Shinichi Aoshima

A Wire Mobile Robot with Multi-unit Structure

This paper proposes a mechanism and a control system for a wire mobile robot with a multi-unit structure The mobile robot has an ultrasonic sensing system for environment recognition enabling it to move autonomously With this mechanism, control and sensing system, the robot can transfer to a branch wire and avoid obstacles on the wire This paper first clarifies the design of a mechanism and a method for avoiding obstacles and transferring the robot to a branch wire Then it shows experimental results using a prototype of mobile robot with an ultrasonic sensing system

Compact mass axis alignment device with piezoelements for optical fibers

A compact mass axis alignment device with piezoelements which can independently align individual optical fibers is proposed. Axis alignment experiments were performed with the fabricated device. The authors describe the construction of the mass axis alignment device. Experimental results of axis alignment with the fabricated device are reported. Splice loss reduction through the use of the proposed device is outlined. The estimated splicing loss that occurs when using the proposed device is 0.063 dB for 1.55- mu m DSF.<<ETX>>

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.

The object discrimination system using a neural network with inputs for distance and sensitivity information of an ultrasonic sensor

Proposed a discrimination system using a neural network with inputs for distance and sensitivity information of an ultrasonic sensor. This system consists of the following three elements: (1) ultrasonic sensor receiving and transmitting ultrasonic wave; (2) transducer that changes the output signal of sensor to distance and sensitivity information; (3) neural network for object discrimination with inputs for distance and sensitivity, with outputs corresponding to each object. We confirmed the validity of the system by experiments using different kinds of objects, objects with different grain size, and objects with different surface roughness. The proposed discrimination system can be applied to industrial processes.

A leg-wheel prototype rover designed to climb steep slope of uncompacted loose sand

An unmanned rover is widely used for exploration, for example planetary rovers and surveying in places too dangerous for a person to enter, such as poisonous, radioactive and high volcanic activity areas. It is very important for the rover to be able to maintain mobility in all ground conditions, as the success of the operation depends on it. Most of the current rovers are equipped with wheels or tracks, which have a high tendency to get stuck when climbing steep slope made out of loose sand. We are developing a legged-wheel prototype rover that is mechanically simple, which is designed to climb steep slope of loose sand with the help of an independent variable center of gravity mechanism and adjustable leg angle. Experiments were done on natural uncompacted loose sand and the soft sand slope climbing performance of the mechanism is compared with a wheel with grousers. The effect of the position of the center of gravity on the climbing performance is also investigated.

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.

Auto-tuning of feedback gains using a neural network for a small tunnelling robot

Describes the auto-tuning of feedback gains for a small tunnelling robot. The authors (1989) have already proposed the directional control method that the head angle of the control input is the sum of the deviation multiplied by feedback gain Kp and the angular deviation multiplied by feedback gain Ka. In this paper, they use a neural network to obtain feedback gains Kp and Ka. The inputs of the neural network are an initial deviation and an initial angular deviation. The outputs of the neural network are the feedback gains Kp and Ka. This neural network learns from the deviation errors. The optimum gains obtained by the proposed method agreed with the optimum gain obtained by trial and error. The neural network which can apply to any initial deviations were formed by using plural initial deviations in learning. Moreover, this method can tune the optimum gains to any design line. The results showed the validity of the proposed auto-tuning method.<<ETX>>

Development of wheeled rover for traversing steep slope of cohesionless sand with stuck recovery using assistive grousers

Typical rovers with conventional fixed grousers attached to the wheels are prone to get stuck in unconsolidated sandy dune inclines due to the sinking of the wheels in the sand. This is caused by the rotating motion of the grouser which displaces the sand from under the wheel toward the back, embedding the wheel. In this paper, we are proposing the concept of an assistive grouser attached to the side of a conventional rover wheel to aid in climbing a steep slope of sand with minimal sand movement and sinkage into the sand. The assistive grousers are able to autonomously maintain a uniform angle relative to the rover body independent of the rotation of the wheels by devising its mechanical design. When the wheel is turned, the assistive grousers penetrate the sand slope surface at a constant angle of attack without additional control. The assistive grousers act as an anchor, provide additional traction to the wheel, and by maintaining a uniform grouser angle instead of a rotating motion, also assists in pulling the grouser out of the sand smoothly without moving sand towards the back of the wheel. Experimental results show that for slope angle of 0 to 30 degrees, the rover equipped with the proposed assistive grousers produce significantly smaller sinkage and current consumption compared to the conventional grouser attached wheel rover in the comparison tests. The modified wheel managed to climb the 30 degree slope with an additional weight of 6kg from the initial 23kg. The assistive grousers were also proven to be able to assist in recovering the mobility of the wheel after the wheel is embedded into the sand.

Development of rover designed to climb steep slope of uncompacted loose sand

Unmanned rovers have proved their usability in various operations, often involving challenging terrain environments, for example the sand dunes of Mars for planetary rovers and ash with rubbles for volcanic observation. Most of the current rovers are equipped with wheels or tracks, which have a high tendency to get stuck when climbing steep slope made out of loose sand. We are developing a prototype rover leg-wheel that is mechanically simple, which is designed to climb steep slope of loose sand with the help of a variable center of gravity mechanism and an independently adjustable lower-leg angle. Preliminary experiments were done on natural uncompacted loose beach sand and the soft sand slope climbing performance of the mechanism using the first prototype is compared with a wheel with grousers. The effect of the position of the center of gravity on the climbing performance was also investigated. It was observed that the proposed leg-wheel mechanism generates less slippage when climbing 20 and 30 degree slopes of soft sand. The leg-wheel mechanism also requires less maximum output torque to climb the slopes. Shifting the center of gravity forward while moving upslope also increased the average travel distance of the rover. The flaws of the first prototype, which is the vertical bobbing during movement, exposed moving mechanical parts and short travel distance per revolution is addressed by designing a new prototype rover. To ensure a more consistent sand condition and allow more accurate modeling, a new indoor sand testbed was designed for a more thorough investigation.