WO2005077466A2

WO2005077466A2 - Method and device for displaying parameters of the trajectory of at least one moving object

Info

Publication number: WO2005077466A2
Application number: PCT/CH2005/000080
Authority: WO
Inventors: Markus Bickert; Hermann Beer; Marcel Jerg; Mauro Kern
Original assignee: Sensitec Ag
Priority date: 2004-02-11
Filing date: 2005-02-11
Publication date: 2005-08-25
Also published as: WO2005077466A3; EP1715928A2

Abstract

In Fig. (1) it is possible to see a simplified drawing of a football pitch (1) and two goals (2 and 3) which are located at opposite ends of the playing field (1). The device for carrying out the method for displaying the parameters of the trajectory of at least one moving object comprises two sets (6, 7) of radar sensors (5), whereby one of said set of sensors is respectively arranged in the region of one of the goals (2,3) of the playing field (1). The sensors (5) of each respective set (6, 7) are connected to a data concentrator (8) which combines signals received from individual sensors to form one or several signals before said signals are forwarded to a computer (9). The computer (9) then forwards the processed signals in the form of video signals to a video mixing desk or directly to a large display (10) such as those which are often installed in stadiums.

Description

Method and device for displaying parameters of the path of at least one moving object

The present device relates to a method for displaying parameters of the path of at least one moving object and a device for carrying out this method.

WO 01/38898 discloses a method and a device of this type. This prior art document is primarily concerned with the fact that the speed of a golf ball is displayed at the moment it is hit. For this purpose, radar sensors are used, which are arranged in the area where the golf ball's teeing point is. Since the direction of movement of the golf ball is at least essentially known after it has been struck, it is possible to bring the main axes of the radar sensors into line with the direction of flight of the golf ball.

However, there are also situations in which the beginning of the movement or de trajectory of a moving object, for example a sports object such as e.g. of a ball, puck etc. is unknown and yet one should be able to measure and display the speed of the object inside a target area.

The main object of the present invention is to provide a method by means of which the speed of an object inside a target space can be measured and displayed, although the beginning of the movement or trajectory of the moving object is unknown or not determined in advance can.

This object is achieved in accordance with the invention in methods of the type mentioned at the outset, as is the case in the characterizing part of patent claim 1 is defined.

The stated object is also achieved by means of a device which is defined in the characterizing part of patent claim 6.

Embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. 1 shows the essential components of a device for carrying out the present method, which contains, among other things, radar sensors, FIG. 2 shows a block circuit diagram of a section of the present device, this section of the present device being one of the radar sensors and the circuits connected to them 3 includes a block diagram which illustrates the design of the radar sensor,

4 shows the superimposition of signals relating to two speeds, which were measured by the radar sensors,

5 is a vectorial representation of the situation of a gate,

6 shows a plan view of one of the goals of a playing field, including its apron and the radar sensors assigned to this goal, including their main radiation directions,

7 shows a top view of the radiation lobes of the radar sensors from FIG. 6, FIG. 8 shows a front view of the gate with its apron and the radar sensors assigned to this gate including their main radiation directions, FIG. 9 shows a front view of the radiation lobes of the sensors from FIG. 8 10 shows a series of speed profiles which can be used to determine the speed of a flying sport object,

11 and 12 show a further possibility for determining the actual speed of a flying sport object using a single sensor, and 13 is a curve which illustrates the evaluation of the speed measurements with club suppression.

Fig. 1 shows = € h ^' e essential components of a device for performing the present method. The present method can be used with special advantages in connection with sports events. If it is a matter of sporting events in which a ball moves, such as handball, football or the like, then the speed of the ball can be measured and displayed in a target area, for example in front of one of the goals. In ice hockey, the speed of the puck can be measured using the present method and device, etc.

1 shows in simplified form a soccer field 1 including two goals 2 and 3, which are located at opposite ends of the field 1. The relevant measuring system comprises two sets 6 and 7 of radar sensors 5, each of which one of these sensor sets 6 and 7 is arranged in the area of one of the gates 2 and 3. In the case shown in FIG. 1, the sensors 5 are arranged behind the gates 2 and 3. However, it is also possible for the sensors 5 to be arranged in front of the gates 2 and 3, ie inside the playing field 1. The sensors 5 of the respective set 6 or 7 are connected to a data concentrator 8. The respective data concentrator 8 combines the signals received by individual sensors 5 into one or more signals before these signals are forwarded to their destination, which is normally a higher-level computer or a display. These data concentrators can also be designed in such a way that they preprocess the measured values obtained from the sensors 5 and can only then forward them. In the case shown in FIG. 1, the measured values are passed from the concentrators 8 to a higher-level computer 9. This computer 9 processes the received in such a way that it, for example are available as a video signal for a video mixer or directly for a large display 10, as is often installed in the sports stadiums.

The radar sensors 5 mentioned are not directed to a specific launch point of the object to be tracked, such as e.g. of a ball, because such a shooting point is not known in advance during the game. The individual radar sensors 5 are aligned in such a way that the antenna characteristics of the radar sensors 5 cover the space from the relevant gate 2 or 3 as efficiently as possible. Such an arrangement of the radar sensors 5 makes it possible to measure shots fired in the direction of the goal, even during the regular course of play in sports in which the players move freely in the field of play. Such use of one or more radar sensors 5 also allows a speed measurement if players, in particular the goalkeeper, the line of sight between one or more of the radar sensors 5 and the ball is temporarily interrupted. If only a single radar sensor is used in the area of the gate 2 or 3, then this sensor 5 must be arranged relatively high above the gate 2 or 3. The present measuring device is designed in accordance with the circumstances of the relevant sport (football, ice hockey, etc.) with regard to the number of radar probes used behind the goal 2 or 3 in such a way that at least one sensor 5 always has direct visual contact with the sport object 4 at a suitable point , The speed of the sport object 4 can thus be measured, although it is shot at an unknown time and from an undefined point or position in the direction of goal 2 or 3.

2 shows a block circuit diagram of a section of the present device, this section of the present device comprising one of the radar sensors 5 and the circuits connected to them for evaluating the signals emitted by the radar sensor 5. Fig. 3 shows a block Circuit diagram which illustrates the design of the radar sensor 5.

The radar sensor 5 comprises an oscillator 11 which generates vibrations whose frequency can be between 2 GHz and 100 GHz. These vibrations are fed to an SE coupler 12, in which the vibrations supplied are divided into a transmission path 13 and a reception path 14. Via the transmission path 13, the vibrations reach the transmission antenna 15, which emits these vibrations as a progressing wave 16 to the object 4 (FIG. 2). A part 17 of these waves is reflected by objects 4 and a part of the reflected signal 17 reaches the receiving antenna 18 of the sensor 5. After amplification of the weak reception signal in a preamplifier 19, this signal is fed to a power divider 20, in which the latter Received signal is divided so that it can be fed to two mixers 21 and 22. There is a delay element 23 between the power coupler 20 and one of the mixers 22, so that the received signal is fed to this second mixer 22 by a quarter of the wavelength. This part of the oscillation reaches a second coupler 24 via the receive path 14, in which this signal is divided into two signals, one of these divided signals being fed to the second input of the mixers 21 and 22.

The phase of the signals at the outputs of the mixers 21 and 22 is then +/- 90 degrees to one another, depending on whether the object 4 is moving towards the sensor 5 or away from it.

In addition to the ball 4, FIG. 2 also schematically shows one of the players 25. These are located in front of a cutout 26 from the net of the gate 2. Assume that the ball 4 moves against the net 26 of the gate 2 at a speed v1 of approximately 30 m / sec. A player 25 normally moves at a speed v2, which is generally well below 10 m / sec. The waves 17 returning to the sensor 5 contain information about these two speeds v1 and v2. The course of one of the signals which appears at the relevant terminal K1 or K2 is shown schematically in FIG. 4. The lower speed v2 of the movement of the player 25 corresponds to a signal with a frequency f2 which is lower than that frequency f1 which carries the signal with the information about the speed v1 of the ball 4. The signal with the higher frequency f1 is superimposed on the signal with the lower frequency f2, as shown in FIG. 4.

The .Circuits of the evaluation part of the present device are then connected to the terminals K1 and K2 of the radar sensor 5. An evaluation circuit 31 or 32 is connected to the respective terminal K1 or K2. The respective evaluation circuit 31 or 32 contains bandpasses 33 and 34, with the aid of which the radar signal is divided into adjacent frequency ranges. The first of the bandpasses 33 is a bandpass for high speeds, which passes signals H1 and H2 at a higher frequency. The second of the bandpasses 33 is a bandpass for low speeds, which passes signals L1 and L2 with a lower frequency L1 and L2. The subdivision mentioned can be carried out with the aid of analog filter circuits or as a digital filter in a DSP (digital signal processor).

The speed range to be evaluated is divided into two ranges in the case shown, namely, in the higher range H1, H2 etc., ie radar stereo signal for the “high speed” range, and in L1, L2 etc., ie radar stereo signal for the "Low speed" range. This subdivision results in a gain in the signal-to-noise ratio, especially when there are many moving objects of different speeds in the detection field 1. A division into more than two sub-speed ranges brings a further improvement in the measurement results. The radar signals are evaluated in parallel for all speed ranges. The highest of the parallel The speeds determined are processed further in the evaluation of the speed measurements.

In each frequency band there is a comparator with a trigger threshold, which converts a dominant signal into a square-wave signal. In contrast to the movements of a player 25, the sports object 4 to be detected is characterized by a frequency-constant square-wave signal that occurs over a relatively long time interval. The occurrence of such a signal is recognized by the digital signal processing and as a flying sport object 4, i.e. Ball, puck, etc. recognized.

As already mentioned, each radar sensor 5 generates speed values of the sport object 4 and of any player 2 present, which are expanded / developed by the concentrator 8. The simplest type of this further processing is that the maximum value of the received measured values is passed on to the higher-level computer 9 or to the display, provided that the radar sensors can no longer determine speed measured values from the sport object 4 over a certain period of time. The plausibility of the measured speed values can be checked. This test concerns in particular the test with regard to a sufficiently long flight phase with only a small acceleration dv / dt. In addition, this check can relate to checking whether the measured maximum value is within plausible limits. Because the range of possible speeds of a ball 4 or the like is known. As long as the speed value is within these limits, it can be considered plausible. In addition, it is known that a ball 4 or the like flying towards goal 2 or 3 has a relatively constant speed or only slight deviations dv / dt from a speed initially communicated to it. The speed is only output if the speed values are within the plausible limits. Fig. 5 shows a vectorial representation of the situation in front of a goal 2 or 3, against which the ball 4 is shot. 5 shows a system of axes x, y and z which are at right angles to one another. A first level Tau1, in which the axes x and y lie, lies in the plane of the playing field 1. A second plane Tau2, in which the axes y and z lie, is perpendicular to the first plane Tau1 and this second plane Tau2 coincides with the mouth one of the gates 2 or 3 together. The ball 4 initially lying on the floor 1 is shot from the middle of the width of the goal 2 or 3 laterally to the left and upwards against the goal at a speed v1. We call the angle which the trajectory of the ball 4 makes with the horizontal plane Tau1 Phi. We call the angle which the trajectory of the ball 4 makes with a plane running vertically and perpendicular to the second plane Tau2, gamma. The individual radar sensors 5 do not measure the actual speed of the sport object 4, but only those vector components of the speed of the sport object 4 which point in the direction of the main axis A of each of the radar sensors 5 in the second plane Tau2 (FIG. 5). The measured speed results in: v (measured) = v (actual) * cos (vertical error angle Phi) ^* cos (horizontal error angle gamma)

If, due to the arrangement of the radar sensor 5 used, the maximum error angles Phi and gamma that occur are so small that they do not falsify the measurement result below an acceptable limit value, this method of outputting the highest measured value is permissible. Because if there is a small misalignment to at least one of the sensors in plane Tau 2, which could record speed measurements of the sport object 4, only a slightly lower speed is displayed. However, if the speed of the sport object 4 is to be determined with a higher degree of accuracy, then several radar sensors 5 must be used and the measurement results obtained in this way must be taken into account at the same time. A relevant arrangement of the radar sensors 5 for a soccer field 1 is shown in FIGS. 6 to 9. 6 shows a plan view of one of the gates 2 together with its apron and the radar sensors 5 assigned to this gate 2 and their main radiation directions. FIG. 7 shows a top view of the radiation lobes of the radar sensors 5 from FIG. 6. FIG. 8 shows a front view of the gate 2 together with its apron and the radar sensors 5 assigned to this gate 2 and their main radiation directions. FIG. 9 shows a front view of the radiation lobes of the radar sensors 5 from FIG. 8. In the case shown in FIGS. 6 to 9, there are several radar sensors 5 behind the gate 2. These radar sensors 5 are corresponding to the front surface over the surface Tau 2 of gate 2 distributed. The radar sensors 51, 52, 53 and 54 are closer to the upper edge 27 of the gate 2. The radar sensors 55, 56, 57 and 58 are closer to the floor 1. FIGS. 7 and 9 show the positions and the directions of the lobes K51 to K58 of the radar sensors 51 to 58.

The radar sensors 51 to 58 oriented as shown are synchronized by the data concentrator 8 with a reference time signal. In addition to the speed measurement value emitted by the respective radar sensor 51 to 58, the time at which the speed measurement value occurs is determined and passed on to the data concentrator 8. The data concentrator 8 either takes over the calculation of the speed correction itself or it forwards the data to the higher-level computer 9. In such a case, the following processing steps take place there:

The speed measurements of the individual radar sensors 51 to 58 are each interpolated with a polynomial such that there is a speed-time curve for each sensor 51 to 58. These curves are generally not available for every sensor or for the entire flight time of the sport object 4, since the sport object can be covered by players 25. The sport object 4 can, however, also move away from the measuring range of the corresponding radar sensor. Time points are determined at which speed data (measured or interpolated) are available from as many sensors 51 to 58 as possible. At these times, the speed distribution, which was measured on the radar sensor level behind gate 2, is standardized and compared with stored speed profiles.

Figure 10 shows a number of such speed profiles. The respective speed profile comprises three mutually perpendicular planes E1, E2 and E3. The first of these planes E1 represents the basic plane, it runs horizontally and comprises the coordinates y and z from the illustration in FIG. 5. The second plane E2 is perpendicular to the basic plane E1 and the speed values of the sport object 4 are entered in this vertical direction , Within this spatial structure there is a curved plane Eg, which represents the speed profile mentioned. The base plane E1 corresponds to the front mouth Tau 2 of the gate 2, which, however, runs vertically in FIG. 5. The speed signals, which originate from the radar sensors 51 to 58 arranged behind the gate 2, lie on the curved plane Eg when the ball 4 is at a specific position opposite the gate and when the ball has a specific direction of flight. Below the respective speed profile in FIG. 10 there are numerical data which indicate the starting position of the ball 4 relative to the goal 2 and the angle of the trajectory of the ball 4. Depending on this information, the speed profiles have different courses. A large number of such speed profiles is stored in computer 9, for example. stores. Together with each of the speed profiles, a number relating to the corresponding speed is stored in the computer 9.

When assaulted information about the ball 4 comes from the sensors 51 to € 8 into the computer 9, the computer begins to compare this information with the information in the stored speed profiles. When the computer finds a corresponding stored speed profile, it displays the speed corresponding to this speed profile on the display panel 10. Each of the stored speed distributions is linked to a correction factor lambda, with which the measured speeds can be corrected. The position of the sport object 4 is thus not calculated, but rather the actual speed of the sport object 4 is only inferred from the comparison with stored speed distributions. The determined speed is output on the display 10, the superordinate computer 9 or in another suitable form. If no suitable (stored) speed distributions can be found, no speed value is output. As a result, cross passes in the area in front of the gate do not lead to a speed display, since no correction pattern is stored for speed vectors v1 (FIG. 5) which point past the gate at too great a distance.

A further correction possibility is that the distance from moving or static objects can be determined by FMCW or frequency shift keying in the case of frequency-modulated radar modules. The detuning of the transmission frequency results in a phase shift of the received Doppier signal that is proportional to the frequency deviation and distance. This phase shift can also be measured in the NF output signal of the radar module 5. With a suitable evaluation of the radar signal, the speed in the direction of the radar module 5 and also the direct distance between the radar module 5 and the sport object 4 can thus be determined. will be closed.

With the help of trigonometric calculations, which are known from the 3-point location of objects, the position of the sport object 4 can be determined if there are at least three radar sensors. If there are distance measurements from more than three radar sensors, groups of three can be formed and positions can be calculated. The target position is then calculated as a communication of these individual results. If the position of the sports object at the time of the speed measurement is known, the orientation and the amount of the speed vector can be calculated from the additionally available speed measurements.

11 and 12 show a third possibility for determining the actual speed of a flying sport object. In the following circumstances, a single radar sensor 5 may also be sufficient to determine the actual speed of a flying sport object:

- The distance between sports object 4 and radar sensor 5 is known.

- The loss of speed of the sports object in the atmosphere is primarily determined by the air resistance.

- The influence of gravity can be neglected, which is especially true at high speeds of the sport object 4.

- The radar sensor 5 records the speed profile of the sport object 4 over a longer measuring distance.

By comparing the measured speed curve vr (FIG. 12) with the expected speed curve vsoll (in the case of a flight directly in the direction of the radar sensor), the angular deviation of the trajectory of the sport object 4 can be concluded if the distance between the sport object 4 and the sensor 5 is known. With the division by the cosine The actual flight speed can be determined from this angular deviation.

The previous statements have assumed that a player touches the ball 4 or the like directly. However, there are also sports in which the player 25 accelerates the ball 4 or the like using an instrument, for example using an o or the like. In such sports there is a risk that the sensors 5 do not indicate the speed of the sport object 4 but the speed of the racket. In some sports, the speed of the racket can be higher than the speed of the sport object 4. This can be the case for ice hockey, for example. A speed curve determined by the radar signal evaluation is shown in its typical form in FIG. 13. This curve is composed of discrete speed measurements. When evaluating such a curve, this curve is checked against defined criteria in order to recognize the point in time at which the recorded curve is the free flight phase of the sport object 4, without the action of the racket. These criteria are as follows: - Monotonous decrease in speed values. - Small and defined negative speed change depending on the flight time of the sport object 4.

The movement sequence of the racket does not meet these criteria and in this way the present method can distinguish between the movement parameters of the sport object 4 and the movement parameters of the racket accelerating it.

The negative speed change as a function of time (deceleration) assumed by the evaluation depends on the sports object 4 used, its speed, the air resistance, the shape, the surface and the weight of the sports object 4. As a further criterion of the A minimum flight altitude of the sport object 4 can be requested for evaluation. This is calculated from the duration of the recorded speed curve and the individual speed values with the known relationship s = v * t. This increases the security against incorrect measurements. There is also the possibility, for example, of only displaying long-range shots. The evaluation generally only outputs the maximum value of the speed of the free flight phase of the sports object. The automatic output takes place only if no new speed values are measured during a certain interval.

Claims

claims

1. A method for displaying parameters of the path of at least one moving object by means of a radar, characterized in that this method is designed such that the parameters of the path of the moving object can also be measured and displayed when the beginning of the path of movement is unknown is.

2. The method according to claim 1, characterized in that at least the speed of the moving object is measured and that at least this speed is displayed as one of the parameters of the movement path of the object.

3. The method according to claim 1, characterized in that at least the speed of the moving object and the speed of at least one second object in the tracking area are measured simultaneously, so that there is a mixture of two signals corresponding to the speeds of the objects, these speed signals having different frequencies, that the speed signal relating to the flying object is separated from the speed signal of the other object and that the speed signal relating to the flying object is displayed.

4. The method according to claim 2, characterized in that the range of frequencies of the speed signals, which are to be expected during the tracking of the moving objects, is subdivided into sub-ranges, that the speed signals of the objects are assigned to the corresponding sub-ranges of the frequencies and thereby are separated from one another and that at least one of these speed signals is displayed.

5. The method according to claim 3, characterized in that at least two antenna characteristics in the tracking area of the objects lie horizontally next to each other.

6. Device for performing the method according to claim 1, with at least one radar unit and with an evaluation part for processing the signals received by the radar unit, ¹ characterized in that the device is designed so that the parameters of the path of the moving object are then measured and can be displayed if the beginning of the trajectory is unknown.

7. Device according to claim 6, characterized in that the device is designed so that it can distinguish objects from one another, their movements have different speeds and that a display device is connected to the output of the evaluation unit, which can display the measured speed.

8. Device according to claim 6, characterized in that the evaluation part contains a filter whose cut-off frequency lies between those frequencies which corresponds to the speeds of the movements of the objects to be distinguished from one another.

9. Device according to patent claims, characterized in that at least two radar units are assigned to the area where the paths of the moving objects are to be tracked.