Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/483—Details of pulse systems
  • G01S7/486—Receivers
  • G01S7/487—Extracting wanted echo signals, e.g. pulse detection
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
  • G01S17/06—Systems determining position data of a target
  • G01S17/08—Systems determining position data of a target for measuring distance only
  • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/88—Lidar systems specially adapted for specific applications
  • G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
  • G01S17/931—Lidar systems specially adapted for specific applications for anti-collision purposes of land vehicles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/497—Means for monitoring or calibrating
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/88—Radar or analogous systems specially adapted for specific applications
  • G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
  • G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/88—Sonar systems specially adapted for specific applications
  • G01S15/93—Sonar systems specially adapted for specific applications for anti-collision purposes
  • G01S15/931—Sonar systems specially adapted for specific applications for anti-collision purposes of land vehicles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
  • G01S17/50—Systems of measurement based on relative movement of target
  • G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems

Definitions

• the distance of a reference object to moving or stationary objects (target objects) and / or the speed and / or the acceleration of moving or stationary objects (target objects) must be determined for different areas of observation (distance ranges).
• observation areas with a short distance between the pulling object and the target objects are of interest ("close range", for example depending on the application up to 20 m or 250 m distance), e.g. to detect the traffic area surrounding a motor vehicle, i.e.
• the measuring systems used for this purpose in particular have a measuring unit with a transmitting unit and a receiving unit, as well as a
• the transmission signal is cyclically interrupted in accordance with a clock specified by a clock generator, ie it is triggered by controlling the transmission unit with a specific one
• P303I98 DOC Control signal emitted as a transmission signal transmission pulses with a certain pulse duration; in the pulse pauses between two transmission pulses, the reflection signals of the preceding transmission pulses are detected as reception signals, ie the reflection signal of a transmission pulse is recorded at fixed time intervals and the signal transit time is measured over the elapsed time in the form of clock units, and the distance to the target objects is determined therefrom.
• This distance to the target objects should be determined with sufficient accuracy in the entire observation area; this is particularly important if (as is the case with clocked measurement systems) further information is derived from the distance to the target objects, e.g. by
• sampling methods are often used in which the received signal is sampled at a sampling frequency (sampling period) predetermined by a clock, i.e. measured values are generated on the basis of the received signal at specific sampling times;
• the accuracy of the distance determination can be increased by an interpolation or center of gravity of the measured values.
• the greater the ratio of the pulse length of the transmit pulses to the sampling period the better: when the pulse length of the transmit pulses is increased, however, the possibility of separating different target objects is adversely affected; with a reduction in the sampling period, the demands on the clock generator, the receiving unit and the control unit (evaluation unit) become very high (in particular with regard to the speed and quality of the components, and with regard to the stability with regard to parameter scattering and temperature changes), which in turn entails high costs.
• the invention has for its object to provide a method for determining the distance between a reference object and at least one target object according to the preamble of claim 1, with which the distance to simple
• the invention is based on the knowledge that with scanning methods (in particular when evaluating their measured values by means of interpolation or center of gravity formation) the achievable distance accuracy, i.e. the functional dependency of the distance (the measured distance) between the reference object and the target object determined by the scanning method on the actual distance between the reference object and the target object has a periodic behavior with the periodicity of the sampling frequency (sampling period), since the distance determined by the scanning method (the measured Distance) differs from the actual distance depending on the location of the sampling time; E.g. the achievable distance accuracy (and thus the actual distance) has a sinusoidal shape with respect to the measured distance.
• the minima of the achievable distance accuracy are always in a fixed phase relationship
• Received signal (ie for controlling the receiving unit) uses different, mutually detuned control signals (clock signals); the phase shift between these two control signals (clock signals) is chosen so that the achievable range accuracy has a minimum given the resulting phase position of the transmitted signal and the received signal, ie that the deviation between the distance determined by the scanning method (the measured distance) and the actual distance becomes minimal.
• the phase shift between the two control signals (clock signals) is preferably controlled in small steps or linearly by means of suitable circuit means, and is preferably regulated by means of a control loop.
• the same clock generator is used to control the transmission unit and to control the reception unit, whose clock signal is the first control signal either for the transmission unit or for the reception unit.
• the receiving unit is supplied with the unchanged clock signal) as the second control signal and the transmitting unit with the phase-shifted clock signal as the first control signal.
• phase shift between the two control signals must be taken into account as an offset when determining the distance, i.e. the distance resulting from the phase shift must be added to the measured distance.
• the phase shift can be measured in a simple manner; with a value specified by means of a control or regulation, the phase shift is known as a control variable or controlled variable or reference variable.
• the method according to the invention can only be used for certain (selected) of the target objects located in the field of observation and thus the
• Determination of their distance are carried out with high accuracy, while the distance to the other target objects located in the observation area is determined with the "normal" measurement accuracy resulting from the scanning method; in particular, the method according to the invention is used for target objects with high relevance, for example target objects , in which further measured variables are derived from the distance (e.g. the speed or the acceleration) or for target objects which are used for control functions and / or regulating functions.
• the sampling frequency of the sampling method can be reduced (simple re handling of the measuring system) and the resulting reduction in the range accuracy via the phase shift between the two control signals (clock signals) can be compensated or overcompensated again
• the specified phases of the two control signals or their phase shifts only have to be stable during the duration of the measurement and the phase control; E.g. this period of time is clocked at RF measurement systems (radar measurement systems) or clocked optical measuring systems (laser measurement systems) between 10- 5 and 10 "s.
• the method can be implemented in a simple manner with a small number of inexpensive and commercially available components, so that the distance resolution and thus the accuracy of the distance determination for a given (arbitrary) number of target objects is increased significantly by simple means and consequently with only a small additional cost can be.
• FIG. 2 shows the functional dependency of the distance deviation on the measured distance
• FIG. 3 is a schematic block diagram with the for the phase shift
• the distance and / or the speed and / or the acceleration of those located in the observation area can be
• Target objects ie the distance between your own motor vehicle and vehicles ahead, oncoming or following vehicles, people and other reflection objects and / or the speed of your own motor vehicle with regard to vehicles traveling ahead, oncoming or following vehicles, people and other reflection objects and / or the acceleration of your own Motor vehicle with regard to preceding, oncoming or following vehicles, people and other reflection objects can be used as the basis for driver assistance systems.
• the distance and / or speed and / or acceleration must be determined clearly and with high resolution: e.g. the desired range uniqueness range is 10 m Desired distance resolution 0.5 m, the desired speed resolution 1 m / s and the desired acceleration resolution 0.1 m / s 2 .
• Target objects 2 for example the vehicles or obstacles in front
• received reflection signal 14 is detected by the receiving unit 5 of the measuring unit 3 at certain times during the pulse pause of the transmission signal 13 as an analog reception signal. From the control unit 7, e.g.
• a CPU central process unit
• central process unit which also functions as an evaluation unit, scans the received signal at certain times ("sampling") and thereby increases the accuracy of the distance measurement;
• the scanned measured values are evaluated with regard to the transit time, from which the distance information and / or the speed information and / or the acceleration information is obtained by processing the distance information, i.e. the distance dz between the motor vehicle as reference object 1 and the reflection object as target object 2 and / or the speed of the reflection object as target object 2 and / or the acceleration of the reflection object as target object 2.
• the opening field 22 or the detected angular range (opening angle ⁇ , ⁇ ) is subdivided into several target sectors 21 (for example in 1 ⁇ target sectors 21), each of which is assigned to detecting reflection object is assigned as target object 2 and by means of the information of which an object matrix of target objects 2 is created.
• the various e.g.
• this "distance accuracy function” results in a more or less large distance deviation ⁇ d or a more or less large difference between the measured distance dz and the actual distance d s ;
• the distance deviation ⁇ d can thus have a value between ⁇ d TM (minimum distance deviation ⁇ d with a symmetrical position of the sampling times with respect to the received signal) and ⁇ d, TM ( maximum distance deviation ⁇ d with an asymmetrical position of the sampling times with respect to the received signal), in particular this distance deviation ⁇ d and thus the distance accuracy function due to the statistical distribution of the sampling times with respect to the received signal as a periodicity with the period T * of the scanning process, e.g.
• the control signal the clock signal
• the minimum distance deviation ⁇ d TM is 1 cm and the maximum distance deviation ⁇ d m »10 cm.
• the phase shift ⁇ between the first control signal AS1 and the second control signal AS2 can assume any values within a period of the control period, ie the phase shift ⁇ can be between 0 ° and 3 ⁇ 0 °.
• FIG. 3 shows the components of the measuring system 10 which are relevant for the specification of the control signals AS1, AS2 and their relative phase shift.
• the transmitter unit 4 of the measuring unit 3 has, for example. a transmission element designed as a pulsed IR semiconductor laser, which emits a pulse-shaped transmission signal 1 3
• the clock generator ⁇ is provided (for example a quartz oscillator), the clock frequency fT of which, for example. Is 100 MHz.
• the receiving unit 5 is driven directly by the clock generator 6, that is to say it is operated in clocked fashion with the second control signal AS2, which is unchanged in the phase position, with the clock frequency fT for specifying the sampling times of the received signal 14.
• the transmitter unit 4 is driven by the clock generator 6 via a phase shifter 8, that is to say it is operated in a clocked manner with the first drive signal AS1, which has been changed in the phase position, for specifying the pulse-shaped transmission signal 13 at the clock frequency fT.
• a phase shifter 8 for specifying the phase difference or phase shift ⁇ between the first control signal AS1 and the second control signal AS2, for example, an easy to implement, analog controllable delay element is provided.
• the results (data) of the distance measurements are transmitted to the control unit 7 (evaluation unit) connected downstream of the measuring unit 3 and evaluated by the latter; From the results of the distance measurements, ie the measured distances dz to the target objects 2 in the observation area, speed values and / or acceleration values can be derived and the temporal processes of the measuring process can be controlled, in particular the coordination of transmission mode and reception mode, ie the coordination of the transmitter unit 4 for specifying the pulse-shaped transmission signal 13 and receiving unit 5 for specifying the sampling times of the received signal 14.
• the output signal of the phase shifter 8 is fed to a (easy to implement) phase detector 9 (at the same time, the phase shifter 9 is also included with the second drive signal AS2 generated by the clock generator ⁇ the clock frequency fT), the output signal of which is in turn processed by the control unit 7 and used to control the phase shifter 8; this means that a simple control realized by the resulting phase shift ⁇ between the second control signal AS2 for controlling the receiving unit 5 and the first control signal AS1 for controlling the transmitting unit 4 depending on the position of the sampling times with respect to the received signal.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Electromagnetism (AREA)
• Radar Systems Or Details Thereof (AREA)
• Optical Radar Systems And Details Thereof (AREA)

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• 2000
  • 2000-05-25 DE DE10025844A patent/DE10025844A1/de not_active Ceased
• 2001
  • 2001-05-10 JP JP2001586491A patent/JP2003534556A/ja not_active Withdrawn
  • 2001-05-10 EP EP01940441A patent/EP1295151A1/de not_active Withdrawn
  • 2001-05-10 WO PCT/EP2001/005322 patent/WO2001090778A1/de active Application Filing

Non-Patent Citations (1)

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