DE3445651A1 - North-determining course and position reference device for vehicles - Google Patents

Abstract

This device has three rate-of-rotation sensors for three mutually perpendicular vehicle axes, according to German Patent Application 3322632, with three rate-of-rotation sensors on a common pendulum (5) representing the perpendicular, which can oscillate around arbitrary axes within the horizontal plane, one of the three measuring axes of the three rate-of-rotation sensors coinciding with the longitudinal axis of the pendulum (5) or being located parallel to the latter, the two measurement axes (2,3) of the remaining rate-of-rotation sensors being located perpendicular to the first measuring axis (5) and perpendicular to one another, the pendulum (5) being gimbal-mounted or supported by a spherical shell bearing and angle-measuring elements (17,18) being provided in the gimbal axes (10,11), and, due to the required rebalancing moments in the two measuring axes, two corresponding rate-of-rotation signals being generated and being used for mathematically evaluating the north direction and the angle measuring elements (17,18), together with the rate-of-rotation signals, being used for determining the angles. To obtain additional information on the linear movement in all three vehicle axes, an additional accelerometer (29) is provided, the input axis (30) of which is parallel to the pendulum axis (5), and simple evaluating electronics for determining the linear speed and the linear movement ... Original abstract incomplete. <IMAGE>

Description

Nordermittelndes course and position reference device for vehicles The invention refers to a north-averaging heading and position reference device for vehicles according to the preamble of claim 1.

Such a device is in German patent application P 33 22 632.6, to which the present application is an additional application.

For certain purposes of such reference devices, the determination is the horizontal-linear movement caused by the sea, for example for the dynamic positioning of a ship. The same is used for surveying purposes the lifting movement, as the vertical movement of a ship, for the correction of the Water flow measurement required.

Surface vehicles such as B. Ships change operationally not their mean height. To record the stroke movement, the simple or double integration of the output of a vertically arranged accelerometer in a limited frequency range.

The detection of a horizontal movement of a vehicle takes place analogous to the stroke movement also through single or double integration of the output signals of two accelerometers arranged at 90 ° in the horizontal in one limited frequency range. Since with this method there is no mean change in position can be recorded, it is necessary to use a separate center position To record the measuring system and with these values the obtained by the double integration A relative position has to be supported Such for support suitable measuring systems are available on the market from various companies. All of this system are, however, attein not able to change position in the area below of a meter or to be recorded quickly enough.

Existing so-called strapdown systems naturally contain 3 acceleration meters and can determine the three-axis linear movements according to the above-mentioned method. The accelerometers present in these systems that are used to determine the Serving north reference are accordingly extremely accurate and therefore extremely expensive.

There is another possibility to determine the linear movement in the use of a gyro-stabilized vertical or horizontal reference, which is also equipped with three accelerometers. However, this makes one complete and expensive additional system required.

In the device described in the parent application P 33 22 632.6 to reduce the dynamic range the speed sensors on a pendulum arranged.

Such a pendulum appears in the light of horizontal accelerations lot.

The illusion is the resultant of that which is to be set as constant Acceleration due to gravity and the horizontal acceleration, so that the angular deflection from the vertical is a measure of the horizontal acceleration.

In the case of a biaxially supported pendulum, the pendulum itself acts as a dual axis accelerometer.

The invention is based on the object of providing a reference device according to to design the preamble of claim 1 so that in addition to the three position angles of the vehicles also provides information about the linear movement in a cost-effective manner is made possible in all three vehicle axles.

According to the invention, the object is achieved by the features of the label of claim 1 or claim 2 solved.

The essential aspect of the solution lies in the arrangement of an accelerometer with its measuring axis parallel to the pendulum's longitudinal axis. This makes a three-axis Acceleration measurement enables.

The requirements for the quality of the additional accelerometer are only due to the requirements for sensing the stroke movement.

Embodiments of the invention are shown in the drawing. In order to avoid repetitions, please refer to the corresponding statements in the parent application referenced.

It shows: FIG. 1 in a perspective schematic illustration Exemplary embodiment with rotatable mounting of the entire reference device, FIG. 2 the representation of the three measuring axes of the gyroscope to the navigation frame by so-called Euler angle, Figure 3 the schematic circuit arrangement for determining the course angle, FIG. 4 shows the frequency responses of the reference device, and FIG. 5 shows a schematic circuit arrangement for determining the lifting speed and the lifting path, FIG. 6 the schematic Circuit arrangement for determining the three-axis linear speed and movement with coordinate transformation.

Description of Fig. 1 A free gyro 1 equipped with two Measuring axes 2 and 3, together with a rotational speed sensor 4, is arranged in such a way that that both are components of a mechanical assembly within a cardan frame 15 about a first cardan axis 10 and together with this about a second cardan axis Can exercise 11 angular movements.

Since the focus of this assembly is below the intersection of the two cardan axles 10 and 11 is located. this represents a pendulum. Its longitudinal axis 5 represents the perpendicular in a stationary exercise.

The arrangement of the free gyro 1 is chosen. that its twist axis is identical to the pendulum longitudinal axis 5 and its measuring axes 2 and 3 are perpendicular stand in one plane on this.

The two measuring axes are each represented by a pick-up element 6 and 7. They are lying in one plane, perpendicular to one another and are in the Able to scan the position of the gyro rotor in relation to its spin axis.

About guide motors 6 and 7 also arranged in the measuring axes it possible. To exert moments on the centrifugal motor and put it in its zero position, for example to captivate.

The zero position is given when the figure axis of the gyro with coincides with the twist axis.

The rotational speed sensor 4, e.g., a rate gyro, is known Design type. is located at the lower end of the pendulum. Its measuring axis coincides with the Pendulum longitudinal axis together or is parallel to this. He is thus able to To sense rotary movements around the longitudinal axis of the pendulum.

Also at the bottom of the pendulum is, over three spokes 8, 8 and, 8 "attached, a spherical shell 9 is arranged, the geonietrischer center point of which coincides with the intersection of the two cardan axes 10 and 11.

Together with one arranged on the part 12 of the device that is fixed to the vehicle Magnet 13 gives the spherical shell an eddy current damping, which the movements of the Pendulum around the cardan axles 10 and 11 dampens.

In the cardan axes angle measuring elements 17 and 18 are arranged, the a rotation of the inner cardan axis 10 relative to the Kardanrahiiien 15 and a Measure the rotation of the cardan frame 15 with respect to the part 21 fixed to the vehicle.

If the device is arranged on a vehicle so that the vehicle's longitudinal axis 14 is parallel to the outer or inner cardan axis 11. so can with this Winkelmeßelenienten determines an inclination of the vehicle about its longitudinal and transverse axis when stationary will.

Fig. 1 shows an arrangement in which the device by a! Xlotor 19 and a bearing 20 are rotated about an axis perpendicular to the installation surface 21 can. This is necessary if certain (under B) or C) of the parent application P 33 22 632.C) older methods for searching north or one of the following described method used to compensate for the drift of the free gyro will. Here, too, the same parts are provided with the same reference numerals.

Is one of the in the parent application P 33 32 632.6 under B) or C) provided according to the method described, it makes sense to only use the free Rotatable gyroscope so that the assignment of the cardan axles to the vehicle's longitudinal or transverse axis is retained. In the process A) mentioned, one forms the to Shackling of the free gyroscope required moments in electrical signals around and determined by comparing them the north direction (device fixed). According to method B), as in Figure 1 of this application is shown either the entire device or just the free rotatable rotatable bearings. If you turn the device or the gyro until in one of the measuring axes the torque required for restraint is a maximum and the restraint element reaches a minimum in the second measuring axis, the position corresponds to the first called measuring axis of the north-south direction (device rotated to certain points). In the case of a method C), which is also described, the entire device is also used or only the free top rotated continuously at constant speed.

The course of the moments required to restrain the free top corresponds to a sine function, with the signals obtained from these moments are shifted by 90 ° from the two measuring axes and to determine the north direction can be used. The method according to A) essentially corresponds to strap-down platforms, as used in land, air and water vehicles. As sensors are requires three rotational speed sensors and three accelerometers. The measuring range of these sensors must be sufficient in the entire dynamic range have high accuracy.

Due to the chosen pendulum arrangement of the proposed system eliminates the need for two accelerometers. The pendulum suspension in connection With a suitable damping leads to a reduction of the dynamic range of the rotation speed sensors.

This leads to an inexpensive solution.

Functional description with reference to FIGS. 2 and 3 on a moving The vehicle can move the measuring axes of the gyroscopes to the navigation frame (perpendicular, east, north) can be described by the Euler angles (Fig.

2).

The index coordinate system related to the horizontal is identical with the navigation coordinate system indexes when CC = 0.

The angular rotational speeds measured in the gyroscope contain the components of the earth’s rotational speed WE, the rotational speed V generated by the vehicle movement on the surface of the earth R b and the vehicle rotational speed # F Due to the selected pendulum arrangement, the angles # and γ are small and can therefore be neglected. If the vehicle is not moving, the angular rotational speeds measured in the two measuring axes of the free gyro can be described as follows: #ys = #E. cos (#) sin (α) (1) #zs = #E. cos (#) cos (α), (2) from which the angle between north and the vehicle's longitudinal axis (course) can be calculated. I - arctan C3,, = g = arctant- W s 7 (3) For a vehicle moving at speed V, the following angular rotational speed t is measured by the free gyroscope. This results in: V # ys - # ys + (4) R # Zs = # zs (5) from this dC can be calculated. gold = arctan (½Ü t6 This means that αi can be calculated continuously. The angular rotational speeds measured in the measuring axes of the free gyro can only be determined over a correspondingly long averaging time. This also applies to αi.

For higher angular rotation speeds this is not acceptable, so that a further sensor signal is required, which is able in this period of time to determine a sufficiently precise change in the course a α.

For this purpose, another rotational speed sensor, such as. B. a Rate gyro, required.

The integrated signal of this sensor is used. to determine the course change in the time interval #t.

In addition to the desired #p, the yaw rate sensor measures the vertical component the earth rate and the travel component of the vehicle.

These quantities can be represented mathematically and thus compensated.

αi thus gives the current course value of the vehicle.

Fig. 3 shows schematically a possibility from (tell both gyro signals A free top, e.g. B. a dynamically tuned gyro (DAK), whose spin axis is arranged vertically, via an electronic system 23 in both measuring axes held in the zero position. The top is thus forced. the horizontal component to follow the rotation of the earth.

The torques required for this are proportional to #ys and WeS Aus these two values will be dead; calculated by a computer 25.

This physical principle is known and is one of the basics the inertial navigation.

The signals WS and S are due to the vehicle movements with higher frequencies Superimposed on signals that interfere with the calculation of the course angle. For this reason a filter 26 is provided.

This arrangement is only suitable for stationary applications, as this Principle is not able to achieve rotational speeds like those of moving vehicles occur to sensation.

To realize this, another rotational speed sensor is used 24 is provided, which can detect these angular movements without delay.

As shown in Figure 3, the vehicle turning speed is determined by a rotation rate sensor 24 measured and one proportional to the rotation speed Signal #F provided with a corner frequency K 1.

This signal is added to the signal, and in the manner shown gives the current course angle with ot i.

Here, K1 is to be selected so that the required angle values are sufficient can be offered quickly.

Fig. 4 shows the frequency responses of the proposed system a: shows the frequency response of the course signal, determined from the bondage moments of the DAK, b: shows the frequency response of the rotational speed signal generated by the rotational speed sensor, c: shows the frequency response of the course signal to the vehicle rotational speed d: shows the characteristic curve of the course signal for the integrated rotational speed of the vehicle, e: shows the frequency response of the sum of the signals determined by both sensors.

Determination of the horizon The proposed system is with additional Angle measuring elements in the cardan axes of the self-aligning bearing (Fig. 1) are able to In addition to the heading angle, there are also angular movements around the vehicle's longitudinal and transverse axis to investigate.

These angle measuring elements 17, 18 determine the angle K and YK between Vehicle and pendulum. This value, filtered accordingly, represents the horizon angle in the respective vehicle axle. The quality of this information depends on the accuracy of the pendulum bearings and the angle measuring elements.

Because of the time constants required by the filter networks, this Signal does not represent the respective current angle value. To obtain this, is a link with the rotational speed signals obtained from the tied gyroscope len required.

The from the Winkelmeßelemente 17 and 18 of the Kardanmeßachsen of the Peridcls The signals e K and γ K obtained are transmitted via a loop consisting of K4 and 1 / S, filtered.

As already described when determining the course, on becomes off filtered rotational speed signal obtained from the measuring axes of the DAK s (free gyro) / and 9 fed in.

The same frequency responses result as when determining the course (Fig. 4).

To compensate for errors To be inexpensive for the proposed system To be able to use free gyroscopes (e.g. DAK) is the correction of the gyro drift necessary.

This can be done as follows: When measuring the bondage moments The circular drift can be determined in two azimuth positions pivoted by 180 °. This method is known and is used to test gyroscopes.

As shown in Fig. 1, a device is provided that it allows you to turn the compass by 180 ° in order to use the above test method.

This can be done manually or automatically, both stationary and on carried out on a moving vehicle.

In this case the rotation must be at a known speed can be carried out and can thus be compensated arithmetically.

When the vehicle accelerates linearly, the pendulum-suspended one goes Arrangement in the note lot.

The relationship applies to a small angle The centrifugal acceleration that occurs when driving in circles causes a deflection around the other axis.

The advance speed is determined via the trip measuring system. from which the linear acceleration can be calculated.

The speed of rotation WF. is proposed by the rate gyro System measured.

This means that both quantities can be calculated according to the equations @ 12 and 13) and compensated for by suitable measures.

The driving error caused by the vehicle driving itself with gyro compasses is physically determined by the speed of travel The geographical latitude and the course are determined and can therefore also be calculated and compensate.

The tangent function shows discontinuities in the areas at # / 2 and 2.

The same applies to the cot function at α = 0 and 8 Da equation (8) contains the tangent function. occur with limited resolution arithmetic errors.

To avoid this, the entire area becomes 0 # α # 2 # in eight Segments divided. (Fig. 10 parent application) The range limits are for tan α and cot CL at f 1.

Hence, α only needs in the areas of + 450 from the tangent respectively.

Cotangent to be calculated.

The segments are arranged as shown in Figure 10 of the parent application and defined by comparing ys and off.

Determination of vertical movement For applications on ships in addition to the determination of the course, roll and stand angles, also the lifting movement of importance (e.g. helicopter landings).

For this application the subject of the invention is provided with an accelerometer 29 (Fig. 1) equipped, the measuring axis (30) coincides with the pendulum axis 5 or is arranged in parallel.

According to FIG. 5, the stroke acceleration is b stroke in an electronic evaluation system (31) integrated twice within a limited frequency range and so the Stroke speed V stroke and the stroke distance stroke are determined. Due to the adjustable Pendulum damping and an installation of the system in the vicinity of the ship's pivot point the influence of the dummy solder can be neglected.

FIG. 6 shows an arrangement for determining the three-axis linear movement shown. This arrangement means that there are no restrictions with regard to the installation site. This is explained in more detail below: The rotational speed signals known from FIG. @ # and # repräys sense the rotational speeds es and ç s the integral of these Rotational speeds result in the angular movement of the pendulum is and γs. There the pendulum hangs vertically on average over time, the angles and γs relate on the vertical and represent the respective apparent perpendicular angle and are thus proportional to the accelerations in the Y and in the z direction of the system.

Due to the fact that the pendulum is vertical on average over time depends, it is also allowed to integrate the signals #s and γs with the help a traced integration (32), i.e. above a corner defined by KG frequency to perform.

The acceleration along the pendulum axis is carried out with the aid of the accelerometer (29) and results in the signal b. In the coordinate transformation (33), the signals γs, #s and bxs linked so that the on a horizontal coordinate system related acceleration signals bxH, byH and bzH arise.

According to the coordinates given in FIG. 2, the coordinate transformation has the following transfer behavior: bxH = bxs. cosγ. cos # (1) b = b sin yH xs (2) bzH = -bxs. cosγ. sin # (3) In the evaluation electronics 31 are now as described by means of simple double integration Linear speeds VXH, VYH and VZH and the linear movements SXH, S YH and SZH determined.

- L e r s e i t e -

Claims (2)

PATENT APPROACH 1. Nordermittelndes course and position reference device for vehicles, with three rotation speed sensors for three perpendicular to each other standing vehicle axles, according to German patent application 3322632, a) where the three Rotation speed sensors (1; 2, 3; 4) on a common, the Lot1 representing Pendulum (5) are arranged around any axis within the horizon plane can oscillate, b) where one of the three measuring axes of the three rotational speed sensors coincides with the longitudinal axis of the pendulum (5) or lies parallel to it, and wherein the two measuring axes (2, 3) of the two remaining rotational speed sensors perpendicular to the first measuring axis (5) and perpendicular to each other, c) where the Pendulum (5) is gimbaled or supported by a spherical spherical cap bearing, and where in the cardan axes (10, 11) angle measuring elements (17, 18) such as potentiometers / Synchros including resolvers, diaital angle measuring elements and the like are provided are, d) where from the for tying the free top (1) in his two measuring axes (2, 3) required shackle moments two corresponding Rotational speed signals (#ys, #zs) (in a circuit) are generated, where the rotational speed signals with regard to absolute amount, amount ratio and Signs are evaluated, and from the result of this evaluation arithmetically the north direction is determined, e) and where the angle measuring elements (17, 18) generated angle measurement signals (V; <) (in electronics) with the rotational speed signals of the rotation speed sensors (1, 2, 3) are linked to the angle 1 e, V) to be determined, characterized by I an additional accelerometer (29, Figure 3), the input axis (30) of which lies parallel to the pendulum axis (5), II a simple evaluation electronics, which according to a known method by simple and Double integration of the acceleration along the pendulum axis in a limited way Frequency range the linear speed and the linear movement along the pendulum axis determined. 2. Nordermittelndes course and position reference device for vehicles, with three rotation speed sensors for three mutually perpendicular vehicle axles, according to German patent application 3322632, a) the three rotation speed sensors (1; 2, 3; 4) are arranged on a common pendulum (5) representing the perpendicular, that can oscillate around any axis within the horizon plane, b) where a of the three measuring axes of the three rotational speed sensors with the longitudinal axis of the Pendulum (5) coincides or lies parallel to this, and the two measuring axes (2, 3) of the other two rotational speed sensors perpendicular to the first measuring axis (5) and are perpendicular to each other, c) the pendulum (5) being cardanic or is supported by a spherical spherical cap bearing, and wherein in the cardan axes (10, 11) Angle measuring elements (17, 18) such as potentiometers. Synchros including resolver, di "itale Angle measuring elements and the like are provided, d) wherein from the for restraint of the free gyro (1) in its two measuring axes (2, 3) required shackle moments two corresponding rotational speed signals (#ys, #zs) (in a circuit) generated the rotational speed signals in terms of absolute amount, amount ratio and signs are evaluated, and from the result of this evaluation arithmetically the north direction is determined (arrangement according to FIG. 1), e) and where the angle measurement signals (#K, γK) generated by the angle measurement elements (17, 18) ) (in electronics) with the speed signals of the speed sensors (1, 2, 3) are linked to determine the angles (V), indicated by I an additional accelerometer (29, Figure 3), the input axis (30) parallel to the pendulum axis (5), II a first evaluation circuit (32), which consists of the rotational speed measured by the gyro (1) in a limited frequency range Angle measurement signals (#s) for the acceleration angle supplies, III a second Evaluation circuit based on the rotational speed measured by the gyro (1) Determines the acceleration angle (e 5) in a limited frequency range IV a device (33) for transforming coordinates from the two angles of acceleration (γs, # s) and the acceleration (bxs) the three accelerations into three perpendicular directions (byH /, b zH, b xH) are determined, V a third evaluation circuit (31), which is based on the values determined above Single and double integration of the accelerations in a limited frequency range the associated linear velocities with respect to the three perpendicular to each other stationary axes (vxH, vyH, v zH as well as the corresponding linear movements in the three mutually perpendicular directions (S xH, S yH, S zH) are determined.