Showing papers on "Obstacle published in 1982"

System of safety zones for vehicles

Abstract: The invention allows collisions with fixed obstacles, which threaten in the close range of a vehicle (up to approximately 10 m), to be detected and, as a result, to be avoided. This is achieved by the fact that the vehicle is equipped on its periphery with transmitters and receivers, the signals of which are continuously evaluated by an on-board computer with the aim of determining an image of obstacles in the vicinity of the vehicle. The environment of the obstacle is displayed in the vehicle. If there is a risk of a collision, the vehicle is automatically stopped within a safety distance.

Inertial waves above an obstacle in an unbounded, rapidly rotating fluid

Abstract: The slow transverse motion of an obstacle of horizontal dimension L , in a rapidly rotating flow (such that the Rossby number, Ro , is small), is shown to cause an inertial-wave disturbance above and behind the obstacle. This disturbance spreads over an ever-increasing downstream region with increasing vertical distance above the obstacle, but is constrained laterally to lie within a wedge-shaped region. The discussion of Cheng (1977) is shown to give the diffraction pattern due to a point source, and his analysis is modified to allow for arbitrary obstacle shapes. Such a modification shows that the amplitude of the disturbance decays downstream at a rate deter­mined by the Fourier transform of the obstacle shape as noted by Johnson (1982) for ridge-like topography. The inclusion of viscosity is shown to damp out the disturbance on a vertical scale of L/Ek (where Ek = v /2 ΩL 2 is an Ekman number for the flow). At moderate Reynolds numbers visco­sity reduces the amplitude of the disturbance in the neighbourhood of the caustic at the wedge boundary, the attenuation increasing with distance downstream. Internal dissipation removes the short-wavelength com­ponents of the disturbance and thus removes the strong dependence of the wave pattern on the precise shape of the obstacle.

Obstacle detecting device for vehicles

Abstract: An obstacle monitoring device for the rear of a vehicle comprising a plurality of ultrasonic obstacle detectors which are operated sequentially at a predetermined time interval, and an electronic monitor for supplying the obstacle detectors with their operational timing sequences at the predetermined time intervals and for determining distance information for each detector based on the changing pulse width of electric currents for each of the obstacle detectors within a particular time interval, which pulse widths correspond to the distance between an obstacle and the rear of the vehicle. A single transmission line connects the obstacle detectors with the monitor so that the number of wires in a wire-harness is reduced between the obstacle detectors (outside the vehicle) and the monitor (inside the vehicle).

Time‐dependent scattering by a bounded obstacle in three dimensions

Abstract: In the prsent paper we introdue a new method of treating the scattering of transient fields by a bounded obstacle in three‐dimensional space. The method is a generalization to the time domain of the null field approach first given by Waterman. We define new sets of time‐dependent basis functions, and use these to expand the free space Green’s function and the incoming and scattered fields. The scattering problem is then reduced to the problem of solving a system of ordinary differential equations. One way of solving these equations is by means of Fourier transformation, and this leads to an efficient way of obtaining the natural frequencies of the obstacle. Finally, we have calculated the natural frequencies numerically for both a spheroid and a peanut‐shaped obstacle for various ratios of the axes.

Operation controlling method in detecting obstacle, of unattended cargo work vehicle

Abstract: PURPOSE:To raise the work efficiency, by controlling an operation of a vehicle in accordance with a distance between a vehicle and an obstacle, and a car speed, so that it does not occur that the vehicle stops whenever an obstacle is detected. CONSTITUTION:A distance signal S1 between a vehicle and an obstacle, from an obstacle detecting sensor 6 installed to the vehicle, and a car speed signal S2 from a car speed detecting sensor 9 are supplied to a CPU 10, and are compared and discriminated. Subsequently, the CPU 10 decelerates a car speed in accordance with the distance signal and the car speed signal, and thereafter, outputs a damping signal and stops the vehicle. Also, when the obstacle is shunted in the course of deceleration or in the course of damping, the vehicle is reset to its original running state. By controlling an operation of the vehicle in this way, it is unnecessary to stop the vehicle whenever an obstacle is detected, therefore, the work efficiency can be raised.

Obstacle indicator for vehicle

Abstract: PURPOSE:To prevent the wrong indication within a predetermined nearby dead zone, by providing a vehicle obstacle indicator which employs ultrasonic waves or the like and includes a holding means for detecting the presence of an obstacle within a prescribed distance corresponding to the nearby dead zone and for indicating the distance. CONSTITUTION:An ultrasonic wave transmitter 1 and an ultrasonic wave receiver 3 are mounted on the rear of a vehicle 14. The border between a detectable zone A and a dead zone B is 0.5m away from the rear of the vehicle 14. When the vehicle has approached an obstacle so that it is located in the detectable zone A, the obstacle is detected through a time measuring section 5 and a distance judgment section 6 and the distance to the obstacle is indicated on a display section 7. When the vehicle has more approached the obstacle so that it is located in the dead zone B, the obstacle is detected through a dead zone distance judgment section 9 and a holding section 10 and all the lights of the display section 7 are turned on. When the vehicle 14 is thereafter moved forth by 0.5m or more, it is found out through a hold stoppage signal generation section 13 on the basis of the output signals of a moving direction detector 11 and a moving distance detector 12 that the vehicle is moved by 0.5m or more away from the obstacle. At that time, a hold stoppage signal is applied to the holding section 10 to stop holding.

Detecting device for obstacle

Abstract: PURPOSE:To enable the issuance of an alarm even when an obstacle comes into a dead angle of the range of detection, by adding a dead-angle detection circuit and an alarm circuit to an obstacle detection device. CONSTITUTION:When an obstacle approaches an automobile and comes into the dead angle of the range of detection, the output of a distance discrimination circuit 5 is discontinued, and a distance discrimination circuit 8 also delivers no output at this time. Therefore, a dead-angle detection circuit 30 delivers an output to make an alarm circuit 31 deliver a special alarm continuously for a prescribed time. This constitution makes it possible to inform a driver that the obstacle comes very near to the automobile and to call his attention thereto.

Stability of automatic guidance for a mobile robot

Abstract: A control law for the automatic guidance is proposed in this paper as if each obstacle exerts upon the mobile robot a repulsion, which varies inversely with the distance between the robot and the obstacle, and becomes infinite as the robot approaches the obstacle. Stability of the automatic guidance is studied when the mobile robot deviates from the ideal path. The results lead to criteria of selecting control parameters for better guidance.