Generalization of Series Elastic Actuator Configurations and Dynamic Behavior Comparison

Ryu

IEEE Trans. Ind. Electron.

et al. 2021

Self Cite

This article offers a new insight to the achievable stiffness limitation of the impedance control of series elastic actuators (SEAs) by suggesting a comparative analysis of energy ports and passivity control framework at the energy port to enhance the maximum achievable rendered stiffness of SEAs. To this end, it is explored that SEAs have two different port definitions to assess energy and passivity of the system-spring port and load port; and conservatisms for passivity evaluation of two ports are investigated and compared utilizing frequency characteristics. The results reveal that the load port passivity exhibits less conservatism, which allows to render larger achievable stiffness in impedance-controlled SEAs. Moreover, key parameters that determine the passivity characteristic of the SEA impedance control are discovered based on the load port passivity analysis. A novel passivity control framework that incorporates the time-domain passivity observer and the passivity controller is designed utilizing the load port energy monitoring, which offers a less conservative assessment of the systems passivity. Throughout this novel port passivity analysis and the passivity control, it can be achieved to render maximum rendered stiffness of the SEA impedance control much higher than the limitation that has been perceived as the maximum value.

Section: Methodsmentioning

confidence: 99%

Passivity Controller Based on Load-Side Damping Assignment for High Stiffness Controlled Series Elastic Actuators

Ryu

IEEE Trans. Ind. Electron.

et al. 2021

Self Cite

“…There are various types of SEA configurations (Lee et al, 2017) such as the direct force sensing type (FSEA) (Pratt and Williamson, 1995), the reaction force sensing type (RFSEA) (Paine et al, 2014; Park et al, 2018) and the transmission force sensing SEA (TFSEA), Lee and Oh (2016). TFSEA is utilized as the actuators for the proposed robot leg.…”

Section: Methodsmentioning

confidence: 99%

Development, Analysis, and Control of Series Elastic Actuator-Driven Robot Leg

2019

Front. Neurorobot.

Self Cite

The mass-spring system-like behavior is a powerful analysis tool to simplify human running/locomotion and is also known as the Spring Loaded Inverted Pendulum (SLIP) model. Beyond being just an analysis tool, the SLIP model is utilized as a template for implementing human-like locomotion by using the articulated robot. Since the dynamics of the articulated robot exhibits complicated behavior when projected into the operational space of the SLIP template, various considerations are required, from the robot's mechanical design to its control and analysis. Hence, the required technologies are the realization of pure mass-spring behavior during the interaction with the ground and the robust position control capability in the operational space of the robot. This paper develops a robot leg driven by the Series Elastic Actuator (SEA), which is a suitable actuator system for interacting with the environment, such as the ground. A robust hybrid control method is developed for the SEA-driven robot leg to achieve the required technologies. Furthermore, the developed robot leg has biarticular coordination, which is a human-inspired design that can effectively transmit the actuator torque to the operational space. This paper also employs Rotating Workspace (RW), which specializes in the control of the biarticulated robots. Various experiments are conducted to verify the performance of the developed robot leg with the control methodology.

“…According to the relative position of the spring within the actuator, the developed actuators are considered of FSEA (force-sensing series elastic actuator) type [18,29], since the spring is placed at the output of the gear (that is, between the load and the gear). In essence, the four actuator sizes are composed of the same components, which basically solely differ on the type of elastic element used (due to different size constraints).…”

Section: Mechanical Designmentioning

confidence: 99%

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

Fernández

Bargsten

et al. 2020

Actuators

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.