Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2001-04-23
2003-06-03
Vo, Hieu T. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S115000, C701S114000, C123S399000
Reexamination Certificate
active
06574546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of learning the full-closed position of an accelerator pedal disposed in a vehicle, and an apparatus for the same.
2. Description of the Related Art
The driver regulates the output of a vehicle via an accelerator pedal during a drive of the vehicle. It is accordingly required for an accelerator opening sensor or a throttle opening sensor, which measures the depression amount of the accelerator pedal, to transmit an appropriate required output value corresponding to a driver's depression amount of the accelerator pedal. In the case where some required output value is transmitted from the accelerator opening sensor while the driver's depression amount of the accelerator pedal is equal to zero, the vehicle is undesirably accelerated, regardless of the driver's requirement to maintain the current vehicle speed or to even reduce the vehicle speed. The learning technique has accordingly be proposed to change a reference output value of the accelerator opening sensor corresponding to the depression amount of zero (that is, a full closed position of the accelerator pedal) to a more appropriate value.
The prior art technique learns the reference output value of the accelerator opening sensor on the premises that an idle switch is set ON and that the output value of the accelerator opening or throttle opening is stable. This arrangement may cause the reference output value of the accelerator opening sensor to be changed while the depression amount of the accelerator pedal is not equal to zero. In other words, this arrangement may cause the full closed position of the accelerator pedal to be mistakenly learnt. The prior art technique sets a processed value obtained by leveling the difference between a current reference output value and a newly determined reference output value or another processed value obtained by adding or subtracting a predetermined value to or from the current reference output value to the target reference output value of the accelerator opening sensor. This does not always set the optimum value to the target reference output value of the accelerator opening sensor and thereby has a relatively low learning accuracy.
SUMMARY OF THE INVENTION
The object of the present invention is accordingly to provide a technique that effectively prevents a full closed position of an accelerator pedal from being mistakenly learnt and quickly changes a current full closed position of the accelerator pedal to a new, more appropriate full closed position, thus enabling the full closed position of the accelerator pedal to be learnt with a high accuracy.
At least part of the above and the other related objects is attained by a method of learning a full-closed position output value at a full closed position of an accelerator pedal disposed in a vehicle. Here the accelerator pedal enables a required output value to be output to a driving power source of the vehicle in a continuously variable manner and has the full closed position that corresponds to a required output value of 0. The method includes determining whether an output value of the accelerator pedal has exceeded a first threshold value; determining whether the output value of the accelerator pedal is less than a second threshold value, which is smaller than the first threshold value, after the output value of the accelerator pedal has exceeded the first threshold value; when it is determined that the output value of the accelerator pedal is less than the second threshold value, determining whether the output value of the accelerator pedal is converging; and when it is determined that the output value of the accelerator pedal is converging, changing the full-closed position output value to a new full-closed position output value by taking into account the converged output value of the accelerator pedal.
This method of the present invention varies the full-closed position output value by taking into account the converged output value of the accelerator pedal, when it is determined that the output value of the accelerator pedal has exceeded the first threshold value and that the output value of the accelerator pedal is converging. This arrangement effectively prevents the full closed position of the accelerator pedal from being mistakenly learnt and quickly changes the current full closed position of the accelerator pedal to a new, more appropriate full closed position, thus enabling the full closed position of the accelerator pedal to be learnt with a high accuracy. Here the first threshold value is close to a relatively high output value corresponding to a frequently used accelerator position, whereas the second threshold value is close to an output value corresponding to the full closed position of the accelerator pedal.
In accordance with one preferable application of the method of the present invention, determining whether the output value of the accelerator pedal is converging is carried out when the output value of the accelerator pedal monotonously decreases. In accordance with another preferable application of the method of the present invention, determining whether the output value of the accelerator pedal is converging is carried out when a current full-closed position output value is greater than a currently observed output value of the accelerator pedal. Determining whether the output value of the accelerator pedal is converging is carried out on the condition that the output value of the accelerator pedal monotonously decreases, when the current full-closed position output value is not greater than the currently observed output value of the accelerator pedal.
In accordance with one embodiment that attains either one of the above preferable applications, it is determined that the output value of the accelerator pedal monotonously decreases when an absolute difference between a currently observed output value of the accelerator pedal and a previous output value of the accelerator pedal is within a preset range and when a future output value of the accelerator pedal after elapse of a predetermined time period is smaller than the currently observed output value of the accelerator pedal. This arrangement enables learning to be performed even when minute peaks appear due to a simple noise, thus increasing the frequency of learning and enhancing the learning effects. Here the predetermined time period is longer than a sampling time required to detect a variation in output value of the accelerator pedal and is suitable to specify the general characteristics of the output value of the accelerator pedal. In accordance with another embodiment that attains either one of the above preferable applications, it is determined that the output value of the accelerator pedal monotonously decreases when the currently observed output value of the accelerator pedal is smaller than the previous output value of the accelerator pedal. In this embodiment, the continuous decrease in output value of the accelerator pedal is required for the determination that the output value of the accelerator pedal monotonously decreases. Namely learning is not performed when any peak appears due to a noise. This arrangement effectively prevents the full closed position of the accelerator pedal from being mistakenly learnt. In this arrangement, the term ‘monotonous decrease’ is not restricted to the strict sense that does not allow any increasing variation but means a substantially monotonous decrease that allows minute increasing variations, for example, due to the noise.
In the method of the present invention, it may be determined that the output value of the accelerator pedal is converging when a variation in output value of the accelerator pedal is within a predetermined range. This arrangement enhances the speed of determination with regard to the convergence of the output value of the accelerator pedal.
In the method of the present invention, it may be determined that the output value of the accelerator pedal is converging when the currently obser
Toyota Jidosha & Kabushiki Kaisha
Vo Hieu T.
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