Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
  • B60C23/02—Signalling devices actuated by tyre pressure
  • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
  • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
  • G01P3/42—Devices characterised by the use of electric or magnetic means
  • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
  • G01P3/42—Devices characterised by the use of electric or magnetic means
  • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
  • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage

Definitions

• the present invention relates to the measurement of the speed of rotation of the wheels of motor vehicles. These rotational speeds are particularly useful in anti-lock or trajectory control systems.
• Wheel pressure sensors are also known. These tire pressure sensors are becoming more and more widespread, not to say that manufacturers systematically mount them on their vehicles.
• FR 2 774 178 recalls that the signal emitted by the transmitter of a tire pressure sensor, driven in rotation with the wheel, is modulated in amplitude, during the rotation, as a function of obstacles and other fixed masking due to the part of the body which is interposed between said transmitter and the corresponding receiver.
• the envelope for modulating the signal of a tire pressure sensor is a periodic signal with a period equal to the duration of a wheel revolution, and this is how she proposes her invention. .
• the present invention relates to a method for measuring the rotational speeds of the wheels of a motor vehicle, characterized in that the envelopes of the signals from the transmitters of the pressure sensors of the tires of said wheels are detected and that determines their periods to deduce their rotation speeds.
• the advantage of the process of the invention is that it does not use any equipment other than the tire pressure monitoring system.
• the invention also relates to a system for measuring the rotational speeds of the wheels of a motor vehicle for implementing the method, comprising a set of pressure sensors for the tires of the wheels with transmitters mounted on the wheels, means for signal processing to extract the modulation envelopes from the signals from the transmitters, and to calculate the period of these envelopes and deduce the rotation speeds therefrom.
• the measurement system according to the invention may further comprise means for estimating the period of the modulation envelopes before measuring it, for example the means indicating the linear speed of the vehicle.
• FIG. 1 shows the block diagram of the system of the invention
• FIG. 2 shows a typical signal delivered by a pressure sensor and its modulation envelope
• - Figure 3 shows the flow diagram of the method for determining the speed of rotation of a wheel
• FIG. 4 illustrates the implementation of the method on the four wheels of a vehicle.
• FIG. 1 With reference to FIG. 1, it comprises an assembly comprising a pressure sensor 12 and its transmitter 13 mounted on the wheel 11, as well as a fixed receiver 14 intended to process the signal 21 emitted by the transmitter 13.
• the fixed receiver 14 comprises, in series, a receiving antenna 141, a demodulator 142 delivering an analog signal 22 free of its carrier, a filter 143 and an electronics for processing the tire pressure data 144.
• This equipment transforms radio signals into digital signals and calculates tire pressure.
• the system comprises, here downstream of the demodulator 142, a bypass 16 of the signal received by the fixed receiver, supplying means 17 for processing the signal to extract the modulation envelope from the signal and to calculate the speed of rotation of the wheel.
• the signal processing means include, in series, the following means:
• a filtering means 171 for extracting the modulation envelope 23 from the signal
• the system further comprises at least one clock 176 connected to the acquisition means and to the processor itself connected to at least one memory 177 for recording samples and to the vehicle speed indicator 15.
• the system also uses the vehicle's speed indicator 15. It could as well be the odometer, since we have the length of the circumference of the wheels.
• the method consists in cyclically processing the signal coming from the transmitter of the pressure sensor, the cycle comprising an observation time ⁇ during which the amplitude maxima Pu, P i2 are substantially equal and successive and the durations which separate them.
• the signal 22 is recovered at the output of the demodulator 142, it is subjected to low-pass filtering in the filter 143, so as to isolate the envelope.
• This can be obtained by an analog filtering method, by choosing a cut-off frequency of the filter, Fc, slightly higher than the maximum rotation frequency of the wheels.
• the filtered signal is then sampled at a sampling frequency fe determined in advance. According to a well-known signal processing rule, this frequency is at least twice the cut-off frequency Fc.
• the observation time ⁇ is determined from information on the vehicle speed available elsewhere, for example that provided by the on-board instruments: speedometer, odometer.
• the observation time ⁇ can, from a certain number of cycles, be optimized to a lower value, taking into account the signal history, knowledge of the vehicle speed and the position of the maximum in the period, up to a value close to T but always greater so that the periodic signal whose period we seek to determine is there in full.
• n fe. ⁇ . '
• a cycle contains at least one observation duration to which it is necessary, in theory, to add a treatment duration
• the duration of the cycle should be of a longer duration and, in principle, fixed.
• the method makes it possible to have a measurement of the speed of rotation of the wheels continuously at a frequency
• This frequency is variable and depends on the speed of the vehicle. The higher the speed, the higher the frequency. Thus, the faster the speed of the vehicle, the faster the wheel speed is.
• the signal 21 transmitted by the transmitter 13 undergoes parasitic modulation due in particular to the bodywork 10 before being received by the receiver 14 and being processed therein to supply the pressure of the tires .
• the signal 22 at the output of the demodulator 142 is filtered by the filter of the receiver 143 for the normal needs of processing the pressure information.
• the signal 22 is also filtered by the filter 171 of the signal processing means 17, for example an RC filter.
• the filter 171 At the output of the filter 171, the signal 23 is sampled and digitized at the frequency fe permanently by a sampler-blocker 172 which freezes the analog quantities at regular times at the frequency fe and an analog-digital converter 173 which provides at output 24 digital samples Pi of the signal whose period is to be determined.
• a sampler-blocker 172 which freezes the analog quantities at regular times at the frequency fe
• an analog-digital converter 173 which provides at output 24 digital samples Pi of the signal whose period is to be determined.
• the processor 174 transmits the control to the program of memory 178, which acquires and stores (30) these samples Pi in memory 177 from Pi to P n respectively from memory Mi to memory M n .
• the program calculates the speed of rotation of the wheel which it transmits to the on-board computer 175. For this, at this stage, it successively performs the following operations:
• the calculation of the speed at cycle N corresponds to the observation of the signal at cycle N-1.
• the microprocessor after acquiring the n samples, calculates the speed of rotation of which the wheel was driven during the time interval [to + (N-l). ⁇ , to + N. ⁇ ].
• the signal processing means (17 ) are common for the treatment of all four wheels.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Measuring Fluid Pressure (AREA)

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• 2001
  • 2001-10-31 FR FR0114140A patent/FR2831669B1/fr not_active Expired - Lifetime
• 2002
  • 2002-10-30 AU AU2002350860A patent/AU2002350860A1/en not_active Abandoned
  • 2002-10-30 US US10/493,937 patent/US20040267493A1/en not_active Abandoned
  • 2002-10-30 JP JP2003540664A patent/JP4223956B2/ja not_active Expired - Fee Related
  • 2002-10-30 WO PCT/FR2002/003744 patent/WO2003038447A2/fr active Application Filing
  • 2002-10-30 EP EP02785571A patent/EP1442306A2/de not_active Ceased

Patent Citations (1)

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