JP2002544554A - Camera guidance system - Google Patents

Abstract

(57) [Summary] A system for guiding a camera requires a GNSS (Global Navigation Satellite System) receiver, an inertial measurement unit, and other sensors that help determine the position and attitude of an object, especially an object to be imaged. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a camera guidance system as described in the preamble of claim 1.

[0002] A system for guiding a camera is known, such as the system described in the same applicant's application No. PCT / IB94 / 00431, and certain embodiments of this application
A GPS (Global Positioning System) is required to obtain position data of the target, which is aimed by a camera mounted on a table, and the data is expressed in a coordinate system coupled to the table.

In use, in certain cases, multiple GPS receivers, more generally multiple GNSSs (Global Navigation Satellite Systems), systems including conventional GPS, and other systems of the GPS type Turned out to have certain intractable drawbacks. Therefore, the posture of the target is, for example, three Gs arranged on the target.
As determined by the set of NSS receivers, the processing of the data transmitted by these GNSS receivers requires a high computational power, while at the same time three G
The configuration with the NSS receiver gives the system an undesirable rigidity. The aforementioned application consists, for example, of an inertial measurement unit or IMU, each of which consists of three accelerometers and three gyroscopes, the latter measuring angular velocities,
In particular, when a bad reception condition adversely affects the reception of a GNSS signal in a short time,
It summarizes the auxiliary use of an inertial navigation system to supplement the operation of a GNSS receiver.

[0004] The inertial measurement unit is abbreviated below as IMU, but when used wisely,
That is, when one or more targets, one or more stations, or one or more relay stations are moving at a specific speed in three-dimensional space, it can contribute to simplify the operation of the camera guidance system. It's been found. Therefore, the above-mentioned problem is solved by the measures described in the characterizing part of claim 1.

[0005] Attitude of a target, camera, pedestal or relay station, or more generally, only one G
The attitude of a subject equipped with an NSS receiver and an IMU can be determined provided that the subject is traveling at a sufficient speed on any path in three-dimensional space.
The speed must simply be sufficient for the IMU to operate properly, but need not be predetermined and need not be the trajectory of the object. Such a system
Functionally, it is comparable to an attitude determination system with several GNSS receivers, but uses the same receiver to measure several different positions in three-dimensional space. The position measurement by the receiver is performed at time intervals, but the IMU is used to accurately measure the relative change in the position of the object between position measurements by the GNSS receiver. This makes it possible to calculate the direction of the coordinate system coupled to the object with respect to the GNSS coordinate frame coupled to the ground. In other words, if the Euler angles of the coordinate frame connected to the moving object with respect to the coordinate frame connected to the ground are described in another method, it is possible to calculate the precise posture of the object.

[0006] IMU measurements are impaired by errors, so-called drift errors,
These errors can be easily corrected to the required accuracy by applying the duration of the interval separating the two GNSS measurements. Such a more accurate G
The NSS measurement allows to control this drift error at the end of each interval.

In certain embodiments of the invention, the trajectory of the object or vehicle is not arbitrary, but is engraved within known cataloged boundaries, for example, the course of a motor race circuit. In such a case, the boundaries of the course and its three-dimensional terrain with, for example, changes in altitude, hill crosses, bridges, especially tunnels, may be recorded in advance by information processing means. Thereafter, simply equipping the IMU, the position and orientation of the vehicle or object traveling within such pre-recorded known boundaries may be determined by correlating the three-dimensional acceleration and rotation recorded on the IMU. . In addition, the correlation procedure has enough information to calculate the drift error of the IMU and its gyroscope accelerometer. Since the vehicle or object sometimes approaches the boundaries of the trajectory, such as the edge of the course of the case described above, it is simply necessary to obtain truly accurate results. To be more precise, as the vehicle or object rubs the edge of the course, the IMU recognizes the impact caused by the surface changes and uses the information processing means to update the pinpointing of the course boundary. Therefore, IMUs for each vehicle or object
Even if there is only one and the GNSS receiver is not provided, if the course is known and cataloged, it is sufficient in such a case. However, in the case of a car race, G
It is known that the performance of NSS systems is degraded when the path of a vehicle comprises a portion of the tunnel, more generally a signal reverberation or "multipath" characteristic. Very tall buildings and bridges are such cases. Therefore, the data transmitted by the IMU is indispensable for the information processing means to pinpoint the target continuously.

In certain embodiments of the invention, which applies to the above case where the trajectory of the object or the vehicle is engraved within known boundaries, the initialization of the system issues to the information processing means, for example, photovoltaic cells arranged in the trajectory. If a supplementary direction indicator is provided, such as by a traffic light, it can be carried out more simply and quickly. The position of the battery is recorded in the memory of the information processing means, and the signal emitted by the battery is recorded each time any vehicle or object passes in front of this battery, so that the system can accurately detect changes in the position of the vehicle or object. Can follow.

In particular embodiments of the present invention, particularly when the subject must be able to move around at a slow speed or even stop without compromising the effectiveness of the system, a wheel is provided to supply the information processing means with additional data. Alternatively, a sensor for the rotation of the steering member is arranged on the target. On the other hand, during high-speed movement, these sensors are stopped or the data is ignored. Frequent skidding of the wheels leads to random errors and is therefore difficult to correct.

In certain embodiments of the present invention, which operate in a limited environment, particularly in sports or competition buildings, it is possible to replace GNSS satellites with pseudo satellites, which are now commonly referred to as “pseudo satellites”. Yes, it is mounted very close to the building ceiling.
This pseudo satellite has functionality equivalent to that of the GNSS satellite, and can effectively supply data necessary for capturing an image of a target to a table and a camera by information processing means.

In a specific embodiment of the present invention, there are at least two cameras, and the information processing means has an ability to analyze a captured image. This capability allows the system to operate without having to continuously supply data for the information processing means to calculate its position and orientation with respect to the object. In particular, and by way of example, if the target travels in a path that is essentially planar, that is, in two dimensions rather than three dimensions, one of the cameras can be located quite far from this plane. The information processing means analyzes an image taken by the camera whose position is known by the information processing means. with this,
Even if the target does not directly emit information about its position and movement, it can analyze the image and
It is possible to recognize one or more targets and estimate their position in the relevant plane. This estimation is further closer to the target, and its location is also known to the information processing means.
With a table or multiple cameras, refinement can be achieved in a similar manner. Thanks to such image analysis capabilities, it is possible to operate the system even with non-cooperative targets, ie targets that do not directly indicate their location.

The specific operation of the GNSS pseudolite at an indoor sporting event or show will now be described in further detail. The source of the electromagnetic signal is placed on a pseudolite, which is fixed in the immediate vicinity of the ceiling of the building, for example by means of ceiling lighting. While measuring attitude and position with the GNSS pseudolite, the distances from the receiver, or receiving point, or transmitter to the various electromagnetic signal sources are measured, and to determine the position of the receiver or receiving point, Serves as the basis for computation of information processing means.

The speed of the associated signal is close to the speed of light, and the distance traveled by the signal is measured with the help of the time it took to travel the distance from the source or transmitter to the receiver or receiving point. In practice, it is ascertained that there is a certain redundancy in the measurement. This makes it possible to improve the accuracy of the measurement through the calculation of the mean and, optionally, eliminate erroneous measurements through a test of plausibility known per se. In certain cases, distances can be measured using techniques other than electromagnetic waves, especially for indoor applications where the distance between the source, transmitter and receiver is short. Ultrasound is first
Can be an alternative. Another possible method is to use a sensor of the wire-unreel type, for example as described in Swiss Patent Application No. 1996 2538/96 filed Oct. 17, 1996 by the same applicant. is there.
Such a wire-unreel type sensor is composed of a drum and a thin wire wound around the drum, and a restoration spring is mounted on a spindle of the drum and connected to an angle sensor. As the object whose displacement is to be measured pulls the wire, the drum rotates by a certain angle, which is measured by a sensor and provides a measure of the displacement.
The restoring spring keeps the wire taut when the force that caused the subject to move away decreases. Such wire-unreel type sensors exhibit outstanding accuracy characteristics that fully satisfy the needs of the present invention. One example is Space Age Co
PT-001-B of a company called ntrol (38850 20th Street-East, Palmdale, California)
Is described in the pamphlet.

Next, a method of operating the system will be described with reference to the accompanying drawings.

The system shown in FIG. 1 is equipped with a GNSS receiver and comprises a target 8 imaged by an assembly consisting of a camera and a table 7. This assembly with the platform 7 moves on a three-dimensional trajectory 1. The stand 7 is equipped with a GNSS receiver and an IMU (both not shown). During its operation, at least three positions 3, 4 on the trajectory
And 5 are measured for the GNSS coordinate frame 2. Simultaneously with this GNSS position measurement, the IMU also performs a recording of the acceleration experienced by the platform and a position measurement of points 3, 4 and 5 with respect to inertial frame 6. The information processing means uses this position measurement value (at least six or more) to calculate the exact position and the exact attitude of the platform 7, that is, its Euler angle with respect to the fixed frame 2. The position of the target 8 is determined by the GNSS receiver.

From the position of the target 8 and the position and orientation of the platform 7, the information processing means then determines with respect to the platform and also the zoom data of this camera such that the target 8 always enters the field of view of the camera with the desired focus Infer the angle pointed by the camera.

FIG. 2 shows a specific case of a car race shot with at least two cameras. One of the cameras is mounted on an aircraft 9 flying over a race circuit which in this case does not include a tunnel. Information processing means (not shown) has the ability to analyze the images taken by the camera, and estimates the positions of targets 10 and 11, which are the two racing cars in the race. This supplies the second camera 12 with the most appropriate target, for example an element directing towards 10, which target may be selected according to criteria essentially known from, for example, PCT Application No. IB94 / 00431. it can. The second camera 12 may also provide images suitable for processing with the analytical capabilities described above, thereby improving the pinpoint location of the selected target 10 and providing a satisfactory frame of this camera. Becomes possible.

The captured images can be used commercially, especially if the camera is in a position that is considered too dangerous to bet on the photographer's life, for example, in the immediate vicinity of the course. It will be appreciated that the two cameras cooperate with each other in following a target 10 that is selected and deemed uncooperative due to the ability to analyze the images associated with the cameras.

[Brief description of the drawings]

FIG. 1 shows a target photographed by a camera on a table.

FIG. 2 depicts an embodiment having at least two cameras and a non-cooperative target.

Claims (10)

[Claims] 1. A camera guidance system comprising a plurality of objects, which may be one or more targets, one or more cameras supported by one or more platforms, and one or more relay stations. Allowing at least one of the cameras supported by one of the stages to acquire a video signal from at least one of the targets, wherein the video signal is transmitted by a relay station to a receiving station and the Traverse the dimensional space at a particular speed, at least one of which is a GNSS receiver and an IMU
To enable one or more cameras to automatically point to one or more targets by means of processing information emanating from the subject, and by means of an assembly composed of GNSS and IMU Performing a position measurement of the object, the measurement being performed at certain intervals, calculating the position of the object on the one hand, and Euler angles on the other hand, to enable the position and orientation of the object to be determined. System to do. 2. The time interval between two measurements by the GNSS receiver is applied as a function of the drift error of the IMU as noted by the information processing system.
The system according to claim 1. 3. The method according to claim 1, wherein the trajectory of the specific object is within a known boundary stored in the information processing means, and enables calculation of the position and orientation without using a GNSS receiver. The described system. 4. The system according to claim 3, wherein the target is a car race competitor, and initialization is speeded up by equipping the information processing means with a supplementary direction indicator. . 5. The system according to claim 4, wherein a sensor of a member for turning a wheel or steering a racing car in a motor race supplies additional data to the information processing means. 6. The system according to claim 1, 2 or 3, wherein the object is equipped with means for measuring barometric or altimeter pressure, so that the calculation of the position and orientation of the object by the information processing means can be improved. 7. The object is equipped with a magnetometer capable of measuring the direction of the geomagnetic field with respect to the object, and can improve the calculation of the position and orientation of the object by the information processing means.
The system according to claim 1, 2, 3, or 6. 8. The information processing system has an image analysis capability, and the target is basically:
The method according to claim 1, wherein the camera moves in a substantially planar space as viewed by one or more remotely located cameras, so that the position and orientation of a non-cooperative target can be determined. system. 9. The target is a car racing car, and at least one remotely located camera is mounted on an aircraft flying over the race to pinpoint and follow a non-cooperative target. 9. The system of claim 8, wherein the system interacts with at least one other camera to perform the operation. 10. The position and altitude of the object are at least 3
It is calculated with the help of at least six values measuring the distance between one point and at least three other points whose location is known, this distance being determined by a wire-unreel type sensor and / or ultrasound and The system of claim 1, wherein the system is measured with an electromagnetic signal.