Road surface condition determination system for automotive vehicles and anti-skid braking system having the same
First Claim
1. A road surface condition determination system for an automotive vehicle, comprising:
- wheel-speed sensors detecting wheel speeds of each of road wheels; and
a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal from each of said wheel-speed sensors, said control unit comprising;
(a) a wheel-speed fluctuation arithmetic-calculation section which calculates a wheel-speed fluctuation of each of the road wheels on the basis of a previous value of the wheel-speed data signal and a current value of the wheel-speed data signal, (b) a first absolute-value arithmetic-calculation section which calculates an absolute value of the wheel-speed fluctuation of each of the road wheels, (c) a first integration section which produces a first integrated value of the absolute values of the wheel-speed fluctuations of the road wheels, (d) a smoothing section which makes a smoothing operation to the first integrated value to produce a smoothed value, and (e) a road-surface condition determining section which determines a road surface condition on the basis of the smoothed value.
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Accused Products
Abstract
A road surface condition determination system for an automotive vehicle comprises wheel-speed sensors, and a control unit being configured to be electrically connected to the wheel-speed sensors for data-processing a wheel-speed data signal. The control unit calculates a wheel-speed fluctuation of each of the road wheels on the basis of a previous value of the wheel-speed data signal and a current value of the wheel-speed data signal, and calculates an absolute value of the wheel-speed fluctuation of each of the road wheels. A integration circuit is provided to produce a first integrated value of the absolute values of the wheel-speed fluctuations of the road wheels. A smoothing circuit is provided to make a smoothing operation to the integrated value to produce a smoothed value. A road-surface condition determining section is also provided to determine a road surface condition on the basis of the smoothed value. In an automotive vehicle with an ABS system, a skid control section uses the result of discrimination between good and bad roads, executed by the road-surface condition determining section, so as to vary a pressure-reduction threshold depending on the road surface condition detected.
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Citations
18 Claims
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1. A road surface condition determination system for an automotive vehicle, comprising:
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wheel-speed sensors detecting wheel speeds of each of road wheels; and
a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal from each of said wheel-speed sensors, said control unit comprising;
(a) a wheel-speed fluctuation arithmetic-calculation section which calculates a wheel-speed fluctuation of each of the road wheels on the basis of a previous value of the wheel-speed data signal and a current value of the wheel-speed data signal, (b) a first absolute-value arithmetic-calculation section which calculates an absolute value of the wheel-speed fluctuation of each of the road wheels, (c) a first integration section which produces a first integrated value of the absolute values of the wheel-speed fluctuations of the road wheels, (d) a smoothing section which makes a smoothing operation to the first integrated value to produce a smoothed value, and (e) a road-surface condition determining section which determines a road surface condition on the basis of the smoothed value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An anti-skid braking system having a road surface condition determination system for an automotive vehicle, comprising:
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wheel-speed sensors detecting wheel speeds of each of road wheels;
a hydraulic brake unit regulating wheel-brake cylinder pressures of wheel-brake cylinders mounted to each of the road wheels; and
a control unit being configured to be electrically connected to said wheel- speed sensors and hydraulic brake unit for processing a wheel-speed data signal from each of said wheel-speed sensors and for execute skid control based on the wheel-speed data signal from each of said wheel-speed sensors, said control unit comprising;
(a) a wheel-speed fluctuation arithmetic-calculation section which calculates a wheel-speed fluctuation of each of the road wheels on the basis of a previous value of the wheel-speed data signal and a current value of the wheel-speed data signal, (b) a first absolute-value arithmetic-calculation section which calculates an absolute value of the wheel-speed fluctuation of each of the road wheels, (c) a first integration section which produces a first integrated value of the absolute values of the wheel-speed fluctuations of the road wheels, (d) a skid-control dependent wheel-speed fluctuation arithmetic-calculation section which calculates a skid-control dependent wheel-speed fluctuation of each of the road wheels, occurring due to skid control, on the basis of a previous value of the wheel-speed data signal and a current value of the wheel-speed data signal, (e) a second absolute-value arithmetic-calculation section which calculates an absolute value of the skid-control dependent wheel-speed fluctuation of each of the road wheels, (f) a second integration section which produces a second integrated value of the absolute values of the skid-control dependent wheel-speed fluctuations of the road wheels, (g) a correction section which calculates a wheel-speed fluctuation correction value by subtracting the second integrated value from the first integrated value, (h) a smoothing section which makes a smoothing operation to the wheel-speed fluctuation correction value to produce a smoothed value, (i) a road-surface condition determining section which determines a road surface condition on the basis of the smoothed value, and (j) a skid control section preventing wheel lock of each of the road wheels in response to the wheel-speed data signal from each of the wheel-speed sensors, said skid control section executing the skid control depending on the road surface condition determined by the road-surface condition determining section. - View Dependent Claims (9)
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10. A road surface condition determination system for an automotive vehicle, comprising:
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wheel-speed sensors detecting wheel speeds of each of road wheels; and
a control unit being configured to be electrically connected to said wheel-speed sensors for processing a wheel-speed data signal from each of said wheel-speed sensors, said control unit comprising;
(a) a wheel-acceleration arithmetic-calculation section which calculates a wheel-acceleration data signal as a difference between a previous value of the wheel-speed data signal and a current value of the wheel-speed data signal, (b) a wheel-speed fluctuation arithmetic-calculation section which calculates a wheel-speed fluctuation of each of the road wheels on the basis of the wheel-acceleration data signal, (c) a first absolute-value arithmetic-calculation section which calculates an absolute value of the wheel-speed fluctuation of each of the road wheels, (d) a first integration section which produces a first integrated value of the absolute values of the wheel-speed fluctuations of the road wheels, (e) a smoothing section which makes a smoothing operation to the first integrated value to produce a smoothed value, and (f) a road-surface condition determining section which determines a road surface condition on the basis of the smoothed value. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An anti-skid braking system having a road surface condition determination system for an automotive vehicle, comprising:
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wheel-speed sensors detecting wheel speeds of each of road wheels;
a hydraulic brake unit regulating wheel-brake cylinder pressures of wheel-brake cylinders mounted to each of the road wheels; and
a control unit being configured to be electrically connected to said wheel-speed sensors and hydraulic brake unit for processing a wheel-speed data signal from each of said wheel-speed sensors and for execute skid control based on the wheel-speed data signal from each of said wheel-speed sensors, said control unit comprising;
(a) a wheel-acceleration arithmetic-calculation section which calculates a wheel-acceleration data signal as a difference between a previous value of the wheel-speed data signal and a current value of the wheel-speed data signal, (b) a wheel-speed fluctuation arithmetic-calculation section which calculates a wheel-speed fluctuation of each of the road wheels on the basis of a previous value of the wheel-acceleration data signal and a current value of the wheel-acceleration data signal, (c) a first absolute-value arithmetic-calculation section which calculates an absolute value of the wheel-speed fluctuation of each of the road wheels, (d) a first integration section which produces a first integrated value of the absolute values of the wheel-speed fluctuations of the road wheels, (e) a skid-control dependent wheel-speed fluctuation arithmetic-calculation section which calculates a skid-control dependent wheel-speed fluctuation of each of the road wheels, occurring due to skid control, on the basis of a previous value of the wheel-acceleration data signal and a current value of the wheel-acceleration data signal, (f) a second absolute-value arithmetic-calculation section which calculates an absolute value of the skid-control dependent wheel-speed fluctuation of each of the road wheels, (g) a second integration section which produces a second integrated value of the absolute values of the skid-control dependent wheel-speed fluctuations of the road wheels, (h) a correction section which calculates a wheel-speed fluctuation correction value by subtracting the second integrated value from the first integrated value, (i) a smoothing section which makes a smoothing operation to the wheel-speed fluctuation correction value to produce a smoothed value, (j) a road-surface condition determining section which determines a road surface condition on the basis of the smoothed value, and (k) a skid control section preventing wheel lock of each of the road wheels in response to the wheel-speed data signal from each of the wheel-speed sensors, said skid control section executing the skid control depending on the road surface condition determined by the road-surface condition determining section. - View Dependent Claims (18)
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Specification