Boots – shoes – and leggings
Patent
1985-09-17
1988-12-27
Lall, Parshotam S.
Boots, shoes, and leggings
364559, 340576, 180280, 180141, 116 31, B62D 602
Patent
active
047945362
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a steering angle detection device for detecting the steering angle of a steering wheel.
2. Discussion of Background
Recently, it has been practiced to control the steering force generated by a power steering apparatus in dependence upon vehicle speed and steering wheel rotational angle by utilizing a microcomputer. In a steering angle detection device used for detecting the rotational angle of a steering wheel for this purpose, there is used an encoder which outputs a pulse signal each time a steering shaft is rotated a unit angle, and the pulse signal is input to a microcomputer to be counted. A steering angle detection device of this type is advantageous in respect of required space as well as accuracy.
However, in the above-noted steering angle detection device using an encoder, the absolute steering angle cannot be detected, and the turning-off of an ignition switch causes a steering angle being stored in a memory to be lost. Thus, a relative rotational angle which is calculated taking as an origin the position where the steering wheel was located at a previous stop state is detected when electric power is subsequently supplied, whereby a neutral position (straight running condition) of the steering wheel cannot be discriminated.
As one method of solving this problem, it may be conceived to back up the microcomputer by a constant voltage circuit of a small power consumption lest the turning-off of the ignition switch should cause the content of the memory to be lost. However, this method cannot be a complete solution because no countermeasure can be taken in the event of a battery exhausted.
SUMMARY OF INVENTION
The present invention is created to solve the foregoing problems, and the object of the present invention is to provide an improved steering angle detection device capable of approximating a detected neutral position of a steering wheel gradually to a true neutral position as the vehicle runs after the supply of electric power.
Another object of the present invention is to provide an improved steering angle detection device capable of varying a detected neutral position of a steering wheel considerably slower than the variation in the rotational angle of the steering wheel.
Briefly, a steering angle detection device according to the present invention is provided with a counter whose count goes up or down depending upon the rotational direction of a steering shaft each time the steering shaft is turned a unit angle after the supply of electric power, thereby to detect the rotational angle of the steering shaft. When a sampling signal is generated in relation to the running of the vehicle, averaging means reads the rotational angle being stored in the counter and calculates a mean value of cumulative rotational angles. Rotational angle calculation means is further provided, which by calculation, converts the rotational angle being stored in the counter into a rotational angle which is calculated taking as a starting point the mean value or neutral position obtained by the averaging means.
With this configuration, since the neutral position is determined by calculating a mean value of cumulative rotational angles of the steering shaft and the steering angle is calculated taking the neutral position as a starting point, it is possible to detect the steering angle taking the running state of the vehicle subsequent to the supply of electric power into account even after the turning-off of electric power causes the stored steering angle to be lost. Particularly, since the steering angle is determined based upon a mean value of the cumulative steering angles, it is possible to approximate a neutral position obtained by calculation reliably to a true neutral position as the vehicle runs after the supply of electric power.
Other objects, features, and the attendant advantages of the present invention will be readily appreciated when the following embodiment is considered by reference to the accompanying drawings.
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Eto Kunihiko
Mori Yutaka
Ohno Akihiro
Lall Parshotam S.
Toyoda Koki Kabushiki Kaisha
Trans V. N.
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