Hirokazu Seki

Novel Regenerative Braking Control of Electric Power-Assisted Wheelchair for Safety Downhill Road Driving

This paper describes a novel regenerative braking control scheme of electric power-assisted wheelchairs for safety driving on downhill roads. The ldquoelectric power-assisted wheelchairrdquo which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people; however, it has no braking system to suppress the wheelchairs velocity and brings the dangerous and fearful driving particularly on downhill roads. Therefore, this paper proposes a novel safety and efficient driving control scheme based on the regenerative braking system. This paper applies the regenerative braking system with the step-up chopper circuit serially connecting two motors and realizes the velocity feedback control with the variable duty ratio so that it tracks the optimal velocity based on the minimum Jerk model. In addition, the dynamic braking system is also applied at the low-speed range instead of the regenerative braking in order to suppress the acceleration. Some driving experiments on the practical downhill roads show the effectiveness of the proposed control system.

Novel straight road driving control of power assisted wheelchair based on disturbance estimation and minimum jerk control

Power assisted wheelchair which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people. In the practical driving condition, the straight driving can be prevented by the road conditions such as branches, grass and carpets because the right and left wheels drive independently. This paper proposes a novel straight road driving control system based on the disturbance torque estimation. The proposed system estimates the driving torque difference between the right and left wheels by disturbance observer and compensates to one side of the wheels. This paper also describes a minimum jerk trajectory control for power assisted wheelchair to improve the ride quality and safety. Some practical experiments on the various practical roads show the effectiveness of the proposed control systems and the possibility for the multi purpose and high performance system of power assisted wheelchair.

Minimum jerk control of power assisting robot on human arm behavior characteristic

This paper presents a novel trajectory control-method for power assisting robot. Human input force is intermittent in many cases such as assisting devices for upper limbs and power assisting wheelchair; therefore, the suitable trajectory must be generated also after the human decreases his force. This paper tries to solve this significant problem based on minimum jerk model closely approximating human arm movements because smooth and human-friendly power assisting robot can be realized by imitating human arm behavior characteristic. Some experiments and evaluation by trial subjects on power assisting robot show the effectiveness of the proposed method

A Study of Energy-Saving Shoes for Robot Considering Lateral Plane Motion

In this paper, we propose a flexible shoe system for biped robots to optimize energy consumption of the lateral plane motion. This shoe system is made to deform decline outside in the lateral plane and it can absorb the kinetic energy of the robot in the lateral plane. Furthermore, this hardware (shoes) and software (controller) can be easily applicable to the ordinary walking robot system. The effectiveness and characteristics of this system are confirmed by computer simulations and experimental results. It is confirmed that the stiffness of the shoe is a very important parameter for energy consumption by using computer simulations and experimental results.

Straight and circular road driving control of power assisted wheelchair based on balanced assisted torque

This paper describes a straight and circular road driving control scheme for power assisted wheelchair. Power assisted wheelchair which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of the straight and circular road driving must be further improved because the two wheels are driven independently. This paper proposes a straight and circular road driving control scheme based on the balanced assisted torque between the two wheels. The balanced assisted torque is determined from the proportion of the human input torque to the right and left wheels. Some experiments and subjective evaluation show the effectiveness of the proposed control system.

Velocity pattern generation for power assisted wheelchair based on jerk and acceleration limitation

This paper describes a novel velocity pattern generation scheme for power assisted wheelchair based on jerk and acceleration limitation. Power assisted wheelchair which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people. As one of the high performance control systems for the power assisted wheelchair, this paper proposes a real-time velocity pattern generation scheme to improve the ride quality and safety. The proposed system generates various velocity patterns with the limited jerk and acceleration and humans intent can be well reflected in the velocity patterns such as the driving distance. Some experiments show the effectiveness of the proposed control system.

Fuzzy Control for Electric Power-Assisted Wheelchair Driving on Disturbance Roads

This paper describes a driving control scheme of electric power-assisted wheelchairs for assistive driving on various large disturbance roads. The “power-assisted wheelchair” that assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people; however, there are lots of large disturbance roads such as uphill roads and rough roads and operators need to push hand-rims with larger power load in order to obtain enough driving distance and velocity. For example, wheelchairs might move backward on uphill roads due to the driving torque shortage. Therefore, this study proposes a fuzzy-algorithm-based torque control scheme in order to realize the assistive driving on large disturbance roads. The proposed fuzzy controller has a simple structure because high-performance CPUs and controllers are difficult to be carried on practical wheelchairs. The assisted torque after the operator releases hand-rims will be adjusted so that the enough velocity is kept even on large disturbance roads. Driving experimental results and evaluation results are provided to verify the effectiveness of the proposed control system.

Fuzzy inference based non-daily behavior pattern detection for elderly people monitoring system

This paper describes an abnormal behavior detection system based on an omni-directional vision sensor as one of the important elements in realizing ”Sensing and Robotic Support Room” for elderly people. Such support rooms are expected to be further developed in the future with the high performance to automatically recognize elderly people’s actions and behavior patterns and detect the unusual patterns using some sensors and to support their daily motions using some robotic manipulator control systems. The proposed monitoring system using an omni-directional vision sensor automatically learns the daily behavior patterns and detects the unusual behavior patterns and actions using fuzzy inference approach. The fuzzy rules are constructed using image feature values such as the area and center-of gravity values extracted from the captured image sequence and their patterns appearance frequency. Unusual behavior patterns can be automatically detected based on the possibility distribution inference method. Some experiments based on the investigation of elderly people’s typical daily behavior patterns show the effectiveness of the proposed system.

Driving trajectory generation of electric powered wheelchair using spline curve

This paper describes a novel smooth and stable driving trajectory generation scheme for electric powered wheelchair based on the third order spline curve. Electric powered wheelchair moved by the right and left electric motors based on the humans joystick input is expected to be widely used as a mobility support system for elderly people and disabled people. As one of the high performance control systems for the electric powered wheelchair, this paper proposes a real-time driving trajectory generation scheme to improve the ride quality and safety. The proposed system generates various driving trajectories with the spline curves based on the circle equations and the future passing positions are estimated using the turning radius circle equations. The humans intent from the joystick input can be well reflected in the driving trajectory such as the turning radius. The third order spline curve trajectory can be generated from four passing positions including one past passing position, one present position and two estimated future positions. Some simulation and experiment results show the effectiveness of the proposed control system.

Operationality improvement control of Electric power assisted wheelchair by fuzzy algorithm

This paper describes the operationality improvement control for electric power assisted wheelchairs. “Electric power assisted wheelchair” which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of the straight and circular road driving must be further improved because the two wheels drive independently. This paper proposes the operationality improvement control by fuzzy algorithm to realize the stable and reliable driving on straight and circular roads. The suitable assisted torque of the right and left wheels is determined by fuzzy algorithm based on the posture angular velocity, the posture angle of the wheelchair, the human input torque proportion and the total human torque of the right and left wheels. Some experiments on the practical roads show the effectiveness of the proposed control system.