Multistable series elastic actuators: Design and control

Series Elastic Actuators are force actuators with applications in robotics and biomechanics. In linear Series Elastic Actuators, a large force bandwidth requires a stiff sensor (spring), but the output impedance puts an upper limit on this parameter, therefore selecting the proper spring is difficult in these actuators. In this paper, Series Elastic Actuator is modeled with a nonlinear, stiffening spring and controlled using the Gain Scheduling method. Simulations show that both linear and nonlinear models have similar force bandwidths, but the nonlinear one shows much lower output impedance. Hence, the choice of spring for actuator design is an easier task than that of the linear model. Also, as a force-augmenting device for the knee joint in normal human gait, the nonlinear model acts better in simulations.

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Design, Modelling and Control of Novel Series-Elastic Actuators for Industrial Robots

Actuators ◽

10.3390/act9010006 ◽

2020 ◽

Vol 9 (1) ◽

pp. 6 ◽

Cited By ~ 1

Author(s):

José de Gea Fernández ◽

Bingbin Yu ◽

Vinzenz Bargsten ◽

Michael Zipper ◽

Holger Sprengel

Keyword(s):

Industrial Robots ◽

Data Driven ◽

User Needs ◽

End User ◽

Different Types ◽

Series Elastic Actuators ◽

And Control ◽

Collaborative Robot ◽

Modelling Methods ◽

Series Elastic

This paper describes data-driven modelling methods and their use for the control of a novel set of series-elastic actuators (SEAs). A set of elastic actuators was developed in order to fulfill the end-user needs for tailored industrial collaborative robot manipulators of different morphologies and payloads. Three different types of elastic actuation were investigated, namely, disc springs, coil springs and torsion bars. The developed algorithms were validated both on single actuators and on a 6-DOF robotic arm composed of such actuators.

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Modeling and Control of Four-bar Mechanism with Series Elastic Actuators

10.48011/asba.v2i1.1396 ◽

2020 ◽

Author(s):

Felipe R. Lopes ◽

Marco A. Meggiolaro

Keyword(s):

Human Interaction ◽

Robotic Manipulation ◽

Modeling And Control ◽

Lqr Control ◽

In Series ◽

Flexible Behavior ◽

Series Elastic Actuators ◽

New Generation ◽

And Control ◽

Series Elastic

A new generation of robots that work in cooperation with humans (called collaborative robots) needs some flexibility to adapt to the environment and activities with people. That is why the Series Elastic Actuator (SEA) has been a breakthrough in actuator technologies. The idea of inserting an elastic element in series with a motor allows a lower output impedance, consequently a flexible behavior in the manipulator, in addition to providing torque feedback to better compensate disturbances caused e.g. by friction losses. This article presents a four-bar mechanism with SEA for the purpose of robotic manipulation. Its kinematics and dynamicsare studied, as well as its regulation and trajectory control. The behavior of the decoupled four-bar mechanism and the characteristics of the SEA are also analyzed. Then the regulation control of the complete system is carried out using LQR control. Finally, a circular trajectory is controlled in a simulation to validate the proposed control strategy. The simulation results show the effectiveness of the proposed controller for the mechanism in the presence of SEAs estimating torque and providing the desired compliance for human interaction.

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