Toshiro Noritsugu

Application of rubber artificial muscle manipulator as a rehabilitation robot

The application of a robot to rehabilitation has become a matter of great concern. This paper deals with functional recovery therapy, one important aspect of physical rehabilitation. Single-joint therapy machines have already been achieved. However, for more efficient therapy, multjoint robots are necessary to achieve more realistic motion patterns. This kind of robot must have a high level of safety for humans. A pneumatic actuator may be available for such a robot, because of the compliance of compressed air. A pneumatic rubber artificial muscle manipulator has been applied to construct a therapy robot with two degrees of freedom (DOF). Also, an impedance control strategy is employed to realize various motion modes for the physical therapy modes. Further, for efficient rehabilitation, it is desirable to comprehend the physical condition of the patient. Thus, the mechanical impedance of the human arm is used as an objective evaluation of recovery, and an estimation method is proposed. Experiments show the suitability of the proposed rehabilitation robot system.

Development of Active Support Splint driven by Pneumatic Soft Actuator (ASSIST)

In this study, in order to realize an assist of independent life for the elderly or people in need of care and relieve a physical burden for care worker, an active support splint driven by pneumatic soft actuator (ASSIST) has been developed. ASSIST consists of a plastic interface with the palm and arm and two rotary-type soft actuators put in both sides of appliance. In this paper, the fundamental characteristics of ASSIST is described, and then the effectiveness of this splint is experimentally discussed. Finally, the operation of ASSIST based on a human intention is described.

Development of Wrist Rehabilitation Equipment Using Pneumatic Parallel Manipulator

In this study, we aim at developing a mechanical device to support human rehabilitation motion of their wrist joint instead of a physiotherapist. Pneumatic parallel manipulator is introduced as a mechanical equipment from a view that pneumatic actuators bring minute force control property owing to the air compressibility and parallel manipulators feature of multiple degrees of freedom is suitable for the complex motion of human wrist joint. To cope with the shortage of physiotherapist, we propose a method to acquire P.T.s rehabilitation motion and implement it for a patient using the equipment. The validity of the proposed system is confirmed through some experiments.

Visual servoing of nonholonomic cart

This paper presents a visual feedback control scheme for a nonholonomic cart without capabilities for dead reckoning. A camera is mounted on the cart and it observes cues attached on the environment. The dynamics of the cart are transformed into a coordinate system in the image plane. An image-based controller which linearizes the dynamics is proposed. Since the positions of the cues in the image plane are controlled directly, possibility of missing cues is reduced considerably. Simulations are carried out to evaluate the validity of the proposed scheme. Experiments on a radio controlled car with a CCD camera are also given.

Performance and sensitivity in visual servoing

Describes the relationship between the control performance and the number/configuration of the image features in feature-based visual servoing. The performance is evaluated by two ways: accuracy and speed. A quantitive definition of the sensitivity is given and the relationship among the sensitivity, the speed of convergence and the accuracy are discussed by using the image Jacobian. It is proved that these performance indices are increased effectively by using a point with different height. Experiments on Puma 560 are given to show the validity of these performance measures.

Modeling and control of robotic yo-yo with visual feedback

Yo-yo is a toy made of two thick circular pieces of wood, plastic, etc., connected with a short axle that can be made to run up and down, by moving a string tied to it. Humans can play with a yo-yo without difficulty. However, developing a robot system that can play with a yo-yo presents a significant challenge to controller design, because the dynamics of the yo-yo are difficult to model precisely. Moreover, since the dynamics are not continuous and there are integral-type constraints on the hand trajectory, conventional continuous time feedback control theory does not work well. This paper present a model and a control scheme for robotic yo-yo with visual feedback. Experiments on a PUMA 560 are carried out to evaluate the validity of the discrete dime formulation and the controller design.

Robust positioning control of pneumatic servo system with pressure control loop

The goal of this paper is to attain a robust positioning control of a pneumatic driving system. A positioning control system positively focusing on the pressure control is investigated from the view that the pressure control is indispensable for improvement of control performances. A disturbance observer is employed to improve the pressure response and compensate the influence of friction force and parameter change. Consequently the improvements of robustness against payload and of positioning accuracy have been attained.

Visual servoing based on object motion estimation

The paper proposes a visual servoing scheme based on object motion estimation. A long term prediction algorithm with multiple motion models is developed. The object position and velocity of a few hundreds of samples ahead is predicted. Thus object tracking without visual information can be achieved during this period. As an example, pick up task of moving object is conducted. The task requires object motion prediction because the hand mounted camera loses the object when the hand approaches the object. Simulations show convergence of prediction. Real-time experiments of picking up a moving object demonstrate the effectiveness of the proposed long term predictor.

Design of Wearable Power Assist Wear for Low Back Support Using Pneumatic Actuators

This research focuses on developing a safe, lightweight, power assist device that can be worn by people during lifting or static holding tasks to prevent them from experiencing low back pain (LBP). In consideration of their flexibility, light weight, and large force to weight ratio, two types of pneumatic actuators are employed in assisting low back movement for their safety and comfort. At first, McKibben-type pneumatic rubber artificial muscles were chosen as actuator A to provide the assistance force, and subsequently it is improved by using elongation type pneumatic rubber artificial muscles as actuator A. Actuator A is installed in the outer layer of the garment, and its two ends are fixed on the shoulders and thighs. It can output contractile force, assisting the erector spinae muscles in the same direction. Compared to McKibben-type pneumatic rubber artificial muscle, the elongation type has a larger contraction rate. Actuator B is a layer-type of pneumatic actuator; it is composed of two balloons, and it is installed in the inner layer of the garment. The biomechanical model of the human spine is analyzed, and get to know the main reason of LBP: when the human is bending forward and lifting a load, for the erector spinae muscles have a small lever arm, the spine has to bear a large amount of force, which is several times of body weight. By taking into account the biomechanic structure of the human spine, this device can provide support in two ways. Actuator A acts as an external muscle power generators to reduce the force requirement for the erector spinae muscles. As actuator B acts as a moment arm of the contractile force generated by actuator A, it will increase the effective amount of torque. The device can be worn directly on the body like normal clothing. Because there is no rigid exoskeleton frame structure, it is lightweight and user friendly. The systems Inertial Measurement Unit (IMU), composed of accelerometer sensors and gyro sensors to measure the human motion signals, can monitor the angles of the human body in real-time mode. By measuring the EMG signal of the human erector spinae muscles, the assistance effectiveness of the proposed device has been proven through experiments.

Power Assist Wear Driven with Pneumatic Rubber Artificial Muscles

In the coming advanced age society, an innovative technology to assist the activities of daily living of elderly and disabled people and the heavy work in nursing is desired. To develop such a technology, an actuator safe and friendly for human is required. It should be small, lightweight and has to provide a proper softness. A pneumatic rubber artificial muscle is available as such actuators. We have developed some types of pneumatic rubber artificial muscles and applied them to wearable power assist devices. A wearable power assist device is equipped to the human body to assist the muscular force, which supports activities of daily living, rehabilitation, heavy working, training and so on. In this paper, some types of pneumatic rubber artificial muscles developed in our laboratory are introduced. Further, two kinds of wearable power assist devices driven with the rubber artificial muscles are described. Some evaluations can clarify the effectiveness of pneumatic rubber artificial muscle for such an innovative human assist technology.