Comparison of various active impedance control approaches, modeling, implementation, passivity, stability and trade-offs

Mosadeghzad, Mohamad; Medrano-Cerda, Gustavo A.; Saglia, Jody A.; Tsagarakis, Nikos G.; Caldwell, Darwin G.

doi:10.1109/aim.2012.6265960

Cited by 44 publications

(31 citation statements)

References 13 publications

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“…procedure ControllerSolver(f n , ζ 1 , ζ 2 , sysParam) Deterministically solve nominal controller gains K qn , B qn , K τn , B τn refer to (16) if Gain scale GS = 1 then…”

Section: Sea Impedance Analysismentioning

confidence: 99%

“…Series elastic actuators [11,12,13,14,15], as an emerging actuation mechanism, provide considerable advantages in compliant and safe environmental interactions, impact absorption, energy storage and force sensing. In the control literature, adopting cascaded impedance control architectures for series elastic actuators (SEAs) has attracted increasing investigations over the last few years [16,13,17]. Compared to full-state feedback control [18,19,20], the cascaded control performs superior when the controlled plant comprises slow dynamics and fast dynamics simultaneously.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, this study focuses on the cascaded control structure to simulate the distributed control structure for humanoid robots accompanied with a variety of delayed feedback loops [21,1]. This class of cascaded control structures nests feedback control loops [16,13], i.e., an inner-torque loop and an outer-impedance loop for the task-level control, such as Cartesian impedance control. Recently, the works in [13,17] proposed to embed a motor velocity loop inside the torque feedback loop.…”

Section: Introductionmentioning

confidence: 99%

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Distributed impedance control of latency-prone robotic systems with series elastic actuation

Zhao

Sentis

2019

Stability, Control and Application of Time-Delay Systems

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Robotic systems are increasingly relying on distributed feedback controllers to tackle complex and latency-prone sensing and decision problems. These demands come at the cost of a growing computational burden and, as a result, larger controller latencies. To maximize robustness to mechanical disturbances and achieve high control performance, we emphasize the necessity for executing damping feedback in close proximity to the control plant while allocating stiffness feedback in a latency-prone centralized control process. Additionally, series elastic actuators (SEAs) are becoming prevalent in torque-controlled robots during recent years to achieve compliant interactions with environments and humans. However, designing optimal impedance controllers and characterizing impedance performance for SEAs with time delays and filtering are still under-explored problems. The presented study addresses the optimal controller design problem by devising a critically-damped gain design method for a class of SEA cascaded control architectures, which is composed of outer-impedance and inner-torque feedback loops. Via the proposed controller design criterion, we adopt frequency-domain methods to thoroughly analyze the effects of time delays, filtering and load inertia on SEA impedance performance. These results are further validated through the analysis, simulation, and experimental testing on high-performance actuators and on an omnidirectional mobile base.

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“…procedure ControllerSolver(f n , ζ 1 , ζ 2 , sysParam) Deterministically solve nominal controller gains K qn , B qn , K τn , B τn refer to (16) if Gain scale GS = 1 then…”

Section: Sea Impedance Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Distributed impedance control of latency-prone robotic systems with series elastic actuation

Zhao

Sentis

2019

Stability, Control and Application of Time-Delay Systems

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“…2) Stiffness range: SEA physical stiffness needs to be carefully selected to trade off intrinsic compliance, accuracy of force measurement, displacement range and bandwidth of force control [9], [10], [14], [15]. Furthermore, when addressing rehabilitation of joints with intrinsic compliance, the values of physical stiffness of the human counterpart in resting and pathological conditions also needs to be taken into account.…”

Section: A Definition Of Design Specificationsmentioning

confidence: 99%

Design of a series elastic actuator for a compliant parallel wrist rehabilitation robot

Sergi

Lee

O’Malley

2013

2013 IEEE 13th International Conference on Rehabilitation Robotics (ICORR)

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This paper presents the design of a novel linear series elastic actuator purposely designed to match the requirements of robots for wrist rehabilitation: backdriveability, intrinsic compliance, and capability to be controlled as ideal force/torque sources. An existing rehabilitation robot is adapted to include intrinsic compliance in the design. A novel linear compliant element is designed to meet dimensional and force/stiffness requirements; a force sensing scheme involving a Hall-effect sensor is optimized in FEM simulations and developed. Linearity tests of the compliant sensing element show a maximum of 4.5% of FSO combined nonlinearity and hysteresis errors. Characterization experiments show that the developed system introduces physical compliance, still guaranteeing accurate force control in a frequency range largely compatible with that required for wrist assistance during rehabilitation.

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“…The stiffness of the ankle pitch passive compliant joint is 520[N m/rad]. The impedance regulator [31] is used to supply nonlinear torques (12) to the ankle. The inner loop torque controller proposed in [31], is exploited, and an outer loop based on (12) is closed on the link side, to provide the reference torque of the torque controller.…”

Section: Humanoid Experimentsmentioning

confidence: 99%

Optimal human-inspired ankle stiffness regulation for humanoid balancing control

Mosadeghzad

Karavas

Ajoudani

et al. 2014

2014 IEEE-RAS International Conference on Humanoid Robots

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In this work, a novel optimal human-inspired balancing control for the compliant humanoid, CoMAN, is introduced. The presented technique was motivated by the results of a human balance analysis. In particular, a human balancing experiment was carried out to investigate the torqueto-angular displacement profiles about the ankle joint. Experimental results obtained from this study, indicated that both the dorsiflexion and plantarflexion torques present an approximately exponential behavior. These findings served as an inspiration for the development of an optimal, nonlinear stiffness stabilizer, based on an ankle strategy. The balance stabilizer was experimentally validated on the compliant humanoid, CoMAN, demonstrating its balance inducing ability.

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Comparison of various active impedance control approaches, modeling, implementation, passivity, stability and trade-offs

Cited by 44 publications

References 13 publications

Distributed impedance control of latency-prone robotic systems with series elastic actuation

Distributed impedance control of latency-prone robotic systems with series elastic actuation

Design of a series elastic actuator for a compliant parallel wrist rehabilitation robot

Optimal human-inspired ankle stiffness regulation for humanoid balancing control

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