Comparison of Controllable Transmission Ratio Type Variable Stiffness Actuator with Antagonistic and Pre-tension Type Actuators for the Joints Exoskeleton Robots

Kizilhan, Hasbi; Kılıç, Esma; Ulusoy, Necati

doi:10.5220/0005507801880195

Cited by 11 publications

(12 citation statements)

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“…The minimized power requirement provides the use of small motors and energy efficiency in exoskeletons. The power requirement of variable stiffness actuator designs has been investigated in [21], and this study concluded that the controllable transmission ratio type actuator provides the minimum power requirement and maximum energy efficiency. Therefore, it was selected for the design of the ankle joint of the robot.…”

Section: Kinematic Design and Power Requirement Of Biocomex Jointsmentioning

confidence: 99%

Biomimetic compliant lower limb exoskeleton (BioComEx) and its experimental evaluation

Kizilhan

Kılıç

2019

J Braz. Soc. Mech. Sci. Eng.

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Exoskeleton robots are generally used for rehabilitation and load-carrying applications. Stable and flexible walking with minimal energy consumption of the human body is achieved by the compliant operation of the human joints. Essentially, the stiffness of the human ankle joint varies continuously, while the stiffness of the knee and hip joints remains nearly constant during loading phases of the walking cycles. With inspiration from the human leg biomechanics, a new biomimetic compliant lower limb exoskeleton robot (BioComEx) was constructed and its preliminary experimental tests were carried out in this paper. A variable stiffness actuator was developed for the ankle joint of BioComEx, and series elastic actuator designs were employed in the knee and hip joints of the robot. The joint actuators of BioComEx were designed longitudinally in order to be embedded inside of the thigh and shank leg segments for the compactness. Separate force sensors were employed in each segment of the robot for the modularity of the control strategies. Since the exoskeletons can be used for both load-carrying and rehabilitation, the developed robot was tested in both human-in-charge and robot-in-charge modes, respectively. The robot needs to mimic movement of healthy user joints in the human-in-charge mode and maximize the compliance between the user and robot; thus, the interaction forces should be reduced as possible. Hence, a modular closed-loop impedance control algorithm was developed for this mode. On the other hand, in the robot-in-charge mode, the robot joints need to track predefined gait references to make the patient walk. PID position control algorithm was chosen for preliminary test of the robot in this mode. Experimental results show that BioComEx is sufficiently satisfactory for walking applications of healthy and paralyzed users.

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Section: Kinematic Design and Power Requirement Of Biocomex Jointsmentioning

confidence: 99%

Biomimetic compliant lower limb exoskeleton (BioComEx) and its experimental evaluation

Kizilhan

Kılıç

2019

J Braz. Soc. Mech. Sci. Eng.

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“…Moreover, the kineto-static analyses of the antagonistic-controlled actuators along with the mechanically controlled actuator are presented and compared to the novel actuator design presented in this research. The details of the kineto-static analyses of the available designs in the literature are given in a previous study [6].…”

Section: Variable Stiffness Actuator Designsmentioning

confidence: 99%

“…All details are given in Ref. [6]. Equations (9) and (10) are used to calculate the forces of the first motor (F 1 ) and the second motor (F 2 ), respectively.…”

Section: The Mechanically Controlled Actuator Designmentioning

confidence: 99%

“…In the literature, various compliant actuators exploiting the advantages of passive elastic elements to regulate output stiffness have been proposed. Kizilhan et al divided these actuators into 5 different categories [6]: (1) equilibrium-controlled stiffness [5], (2) antagonistic-controlled stiffness [7][8][9][10][11], (3) structurally controlled stiffness [12], (4) mechanically controlled stiffness [13,14] and (5) controllable transmission ratio stiffness [15][16][17]. Compliant actuators have been used in various exoskeletons because of their ability to absorb forces and store/release power during their use.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical design and preliminary tests of VS-AnkleExo

Kizilhan

2018

J Braz. Soc. Mech. Sci. Eng.

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Exoskeletons and wearable robotic systems have advanced substantially over the last decade for gait assistance, rehabilitation and load-carrying purposes. Currently, there are commercially available devices with stiff actuators. However, these actuators cannot adapt to their unpredictable environments. Thus, compliant actuators like series elastic and variable stiffness actuators have been implemented in exoskeletons and active orthoses. This paper presents a novel design and experimental characterization of a compliant actuator with adjustable stiffness for a lower limb wearable ankle robot (VS-AnkleExo). The proposed actuator is designed to mimic the behavior of biological ankle and maximizes the compliance between user and robot during a gait cycle. The adjustable stiffness of actuator is achieved through a controllable transmission ratio mechanism. Both transparency and tracking performance experiments are performed to demonstrate reduced the user-robot interaction force and improved the tracking performance of the proposed actuator, respectively. Experimental results showed that interaction forces between the user and robot are minimized in the transparency experiments, while the actuators proposed are able to track the given torque signals at various frequencies in the tracking experiments.

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“…Variable stiffness actuators (VSAs) are a new generation of robotic actuators that are proposed to allow for stiffness adjustment in addition to the ability to tune their position [1][2][3][4][5][6]. This stiffness adjustability is essential in many applications, especially in physical human-robot-interactions (pHRI) where robots and humans work in close vicinity [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

A Novel Mechanically Overdamped Actuator with Adjustable Stiffness (MOD-AwAS) for Safe Interaction and Accurate Positioning

2017

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This paper presents the design and development of a novel mechanically overdamped actuator with adjustable stiffness (MOD-AwAS). The novelty of MOD-AwAS compared to other variable stiffness actuators relates to its mechanical design, which prevents oscillations at the output link. Almost all variable stiffness actuators have an overshooting problem that require a sophisticated control algorithm to be able to perform accurate positioning. MOD-AwAS can regulate the stiffness from zero to its maximum (theoretically infinite) in less than 0.2 s by changing the position of the pivot point of its lever mechanisms. MOD-AwAS employs only one rotational spring with no pre-deflection, which gives it full accessibility to its energy storage capacity. Experimental results are presented to show the ability of MOD-AwAS to control its position accurately with a wide range of stiffness adjustment.

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Comparison of Controllable Transmission Ratio Type Variable Stiffness Actuator with Antagonistic and Pre-tension Type Actuators for the Joints Exoskeleton Robots

Cited by 11 publications

References 0 publications

Biomimetic compliant lower limb exoskeleton (BioComEx) and its experimental evaluation

Biomimetic compliant lower limb exoskeleton (BioComEx) and its experimental evaluation

Mechanical design and preliminary tests of VS-AnkleExo

A Novel Mechanically Overdamped Actuator with Adjustable Stiffness (MOD-AwAS) for Safe Interaction and Accurate Positioning

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