A new position identification method for mobile robot is proposed. The method is to find out own position and orientation of the robot in wide unknown environment by means of horizontal cross section information measured by the range finder and compare it with pre-registered map information. The map information is expressed by five geometrical characteristics of the pair of segments which simplifies the contour of the local environments and the map is registered in the form of binary tree. On-line searching of the position and orientation is then executed on the binary tree. Position identification experiment is performed in a corridor of 50m in length resulted with 57% and 79% correct answer rates both in the condition of single point measurement and double points measurement, respectively. The required times are proved to be 10 second for range measurement by the range finder and 3 second for position identification calculation.
In this paper, we propose a photo response model of the optical piezoelectro actuator, which reacts by light beam. Based on response experiments by U.V. beam, the response in this model is costituted with three effects: 1) photostrictive effect; 2) pyroelectro effect; 3) thermal deformation. Those effects are different in response magnitude and response time each other; influenced by the characteristics of the light beam. In consequence, it is possible that a photo response is controlled by changing characteristics of light beam. As a whole, results of the simulations of this model agree with those of the experiments.
Pneumatic drive systems have higher power/weight ratio. So, it is easy to make a compact and lightweight robot manipulator. On the other hand, compressibility of air and very large friction, which is caused by mechanical seal, worsen the performance of positioning for a pneumatic drive system. Therefore, our goal of this study is to propose a positioning control scheme for pneumatic drive systems. In the proposed control scheme, full state feedback control and the disturbance compensator, which is composed by a disturbance observer and integral control action, are used in order to eliminate the effects of compressibility and friction. Further more, to eliminate the delay of a pneumatic servo valve, we designed the electric motor-driven servo valve which can respond very quickly. The effectiveness of the proposed control scheme and electric motor-driven servo valves is shown through experiments. As a result, by using out this method, a pneumatic drive system can be positioned at arbitrary point as fast as an electric motor does.
Walking robots have the potential to adapt to changes in walking conditions. However, it is necessary to sense these conditions and change the gait in order to realize this potential. In this paper, two kinds of gait generating schemes for a quadruped walking robot which can adapt to changes in the walking conditions are proposed. One is a gait which adapts to the position of the center of gravity (C.O.G) of the robot, and the other is a gait for inclined terrain. In the case of static walking, the position of the C.O.G affects the walking stability. The position of the C.O.G of the actual robot sometimes changes, and the gait must be changed for stable walking. The proposed gait adapting to the position of the C.O.G is able to change the leg transferring timing according to the position change of the C.O.G. The inclination of the terrain also affects the stability. The proposed adaptive gait for inclined terrain can change the leg transferring timing according to the inclination of the terrain. To perform these two adaptive gait schemes, only one-axis force sensors attached in each foot are used.
This paper investigates a coordinate control of multiple manipulators in space robots. The authors firstly derive the generalized Jacobian matrix and equation of motion for a space robot with multiple arms, then develop a method optimizing the sum of squared control torque in the sence of local (instantaneous) minimization by means of redundancy. The method is applied to a realistic model installing with a mission arm, a stbilizing arm and reaction wheels. The simulation results show the effectiveness of the presented coordinated control method with assistance of the stabilizing arm. This paper concluds that the installation and utilization of such redundant arm as the stabilizing arm makes a good hardware configuration and of great importance from the view point of satellite attitude controller design.
When the minimum-time trajectory of a manipulator along a geometrically prescribed path is planned considering the manipulator dynamics and actuator torque limits, at least one of the joints is at the torque limit. The execution of such a trajectory by a conventional feedback control scheme results in torque saturation. Consequently, the tracking error cannot be suppressed and the manipulator may deviate from the desired path. In this paper, we propose a feedback control method for path tracking which takes the torque saturation into account. Based on the desired path, a coordinates system called“path coordinates”is defined. The path coordinates are composed of the coordinate along the path and the coordinates normal to the path. The equations of motion are described in terms of the path coordinates. Control of the coordinates normal to the path is given priority in order to keep the motion of the manipulator on the path. The simulations by a two-degree-offreedom manipulator show the effectiveness of this method.
This paper deals with a sensor for the measurement of an overall direction of a resultant force of both gravity and motion acting on objects in-a-3-D space. The sensor uses a spherical weight suspended by springs freely, without producing lateral distortion of the springs. When a platform on which the sensor is attached accelerates, the weight moves toward the direction in which a composite direction of motional and gravitational accelerations is obtained. Displacement of the weight is proportional to the magnitude of the acceleration. Four small-sized magnets are installed on the surface of the weight so that the displacement is measured by using halleffect devices. In order to evaluate total stiffness and natural frequency of the suspended weight, behavior of the weight is analysed. Experimental results show that the measurement error in a steady condition is within 5.8° in all directions of gravity.