High-Precision Robust Force Control of a Series Elastic Actuator

Oh, Sehoon; Kong, Kyoungchul

doi:10.1109/tmech.2016.2614503

Cited by 229 publications

(87 citation statements)

References 26 publications

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“…A force control performance of SEA depends on the natural open-loop bandwidth of SEA which is related with the spring stiffness [23,28]. According to this aspect, several studies have focused on a design of spring itself to increase the control bandwidth with high stiffness [29].…”

Section: Discussion 3: Relation With Force Controlmentioning

confidence: 99%

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Generalization of Series Elastic Actuator Configurations and Dynamic Behavior Comparison

Lee

Kwak

et al. 2017

Actuators

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Abstract:The Series Elastic Actuator (SEA) has recently been developed by many research groups and applied in various fields. As SEA is the combination of motor, spring, gear and load, various types and configurations of mechanism have been developed as SEAs to satisfy many requirements necessary for the applications. This paper provides a theoretical framework to categorize and compare these various configurations of SEAs. The general structure and model of SEA is provided, and SEA configurations are categorized into Force-sensing Series Elastic Actuator, Reaction Force-sensing Series Elastic Actuator and Transmitted Force-sensing Series Elastic Actuator, based on the relative location of the spring. Criteria such as Force sensitivity, Compliance and Transmissibility of SEA are derived and compared using actual SEAs that have been developed previously.

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Section: Discussion 3: Relation With Force Controlmentioning

confidence: 99%

“…SEA is basically a flexible system consisting of two masses, and [23] has thoroughly investigated the dynamics of SEA using the two-mass dynamic model. The two-mass dynamic model can be interpreted as the combination of three kinds of free-body dynamics as illustrated in Figure 10a.…”

Section: Dynamic Model Of Crseamentioning

confidence: 99%

Generalization of Series Elastic Actuator Configurations and Dynamic Behavior Comparison

Lee

Kwak

et al. 2017

Actuators

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“…For the case where the motor parameter variations are zero, the disturbance force is given by (13). (10) and (11), the disturbance torque is expressed by (14).…”

Section: Disturbance Observer For Force Estimationmentioning

confidence: 99%

“…A generalized disturbance observer has been proposed by Kim et al to estimate higher order disturbances in the time series expansion (12) . Oh and Kong have proposed the disturbance observer and feed-forward controller as the model-based control algorithm to achieve the high-precision force control of a series elastic actuator (13) . Although the DOB has superior performance in terms of robustness, its force sensing performance deteriorates with noise.…”

Section: Introductionmentioning

confidence: 99%

Disturbance Observer and Kalman Filter Based Motion Control Realization

et al. 2018

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Many effective robot-manipulator control schemes using a disturbance observer have been reported in the literature in the past decades. Besides, the disturbance observer combined with the Kalman filter has attracted the attention of researchers in the field of motion control. The major advantage of a motion control system based on the Kalman filter and disturbance observer is the realization of high robustness against disturbance and parameter variations, effective noise suppression and wideband force sensing. This paper presents a survey of motion control based on the Kalman filter and disturbance observer, which have been previously introduced by the authors. Several control schemes, as well as formulations and applications of the Kalman filter and disturbance observer, are described in the paper. The performance and effectiveness of the control schemes are evaluated to give a useful and comprehensive design of the Kalman filter and disturbance observer in various motion control applications.

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“…Conventional impedance control approaches design the controller in a cascaded manner and lots of such control strategies with a PID-based inner force/torque loop have been employed for SEA [4], [5], [12], [19]- [21]. Disturbance observer (DOB) based torque or impedance control strategies have also been proposed to improve SEA control accuracy and robustness [22]- [26]. Recently, adaptive torque or impedance controllers have been developed to guarantee predictable performance despite uncertainties or disturbance in the SEA or human side [27]- [32].…”

Section: Introductionmentioning

confidence: 99%

Passivity guaranteed stiffness control with multiple frequency band specifications for a cable-driven series elastic actuator

Zou

Sun

2019

Mechanical Systems and Signal Processing

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Impedance control and specifically stiffness control are widely applied for physical human-robot interaction. The series elastic actuator (SEA) provides inherent compliance, safety and further benefits. This paper aims to improve the stiffness control performance of a cable-driven SEA. Existing impedance controllers were designed within the full frequency domain, though human-robot interaction commonly falls in the low frequency range. We enhance the stiffness rendering performance under formulated constraints of passivity, actuator limitation, disturbance attenuation, noise rejection at their specific frequency ranges. Firstly, we reformulate this multiple frequencyband optimization problem into the H∞ synthesis framework. Then, the performance goals are quantitatively characterized by respective restricted frequency-domain specifications as norm bounds. Further, a structured controller is directly synthesized to satisfy all the competing performance requirements. Both simulation and experimental results showed that the produced controller enabled good interaction performance for each desired stiffness varying from 0 to 1 times of the physical spring constant. Compared with the passivity-based PID method, the proposed H∞ synthesis method achieved more accurate and robust stiffness control performance with guaranteed passivity.

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High-Precision Robust Force Control of a Series Elastic Actuator

Cited by 229 publications

References 26 publications

Generalization of Series Elastic Actuator Configurations and Dynamic Behavior Comparison

Generalization of Series Elastic Actuator Configurations and Dynamic Behavior Comparison

Disturbance Observer and Kalman Filter Based Motion Control Realization

Passivity guaranteed stiffness control with multiple frequency band specifications for a cable-driven series elastic actuator

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