Historically, series elastic actuators (SEAs) used linear springs as the torque transmitting element in their drivetrains [1]. Use of linear springs requires tradeoffs between desired actuation bandwidth and measurable torque resolution. Nonlinear transmission elements overcome this limitation, enabling variable torque resolution and bandwidth through their deflection range. Many have recognize...

Compliant actuators are significant for safe physical human–robot interaction. Series elastic actuator (SEA) is the most popular type of compliant actuators, which possesses several attractive features, such as low output impedance, back drivability, shock tolerance, smooth force transmission, and energy efficiency. This brief focuses on the adaptive command-filtered backstepping control (CFBC)...

An active orthosis was designed to support users with reduced muscle strength with an additional knee joint torque to improve the independency in everyday activities. In two persons the hypothesis was tested that less muscle activity is necessary when standing up with the active support of a motorized orthosis. The orthosis is a custom-made knee-ankle-foot orthosis and is equipped with a series...

This paper presents an analytical, numerical and experimental study of an asymmetric piezoelectric actuator/sensor cantilever beam. The structure consists in a three-layered laminate with a piezoceramic acting as actuator, an elastic material layer and a second piezoceramic layer that can operate as a sensor or actuator. The coupled expansion-bending motion of the system is analytically resolve...

A new overground body-weight support system called ZeroG has been developed that allows patients with severe gait impairments to practice gait and balance activities in a safe, controlled manner. The unloading system is capable of providing up to 300 lb of static support and 150 lb of dynamic (or constant force) support using a custom-series elastic actuator. The unloading system is mounted to ...

Existing legged robots lack energy-efficiency, performance and adaptivity when confronted with situations that animals cope with on a routine basis. Bridging the gap between artificial and natural systems requires not only better sensorimotor and learning capabilities but also a corresponding motion apparatus and intelligent actuators. Current actuators with online adaptable compliance pose hig...

In-situ sampling and analysis are important capabilities to allow meeting the major objectives of future NASA’s planetary exploration missions. The development of an ultrasonic device that can serve as a probe, sampler and sensors platform for in-situ analysis is currently underway at JPL. The device is based on the novel Ultrasonic/Sonic Driller/Corer (USDC) technology, which was co-developed ...