Design of a Payload Adjustment Device for an Unpowered Lower-Limb Exoskeleton

This paper proposes a device that can change the payload of an unpowered lower-limb exoskeleton supporting the weights of humans and loads. Our previous exoskeletons used a cam–follower structure with a spring applied to the hip joint. This exoskeleton showed satisfying performance within the payload; however, the performance decreased when the payload was exceeded. Therefore, a payload adjustment device that can adjust the wearer’s required torque by easily applying it to the cam–follower structure was developed. An exoskeleton dynamic equation that can calculate a person’s required joint torque given the required payload and the wearer’s posture was derived. This dynamic equation provides a guideline for designing a device that can adjust the allowable joint torque range of an unpowered exoskeleton. In the Adams simulation environment, the payload adjustment device is applied to the cam–follower structure to show that the payload of the exoskeleton can be changed. User convenience and mass production were taken into account in the design of this device. This payload adjustment device should flexibly change the payload of the level desired by the wearer because it can quickly change the payload of the exoskeleton.

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Walking Classification of Hip Joint Lower Limb Exoskeleton

2019 2nd International Conference on Applied Engineering (ICAE) ◽

10.1109/icae47758.2019.9221701 ◽

2019 ◽

Author(s):

Riska Analia ◽

Joshua Ferdinand M. ◽

Susanto ◽

P. Daniel Sutopo ◽

Hendawan Soebhakti ◽

...

Keyword(s):

Hip Joint ◽

Lower Limb ◽

Lower Limb Exoskeleton

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Decision Tree for Torque Assistive Generation on Hip Joint of Lower Limb Exoskeleton

2019 2nd International Conference on Applied Engineering (ICAE) ◽

10.1109/icae47758.2019.9221697 ◽

2019 ◽

Author(s):

Riska Analia ◽

Jan Hong ◽

Susanto ◽

P Daniel Sutopo ◽

Hendawan Soebhakti ◽

...

Keyword(s):

Decision Tree ◽

Hip Joint ◽

Lower Limb ◽

Lower Limb Exoskeleton

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Bounded Control of an Actuated Lower-Limb Exoskeleton

Journal of Robotics ◽

10.1155/2017/2423643 ◽

2017 ◽

Vol 2017 ◽

pp. 1-20

Author(s):

Michael Oluwatosin Ajayi ◽

Karim Djouani ◽

Yskandar Hamam

Keyword(s):

Lower Limb ◽

Angular Position ◽

High Gain ◽

Joint Torque ◽

Control Law ◽

Bounded Control ◽

Joint Torques ◽

Lower Limb Exoskeleton ◽

High Gain Observer ◽

Angular Velocities

A bounded control strategy is employed for the rehabilitation and assistance of a patient with lower-limb disorder. Complete and partial lower-limb motor function disorders are considered. This application is centered on the knee and the ankle joint level, thereby considering a user in a sitting position. A high gain observer is used in the estimation of the angular position and angular velocities which is then applied to the estimation of the joint torques. The level of human contribution is feedback of a fraction of the estimated joint torque. This is utilised in order to meet the demands for a bounded human torque; that is, τh≤N2,n≤N1,n. The asymptotic stability of the bounded control law without human contribution and the convergence analysis of the high gain observer is verified using Lyapunov-based analysis. Simulations are performed to verify the proposed control law. Results obtained guarantee a fair trajectory tracking of the physiotherapist trajectory.

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Bio-inspired control of joint torque and knee stiffness in a robotic lower limb exoskeleton using a central pattern generator

2017 International Conference on Rehabilitation Robotics (ICORR) ◽

10.1109/icorr.2017.8009442 ◽

2017 ◽

Cited By ~ 2

Author(s):

Stefan O. Schrade ◽

Yannik Nager ◽

Amy R. Wu ◽

Roger Gassert ◽

Auke Ijspeert

Keyword(s):

Central Pattern Generator ◽

Lower Limb ◽

Pattern Generator ◽

Joint Torque ◽

Knee Stiffness ◽

Lower Limb Exoskeleton

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Learning and planning of stair ascent for lower-limb exoskeleton systems

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-03-2018-0054 ◽

2019 ◽

Vol 46 (3) ◽

pp. 421-430

Author(s):

Qiming Chen ◽

Hong Cheng ◽

Rui Huang ◽

Jing Qiu ◽

Xinhua Chen

Keyword(s):

Dynamic Model ◽

Lower Limb ◽

Simulation Environment ◽

Content Type ◽

Lower Limb Exoskeleton ◽

Stair Ascent ◽

Cord Injury ◽

Machine Learning Approach ◽

External Forces ◽

The Cost

Purpose Lower-limb exoskeleton systems enable people with spinal cord injury to regain some degree of locomotion ability, as the expected motion curve needs to adapt with changing scenarios, i.e. stair heights, distance to the stairs. The authors’ approach enables exoskeleton systems to adapt to different scenarios in stair ascent task safely. Design/methodology/approach In this paper, the authors learn the locomotion from predefined trajectories and walk upstairs by re-planning the trajectories according to external forces posed on exoskeleton systems. Moreover, instead of using complex sensors as inputs for re-planning in real-time, the approach can obtain forces acting on exoskeleton through dynamic model of human-exoskeleton system learned by an online machine learning approach without accurate parameters. Findings The proposed approach is validated in both simulation environment and a real walking assistance exoskeleton system. Experimental results prove that the proposed approach achieves better performance than the traditional predefined gait approach. Originality/value First, the approach obtain the external forces by a learned dynamic model of human-exoskeleton system, which reduces the cost of exoskeletons and avoids the heavy task of translating sensor input into actuator output. Second, the approach enables exoskeleton accomplish stair ascent task safely in different scenarios.

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Comparison of Biomechanical Factors among Straight, Curve and Knuckle Kicking Motions in Soccer

Proceedings ◽

10.3390/proceedings2020049119 ◽

2020 ◽

Vol 49 (1) ◽

pp. 119

Author(s):

Kaoru Kimachi ◽

Richong Liu ◽

Masaaki Koido ◽

Sungchan Hong ◽

Shuji Shimonagata ◽

...

Keyword(s):

Motion Capture ◽

Hip Joint ◽

Lower Limb ◽

Three Dimensional ◽

Joint Torque ◽

Before And After ◽

Foot Posture ◽

The Moment ◽

Biomechanical Factors ◽

Practice Period

The rotation of a soccer ball is affected by several factors, such as impact point and foot posture, which are generated by joint torque in the lower limb. This study aimed to investigate joint torque in the lower limb that generates foot posture and swing trajectory, and compare three types of kicks before and after a practice period for participants to learn to control the ball rotation. An optical three-dimensional motion capture system was used to record the kicking motion of the participants. The results indicate that the adduction torque of the hip joint at the moment of impact decreased for curve kicks (from 0.56 to 0.25 Nm/kg) and increased for knuckle kicks (from −0.09 to 0.37 Nm/kg). We considered that the curve and knuckle kicks swing towards the inside (because of their positive values in the post experiment) with hip joint adduction before impact to control ball rotation.

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Analysis of a Cam-Follower Mechanism for a Passive Parallel Lower Limb Exoskeleton

Journal of Physics Conference Series ◽

10.1088/1742-6596/2120/1/012014 ◽

2021 ◽

Vol 2120 (1) ◽

pp. 012014

Author(s):

D V Lim ◽

D T K Tien ◽

E C Y Chung

Keyword(s):

Potential Energy ◽

Lower Limb ◽

Energy Requirement ◽

Gravitational Potential Energy ◽

Walking Gait ◽

Lower Limb Exoskeleton ◽

Cam Follower ◽

Good Potential ◽

External Power ◽

Gait Study

Abstract This project focused on the implementation of a novel cam-follower mechanism that was deemed to have good potential for practical application into a passive lower limb exoskeleton to determine its effectiveness in reducing the energy requirement of the user and its ability to match the walking gait of the user. The design of this novel-cam follower mechanism is inspired by the retractable mechanism of a ballpen. The cam follower mechanism was incorporated into a passive lower limb exoskeleton that was available prior to the study. Passive exoskeletons are intended to augment the load carrying capacity of the user through mechanical means instead of relying on external power. The walking gait study was conducted using physical testing. The mechanism was found to cause the user to bend below his natural centre of gravity a couple of times throughout the walking cycle. The user also had to stabilize himself from being rocked from side to side. Energy calculations were likewise conducted to investigate the energy consumption for a full cycle. The interchange among gravitational potential energy, spring potential energy and kinetic energy of the mechanism for a full walking cycle did not indicate possible advantage for the user.

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On the kinematic design of anthropomorphic lower limb exoskeletons and their matching movement

International Journal of Advanced Robotic Systems ◽

10.1177/1729881419875908 ◽

2019 ◽

Vol 16 (5) ◽

pp. 172988141987590 ◽

Cited By ~ 1

Author(s):

Bin Ren ◽

Jianwei Liu ◽

Xurong Luo ◽

Jiayu Chen

Keyword(s):

Hip Joint ◽

Lower Limb ◽

Parallel Mechanism ◽

Medical Rehabilitation ◽

Limb Movements ◽

Matching Model ◽

Kinematic Design ◽

Lower Limb Exoskeleton ◽

Human Data ◽

Simulation Results

The lower limb exoskeleton is a wearable device for assisting medical rehabilitation. A classical lower limb exoskeleton structures cannot precisely match the kinematics of the wearer’s limbs and joints in movement, so a novel anthropomorphic lower limb exoskeleton based on series–parallel mechanism is proposed in this article. Then, the human lower limb movements are measured by an optical gait capture system. Comparing the simulation results of the series–parallel mechanism with the measured human data, the kinematics matching model at the hip joint is established. The results show that the kinematic matching errors in the X, Y, and Z directions are less than 2 mm. So, the proposed kinematics matching model is effective and the anthropomorphic series–parallel mechanism has a significant improvement in tracing the human positions at the hip joint.

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