DE3238186A1 - Compound navigation method for determining the nominal position of a vehicle - Google Patents

Abstract

The compound calculation is carried out with a course reference device exhibiting an unknown drift (DN). Furthermore, a position is determined using as a basis an arbitrarily selected pseudo drift (DP). For determining the actual position of the vehicle, the course direction is determined by measuring the north direction after a period of travelling. From the course direction determined by means of the compound calculation, the drift (DN) of the course reference device can be determined. Using this drift and the pseudo drift (DP) and the corresponding position values (PJ, PP), the actual position (PS) of the vehicle is determined by forming a ratio.

Description

Dead reckoning method for determination

the target position of a vehicle The invention relates to a dead reckoning method for determining the target position of a vehicle, the coupling calculation with a drift caused by a Xiurs reference device and at least one other arbitrary selected pseudodrift is carried out.

From DE-OS 28 05 628 a method is known in which with a dead reckoning calculation from the direction signals of a course gyro and the position of a vehicle is calculated from the position signals of a position sensor. These However, position j is falsified by the unknown drift of the heading gyro. Farther' one with a specific one is given in an additional coupling calculation Drift or pseudodrift afflicted vehicle position determined.

In order to determine the unknown drift of the course gyro and thus in further determining the actual position of the vehicle, use this if possible To determine precisely, it is necessary to move to and from a known position the ratio of the distances between the displayed positions and the actual position of the vehicle and the angles of direction of these positions North direction perform the correction calculation.

However, this procedure is only possible if knowledge of the approximate location and in particular the coordinates of certain reference points available.

In unfamiliar terrain or, for example, in poor visibility, which prevent a reference point from being found, a drift determination and so that a position correction is not carried out.

The object of the invention is to provide a simple method for accurate Specify position determination in which there is no knowledge of the terrain being traveled on are needed.

This object is achieved in that after any travel time the course direction of the vehicle is determined by measuring the north direction and by comparing the one caused by the course reference device with the known one Drift DN and the position coordinates obtained with the pseudodrift Dp and the Ratio of the course angle error caused by the drift and the pseudo drift the actual position of the vehicle is determined.

The north direction can, for example, from the signals of a so-called north-looking roundabout - as it is used in particular in navigation systems wira, won.

will. The north accuracy achieved in this way is an essential one Feature of this gyro and allows very precise navigation of the vehicle. For Purposes for which a low level of accuracy is sufficient can be used to determine the north direction a ground field probe can be used. This is often used in conjunction with a Distance counter for determining the position of road vehicles, such as

Ambulance applied.

Since the signal from the earth field probe is not always available, but is temporarily influenced by interference fields, a steering angle encoder is provided, which delivers a directional signal during the downtime. This directional signal is however, like a course top, it is afflicted with a drift. Especially with a When cornering, there is a significant drift error that falsifies the position display. In one embodiment of the invention, this drift is determined by the relationship DN2 = SN osNN determined.

Here, a N is the difference angle between measured after the disturbance the north direction angle of the determined at the beginning and at the end of the measurement Vehicle, although course change of the vehicle does not take place at this angle is included. This angle is divided by the angle covered during the measurements Route SN.

When determining the drift of a course gyro, the division factor the time between the last two measurements is used because of the drift of the heading gyro is a function of time and independent of the distance traveled, in a simple manner can determine the target position from the values of a pseudodrift DP and the associated north coordinates Np or east coordinates EP and the values of the drift DN and the corresponding coordinates Nj for the north coordinates and EJ for the east coordinates by forming the ratio the drift and the coordinate values can be determined.

This method is essentially for smaller differential angles or drifting. However, larger deviations are due to the high Accuracy requirements on navigation systems are not common. It is well known the proportion of drift that is dependent on the rotation of the earth and the geographical latitude of a course top to compensate with simple means. This just makes it interesting to determine the indeterminable parts of the drift and thereby the position display to improve.

However, this method can also be used to compensate for the total Apply gyro drift.

The invention is described below with reference to the drawing explained in more detail. It is initially assumed that the vehicle is at the beginning is at a known position PO and the heading angle of the vehicle is also known is.

The I coordinates N ,, Eo of this position as well as the euro angle are entered in a known manner in the navigation computer. Now the vehicle begins his journey through the premises, the coupling calculation is carried out in the usual way, through which the distances covered and course changes are constantly evaluated and the coordinates of the respective location, but due to a drift error falsified, determined. The respective location can, for example, in a map device are displayed.

The distance A between the points Po - P5 represents the actual The route taken by the vehicle is shown. A straight route has been used to simplify the illustration selected, but any route is of course possible. the However, the location display in a map device describes the route B between the Points PO - Pd, since the displayed course due to the unknown drift of the course gyro experiences a deviation in direction. This deviation is integrated over time and in certain cases requires a correction of the displayed position coordinates. In addition to calculating the vehicle position from the drift-prone course display of the course gyro, another vehicle position is constantly determined, which is the Distance C between points PO - Pp corresponds. This route is obtained through a course calculation with a so-called pseudodrift, which leads to the unknown Summarized gyro drift. After a travel time TN, which can be chosen at will or is automatically determined on the basis of various criteria, and according to which the Vehicle has reached point P5, the course angle is re-determined. this happens by means of a northerly search by means of a travel compass or a Earth field probe.

The course angle determined here corresponds to the exemplary embodiment through the straight course A the starting course angle. The location or position display however, indicates a position Pj corrupted by the gyro drift and includes a course angle ß 0cN. Half of the angle caused by the drift N N corresponds to the angle that the straight line connecting the points PO - Pj with the segment A occupies.

Calculating the positions with a pseudodrift gives a third location display PP. The unknown drift DN of the course top is now determined in a first calculation according to the relationship αN DN = (1) tN.

To calculate the coordinate values for the actual location of the vehicle is obtained from the ratio of psuedodrift Dp to the associated coordinate values EP, NP to drift DN and the corresponding coordinate values Ej, Nu EP - EJ DP = (2) EJ - ES DN or, after reshaping, the coordinate value ES sought = EJ - (EP - EJ) DN / DP (3) for the east coordinate of the actual position and in the same way according to the relationship DN NS = NJ - (NP - NJ) DP (4 for the north coordinate the.actual position.

The behavior of the drifts can of course also be used of the formula (1) as the ratio of the drift angles αN, * s p, where the Angle α N according to the relationship αN = αF - and the angle αP is to be determined according to the relationship αP = αFP - αF. In here is CC? the angle that appears as the vehicle heading with respect to north and αFP is the angle between the north direction and that caused by the pseudo drift falsified vehicle direction. The angle # is the heading angle, i.e. the actual one Angle between vehicle direction and north direction. By inserting the angular relationships The coordinate values Es, NS can be converted into equations (3) and (4) according to the Relationships αF - # ES = EJ - (EP - EJ) NS = NJ - (NP - NJ) αFP - αF determine.

These values are used to correct the displayed values or the position indicator on the map device.

For the rest of the journey, the position can now be determined using the The drift DN determined in this way is used as a basis, after a further travel time a new position correction is carried out using the same procedure. Based With this method it is thus possible to monitor the drift behavior of the heading gyro and to continuously improve the position display.

L e r s e i t e

Claims (7)

Claims 1. dead reckoning method for determining the target position of a vehicle, the coupling calculation with a course reference device caused drift and at least one further arbitrarily chosen pseudodrift is carried out, characterized in that after any travel time Course direction of the vehicle is determined by measuring the north direction and by Comparison of the drift with the known drift caused by the course reference device DN and the position coordinates obtained with the pseudodrift Dp and the ratio the course angle error caused by the drift and the pseudo drift actual position of the vehicle is determined. 2. dead reckoning method according to claim 1, characterized in that that the drift DN1 is determined according to the relationship DN, = tN, where Oi N is the at the north direction measurement determined course angle error and tN the travel time between the last two measurements. 3. dead reckoning method according to claim 1, characterized in that that the drift DN2 is determined according to the relationship αN DN2 = SK, where αN is the heading angle error and S is the distance traveled between the last two measurements Represents the route. 4. dead reckoning method according to claim 1 and claim 2 or Claim 3, characterized in that the coordinate values of the target position Es, N5 is formed according to the relationships @N ES = EJ - (EP - EJ) DP N3 = Nj - (Np - Nj) DN D P where Ej, Nj are the coordinate values determined by the drift DN, Ep, Np represents the coordinate values determined by the pseudodrift Dp. 5. dead reckoning method according to claim 4, characterized in that that the ratio of the drifts DN / DP from the determined direction angles according to the Relationship DN aF 4 P αFP - αF is formed, where on the angle between displayed vehicle direction and north direction, S is the actual angle between Vehicle direction and north direction and α FP the angle between the through the Pseudodrift represents incorrect vehicle direction and north direction. 6. dead reckoning method according to one of the preceding claims, characterized in that the north direction is determined by means of a gyro compass will. 7. dead reckoning method according to one of claims 1 to 5, characterized characterized in that the north direction is determined by means of a Erdfeldmeßsonde.