Hideki Kadone

Wearable Gait Measurement System with an Instrumented Cane for Exoskeleton Control

In this research we introduce a wearable sensory system for motion intention estimation and control of exoskeleton robot. The system comprises wearable inertial motion sensors and shoe-embedded force sensors. The system utilizes an instrumented cane as a part of the interface between the user and the robot. The cane reflects the motion of upper limbs, and is used in terms of human inter-limb synergies. The developed control system provides assisted motion in coherence with the motion of other unassisted limbs. The system utilizes the instrumented cane together with body worn sensors, and provides assistance for start, stop and continuous walking. We verified the function of the proposed method and the developed wearable system through gait trials on treadmill and on ground. The achievement contributes to finding an intuitive and feasible interface between human and robot through wearable gait sensors for practical use of assistive technology. It also contributes to the technology for cognitively assisted locomotion, which helps the locomotion of physically challenged people.

Gaze anticipation during human locomotion

During locomotion, a top-down organization has been previously demonstrated with the head as a stabilized platform and gaze anticipating the horizontal direction of the trajectory. However, the quantitative assessment of the anticipatory sequence from gaze to trajectory and body segments has not been documented. The present paper provides a detailed investigation into the spatial and temporal anticipatory relationships among the direction of gaze and body segments during locomotion. Participants had to walk along several mentally simulated complex trajectories, without any visual cues indicating the trajectory to follow. The trajectory shapes were presented to the participants on a sheet of paper. Our study includes an analysis of the relationships between horizontal gaze anticipatory behavior direction and the upcoming changes in the trajectory. Our findings confirm the following: 1) The hierarchical ordered organization of gaze and body segment orientations during complex trajectories and free locomotion. Gaze direction anticipates the head orientation, and head orientation anticipates reorientation of the other body segments. 2) The influence of the curvature of the trajectory and constraints of the tasks on the temporal and spatial relationships between gaze and the body segments: Increased curvature resulted in increased time and spatial anticipation. 3) A different sequence of gaze movements at inflection points where gaze plans a much later segment of the trajectory.

Recognizing Emotions Conveyed by Human Gait

Humans convey emotions through different ways. Gait is one of them. Here we propose to use gait data to highlight features that characterize emotions. Gait analysis study usually focuses on stance phase, frequency, footstep length. Here the study is based on the joint angles obtained from inverse kinematics computation from the 3D motion-capture data using a combination of degrees of freedom (DOF) out of a 34DOF human body model obtained from inverse kinematics of markers 3D position. The candidates are four professional actors, and five emotional states are simulated: Neutral, Joy, Anger, Sadness, and Fear. The paper presents first a psychological approach which results are used to propose numerical approaches. The first study provides psychological results on motion perception and the possibility of emotion recognition from gait by 32 observers. Then, the motion data is studied using a feature vector approach to verify the numerical identifiability of the emotions. Finally each motion is tested against a database of reference motions to identify the conveyed emotion. Using the first and second study results, we utilize a 6DOF model then a 12DOF model. The experimental results show that by using the gait characteristics it is possible to characterize each emotion with good accuracy for intra-subject data-base. For inter-subject database results show that recognition is more prone to error, suggesting strong inter-personal differences in emotional features.

The voluntary driven exoskeleton Hybrid Assistive Limb (HAL) for postoperative training of thoracic ossification of the posterior longitudinal ligament: a case report

Context: The hybrid assistive limb (HAL) is a wearable robot suit that assists in voluntary control of knee and hip joint motion by detecting bioelectric signals on the surface of the skin with high sensitivity. HAL has been reported to be effective for functional recovery in motor impairments. However, few reports have revealed the utility of HAL for patients who have undergone surgery for thoracic ossification of the posterior longitudinal ligament (thoracic OPLL). Herein, we present a postoperative thoracic OPLL patient who showed remarkable functional recovery after training with HAL. Findings: A 63-year-old woman, who could not walk due to muscle weakness before surgery, underwent posterior decompression and fusion. Paralysis was re-aggravated after the initial postoperative rising. We diagnosed that paralysis was due to residual compression from the anterior lesion and microinstability after posterior fixation, and prescribed bed rest for a further 3 weeks. The incomplete paralysis gradually recovered, and walking training with HAL was started on postoperative day 44 in addition to standard physical therapy. The patient underwent 10 sessions of HAL training until discharge on postoperative day 73. Results of a 10-m walk test were assessed after every session, and the patients speed and cadence markedly improved. At discharge, the patient could walk with 2 crutches and no assistance. Furthermore, no adverse events associated with HAL training occurred. Conclusion: HAL training for postoperative thoracic OPLL patients may enhance improvement in walking ability, even if severe impairment of ambulation and muscle weakness exist preoperatively.

Decrease of spasticity after hybrid assistive limb® training for a patient with C4 quadriplegia due to chronic SCI

Context: Recently, locomotor training with robotic assistance has been found effective in treating spinal cord injury (SCI). Our case report examined locomotor training using the robotic suit hybrid assistive limb (HAL) in a patient with complete C4 quadriplegia due to chronic SCI. This is the first report examining HAL in complete C4 quadriplegia. Findings: The patient was a 19-year-old man who dislocated C3/4 during judo 4 years previously. Following the injury, he underwent C3/4 posterior spinal fusion but remained paralyzed despite rehabilitation. There was muscle atrophy under C5 level and no sensation around the anus, but partial sensation of pressure remained in the limbs. The American Spinal Injury Association impairment scale was Grade A (complete motor C4 lesion). HAL training was administered in 10 sessions (twice per week). The training sessions consisted of treadmill walking with HAL. For safety, 2 physicians and 1 therapist supported the subject for balance and weight-bearing. The devices cybernic autonomous control mode provides autonomic physical support based on predefined walking patterns. We evaluated the adverse events, walking time and distance, and the difference in muscle spasticity before and after HAL-training using a modified Ashworth scale (mAs). No adverse events were observed that required discontinuation of rehabilitation. Walking distance and time increased from 25.2 meters/7.6 minutes to 148.3 meter/15 minutes. The mAs score decreased after HAL training. Conclusion: Our case report indicates that HAL training is feasible and effective for complete C4 quadriplegia in chronic SCI.

Modeling and identification of emotional aspects of locomotion

Abstract The studies of emotional facial expressions and emotional body language are currently receiving a lot of attention in the cognitive sciences. In this project, we study implicit bodily expression of emotions during standard motions, such as walking forwards. An underlying assumption of our work is that all human motion is optimal in some sense and that different emotions induce different objective functions, which result in different deformations of normal motion. We created a 3D rigid-body model of a human of which we use the forward dynamics simulation in an optimal control context. We performed two kinds of optimizations: (i) reconstruction of dynamic quantities, such as joint torques, of pre-recorded data of emotional walking motions and (ii) forward optimization that generates neutral and varied walking motions using different objective functions. Optimizations are performed with the software package MUSCOD-II, which uses a direct multiple-shooting discretization scheme. The results of this work form the foundation for further analysis of emotional motions using inverse optimal control methods.

Exoskeleton robot control based on cane and body joint synergies

Several methods have been investigated and realized for operation of exoskeleton robots for assistance of human gait. These systems perform motion intention estimation using the bioelectrical signals of muscle activation, body gestures and kinesiological information, or a mixed combination in a hybrid system. For motion intention estimation of the lower limb(s), information of the lower limbs is usually utilized. However, human gait is not only the function of the lower limbs, but also coordination between upper and lower limbs, adding to balance and cognitive functions as well. In this study, we investigate on how to utilize the synergies of upper and lower limbs of human walking in exoskeleton robot control by using the cane (walking aid). We analyse the synergies of human gait with cane in healthy subjects by means of Principal Component Analysis (PCA) in order to investigate the usability of cane for robot-assisted motor rehabilitation. We also implement a semi autonomous control for an exoskeleton robot, single leg version of HAL (Hybrid Assistive Limb) suit, based on the cane and body joint synergies.

The Combined Role of Motion-Related Cues and Upper Body Posture for the Expression of Emotions during Human Walking

The present study aimed at investigating how emotion affect the kinematic aspect of human walking. The gaits of eight professional actors expressing different types of emotions (neutral, joy, anger, sadness and fear) during walking were recorded and analyzed in the sagittal plane. We show both step-related behavioural changes (in terms of step length, speed,etc.) that are common to different emotions and emotion-specific body configuration changes (mainly at the level of the upper body posture) during emotional gaits. Since the overall speed of walking is another major variant in walking, natural walking at different speeds were recorded in another session for a control.

Perception of Emotional Gaits Using Avatar Animation of Real and Artificially Synthesized Gaits

The emotional component of human walking patterns can be characterized by a limited set of kinematic cues [8]. Here, we tested whether artificial synthesis of emotional gaits based on these cues can facilitate emotion perception in human observers. To this purpose, we recorded neutral gaits and artificially modified the walking speed, the upper-body posture or some combination thereof. Nave observers had to judge emotion conveyed by these animated avatars or by real emotional gaits recorded in professional actors. We found that the recognition rates of both animated and real movies were comparable and particularly high (e.g. > 85 %): all emotions but fear were unambiguously perceived in walking avatars thanks to a particular combination of walking speed and head/trunk posture. This reveals a strong coupling between motor and perceptual processes underlying emotion expression and recognition. The potential applications of these findings in the fields of animated motion picture and humanoid robotics are discussed.

The Hybrid Assistive Limb® intervention for a postoperative patient with spinal dural arteriovenous fistula and chronic spinal cord injury: a case study

Context: The purpose of this report was to describe the improvement in walking ability using the Hybrid Assistive Limb® (HAL®) intervention in the case of a patient with paraplegia after spinal cord injury whose condition deteriorated because of a spinal dural arteriovenous fistula (SDAVF). Findings: A 48-year-old man started the HAL® intervention twice per week (total 10 sessions), after his neurologic improvement had plateaued from 3 to 6 months postoperatively for an SDAVF. During the HAL® intervention, the 10-m walk test (10MWT) without HAL® was performed before and after each session. An electromyography system was used to evaluate muscle activity of both the gluteus maximus (Gmax) and quadriceps femoris (Quad) muscles in synchronization with the Vicon motion capture system. The International Standards for Neurological and Functional Classification of Spinal Cord Injury (ISNCSCI) motor scores of the lower extremities and the Walking Index for Spinal Cord Injury II (WISCI II) score were also assessed to evaluate motor function. The HAL® intervention improved gait speed and cadence during the 10MWT. Before the intervention, both the Gmax and left Quad muscles were not activated. After the intervention, the right Gmax and both Quad muscles were activated in stance phase rhythmically according to the gait cycle. The ISNCSCI motor score also improved from 14 to 16, and the WISCI II scored improved from 7 to 12. Conclusion/clinical relevance: Our experience with this patient suggests that the HAL® can be an effective tool for improving functional ambulation in patients with chronic spinal cord injury.