JPH0396863A - Ground speed indicator - Google Patents

Abstract

PURPOSE:To improve the measurement accuracy by fitting an image pickup device on the reverse surface of a moving body opposite a road surface and measuring a ground moving speed from the movement quantity of image pickup information obtained at constant intervals of time. CONSTITUTION:The image pickup device 1 is fitted on the reverse surface of the moving body opposite the road surface and an image pickup signal which is obtained from the device 1 at constant intervals of time is stored in recording devices 2 and 3 alternately. Then the signal of the device 2 or 3 is passed through a delay circuit 4 and a comparator 5 compares the signal of the device 3 or 2 which is not passed through the circuit 4 with the signal of the circuit 4; and an arithmetic circuit 5 calculates a control signal for the circuit 4 for making both the signals coincident and the ground moving speed of the device 1 is measured.

Description

[Detailed Description of the Invention] (a) Industrial Application Field This invention is applicable to vehicles, trains, work machines, and other means of transportation and movement that run on road surfaces, and to calculate the speed of movement of these moving objects over the ground. Regarding the ground speed meter to be detected.

(Example) PRIOR TECHNOLOGY Conventionally, two methods have been used for measuring the speed of a moving object over the ground, depending on the type of dog. Taking a car as an example, this method uses a contact method to measure the number of rotations of some part that rotates at a certain ratio to the wheel of the car, and calculates the number of rotations per unit time of the wheel. This is a method of measuring the speed of The second method is a non-contact method, where an ultrasonic transmitter is placed on top of the moving object, emits ultrasonic waves slightly downward in the moving direction of the moving object, and uses the Doppler effect of the reflected waves that return. This is a method of measuring the ground moving speed of a moving object. The former is a method commonly used in modern automobiles, etc., but under special conditions,
For example, when testing the brakes of a car or driving on a frozen road surface, it is difficult to accurately measure the ground speed due to slippage and lock-up of the wheels. There were many problems and shortcomings, such as vertical movement and the difficulty of accurately measuring ground movement speed.

(c) Problems to be Solved by the Invention The present invention uses a non-contact type ground movement speed measurement method based on a completely different principle from the conventional method, completely eliminating irregular errors caused by slips etc. that are present in the contact type method. The purpose of this method is to eliminate irregular errors caused by the vertical movement of a moving object due to unevenness of the road surface in non-contact methods, and to accurately measure ground movement speed.

(2) Means for Solving the Problems First, the principle structure of the present invention will be explained as follows based on the drawings. First, in FIG. 1, 1-A is an image taken by an imaging device such as a video camera at a certain point in time;
1-B is an image capture screen when the image capture device itself moves in the advancing direction of the arrow shown in the upper figure. Next, in FIG. 2, soil is an imaging device such as a video camera, 2 and 3 are storage circuits such as a frame memory that accumulate signals from l, and 4 is a storage circuit such as a frame memory that stores signals from 2 and 3.
, 5 is a delay circuit that delays the output signal of , 5 is a comparison circuit that compares the output signal of 2 and 3 with the output signal of 4, 6 is a comparison circuit of 4,
7, 8, and 9 are respective changeover switches, and 10 is an output terminal of 6.

(E) Function This invention attempts to accurately measure the ground moving speed of a moving object by attaching an imaging device such as a video camera to the lower surface of a moving object so as to face the road surface, and based on the moving speed of the imaging results as the moving object moves. It is something. That is, FIG. 1-A is an image taken by an imaging device such as a video camera at a certain point in time, and after a certain period of time, the image becomes the image shown in 1-B.

This is because the imaging device itself moved in the advancing direction of the arrow shown in FIG. Therefore, if the imaging screen 1-A is electrically memorized and shifted in the direction opposite to the advancing direction of the arrow shown in FIG. Then, the M part) should appear. Since the amount of shift in the opposite direction corresponds to the moving distance of the imaging device itself at a constant ratio, the ground moving speed of the moving object can be measured from the time difference between capturing the two imaging screens.

(F) Embodiment An embodiment of the present invention will be explained based on the drawings. In FIG. It is taken into the memory circuit.

After T seconds in the second step, the switch 7 is turned down, and the signal from the imaging device such as a video camera is taken into the storage circuit 3. 8
The switches of , are turned down, and the output signal of 3 is delayed by P clocks by the delay circuit of 4, and sent to the comparison circuit of 5. The switch 9 is turned upward, and the comparator circuit 5 compares the output signal of the storage circuit 2 and the output signal of the delay circuit 4, and delays 4 until the two signals match within a certain range. Controls the amount of clock in the circuit. When the two signals match, the delay amount of the delay circuit 4 is sent to the arithmetic circuit 6, where a certain calculation is performed and the ground speed measurement amount is 1.
0, is output from the output terminal.

Third step: After a further T seconds, the switch 7 is turned upward, and the signal from the imaging device such as a video camera is again taken into the memory circuit 2. , 8 are turned upward, and the output signal of 2 is delayed by P clocks by the delay circuit of 4 and sent to the comparison circuit of 5. The switch of 9 is turned downward, and the comparison circuit of 5 is connected to the output signal of the storage circuit of 3 and 4.
The output signals of the delay circuits 4 and 4 are compared, and the clock amount of the delay circuit 4 is controlled until the two signals match within a certain range. When the two signals match, the delay amount of the delay circuit 4 is sent to the arithmetic circuit 6, where a certain calculation is performed and output from the output terminal 10 as the measured ground speed.

1 5 11 〇 1 Fourth step Perform the same action as the second step. That is, thereafter, the second step and the third step are repeated alternately. The time interval between each step is constant and is defined as T (seconds). Next, regarding the ground movement speed of a moving object, when an imaging device such as a video camera moves parallel to the road surface, the length A (meters) of the road surface viewed by the optical system in the traveling direction of the imaging device Assuming that the length B (meters) of the imaging surface of is K times (a constant magnification determined by the optical system of the imaging device), the following equation is obtained.

A=BXK [Metric length K of the imaging surface shifted by the delay circuit
Multiplied by the distance actually traveled by the moving object.

Also, if the total length B (meters) of the imaging surface is divided into Q and all B (meters) are replaced at Q clock, then the length of the imaging surface in one clock is (B/Q) (meters). ), and the length at P clock is as follows.

(BxP)/Q [meter] (engine) (1
) equation is multiplied by K to find the actual distance traveled by the moving object, and since the time required for this is T (seconds), the ground moving speed S of the moving object is finally expressed by the following equation.

S = (EXKXP) / (Q XT) [meters/second] Therefore, the measured value corresponding to this S is T (seconds) 46 and 10
will be output from the output terminal of .

(G) Effects of the Invention The present invention is constructed as described above, and by virtue of its operation, has many excellent effects not found in conventional ground speed meters. That is, (1) Since non-contact measurement is possible, there are no problems such as mechanical friction, slippage, and power consumption for measurement that are encountered with contact-type measuring instruments.

■ Measurements can be made with the same measurement accuracy from ultra-low speeds to ultra-high speeds.

■ Since the entire speedometer can be made extremely small and lightweight, there are fewer restrictions on where it can be installed as a ground speedometer.

■ Since the sensor part can be placed perpendicular to the road surface, it is virtually unaffected by the vertical movement of the moving object due to unevenness of the road surface.

■ Since the entire speedometer can be constructed to be extremely small and lightweight, the total cost including installation cost is low and the economical effect is great.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the basic principle of this invention, and FIG. 2 is a structural diagram for explaining one embodiment of this invention. 1-A...Image captured by an imaging device such as a video camera at a certain point in time, 1-B...Image captured after a certain period of time, 1...Imaging device, 2...Storage circuit, 3.・
・Memory circuit, 4...Delay circuit, 5...Comparison circuit, 6
... Arithmetic circuit, 7... Selector switch, 8... Selector switch, 9... Selector switch, 10... Output terminal.

Claims (1)

[Scope of Claims] 1. In a ground speed meter that measures the ground speed of a moving body moving on a road surface, an imaging device such as a video camera is attached to the bottom of the moving body facing the road surface, and the speed is measured as the moving body moves. A ground speed meter configured to measure the ground moving speed of a moving object from the amount of movement of imaged information at regular time intervals. 2. Imaging device, two sets of memory circuits, delay circuit, comparison circuit,
an arithmetic circuit, the imaging signal is alternately stored in two sets of memory circuits, and the output signal of one memory circuit that has passed through the delay circuit is compared with the output signal of the other memory circuit that is not passed through the delay circuit. Claim 1, wherein the control signal for the delay circuit is calculated by the calculation circuit to compare them in a circuit and make them match, thereby measuring the ground movement speed of the imaging device. ground speed meter.