Traditional stiff actuators have a high reflected inertia, which do not meet the safety requirements, are bad to absorb shocks and cannot store and release energy which are for different applications required. Initiated by the introduction of the Series Elastic Actuator (SEA) by Gill A. Pratt in 1995, a wide range of Variable Impedance Actuators (VIA) are developed, for which inspiration was fo...

The CompActTM actuator features a clutch mechanism placed in parallel with its passive series elastic transmission element and can therefore benefit from the advantages of both series elastic actuators (SEA) and rigid actuators. The actuator is capable of effectively managing the storage and release of the potential energy of the compliant element by the appropriate control of the clutch subsys...

This paper deals with force and impedance control of series elastic actuators for driving the joints of an exoskeleton for lower limbs. Series elastic actuators are devices where elastic components are introduced between the motor’s output and the load. From the deflection of these components, it is possible to measure the force applied to the load and to control it. Also, the mechanical impeda...

Figure 1. The bionic prosthesis’ mass of 2.0 kg is equivalent to a biological foot and partial shank of an 80 kg person. The prosthesis includes a carbonfiber in-series leaf spring, unidirectional parallel leaf spring, and heel and forefoot leaf springs that provide elasticity. A series-elastic actuator performs negative and positive work. The actuator is comprised of a 200-Watt DC brushless mo...

We present a hydro-elastic actuator that has a linear spring intentionally placed in series between the hydraulic piston and actuator output. The spring strain is measured to get an accurate estimate of force. This measurement alone is used in PI feedback to control the force in the actuator. The spring allows for high force fidelity, good force control, minimum impedance, and large dynamic ran...

This paper proposes a new approach to the design of a robot actuator with physically variable stiffness. The proposed approach leverages the dynamic characteristics inherent in a pneumatic actuator, which behaves in essence as a series elastic actuator. By replacing the four-way servovalve used to control a typical pneumatic actuator with a pair of three-way valves, the stiffness of the series ...

Series Elastic Actuators have linear springs intentionally placed in series between the motor and actuator output. The spring strain is measured to get an accurate estimate of force. Despite using a transmission to achieve high force/mass and high power/mass, the spring allows for good force control, high force fidelity, minimum impedance, and large dynamic range. A second order linear actuator...

This contribution aims at presenting the first clinical evaluation trials of a Series-Elastic-Actuator based exoskeleton for post-stroke elbow rehabilitation, NEUROExos, from the BioRobotics Institute of Scuola Superiore Sant'Anna.

It is traditional to make the interface between an actuator and its load as stiff as possible. Despite this tradition, reducing interface stiffness offers a number of advantages, including greater shock tolerance, lower reflected inertia, more accurate and stable force control, less inadvertant damage to the environment, and the capacity for energy storage. As a trade-off, reducing interface st...