RU2572222C1 - Method of correcting linear and angular coordinates of helmet of aircraft operator and ultrasonic helmet-mounted system therefor - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: four helmet-mounted ultrasonic receivers are mounted at reference points on an operator's helmet, and four ultrasonic radiators are mounted in the cockpit above the operator's helmet in the bound coordinate system of the cockpit. Four ultrasonic receivers of four correcting channels are mounted at the edges of the working area of possible helmet positions. Pulsed ultrasonic signals are transmitted and received. The delay time of signals from each ultrasonic radiator to each helmet-mounted ultrasonic receiver and to four ultrasonic receivers of correcting channels is measured. Direction is determined based on the data of said correcting channels.

EFFECT: high accuracy of determining coordinates of an operator's helmet in vibration conditions and varying external conditions.

2 cl, 4 dwg

Description

The claimed invention relates to the technique of acoustic helmet-mounted positioning systems and can be used in devices that use data on three position coordinates and three angles of orientation of the operator’s head, mainly in helmet-mounted target designation and indication systems of aircraft, in the helicopter’s searchlight control system, in aircraft and exercise machines, in virtual reality systems.

Closest to the claimed invention in technical essence is a method of compensating coordinate measurement errors used in the patent (see RU No. 2357184, F41G 3/22, 05.27.2009) and in the patent (see RU No. 2449242, G01B 04/27, 27.04 2012, “Ultrasonic Helmet Positioning System” adopted as a prototype.

The prototype uses a range-finding method for determining the coordinates of ultrasonic receivers located on the operator’s helmet, by measuring the distances between the basic ultrasonic emitters located in the aircraft cabin (LA) with known coordinates in the coordinate system associated with the aircraft, and ultrasonic receivers located on the helmet. To solve the navigation problem of determining the coordinates of helmet-mounted receivers in the prototype measure the distance from each emitter in the cockpit of the aircraft to each helmet-mounted receiver and to the receiver of the correction channel.

The operation of the prototype ultrasonic helmet-mounted positioning system (USNSP) is illustrated by the structural diagram shown in FIG. 1, where are indicated:

1, 2, 3, 4 - ultrasonic emitters;

5 - multiplexer;

6 - signal conditioner;

7 - synchronizer;

8, 9, 10, 11 - ultrasonic helmet-mounted receivers;

12 - ultrasonic receiver of the correction channel;

13 - signal amplifier helmet-mounted receivers with AGC;

14 - meter time delay signals helmet-mounted receivers;

15 - signal amplifier of the correction channel;

16 - meter time delay signal correction channel;

17 - on-board computer.

Channels containing meters 14 will be called measuring, and the channel containing the meter 16, corrective.

Ultrasonic emitters 1-4 are located in the cockpit above the pilot helmet at spaced points with known coordinates in a linked coordinate system, helmet-mounted ultrasonic receivers 8-11 are placed crosswise at the reference points, the correction channel ultrasonic receiver 12 is rigidly fixed in close proximity to the pilot helmet with known distances r [i] to each i-th emitter. Ultrasonic emitters 1 ... 4, excited by the signal shaper 6 through the multiplexer 5, alternately emit ultrasonic signals each during the interval T _P determined by the synchronizer 7. This makes it possible to identify the number of the emitter, the signals of which are received by all receivers on this time interval.

To solve the navigation problem - determining the coordinates of helmet-mounted receivers - at each time interval T _P measure the propagation delay of ultrasonic waves (USW) from the emitter active in this period to all helmet-mounted receivers 8 ... 11 and the receiver of the correction channel 12.

The system operates as follows. Synchronizer 7 generates clock pulses in the form of a two-bit number with a repetition period T _P , which cyclically changes from period to period, running through the values 00, 01, 10, 11. Signal conditioner 6 generates phase-shifted signals of the form (+ -) or (- +) depending from the parity of the clock signal coming into it. The same clock signals switch the multiplexer 5. As a result, the ultrasonic emitters 1, 2, 3 and 4 emit the signals alternately, with a shift of T _P and the corresponding phase rotation, and the helmet-mounted receivers 8 ... 11 and the receiver of the correction channel 12 receive the signal of the active emitter during the observation interval .

The prototype uses a method of compensating for a possible change in the velocity of propagation of an ultrasonic ultrasound with a change in temperature, pressure or the presence of air flow in the cockpit of the aircraft and changes in the coordinates of the emitters in the cockpit caused by the vibration of the walls of the cockpit of the aircraft, consisting in the fact that the travel time of the ultrasound from the emitter to the helmet-mounted receiver is using an additional correction channel, which measures the travel times of the ultrasonic ultrasonic scanner TKK [i] from each i-th emitter to the correction channel receiver (fixed in the aircraft cabin) ( RMKK), located near the operator's helmet. The distances r [i] between the ith emitter and the PRMKK are known during the installation of the system or can be measured by the ultrasonic method at any time.

The following is a description of the method of compensation of errors in measuring the coordinates of the object, adopted in the prototype.

The distance R [ij] between the j-th receiver and the i-th emitter is found as the product of the travel time of the ultrasonic vibrator T [i, j] between them and the speed of the ultrasonic vibrator. The speed of the ultrasonic ultrasound ν _i is determined from measurements in the correction channel for each emitter:

ν _i = r [i] / TKK [i].

Further, according to the data on time delays in the correction and measuring channels, the distances from each helmet-mounted receiver to each emitter are calculated according to the formula:

R [i, j] = T [i, j] r [i] / TKK [i].

Obviously, the last expression takes into account the changes in the velocity of the ultrasonic ultrasound associated with temperature and pressure, since TKK [i] carries information on the velocity of the ultrasonic ultrasound taking into account the radial velocity of air flows in the aircraft cabin. The location of the receiver of the PRMKK correction channel in the immediate vicinity of the operator's helmet makes it possible to compensate for the influence of vibrations on the measurement accuracy, since the times T [i, j] and TKK [i] change synchronously and proportionally with vibration.

The calculation of the coordinates of the helmet-mounted receivers, and from them the linear and angular coordinates of the helmet, is carried out in the on-board computer 17.

Here is a detailed description of the method for correcting vibration of emitters, adopted in the prototype. The description is illustrated in FIG. 2, where indicated:

And - the amplitude of the vibrations of the emitter;

R _i is the distance from the helmet to the i-th stationary emitter;

r ₁ is the distance from PRMKK to the i-th stationary emitter;

dr _i is the increment of distance r _i due to vibration;

dr _i - the increment of the distance R _i due to vibration;

γ _W - the angle between the direction of vibration and the direction of the helmet;

γ is the angle between the direction of vibration and the direction of the PRMKK.

We write the increments of the measured distances taking into account A << r _i , R _i as:

dr _i ≈A cosγ = dR _i (cosγ / cosγ _w )

dR _i ≈A · cosγ _w = dr _i · (cosγ _w / cosγ)

When processing the received signals in the on-board computer 17, the distances R [i, j] between the RFL and the PFP are calculated as R [i, j] = T [i, j] · ν _i , where: ν _i = (r _i + dr _i ) / TKK [i] is the ultrasonic velocity measured in the correction channel, TKK [i] is the ultrasonic propagation time in the correction channel, T [i, j] is the ultrasonic propagation time in the measuring channel. Here i is the number of the emitter, j is the number of the helmet-mounted receiver.

Thus, the delay of the signals in the measuring channels 14 is defined as:

T [i, j] = TKK [i] (R _i + dR _i ) / (r _i + dr _i ) = TKK [i] (R _i / r _i ) (1 + dR _i / R _i ) / (1 + dr _i / r _i ) ≈TKK [i] (R _i / r _i ), because it is reasonable to consider (1 + dR _i / R _i ) / (1 + dr _i / r _i ) ≈1.

The last equality is true if:

The relationship of the true distance with the measured propagation times of the ultrasound is given by the expression:

or, after small conversions:

The first term in (1), (2) does not depend on the presence of vibration, the rest describe its effect. It is clearly seen the attenuation of the influence of vibration on the accuracy of determining R _i due to its compensation in the correction channel. At the same time (2) shows that the vibration compensation will be complete when the condition γ≈γ _{ω is} fulfilled. At the same time, R _i is determined by the ratio of the flight time of the ultrasound in the measuring channel to the flight time in the correction channel. Since the propagation conditions of the ultrasonic waves in both channels are the same, the influence of external conditions on the accuracy of determining R _{i is} thereby excluded.

However, to completely compensate for the effects of vibration and air movement in the cabin, it is necessary that the receiver of the PRMKK correction channel is located in the center of the operator's helmet, under which the condition γ≈γ _ω is fulfilled, which, of course, is impossible. Therefore, the specified compensation is not fully, but only partially. This is a disadvantage of the prototype.

In the patent (see RU 2357184, F41G 3/22, 05.27.2009, “A method for determining the linear and angular coordinates of the operator’s helmet in the cockpit of an aircraft and an ultrasonic helmet-mounted system for its implementation”), the possibility of using two correction channel receivers located symmetrically with respect to helmet, so that their virtual phase center coincides with the center of the helmet. However, the movement of the pilot’s head violates the symmetry condition of the receivers relative to the helmet, which is a disadvantage of the solution proposed in this patent.

The objective of the present invention is to increase the degree of vibration compensation, instability of the speed of sound and air movement in the aircraft cabin.

The technical result consists in increasing the accuracy of determining the coordinates of the helmet of the operator in vibration and changing environmental conditions.

The problem is achieved with the achievement of the above result is solved by the fact that in the method of determining the linear and angular coordinates of the helmet of the operator in the cockpit of the aircraft by the coordinates of the ultrasonic receivers placed on the helmet, at least three ultrasonic emitters with known coordinates in the coordinate system associated with the aircraft are placed in the aircraft cabin , while at the edges of the working area of the possible provisions of the helmet oppositely in the transverse and longitudinal directions place four ultrasonic corrective receivers pulses with known distances to each ultrasonic emitter, emit and receive pulsed ultrasonic signals, measure the delay time of signals from each ultrasonic emitter to each helmet-mounted ultrasonic receiver and to each ultrasonic receiver of the correction channels, calculate the helmet coordinates using the speed of sound measured in any the correcting channel, find the direction closest to the direction to the helmet from the directions from the emitter to the corrective when to the receivers and to the center of the working area of the helmet positions, and calculate the distances from each helmet-mounted ultrasonic receiver to each ultrasonic emitter, taking into account the speed of sound in the found direction, from which the coordinates of the operator's helmet are determined.

A description of the device for implementing the method will be given for the case of four emitters located in the cockpit of an aircraft and four helmet-mounted receivers.

The task in the system is achieved by the fact that the ultrasonic helmet-mounted positioning system, including a calculator and containing four ultrasonic emitters located in the cabin above the operator’s helmet at spaced points with known coordinates in the coordinate system associated with the cabin, four helmet-mounted ultrasonic receivers located at the reference points, four correction channels with four ultrasonic receivers placed opposite on the edges of the working area of the positions of the pilot helmet with known races by the distances to each ultrasonic emitter, a multiplexer, a signal shaper, a synchronizer, four signal amplifiers of the helmet-mounted receivers with AGC, four signal meters of the delay time of the signals of the helmet receivers, four signal amplifiers of the correction channel signals and four time meters of the delay signal of the correction channels, while the synchronizer output is connected to the inputs synchronization: multiplexer, all meters of delay time signals of helmet-mounted receivers, meter of delay time of signals corrector the channel, the signal shaper, the output of which is connected to the signal input of the multiplexer, the separate outputs of which are connected to ultrasonic emitters, the outputs of the helmet-mounted ultrasonic receivers are connected through signal amplifiers of the helmet-mounted receivers with AGC to the signal inputs of the delay time meters of the helmet-mounted receivers, the outputs of which are connected to the inputs of information the data of the calculator, the outputs of the ultrasonic receivers of the correction channels are connected through amplifiers of the signals of the correction channel with signal inputs of delay time meters of the signals of the correction channels, the outputs of which are connected to the data input of the computer, the output of which is the output of the device (Fig. four).

The invention is illustrated by drawings, which depict:

in FIG. 1 is a structural electrical diagram of a prototype;

in FIG. 2 is a drawing explaining a method for correcting errors in a prototype;

in FIG. 3 is a drawing explaining a method for correcting errors in the claimed system;

in FIG. 4 is a structural electrical diagram of the inventive system.

The inventive method for correcting errors in measuring the coordinates of the helmet of the operator is illustrated in the figure of FIG. 3, on which is indicated:

A is the vibration amplitude of the emitter;

R ₁ is the current distance from the emitter to PRKK1;

R ₂ is the current distance from the emitter to PRKK2;

R _M is the current distance from the emitter to the middle of the line connecting PRKK1 and PRKK2 (in the figure - the median of the triangle);

R is the current distance from the emitter to the helmet;

PRKKH, PRKK2, PRKK3, PRKK4 - ultrasonic receivers of correction channels. In order not to clutter up the picture, the distance lines R ₃ , R ₄ from the emitter to the receivers PRKK3, PRKK4 are not shown.

Denote by T [i, j] the delay time of the signal from the i-th emitter to the j-th helmet receiver, and by R [i, j] - the distance corresponding to the delay.

, ãäå i=1,2,3,4, TKKi - время задержки в i-м корректирующем канале.The speed of sound in the correction channels is determined by the ratio $${\nu }_i=\frac{R_i}{TKKi}$$

, ää i = 1,2,3,4, TKKi is the delay time in the i-th correction channel.

The median length (distance from the emitter to the center of the working area of the helmet positions) R _{M is} calculated by the well-known formula:

where c is the distance between PRKK1 and PRKK2.

The propagation time of an ultrasonic wave along the median is calculated as

where TKK1, TKK2 are the delay times of signals in PRKKH and PRKK2, TKS is the propagation time of the ultrasound from PRKKH to PRKK1.

The speed of sound along the median is defined as v _M = R _M / TKKM.

The sequence of steps of the proposed correction method:

- Measure the helmet coordinates, using for measuring the ultrasound velocity ν _nach any correction channel. In this case, for example, ν _nach = R ₁ / TKK1, where TKK1 is the delay time in the first correction channel.

- Determine the direction from each emitter to the helmet.

- For each emitter, the direction to the helmet is compared with the directions to the corrective receivers and the direction of the median and the one closest to the direction to the helmet is selected.

- Re-calculate the distance from each emitter to each helmet-mounted receiver using the speed of sound in the selected direction, which determine the corrected coordinates of the helmet.

, если выбрано направление на корректирующие приемники, и $$R[i,j]={\nu }_{M}T[i,j]=\frac{T[i,j]}{TKKM}{R}_M$$

, если выбрано направление вдоль медианы.Adjusted distances are now defined as $$R[i,j]={\nu }_{i}T[i,j]=\frac{T[i,j]}{TKKi}{R}_i$$

if the direction to the corrective receivers is selected, and $$R[i,j]={\nu }_{M}T[i,j]=\frac{T[i,j]}{TKKM}{R}_M$$

if the direction along the median is selected.

The correction effect is achieved by the fact that all distances (R, R ₁ , R ₂ , R _{M of} Fig. 3) under the influence of vibration and changes in external conditions change synchronously and proportionally, and correction is carried out in each radiation period with parameters determined by the selected direction.

Claims (2)

1. The method of correcting the linear and angular coordinates of the helmet of the operator of the aircraft in an ultrasonic helmet-mounted positioning system containing four helmet-mounted ultrasonic receivers, four ultrasonic emitters in the cockpit of the aircraft, correction channels with their own ultrasonic receivers, characterized in that they use four ultrasonic receivers of correction channels, placed in pairs opposite the edges of the working area of the helmet movements, pre-determine the coordinates of the helmet, using using any correction channel for measuring the speed of sound, the direction to the helmet is determined for each emitter, these directions are compared with the directions to the corrective receivers and the center of the working area of the helmet positions and the nearest to the direction to the helmet is selected from them, the distances to each helmet-mounted receiver are re-calculated using speed of sound in the selected direction, which determine the corrected coordinates of the helmet. 2. Ultrasonic helmet-mounted system for determining the linear and angular coordinates of the helmet of the head of the operator, including a computer and containing four ultrasonic emitters located in the cabin above the helmet of the operator at spaced points with known coordinates in the coordinate system associated with the cabin, four helmet-mounted ultrasonic receivers located in the reference points helmet, correction channels with ultrasonic receivers each, multiplexer, signal conditioner, synchronizer, signal amplifiers of helmet-mounted receivers AGCs, signal delay meters of helmet receivers, signal amplifiers of correction channels and signal delay meters of correction channels, while the synchronizer output is connected to synchronization inputs: multiplexer, all signal delay meters of helmet receivers, all signal delay meters of correction channels, signal shaper the output of which is connected to the signal input of the multiplexer, the separate outputs of which are connected to ultrasonic emitters , the outputs of the helmet-mounted ultrasonic receivers are connected through signal amplifiers of the helmet-mounted receivers to the AGC with the signal inputs of the delay time meters of the helmet-mounted receivers, the outputs of which are connected to the information inputs of the calculator, the outputs of the ultrasonic receivers of the correction channels are connected through the signal amplifiers of the correction channel with the signal inputs of the signal delay time meters correction channels, the outputs of which are connected to the input of the data of the computer, the output of which is Xia output device, characterized in that it comprises four correction channel with four ultrasonic receivers arranged in pairs on opposite edges of the working area of the operator positions the helmet with the known distances to each ultrasonic transducer.

Images