Design and preliminary evaluation of two tool support arm exoskeletons with gravity compensation

Hull, Joshua; Turner, Ranger; Asbeck, Alan T.

doi:10.1016/j.mechmachtheory.2022.104802

Cited by 15 publications

(4 citation statements)

References 20 publications

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“…In addition, gas springs can be compressed smoothly compared with coil springs. Due to their smoothness, they are highly adaptable to ergonomics [24] and have been widely used in worker assistance [25], [26].…”

Section: Assistance Requirements and Simulation Of Assistancementioning

confidence: 99%

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Passive Lower Limb Exoskeleton for Kneeling and Postural Transition Assistance With Expanded Support Polygon

Sugiura

Zhu

Huang

et al. 2024

IEEE/ASME Trans. Mechatron.

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Robotic exoskeletons, which assist in standto-kneel and kneel-to-stand (STK-KTS) movements and static kneeling postures are in great demand in the nursing field. This movement involves continuous adjustment of the center of gravity without a sufficient support polygon, which enhances the required joint effort of the ankle and knee. This study proposes a novel passive lower limb exoskeleton to support the movement. The exoskeleton was attached to the right leg and comprised a gas spring. The design followed an assistive strategy of the expanded support polygon. During the STK-KTS, the gas spring provided extra contact with the ground, thereby expanding the support polygon to increase motion stability and propping the knee to provide torque to the leg. The effectiveness of the gas spring was analyzed using a Lagrange dynamics-based simulation. Moreover, it was confirmed that the support polygon was expanded due to the proposed exoskeleton in real-world experiments. Further, experiments with seven healthy subjects showed that the exoskeleton reduced the time-integrated myoelectric potentials of the legs during STK-KTS (13.6%) and static posture (37.9%). These results imply that the proposed exoskeleton has the potential to reduce physical loads and provide a comfortable working environment for nursing workers.

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Section: Assistance Requirements and Simulation Of Assistancementioning

confidence: 99%

“…The weight of the exoskeleton (4.0 kg) was added to the weight of the human model's shin and thigh. In this simulation, damping elements of the springs were not taken into account for simplicity [26], [27]. The Euler-Lagrange formalism for the human-brace model is as follows:…”

Section: Assistance Requirements and Simulation Of Assistancementioning

confidence: 99%

Passive Lower Limb Exoskeleton for Kneeling and Postural Transition Assistance With Expanded Support Polygon

Sugiura

Zhu

Huang

et al. 2024

IEEE/ASME Trans. Mechatron.

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show abstract

“…The methodology is expansively applied to numerous fields. For example, gravity balancer is used on many tools for surgery [4] or industry [5] to carry the weight of the hand tools and to improve stability during processing, thereby reducing worker injuries and improving productivity. For some automatic robotic arm [6][7][8], springs are used to share the heavy weight, which reduce the load on the driving system.…”

Section: Introductionmentioning

confidence: 99%

Spring-balanced 3-DoF serial planar manipulators for constant forces in arbitrary directions

2023

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With the use of springs, a method to balance the constant forces in arbitrary directions on a planar serial manipulator is developed in this study. Gravity balancing has been discussed a lot in the past. However, manipulators usually bear forces from various directions rather than only a fixed one as gravity. For instance, an industrial manipulator would bear forces from everywhere during the working process. Therefore, a method to balance these forces in arbitrary directions with springs is proposed. Based on the representation of energy, spring energy is the function of springs’ attachment points. Two spring systems with different attachment angles are needed to balance respectively forces in arbitrary directions and gravity. The spring installations of the above systems on 3-DoF manipulators are proposed. Finally, a resistive force-balanced manipulator with/without gravity balance in the grinding process is shown. In sum, this paper for the first time develops the balancing method for forces in arbitrary directions, expanding the spring balance theory to a broader application.

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“…Consequently, the construction of these devices requires incorporating gravity compensation units that consider the arm's range of motion, leading to a significant increase in device size. A device proposed in [33] adopts a different approach by providing load assistance at the end of the arm while positioning the gravity compensation unit on the user's back. However, this device presents a challenge in that the force-transmitting pantograph structure is aligned with the arm, potentially limiting arm movement or causing interference during operation.…”

Section: Introductionmentioning

confidence: 99%

Design and Evaluation of AX-Deminer Forearm Assistance for Demining Soldier

Lee,

Kim,

Kim

et al. 2023

IEEE Access

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Mine clearance operation using a mine detector often strains arm muscles because of the extended form of the detection pole. Implementing a gravity compensation device may be beneficial for alleviating this issue. Therefore, this paper presents a novel concept of passive-type forearm assistance for a mine-detection soldiers. The proposed forearm assistance features a decoupled structure between a sweeping module and a gravity compensation unit. The sweeping module is implemented using a planar serial chain, allowing the required range of arm-sweeping motion for mine detection. The gravity compensation module, featuring a six-bar linkage with a linear spring, is located at the wearer's back and compensates the detector's weight transmitted through the sweeping module. The decoupled structure enables minimal exposure of the mechanism to the wearer. Design requirements are determined from motion analysis of mine-detection soldiers; kinematic relationships are derived for sweeping and gravity compensation modules. Based on the kinematic relationships, optimal synthesis methods are presented to determine design parameters. The proposed gravity compensation device has been experimentally validated for four mine-detection soldiers. Electromyography measurements of the upper limb demonstrate a significant reduction of up to 66% in % maximum voluntary contraction (MVC) when using forearm assistance. Thus, the proposed forearm assistance may reduce arm fatigue, enabling more extended operation duration during mine clearance tasks.

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Design and preliminary evaluation of two tool support arm exoskeletons with gravity compensation

Cited by 15 publications

References 20 publications

Passive Lower Limb Exoskeleton for Kneeling and Postural Transition Assistance With Expanded Support Polygon

Passive Lower Limb Exoskeleton for Kneeling and Postural Transition Assistance With Expanded Support Polygon

Spring-balanced 3-DoF serial planar manipulators for constant forces in arbitrary directions

Design and Evaluation of AX-Deminer Forearm Assistance for Demining Soldier

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