation. Rather than using an actuator to drive a mechanical system into its desired behavior, structure control alters the natural response of the system. Manipulation of the passive mechanical parameters allows a system to respond as desired, passively. Proper use of this method can lead to the design of robust, energy conservative actuators.; A Jack Spring(TM) is a new type of mechanical actuator, which is based upon the concept of structure control. An example Jack Spring mechanism is evaluated for ankle gait assistance. The Jack Spring actuator uses its inherent elastic nature to reduce both peak power and energy requirements for its motor. In the final example, peak power required of the motor for ankle gait is reduced from 247W to just 85W. In addition, energy requirements are reduced from nearly 51 Joules to just 26 Joules per step when compared to a simple motor/gearbox combination. Using this approach, an initial prototype is expected to provide 100% of the power and energy necessary for ankle gait in a compact 0.54kg package. This weight is 12 times less than predicted for a comparable motor/gearbox approach. |
