Wearer's Motion Research Articles

Designs and Applications for the Multimodal Flexible Hybrid Epidermal Electronic Systems.

Research on the flexible hybrid epidermal electronic system (FHEES) has attracted considerable attention due to its potential applications in human-machine interaction and healthcare. Through material and structural innovations, FHEES combines the advantages of traditional stiff electronic devices and flexible electronic technology, enabling it to be worn conformally on the skin while retaining complex system functionality. FHEESs use multimodal sensing to enhance the identification accuracy of the wearer's motion modes, intentions, or health status, thus realizing more comprehensive physiological signal acquisition. However, the heterogeneous integration of soft and stiff components makes balancing comfort and performance in designing and implementing multimodal FHEESs challenging. Herein, multimodal FHEESs are first introduced in 2 types based on their different system structure: all-in-one and assembled, reflecting totally different heterogeneous integration strategies. Characteristics and the key design issues (such as interconnect design, interface strategy, substrate selection, etc.) of the 2 multimodal FHEESs are emphasized. Besides, the applications and advantages of the 2 multimodal FHEESs in recent research have been presented, with a focus on the control and medical fields. Finally, the prospects and challenges of the multimodal FHEES are discussed.

Walking and scuba diving assisted amphibious exoskeleton robots: the designing of power assist control and myoelectricity based wearers' fatigue evaluation.

Exoskeleton robots have the potential to augment human motor capabilities. however, current control strategies often require task-specific control laws tailored for different scenarios, which limits the applicability of exoskeletons. In this study, we propose a control strategy for exoskeleton robots that is adaptable across various scenarios. We employ adaptive oscillators (AO) with feedback control to rapidly estimate the wearer's motion phase and subsequently provide torque assistance to the wearer's hip joint based on a TCN-LSTM model. During experiments, we collected surface electromyographic (sEMG) signals from the tibialis anterior, gastrocnemius, and rectus muscles of seven groups of subjects performing treadmill walking and inclined treadmill exercises. We utilized the short-time Fourier transform to extract frequency characteristics of the signals and statistically analyzed the rate of frequency change in each muscle group under different strategies. The results indicate that when wearing the exoskeleton, the overall muscle frequency changes more slowly, suggesting that subjects can maintain activity for a longer duration before fatigue sets in. This control strategy effectively reduces the energetic cost of lower limb work for the wearer and enhances the exoskeleton's versatility in various applications.

A Robust Adaptive Admittance Control Scheme for Robotic Knee Prosthesis Using Human-Inspired Virtual Constraints

A robust adaptive admittance control scheme using human-inspired virtual constraints was presented for a robotic knee prosthesis. The controller is able to deal with the wearer's motion intention as well as the partial unknown parameter values of the prosthesis dynamics. The desired trajectory of the prosthetic knee joint is parameterized by the amputee-driven thigh phase variable and implemented by human-inspired virtual constraints rather than the preprogrammed time-dependent trajectory or human data replaying. A reference admittance model was set up to make the prosthesis be more compliant in the presence of ground reaction forces impact. A composite reaching law is proposed to cope with the chattering phenomenon and the finite-time convergence problem. The controller is designed by the back-stepping method based on Lyapunov. The tracking performance and the stability of the closed-loop system are proven via Lyapunov stability analysis. The feasibility and effectiveness of the proposed control scheme are proved in simulation results.

Design and Evaluation of a Balance Assistance Control Moment Gyroscope

We recently proposed the theoretical idea of a wearable balancing aid, consisting of a set of control moment gyroscopes (CMGs) contained into a backpacklike orthopedic corset. Even though similar solutions have been reported in the literature, important considerations in the synthesis and design of the actuators remained to be addressed. These include design requirements such as aerodynamic behavior of the spinning flywheel, induced dynamics by the wearer's motion, and stresses in the inner components due to the generated gyroscopic moment. In this paper, we describe the design and evaluation of a single CMG, addressing in detail the aforementioned requirements. In addition, given the application of the device in human balance, the design follows the European directives for medical electrical equipment. The developed system was tested in a dedicated balance test bench showing good agreement with the expected flywheel speed, and calculated power requirements in the actuators and output gyroscopic moment. The device was capable of producing a peak gyroscopic moment of approximately 70 N·m with a total CMG mass of about 10 kg.

Hierarchical Cascade Controller for Assistance Modulation in a Soft Wearable Arm Exoskeleton

In recent years soft wearable exoskeletons, commonly referred to as exosuits, have been widely exploited in human assistance. Hence, a shared approach for a systematic and exhaustive control architecture is extremely important. Most of the exosuits developed so far employ a bowden cable transmission to conveniently place the actuator away from the end-effector. While having many advantages this actuation strategy presents some intrinsic limitations caused by the presence of nonlinearities, such as friction and backlash of the cables, which make it difficult to predict and control the dynamics between the device and the user. In this letter, we propose a novel hierarchical control paradigm for a cable-driven upper limb exosuits that aims at evaluating and consequently deliver the appropriate assistive torque to the user's elbow joint. The proposed control method comprises three main layers: an active impedance control which estimates the user's arm motion intention and guarantees an intuitive response of the suit to the wearer's motion; a mid-level controller which compensates for the backlash in the transmission and converts the reference arm motion to the desired position of the actuator; a low-level controller which is responsible for driving the actuation stage by compensating for the nonlinear dynamics occurring in the bowden cable to provide the desired assistive torque at the joint. Tests on healthy subjects show that wearing the exosuit reduces by 48.3% the muscular effort required to lift 1 kg and that the controller is able to modulate its level of assistance to the wearer's motor ability.

Learning Predictive Movement Models From Fabric-Mounted Wearable Sensors.

The measurement and analysis of human movement for applications in clinical diagnostics or rehabilitation is often performed in a laboratory setting using static motion capture devices. A growing interest in analyzing movement in everyday environments (such as the home) has prompted the development of "wearable sensors", with the most current wearable sensors being those embedded into clothing. A major issue however with the use of these fabric-embedded sensors is the undesired effect of fabric motion artefacts corrupting movement signals. In this paper, a nonparametric method is presented for learning body movements, viewing the undesired motion as stochastic perturbations to the sensed motion, and using orthogonal regression techniques to form predictive models of the wearer's motion that eliminate these errors in the learning process. Experiments in this paper show that standard nonparametric learning techniques underperform in this fabric motion context and that improved prediction accuracy can be made by using orthogonal regression techniques. Modelling this motion artefact problem as a stochastic learning problem shows an average 77% decrease in prediction error in a body pose task using fabric-embedded sensors, compared to a kinematic model.

2P1-I09 運動機能障がい者の普遍的動作を模擬する装着型運動機能障害シミュレータ : 変形性膝関節症患者の起立・着座動作の模擬

It is ethically unacceptable to engage people with impaired motor functions in experiments, wherein they may face pain and risk of injuries. We developed a wearable robot for healthy adults and its control algorithm to simulate the behaviors of patients with knee osteoarthritis. In order to simulate patient movements by a healthy person wearing a robot, we formulated a model motion that represented invariant patient motions. We then determined the output torque of the exoskeletal knee robot such that the wearer's motion followed the model motion. The effectiveness of the method was testified for standing-up and sitting-down motions, and some characteristic impaired motions such as body inclination to the healthy side and imbalanced right and left knee angles were manifested by the simulator.

G1010306 筋電位に基づく動作予測を用いた空気圧式腕用パワーアシスト装置の開発([G101-03]機械力学・計測制御一般セッション(3))

Assistive devices can be worn to enhance the wearer's strength. Such devices need to be safe for the wearer Pneumatic actuators are suitable for driving those devices because they are highly safe for humans. However, the responsiveness of pneumatic actuators is lower than that of electric actuators due to the compressibility of air. In this paper, we use the initial burst in muscle activity to avoid delay in activating our pneumatic arm assistive device for the wearer's motion. The initial burst that always occurs first in voluntary movements indicates the wearer's preparation for movement. It is detected based on an inflection point on the cumulative addition curve obtained from a surface electromyogram signal. Experimental verification shows that the activation of the assistive device prior to the wearer's actual movement is possible.

Development of a Wearable Assist Suit for Walking and Lifting-Up Motion Using Electric Motors

As birth rates drop and societies age, the physical burden on long-term personnel grows and labor shortages become an increasing problem for society. We developed a practical wearable assist suit that supports motion in an antigravitational direction using electricmotors while ensuring that passive joints do not interfere with wearer motion. Results of experiments show the effectiveness of the proposed wearable assist suit.

Power assist method based on Phase Sequence and muscle force condition for HAL

An exoskeleton robot can replace the wearer's motion function by operating the human's body. The purpose of this study is to propose a power assist method of walking, standing up and going up stairs based on autonomous motion of the exoskeleton robot suit, HAL (Hybrid assistive Limb), and verify the effectiveness of this method by experiment. In order to realize power assist of tasks (walking, standing up and going up stairs) autonomically, we used the Phase Sequence control which generates a task by transiting some simple basic motions called Phases. A task was divided into some Phases on the basis of the task performed by a normal person. The joint moving modes were categorized into active, passive and free modes according to the characteristic of the muscle force conditions. The autonomous motions which HAL generates in each Phase were designed corresponding to one of the categorized modes. The power assist experiments were performed by using the autonomous motion with a focus on the active mode. The experimental results showed that the wearer's muscle activation levels in each Phase were significantly reduced. With this, we confirmed the effectiveness of the proposed assist method.

Dependency on Turn-round Angle of a Moving Mannequin Stand with a Flared Skirt about Evaluation of Clothing Appearance.

The purpose of this study is to evaluate aesthetic appearance of flared skirts in dynamic state objectively, in consideration of the actual wearer's motion. We studied the relationship between subjective values obtained from sensory test of moving skirts' appearance and turn-round angle of a mannequin stand. From the agreed results of panels, we found the optimum conditions of turn-round angle and speeds of a mannequin stand. By using subjective values obtained from sensory test under the optimum conditions, we selected mechanical and vibrational parameters for an objective evaluation equation of beautiful appearance of moving flared skirts by cluster analysis. The objective evaluation equations were derived for “flowing”, “rhythmical”, “airy”, “flexible”, “graceful”, “lively”, “dynamic” and “beautiful” moving flared skirts by using those parameters. The basic and combined mechanical parameters such as WT and ³√G⁄W are related to moving clothing appearance significantly. The total beautiful appearance of flared skirts in dynamic state was evaluated mainly by flowing, rhythmical, airy, flexible, graceful and lively movement subjectively.