Masatake Shiraishi

One-hand drive-type power-assisted wheelchair with a direction control device using pneumatic pressure

In this paper, we propose and develop a one-hand drive-type power-assisted wheelchair with a direction control device using pneumatic pressure sensors, for disabled persons who can use only their right or left arm. Compared with a joystick-type wheelchair, the advantages of the proposed wheelchair are that a disabled person can keep the functions of their arm, and can feel a sense that they are driving the wheelchair by the power of their arm. In the case of the wheelchair for disabled persons who can use only their right arm, the right wheel is rotated by the right hand and arm of the person. The left wheel is driven by an electric motor. For traveling in a straight line, the computer controls the motor as the angles of the right and left wheel are the same. When changing the direction of travel, the user uses a direction control device that consists of two vinyl tubes attached to both sides of a hand rim and pneumatic pressure sensors. Traveling experiments on a flat course with obstacles showed the validity of the proposed wheelchair system.

High Accuracy Positioning in SCARA-Type Robot by Sensor-based Decoupling Control

To compensate for the effects of coupling torque and load variations experienced in SCARA-type robots, we propose a new method of sensor-based decoupling control. In this method the plant is first nominalized with the use of a disturbance observer and then nonlinear feedback control is accomplished by this nominalized system based on information from acceleration sensors installed at the end of the robot hand. As a result of high-speed reciprocal motion with a payload of 10 kg mounted on the hand, we were able to achieve satisfactory decoupling using this method. Improvements were also made in steady-state characteristics.

In-process diameter measurement of turned workpiece with curvatures by using sensor positioning

A modified triangular laser displacement sensor having a resolution of 1.0 μm was used to measure the diameter of a turned workpiece with curvatures. This sensor was attached to a specially designed stage mounted on a precision slide unit and operated by three drive motors. In the measurement, the laser sensor was controlled by a 0 motor depending on workpiece curvatures so that the illuminating laser beam is always normal to the part surface and can measure the workpiece diameter in an on-line fashion. This sensor positioning control was found to be effective for measuring the diameter of a curved workpiece with an accuracy of several micrometers.

Manipulator operation by using brain-wave signals

When we look at a comfortable scene or feel relaxed, our brain waves generally exhibit /spl alpha/-wave signals in the frequency band of approximately 8 to 13 Hz. These /spl alpha/ waves particularly exhibit a 1/f fluctuation in which the corresponding power is inversely proportional to frequency 1/f /spl alpha/-wave signals obtained from test subjects listening to relaxing music was inputted to a robot manipulator. To evaluate the resulting motions, test subjects were asked to complete questionnaires while they watched two types of manipulator motions: a 1/f motion and a white-noise-like motion. The results indicated that 90% of the subjects felt comfortable while watching the 1/f manipulator motions.

Disturbance Observer Design Based on Frequency Domain

Generally, the specifications of the system robustness and disturbance or noise applied to the system are often provided in a frequency domain. In this paper, a reduced-dynamic-order observer based on a transfer function in frequency domain is proposed, which is composed of a diophantine equation, and only three steps are required for design. This method is practically used to extract the brain wave signals and various experimental results show the effectiveness of the proposed approach even in the presence of noises among the brain wave signals.

Is It Possible to Control Air Flow by Using Laser Photon Pressure

Extremely low-velocity airflow fluctuations around precision equipment is a primary cause of diminished accuracy of such systems. Unfortunately, there is currently no effective means to control these air fluctuations. Assuming that airflow dynamics can be approximated by a linear equation under low-velocity viscous flow conditions, this paper shows that airflows around equipment can be controlled. A series of experiments is then performed to corroborate the theoretical findings. In the experiments, smoke particles are excited by the photon pressure of an argon laser beam. The behavior of the particles is regulated by an optical system consisting of a convex lens and a neutral density filter. The experimental findings demonstrate that it is indeed possible to control the airflow in the recessed parts of precision equipment using photon pressure of a laser beam.Copyright

Sensory operation of robot manipulator by using brain-wave signals

When we look at a comfortable scene or feel relaxed, our brain waves generally exhibit /spl alpha/-wave signals in the frequency band of approximately 8 to 13 Hz. These a waves particularly exhibit a 1/f fluctuation in which the corresponding power is inversely proportional to frequency f. 1/f /spl alpha/-wave signals obtained from test subjects listening to relaxing music were inputted to a robot manipulator. To evaluate the resulting motions, test subjects were asked to complete questionnaires while they watched two types of manipulator motions: a 1/f motion and a white-noise-like motion. The results indicated that 90% of the subjects felt comfortable while watching the 1/f manipulator motions.

New Design Method of Observer : Frequency Domain Approach

Traditional observer design by Gopinath method is not easy to apply to the practical system because of several design steps, and is difficult to understand its design structure. To overcome this disadvantage, a new design method is proposed based on the frequency domain, i.e., by using transfer function. This method is composed of a diophantine equation and only three steps are required in the design procedure. By choosing the order and coefficients of the equation adequately, various observers such as an n-th order observer, a reduced-order observer, a robust observer etc. can be designed in the same manner. The advantage of the new method is emphasized on its simplicity in construction and understandable structure.

Controllability and Control Method of Air Flow around the Equipment.

Air fluctuation around the fine equipment system seems to be a kind of extremely low velocity air flow and is one of the major causes in deteriorating system working accuracies. Unfortunately there is no active means to control air fluctuation at present. This paper describes the controllability of air flow around the equipment assuming that the air flow dynamics is approximated by a linear equation under the low velocity viscous flow condition. With the verification of its controllability, several experiments are performed to confirm the possibility of air flow control by using smoke particles. Specifically, smoke particles are stimulated by the optical radiation pressure of Ar laser beam. Their behaviors are regulated by the optical system such as a convex lens and an ND filter with the number of stimulated smoke particles. The experimental results basically show the possibility of air flow control using an optical radiation pressure.