SU49521A1 - Method for determining speeds, accelerations and duration of short-term movements - Google Patents

Description

The invention relates to a method for measuring fast-variable speeds, accelerations and time of movement of any system if the whole process takes 1-2 seconds, and the speed can reach about 50 meters per second, and accelerate both positive and negative incomes to 100 g (g 9.8 Ai / ceK). For example, the proposed method can be applied to measure the accelerations of a catapult carriage used to launch aircraft. If the movement of the catapult occurs in 1.5 seconds. and during this time the positive acceleration reaches 6 g, and then is replaced by negative acceleration (deceleration), the time of movement and a complete picture of the change in speed and acceleration over time can be obtained using the proposed method. In the example above, the use of conventional accelerometers and accelerographs based on the use of springs or membranes meets fundamental objections. The fact is that in order to achieve greater sensitivity in mechanical measurement methods, large deformations must be tolerated, which, however, cause a low natural frequency of the measuring instruments. Therefore, accurate fixation of a short-term change process

speed and acceleration through the use of springs or membranes is impossible. Speed and acceleration measurements are also made by recording oscillations of the tuning fork on the shaft, rotated by a cable that is wound on the shaft and attached to the moving system with a free end, but this method makes it possible to roughly fix only positive acceleration; it is not suitable for measuring negative accelerations. An application for measuring the acceleration of devices based on the piezoelectric properties of a quartz plate has the advantage of reducing the inertia of the measuring system, but such devices are complex in design (you must have an amplifier, an oscilloscope, a device for photographing, etc.), which is extremely expensive. device.

The proposed method is free of these disadvantages. It is simple in design, works flawlessly, and has an accuracy sufficient for technical measurements.

This method is as follows. Along the following moving system A (Fig. 1), steel wires pq with a diameter from 1-1.5 mm are pulled on the insulators Kl L. An electromagnet B is fixed to the moving system A,

on the sides of which there are two diamagnetic sleeves a to b. During the motion of system A, the sleeves a and b slide along the pq wire and act as guides for the electromagnet. An alternating electric current is supplied to the winding of electromagnet B from a sound frequency generator with a constant frequency /.

The current is applied from the clamp through the wire rd, bushings a, b, electromagnet coil B, the metal case of the moving system and through the rail directing the movement of the system to the clamp. If the moving system is metallic, then the current to the electromagnet B can be brought through a flexible cord that follows the moving system. During the motion of an electromagnet along a steel wire, last, at regular intervals, namely in s,

receives magnetization reversal and, as a result of the electromagnet moving along the wire, it will be a chain of separate magnets, the length of which is equal to the length of the path D5. These sections of the path D5 system passes for consecutive intervals,

1 equal - sec.

The relationship between the magnetizing current and the arrangement of individual magnets along the wire can be schematically represented as shown in FIG. 2

After the magnetic recording, the steel wire is wound on a wooden coil C and the recording is decoded as follows.

Wood board Q (Fig. 3) has a longitudinal groove with a depth equal to the diameter of the steel wire. The wire PD is rewound from reel C to roll D, pass through the groove. The wooden board is covered with paper on top and covered with small iron filings. On paper, a magnetic spectrum is obtained (fng. 4). The neutral lines of individual magnets on the magnetic spectrum will be represented as centers of small ellipses of sawdust.

The distances between the centers of these ellipses can be fixed to an accuracy of 1 mm. In view of the fact that the neutral lines correspond to a change in the direction of the current in the electromagnet B, and these changes are carried out at regular intervals corresponding to

140 - f sec., The distance D5 between the neutral lines gives the values of the path segments for a number of equal periods of time.

When deciphering a magnetic recording, a table is made (Fig. 5). In this table, the column “time corresponds to successive periods of time,, D, etc., and

 D4

 - sec. Total neutral

lines on the wire n, multiplied by

2, gives the total motion time of the system with an accuracy of -JT seconds. In the second

The distance D5 between adjacent neutral lines on the magnetic spectrum is entered in the graph. The distance between the neutral lines, corresponding to any half-period D multiplied by 2 /, gives the average velocity V / over time. The velocities are entered in the column " speed. Acceleration over time Mff is obtained from the expression a / - (Vk + 1- W) 2 /.

Thus, the table gives movement time and a consistent series of path, speed and acceleration values for equal periods of time. Using the obtained table, one can construct graphs of changes of these values in time or directly have their values at any moment of movement.

The frequency of the AC current supplying the electromagnet B is higher if the speeds of the system are large. When measuring at low speeds (on the order of up to 10 m per second), normal alternating current with a frequency of 50 hertz can be used.

The magnetic recording on the wire after decryption can be erased with a permanent magnet and the wire is again used for the next recording.

The present method may be applicable when conducting research on short-term movements occurring in various fields of technology. In particular, it can be used to measure the acceleration of a catapult carriage at the start of aircraft.

The subject matter of the invention.

Method for determining speeds, accelerations and durations of short-term

movements, characterized in that on a fixed steel wire parallel to the body movement, magnetic recording is made using an electromagnet connected to the body under test and powered by an alternating current of a certain frequency, after which the magnetic spectrum of this recording is obtained using a well-known magnetic spectrum determine the desired values.

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