Anticollision device, notably for motor vehicles

Claim 1

A device to prevent a collision between a moving object and an obstacle, the moving object heading in a given direction along a movement vector and having a relative speed vector directed towards the obstacle, comprising: first and second antennas fixedly joined to the moving object for transmitting, sequentially and in alternation, plural microwave signals liable to be received by the obstacle, and comprising means for preserving an instantaneous phase of plural echoes received during the plural antenna transmissions so as to obtain a Doppler signal constituted by said plural echoes, the Doppler signal indicating an angle, θ, between the movement vector and the relative speed vector; reception means for receiving from said first and second antennas plural echo signals indicative of said plural echoes received from the obstacle; means for analyzing said plural echo signals, comprising determining means for determining a variation with respect to time of the angle, θ, a substantially zero variation of the angle θ indicating a risk of collision; first switching means having first and second switching inputs for receiving said plural signals connected to corresponding first and second antennas and having a first switching output for switching said plural signals; means for obtaining the Doppler signal, connected to the output of said first switching means .and having a Doppler output; a first lowpass filter having a first lowpass output, So, and having a first lowpass input connected to the Doppler output; a second lowpass filter having a second lowpass output, Sπ, and having a second lowpass input; a second switching means having a third switching input connected to the Doppler output and synchronous with said first switching means for switching the Doppler signal to an inverter channel or to a non-inverter channel, the non-inverter channel being switched over when said first antenna is switched over and the inverter channel being switched over when said second antenna is switched over, said inverter and non-inverter channels being connected to said second lowpass input; and means for dividing having first and second inputs connected to said first and second lowpass outputs and having a ratio output, (So/Sπ), of said first and second lowpass outputs indicating the angle, θ.

Claim 2

A device to prevent a collision between a moving object and an obstacle, the moving object heading in a given direction along a movement vector and having a relative speed vector directed towards the obstacle, comprising: first and second antennas fixedly joined to the moving object for transmitting, sequentially and in alternation, plural microwave signals liable to be received by the obstacle, and comprising means for preserving an instantaneous phase of plural echoes received during the plural antenna transmissions so as to obtain a Doppler signal constituted by said plural echoes, the Doppler signal indicating an angle, θ, between the movement vector and the relative speed vector; reception means for receiving from said first and second antennas plural echo signals indicative of said plural echoes received from the obstacle; means for analyzing said plural echo signals, comprising determining means for determining a variation with respect to time of the angle, θ, a substantially zero variation of the angle θ indicating a risk of collision; first switching means having first and second switching inputs for receiving said plural signals connected to corresponding first and second antennas and having a first switching output for switching said plural signals; means for obtaining the Doppler signal, connected to the output of said first switching means .and having a Doppler output; a first lowpass filter having a first lowpass output, So, and having a first lowpass input connected to the Doppler output; a second lowpass filter having a second lowpass output, Sπ, and having a second lowpass input; a second switching means having a third switching input connected to the Doppler output and synchronous with said first switching means for switching the Doppler signal to an inverter channel or to a non-inverter channel, the non-inverter channel being switched over when said first antenna is switched over and the inverter channel being switched over when said second antenna is switched over, said inverter and non-inverter channels being connected to said second lowpass input; and means for dividing having first and second inputs connected to said first and second lowpass outputs and having a ratio output, (So/Sπ), of said first and second lowpass outputs indicating the angle, θ.

Claim 8

The device according to any one of claims 2-4, 1, 5-6, wherein said device measures a speed of the obstacle and a distance between itself and the moving object, the speed and distance being combined with the angle, θ, to indicate a risk of collision.