Development of an unpowered ankle exoskeleton for walking assist

An Unpowered Knee Exoskeleton for Walking Assistance and Energy Capture

In order to reduce the energy consumption of human daily movement without providing additional power, we considered the biomechanical behavior of the knee during external impedance interactions. Based on the theory of human sports biomechanics, combined with the requirements of human-machine coupling motion consistency and coordination, an unpowered exoskeleton-assisted device for the knee joint is proposed in this paper. The effectiveness of this assisted device was verified using gait experiments and distributed plantar pressure tests with three modes: "not wearing exoskeleton" (No exo.), "wearing exoskeleton with assistance " (Exo. On), and "wearing exoskeleton without assistance" (Exo. Off). The experimental results indicate that (1) This device can effectively enhance the function of the knee, increasing the range of knee movement by 3.72% (p < 0.001). (2) In the early stages of the lower limb swing, this device reduces the activity of muscles in relation to the knee flexion, such as the rectus femoris, vastus lateralis, and soleus muscles. (3) For the first time, it was found that the movement length of the plantar pressure center was reduced by 6.57% (p = 0.027). This basic principle can be applied to assist the in-depth development of wearable devices.

Advances on mechanical designs for assistive ankle-foot orthoses

Assistive ankle-foot orthoses (AAFOs) are powerful solutions to assist or rehabilitate gait on humans. Existing AAFO technologies include passive, quasi-passive, and active principles to provide assistance to the users, and their mechanical configuration and control depend on the eventual support they aim for within the gait pattern. In this research we analyze the state-of-the-art of AAFO and classify the different approaches into clusters, describing their basis and working principles. Additionally, we reviewed the purpose and experimental validation of the devices, providing the reader with a better view of the technology readiness level. Finally, the reviewed designs, limitations, and future steps in the field are summarized and discussed.

The Effects of Unpowered Soft Exoskeletons on Preferred Gait Features and Resonant Walking

Resonant walking with preferred gait features is a self-optimized consequence of long-term human locomotion. Minimal energy expenditure can be achieved in this resonant condition. This unpowered multi-joint soft exoskeleton is designed to test whether: (1) there is an obvious improvement in preferred speed and other gait features; (2) resonant walking still exists with exoskeleton assistance. Healthy participants (N = 7) were asked to perform the following trials: (1) walking at 1.25 m/s without assistance (normal condition); (2) walking at 1.25 m/s with assistance (general condition); (3) walking at preferred speed with assistance (preferred condition); (4) walking at the speed in trial (3) without assistance (comparison condition). Participants walked at the preferred frequency and ±10% of it. An average 21% increase in preferred speed was observed. The U-shaped oxygen consumption and lower limb muscle activity curve with the minimum at preferred frequency indicated that the resonant condition existed under the preferred condition. Average metabolic reductions of 4.53% and 7.65% were found in the preferred condition compared to the general and comparison condition, respectively. These results demonstrate that the resonant condition in assisted walking could benefit energy expenditure and provide a new perspective for exoskeleton design and evaluation.

A Wearable Lower Limb Exoskeleton: Reducing the Energy Cost of Human Movement

Human body enhancement is an interesting branch of robotics. It focuses on wearable robots in order to improve the performance of human body, reduce energy consumption and delay fatigue, as well as increase body speed. Robot-assisted equipment, such as wearable exoskeletons, are wearable robot systems that integrate human intelligence and robot power. After careful design and adaptation, the human body has energy-saving sports, but it is an arduous task for the exoskeleton to achieve considerable reduction in metabolic rate. Therefore, it is necessary to understand the biomechanics of human sports, the body, and its weaknesses. In this study, a lower limb exoskeleton was classified according to the power source, and the working principle, design idea, wearing mode, material and performance of different types of lower limb exoskeletons were compared and analyzed. The study shows that the unpowered exoskeleton robot has inherent advantages in endurance, mass, volume, and cost, which is a new development direction of robot exoskeletons. This paper not only summarizes the existing research but also points out its shortcomings through the comparative analysis of different lower limb wearable exoskeletons. Furthermore, improvement measures suitable for practical application have been provided.

Ride-on car training using sitting and standing postures for mobility and socialization in young children with motor delays: a randomized controlled trial

PURPOSE

To examine the effects of ride-on car (ROC) training using different postures on mobility and social function in children with motor delays in comparison with conventional therapy.

MATERIALS AND METHODS

Thirty-eight children (22 males, 16 females) with motor delays were recruited and randomly assigned to three groups: ROC training while sitting (ROC-Sit, n = 15; mean age, 20.25 months; standard deviation [SD], 5.29), ROC training while standing (ROC-Stand, n = 12; mean age, 24.80 months; SD, 8.42), and conventional therapy (control, n = 11; mean age: 20.25 months, SD: 5.37). All groups underwent 2-h training sessions twice weekly over a 12-week intervention phase. The Pediatric Evaluation of Disability Inventory and Goal Attainment Scaling were performed before and after the intervention and at follow-up sessions after 12 weeks.

RESULTS

Mobility and goal achievement improved significantly in all groups after the intervention (p < 0.001; p < 0.0001). However, social function improved significantly only in the ROC-Stand group (p = 0.001), which had the highest number of participants showing clinically meaningful changes in mobility and social function.

CONCLUSION

Increased practice and caregivers' involvement can improve children's mobility and goal achievement. Adopting a standing posture in an ROC can enhance social function.IMPLICATIONS FOR REHABILITATIONProviding active exploratory experience through ride-on cars or practicing specific skills can improve children's mobility function.Ride-on car training in a standing posture allows children to access their distal environment visually, resulting in improved social function.Setting goals with caregivers maximizes the effects of treatment on goal achievement.

Flexible lower limb exoskeleton systems: A review

BACKGROUND

As an emerging exoskeleton robot technology, flexible lower limb exoskeleton (FLLE) integrates flexible drive and wearable mechanism, effectively solving many problems of traditional rigid lower limb exoskeleton (RLLE) such as higher quality, poorer compliance and relatively poor portability, and has become one of the important development directions in the field of active rehabilitation.

OBJECTIVE

This review focused on the development and innovation process in the field of FLLE in the past decade.

METHOD

Related literature published from 2010 to 2021 were searched in EI, IEEE Xplore, PubMed and Web of Science databases. Seventy target research articles were further screened and sorted through inclusion and exclusion criteria.

RESULTS

FLLE is classified according to different driving modes, and the advantages and disadvantages of passive flexible lower limb exoskeletons and active flexible lower limb exoskeletons are comprehensively summarized.

CONCLUSION

At present, FLLE's research is mainly based on cable drive, bionic pneumatic muscles followed and matured, and new exoskeleton designs based on smart material innovations also trend to diversify. In the future, the development direction of FLLE will be lightweight and drive compliance, and the multi-mode sensory feedback control theory, motion intention recognition theory and human-machine interaction theory will be combined to reduce the metabolic energy consumption of walking.

A simulation-based framework with a proprioceptive musculoskeletal model for evaluating the rehabilitation exoskeleton system

BACKGROUND AND OBJECTIVE

Various rehabilitation exoskeletons have been designed to help people regain normal gait from stroke effects. However, the evaluation and further optimization of these exoskeletons are not convenient and usually need complicated experimental works. The present study aims to establish a simulation-based method with a proprioceptive musculoskeletal model to conveniently evaluate the efficiency of a self-developed exoskeleton for further optimization.

METHODS

Three volunteers who suffer from dyskinesia due to stroke were recruited for gait experiments with and without the self-develop exoskeleton. The corresponding simulations were implemented based on the proprioceptive model, the exoskeleton model, and the input kinematic data obtained from the experiments. The joint angles, muscle activations, and metabolic costs as well as the proprioceptor feedback stimulation were extracted for comparative analysis.

RESULT

Several positive effects of the exoskeleton were noted based on the simulation results when using it to aid the patients' rehabilitation during the gait training. The CORA scores of the patients' joint angle to the normal data increased by 11.6~37.8% with the assistance of the exoskeleton. The wave frequency of proprioceptive feedback stimulation that can be directly correlated to the neural rehabilitation obviously inclined during a gait cycle. The muscle activations were also rearranged to better support the patient's walk when using the exoskeleton, while the metabolic costs were reduced for all the patients.

CONCLUSION

In summary, the present simulation-based method can be practical for pre-evaluation and optimization of various exoskeleton design in the future.