DE3640271A1 - Method and device for measuring speed and acceleration - Google Patents

Abstract

The invention relates to a method of measuring speed and/or acceleration by video recordings of the moving body or from the moving body. In the process, in each case time and displacement distance are also recorded so that value pairs for displacement and time can be read off during single-frame viewing. The speed and acceleration can be determined from these value pairs. By means of a suitable device the time can be slotted into the frame and held on the video tape. During single-frame viewing, it is then only necessary to read off the instants at which the moving body has reached certain displacement marks or immediately transmit them to a programmed computer.

Description

The police do speed checks with radar, a process that is known to be not without problems and is often successfully challenged in court. In physics classes of schools and colleges are speeds and Accelerations carried out by distance-time measurements, whereby Light barriers or electrical contactors are used, which often lead to incorrect measurements.

Find to illustrate an accelerated movement stroboscopic recordings in physics textbooks, e.g. B. the Photograph of a ball falling in front of a scale in the dark and was illuminated at intervals of ½₀ sec. A path-time diagram can easily be made from such a recording set up speed and acceleration can be seen. Unfortunately, the recording is only too long after Development time available.

The object of the invention was to find a method by which is the stroboscopic image of a moving body immediately after the path-time measurement becomes available, as well as one To create device which is easy to use this Procedure allowed.

This object was achieved in that the moving body is recorded together with a length scale using a video camera. Since the frame rate is known, a certain distance can be read at any point in time when the recorded scene is repeated in single frame mode. These pairs of values make it easy to create st diagrams or Vt diagrams, from which the speed and / or the acceleration can be found.

If the frame rate is not exactly known, it can also The length scale also included a suitable timepiece be so that z. B. in school trials from each frame both the distance traveled and the time elapsed can be read immediately - especially for students clear and transparent procedure.  

For outdoor speed measurements, such as those carried out by the police, the invention provides for a video system to be equipped with a device by means of which the exact time is superimposed on the image and is also digitally recorded on the audio track. Furthermore, a computer is provided, which takes over the time information on the audio track when the individual images are switched at the push of a button, namely when the first button is pressed as a subtrahend t ₁, when the second button is pressed as a minute t ₂. The computer then forms the reciprocal of the difference t ₂- t ₁, multiplies it by the previously stored distance s between two waymarks and gives the product, the speed

back into the picture.

The police would therefore have to place a pair of stripes at a distance s on the lane perpendicular to the direction of travel and simultaneously record the vehicles to be measured with two cameras, one of which is positioned exactly perpendicular to the lane, the other, however, as parallel as possible to the lane. The former holds the time period t ₁ and t ₂ at what z. B. the front wheel touched the two transverse stripes of the measuring section s , the second serves to hold the license plate number. The two cameras can be coupled in such a way that the recording of one takes place, for example, in the lower half of the image and that of the other in the upper half. The monitor then shows at a glance which vehicle is transferring the test section. If the vehicle registration number is covered by a vehicle driving closely ahead, a single image can be found in most cases by viewing a longer section of the belt, which shows the license plate number (and driver).

To measure acceleration and deceleration more than two waypoints are required, which are at intervals s ₁, s ₂, s ₃,. . . s _n attached to the road and stored in the computer. After entering the observed times t ₁, t ₂, t ₃,. . . t _{n +1,} the programmed computer determines the running times t _i = t _{i + 1} - t _i , the speeds

and the mean acceleration

From the vehicle can also be measured by a timer and a odometer can be recorded at the same time.  

Advantages of these devices are

• - lower costs
  - unproblematic use, even in heavy traffic
  - Flawless documentation of the measuring arrangement and measuring process
  - Suitability for continuous monitoring with simultaneous or later evaluation, even at remote locations
  - any location
  - Even if the measurement is not successful, the educational effect of the waymarks without enlarging the sign forest

Claims (5)

1. A method for measuring speed and / or acceleration, characterized in that a moving body is recorded together with a timepiece and length scale with a video camera and value pairs for distance and time are obtained by viewing individual images. 2. Method for measuring speed and / or Acceleration, characterized in that the moving Vehicle from a stationary scale or a moving one Odometer and a timepiece recorded and by Single image viewing Value pairs for distance and time gained will. 3. Device for performing the method according to claim 1 or 2, characterized in that one is sufficient exact identification of the individual images suitable time is faded in and recorded on the video tape. 4. Apparatus for performing the method according to claim 1 or 2, characterized in that the stored Times are taken from a computer and together with the entered distances for speed and acceleration can be converted. 5. The device according to claim 3 and / or 4, characterized in that multiple video recordings are recorded simultaneously are used to identify the measured object.