A Compact Rotary Series Elastic Actuator for Human Assistive Systems

Kong, Kyoungchul; Bae, Joonbum; Tomizuka, Masayoshi

doi:10.1109/tmech.2010.2100046

Cited by 285 publications

(124 citation statements)

References 12 publications

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“…In order to guarantee an accurate torque estimation and consequent performance, a high linearity of the torque versus the angle is desirable. For this same reason, residual deflection (at zero delivered torque) and hysteresis should be avoided (Kong et al, 2012).…”

Section: Design Process Of Torsional Springmentioning

confidence: 99%

“…Those symmetrical structures have two features, i.e., less optimized parameters and low processing costs. Based on the results presented in Kong et al (2012), the topology of A is superior to that of B.…”

Section: Design Process Of Torsional Springmentioning

confidence: 99%

“…Considering the specialty of robot joint structure, the spring structure is usually rotary. A compact series elastic actuator is designed to satisfy those requirements, e.g., back drivability and low output impedance, and the actuation performance is verified by experiments (Kong et al, 2012). Hao et al (2017) made much progress in the field of elastic actuators for the flexible mechanisms and have given the detailed analysis for the elastic actuators' compliance (Hao et al, 2017;Hao, 2017a, b).…”

Section: Introductionmentioning

confidence: 99%

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Development of a lower extremity wearable exoskeleton with double compact elastic module: preliminary experiments

Long

Chen

et al. 2017

Mech. Sci.

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Abstract. In this paper, a double compact elastic module is designed and implemented in the lower extremity exoskeleton. The double compact elastic module is composed of two parts, i.e., physical human robot interaction (pHRI) measurement and the elastic actuation system (EAS), which are called proximal elastic module (PEM) and distal elastic module (DEM) respectively. The PEM is used as the pHRI information collection device while the DEM is used as the compliance device. A novel compact parallelogram-like structure based torsional spring is designed and developed. An iterative finite element analysis (FEA) based optimization process was conducted to find the optimal parameters in the search space. In the PEM, the designed torsional spring has an outer circle with a diameter of 60 mm and an inner hole with a diameter of 12 mm, while in the DEM, the torsional spring has the outer circle with a diameter of 80 mm and the inner circle with a diameter of 16 mm. The torsional spring in the PEM has a thickness of 5 mm and a weight of 60 g, while that in the DEM has a thickness of 10 mm and a weight of 80 g. The double compact elastic module prototype is embedded in the mechanical joint directly. Calibration experiments were conducted on those two elastic modules to obtain the linear torque versus angle characteristic. The calibration experimental results show that this torsional spring in the PEM has a stiffness of 60.2 Nm rad −1 , which is capable of withstanding a maximum torque of 4 Nm, while that in the DEM has a stiffness of 80.2 Nm rad −1 , which is capable of withstanding a maximum torque of 30 Nm. The experimental results and the simulation data show that the maximum resultant errors are 6 % for the PEM and 4 % for the DEM respectively. In this paper, an assumed regression algorithm is used to learn the human motion intent (HMI) based on the pHRI collection. The HMI is defined as the angular position of the human limb joint. A closed-loop position control strategy is utilized to drive the robotic exoskeleton system to follow the human limb's movement. To verify the developed system, experiments are performed on healthy human subjects and experimental results show that this novel robotic exoskeleton can help human users walk, which can be extended and applied in the assistive wearable exoskeletons.

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Section: Design Process Of Torsional Springmentioning

confidence: 99%

Section: Design Process Of Torsional Springmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Development of a lower extremity wearable exoskeleton with double compact elastic module: preliminary experiments

Long

Chen

et al. 2017

Mech. Sci.

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“…Series elastic actuators (SEAs) are inherently compliant by introducing an elastic element between the actuator and the load [1,2]. They present several unique properties compared to rigid actuators, including low mechanical output impedance, tolerance of impact loads, increased peak power output, and passive mechanical energy storage under certain conditions [3]. New devices try to overcome the bandwidth limitation and improve the performance of SEAs by incorporating an extra (softer) elastic element in the transmission train.…”

Section: Introductionmentioning

confidence: 99%

“…New devices try to overcome the bandwidth limitation and improve the performance of SEAs by incorporating an extra (softer) elastic element in the transmission train. These actuators, such as the compact SEA [4], the high-performance SEA [5], and the Compat Rotary SEA (cRSEA) [3], improve the force-control performance under a wider range of forces/torques at the device joints when compared to traditional SEAs, although the energy storage capability will still depend on the resulting fixed springs constants; thus, a proper selection of the elastic constant based on the application, intended user and control strategy needs to be performed [4].…”

Section: Introductionmentioning

confidence: 99%

A New and Versatile Adjustable Rigidity Actuator with Add-on Locking Mechanism (ARES-XL)

Cestari

Sanz‐Merodio²,

García

2018

Actuators

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Adjustable compliant actuators are being designed and implemented in robotic devices because of their ability to minimize large forces due to impacts, to safely interact with the user, and to store and release energy in passive elastic elements. Conceived as a new force-controlled compliant actuator, an adjustable rigidity with embedded sensor and locking mechanism actuator (ARES-XL) is presented in this paper. This compliant system is intended to be implemented in a gait exoskeleton for children with neuro muscular diseases (NMDs) to exploit the intrinsic dynamics during locomotion. This paper describes the mechanics and initial evaluation of the ARES-XL, a novel variable impedance actuator (VIA) that allows the implementation of an add-on locking mechanism to this system, and in combination with its zero stiffness capability and large deflection range, provides this novel joint with improved properties when compared to previous prototypes developed by the authors and other state-of-the-art (SoA) devices. The evaluation of the system proves how this design exceeds the main capabilities of a previous prototype as well as providing versatile actuation that could lead to its implementation in multiple joints.

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Actuator Control for the NASA‐JSC Valkyrie Humanoid Robot: A Decoupled Dynamics Approach for Torque Control of Series Elastic Robots

Paine

Mehling

Holley

et al. 2015

Journal of Field Robotics

216

119

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This paper discusses the actuator-level control of Valkyrie, a new humanoid robot designed by NASA's Johnson Space Center in collaboration with several external partners. Several topics pertaining to Valkyrie's series elastic actuators are presented including control architecture, controller design, and implementation in hardware. A decentralized approach is taken in controlling Valkyrie's many series elastic degrees of freedom. By conceptually decoupling actuator dynamics from robot limb dynamics, the problem of controlling a highly complex system is simplified and the controller development process is streamlined compared to other approaches. This hierarchical control abstraction is realized by leveraging disturbance observers in the robot's joint-level torque controllers. A novel analysis technique is applied to understand the ability of a disturbance observer to attenuate the effects of unmodeled dynamics. The performance of this control approach is demonstrated in two ways. First, torque tracking performance of a single Valkyrie actuator is characterized in terms of controllable torque resolution, tracking error, bandwidth, and power consumption. Second, tests are performed on Valkyrie's arm, a serial chain of actuators, to demonstrate the robot's ability to accurately track torques with the presented decentralized control approach. C 2015 Wiley Periodicals, Inc.

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A Compact Rotary Series Elastic Actuator for Human Assistive Systems

Cited by 285 publications

References 12 publications

Development of a lower extremity wearable exoskeleton with double compact elastic module: preliminary experiments

Development of a lower extremity wearable exoskeleton with double compact elastic module: preliminary experiments

A New and Versatile Adjustable Rigidity Actuator with Add-on Locking Mechanism (ARES-XL)

Actuator Control for the NASA‐JSC Valkyrie Humanoid Robot: A Decoupled Dynamics Approach for Torque Control of Series Elastic Robots

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