SENSOR SYSTEM, VEHICLE CONTROL SYSTEM AND DRIVER INFORMATION SYSTEM FOR VEHICLE SAFETY

• US 20110035093A1
• Filed: 03/09/2009
• Published: 02/10/2011
• Est. Priority Date: 03/13/2008
• Status: Active Grant

• Current Assignee: TRUMPF Photonic Components GmbH (TRUMPF SE + Co. KG)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Carpaij, Mark, Comberg, Albert, Moench, Holger
• Granted Patent: US 8,751,091 B2
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: G01P 3/366 by using diffraction of light for measuring speed of fluids G01P5/26
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 7/491 Details of non-pulse systems
• CPC Class Codes: G01S 7/4911 Transmitters
• CPC Class Codes: G01S 7/4916 using self-mixing in the laser cavity

Abstract

A sensor system is described, using self-mixing laser sensors (10) and an analyzer circuit (30) in order to determine the velocity of a vehicle, such as a car, and the rotational velocity of a wheel (20) of the car. Deviations between the velocity of the vehicle and the rotational velocity of the wheel (20) can be used to determine sliding of the wheel (20) and, finally, the traction or, more specifically, the coefficient of driving friction between the wheel (20) and the surface the car is driving on. Furthermore, a vehicle control system is described, initiating test accelerations of a wheel (20) by means of a control circuit (50) and control means (300, 400) in order to determine the coefficient of driving friction during driving. The test accelerations initiate short periods of sliding of the wheel (20) and the sliding is detected by means of the sensor system.

Claims

1. A sensor system comprising at least one laser sensor working with self-mixing interference comprising two, three, four or an array of Vertical Cavity Surface Emitting Laser diodes which are adapted to emit laser radiation (11) in essentially the same direction, at least one rotation sensor and an analyzer circuit, the at least one laser sensor being adapted to generate measurement data resulting from a first velocity component of a vehicle, the rotation sensor being adapted to generate measurement data resulting from a first rotational velocity of a first wheel of the vehicle, the analyzer circuit being adapted to receive the measurement data generated by the at least one laser sensor, said rotation sensor and analyzer circuit being further adapted to determine the first velocity component of the vehicle and the first rotational velocity of the first wheel of the vehicle.

2. A sensor system according to claim 1, wherein the rotation sensor is a laser sensor working with self-mixing interference.

4. A sensor system according to claim 1, further comprising a control element which is adapted to vary the focal point of the laser radiation and/or the intensity of the laser radiation and/or the direction of the laser radiation emitted by the Vertical Cavity Surface Emitting Laser diodes in different ways.

5. A sensor system according to claim 1, wherein the at least one laser sensor is further adapted to generate measurement data resulting from a second velocity component of the vehicle different from the first velocity component, and the analyzer circuit is further adapted to determine the second velocity component of the vehicle.

6. A sensor system according to claim 5, wherein the at least one laser sensor is further adapted to generate measurement data resulting from a third velocity component of the vehicle different from the first velocity component and the second velocity component, and the analyzer circuit is further adapted to determine the third velocity component of the vehicle.

7. A sensor system according to claim 1, wherein the at least one laser sensor is further adapted to generate measurement data resulting from a first distance between the mounting location of the laser sensor and a surface the vehicle is driving on and at least a second distance between the mounting location of the laser sensor and the surface the vehicle is driving on, or between the mounting location of the laser sensor and the surface of the first wheel of the vehicle, the first distance being different from the second distance and the analyzer circuit being adapted to determine the first distance and the second distance.

8. A sensor system according to claim 1, wherein the analyzer circuit is further adapted to determine the traction between at least the first wheel and the surface the vehicle is driving on by analyzing the first rotational velocity in relation to the first velocity component and/or the second velocity component and/or the third velocity component of the vehicle.

9. A vehicle control system comprising a sensor system according to claim 1 and a control circuit, wherein the control circuit is adapted to receive data from the analyzer circuit and is further adapted to activate control means (300, 400) taking the data received from the analyzer circuit into account.

10. A vehicle control system according to claim 9, comprising the control means and wherein the control circuit is adapted to activate the control means so as to initiate test accelerations of at least one first wheel of the vehicle independently of the data received from the analyzer circuit, the control circuit being further adapted to determine the maximum frictional force between at least the first wheel and the surface the vehicle is driving on by analyzing the data received from the analyzer circuit.

12. A vehicle control system according to claim 10, wherein the control circuit is adapted to determine the normal force between the first wheel and the surface the vehicle is driving on and is further adapted to determine the coefficient of driving friction between the first wheel and the surface the vehicle is driving on.

13. A driver information system coupled to a sensor system according to claim 1, wherein the driver information system is adapted to receive data from the sensor system and is further adapted to supply optical and/or acoustical information based on the data received from the sensor system to a driver of the vehicle.

14. A driver information system coupled to a vehicle control system according to claim 9, wherein the driver information system is adapted to receive data from the vehicle control system and is further adapted to supply optical and/or acoustical information based on the data received from the vehicle control system to a driver of the vehicle.

3. (canceled)

11. (canceled)

15. A method of determining the traction between a wheel of a vehicle and a surface the vehicle is driving on, the method comprising the steps of:

measuring a first velocity component of a vehicle by means of self-mixing interference,

measuring at least a first rotational velocity of a first wheel of the vehicle by means of a rotation sensor,

measuring a first distance between the vehicle and the surface the vehicle is driving on,

measuring at least a second distance between the vehicle and the surface the vehicle is driving on or between the vehicle and the first wheel, and

determining the traction between at least the first wheel and the surface the vehicle is driving on by analyzing the first rotational velocity in relation to the first velocity component by means of an analyzer circuit, taking the first distance and the second distance into account.