Makoto Sasaki

Development of a 3DOF mobile exoskeleton robot for human upper-limb motion assist

In order to assist physically disabled, injured, and/or elderly persons, we have been developing exoskeleton robots for assisting upper-limb motion, since upper-limb motion is involved in a lot of activities of everyday life. This paper proposes a mechanism and control method of a mobile exoskeleton robot for 3DOF upper-limb motion assist (shoulder vertical and horizontal flexion/extension, and elbow flexion/extension motion assist). The exoskeleton robot is mainly controlled by the skin surface electromyogram (EMG) signals, since EMG signals of muscles directly reflect how the user intends to move. The force vector at the end-effector is taken into account to generate the natural and smooth hand trajectory of the user in the proposed control method. An obstacle avoidance algorithm is applied to prevent accidental collision between the users upper-limb and the robot frame. The experiment was performed to evaluate the effectiveness of the proposed exoskeleton robot.

Neuro-fuzzy based motion control of a robotic exoskeleton: considering end-effector force vectors

To assist physically disabled, injured, and/or elderly persons, we have been developing a 3DOF exoskeleton robot for assisting upper-limb motion, since upper-limb motion is involved in a lot of activities of everyday life. The exoskeleton robot is mainly is controlled by the skin surface electromyogram (EMG) signals, since EMG signals of muscles directly reflect how the user intends to move. This paper introduces the mechanism of the exoskeleton robot and also proposes a control method of the exoskeleton robot considering the generated end-effector force vectors

Development of a new adaptation system for a manual wheelchair based on human body function

In this paper, we propose a new adaptation system for a manual wheelchair to reduce the load on the upper extremity of the user during wheelchair manipulation and also to increase the efficiency of the wheelchair propulsion. The proposed adaptation system is designed to provide optimal position of the handrim and the desired angular position of seat and backrest of the wheelchair based on the users body function. Electromyogram signals from the user muscles, heart rate signals, oxygen uptake, amount of applied pressure on the seat and backrest, force/moment applied on the handrim, joint force/moment of the upper extremity and analytical results using the dynamic manipulating force ellipsoid and the driving force contribution figure are used as index parameters for the proposed adaptation system.

Robotic Exoskeleton for Rehabilitation and Motion Assist

For elderly and or physically disabled people who have lost their body functioning of motions due to geriatric disorders, and/or disease processes including trauma, sports injuries, spinal cord injuries, occupational injuries, and strokes, we have been developing a 3 DOF mobile robotic exoskeleton for rehabilitation and for assisting motion of elbow and shoulder, since human shoulder and elbow motions are involved in a lot of activities of everyday life. The robotic exoskeleton is mainly activated and is controlled by the skin surface electromyogram (EMG) signals, since EMG signals of muscles directly reflect how the user intends to move. This paper focused on the mechanism of mobile robotic exoskeleton and proposed passive and active assist mode of rehabilitation scheme in addition to assist daily upper-limb motion by the aid of robotic exoskeleton. The proportional derivative (PD) control has been applied to the controller for the passive mode of rehabilitation whereas neuro-fuzzy based biological controller is responsible for active assist mode of rehabilitation as well as to assist daily upper limb motion

Control of an artificial-hip-joint simulator to evaluate dislocation

Total hip arthroplasty (THA) is performed to replace all or part of a human hip joint with an artificial joint for patients who have rheumatoid arthritis or osteoarthritis of the hip joint. Although THA might result in postoperative complications of dislocation, wear and/or loose, their mechanisms have not been analyzed enough. We have developed an artificial-hip-joint simulator that can generate the same joint posture and joint contact force as those in daily life motion in order to evaluate the performance of the artificial-hip-joint. Dislocation of the artificial-hip-joint during daily living activities was generated by the simulator in order to analyze its mechanism.

Biomechanical analysis for FES assisted swing-through gait

Swing-through gait is a method of providing paraplegic patients a faster means of mobility. The purpose of this study was to analyze the kinematics of body extremities during swing-through crutches gait with free-knees. Twelve non-disabled adult males participated in this study. Joint angles and ground reaction forces were investigated during the swing-through gait with crutches. A mathematical model consisting of linked rigid bodies was developed to analyze the gait, and the joint moments of lower extremities were calculated. The swing-through gait using Functional Electrical Stimulation (FES) with crutches has a problem that patients upper limbs have to support their body against gravity during the body-swing phase. So we compared the energy consumption in upper limb muscles during the swing-through gait using axillary and elbow crutches to consider the selection of a suitable crutch for the swing-through gait by FES. The energy consumption in pectoralis major, biceps and brachialis using the axillary crutch was significantly larger than the gait using the elbow crutch. The energy consumption in the middle part of the deltoid, and long and short heads of the triceps using the elbow crutch was significantly larger than the axillary crutch walking. But there was no significant difference in the total energy consumption between the crutches. The calculated data has the potential to be applied in the clinical restoration for the swing-through gait in complete paraplegics with free-knees.