Title:
DEVICE FOR DETECTING GROUND SPEED OF VEHICLE
Document Type and Number:
Japanese Patent JP2679527
Kind Code:
B2
Abstract:
PURPOSE: To absorb fluctuation of the output signal as to improve its ground speed detecting accuracy by enabling the device to detect the ground speed of a vehicle by taking the acceleration and deceleration of the vehicle into account.
CONSTITUTION: A ground speed sensor 14 is fixed to the bottom of a vehicle and ultrasonic waves are transmitted against road surfaces from the transmitting section 10 of the sensor 14. The sensor 14 then receives the reflected waves of the ultrasonic waves from the road surfaces by means of its receiving section 12 and transmits signals corresponding to the frequency of the received signals. A signal processing means 16 composed of a CPU, ROM, RAM, and bus is connected to the sensor 14 and the CPU executes a ground speed calculating routine stored in the ROM. The CPU first calculates the current sample ground speed W by utilizing a Doppler effect based on the transmitting and received frequencies of the ultrasonic waves and the inclination of the sensor 14 against the advancing direction of the vehicle. The CPU then calculates the mean speed M of a plurality of preceding sample speeds calculated after the last time and, when the current sample speed X comes within an allowable range with the mean speed M at the center, the sample speed X is stored in the RAM as the current ground speed. When the sample speed X is out of the allowable range, the speed X is considered to be unreliable and excluded from the calculation.
Inventors:
Masashi Mizukoshi
Application Number:
JP12808692A
Publication Date:
November 19, 1997
Filing Date:
April 21, 1992
Export Citation:
Assignee:
TOYOTA JIDOSHA KABUSHIKI KAISHA
International Classes:
B60T8/17; B60T8/00; B60T8/66; G01P3/36; G01P3/488; G01S7/52; G01S7/526; G01S15/60; (IPC1-7): G01S15/60; G01P3/36; G01S7/526
Domestic Patent References:
| JP63241485A | ||||
| JP63131086A | ||||
| JP1267461A | ||||
| JP6321855U |
Attorney, Agent or Firm:
Norikazu Kobe (2 outside)