JP4008588B2 - Electric power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus that directly applies the power of an electric motor to a steering system to reduce a driver's steering force, and particularly relates to an electric power steering apparatus that notifies a driver of a change in reaction force and performs appropriate steering. .
[0002]
[Prior art]
2. Description of the Related Art Conventional electric power steering devices are known that are configured to control reaction force transmission according to vehicle behavior and warn or prevent a driver from turning the steering wheel too much.
[0003]
Such an electric power steering device that controls transmission of reaction force is, for example, when the driver steers on a road surface with a small road surface friction coefficient (μ) such as a snowy road, or even when the road surface friction coefficient (μ) is high. When steering on a road surface in which the lateral force of the steered wheels (tires) is in a non-linear region, the reaction force corresponding to the vehicle behavior is greatly transmitted via the steering wheel and the driver is prevented from turning the steering wheel too much. The behavior is stabilized.
[0004]
[Problems to be solved by the invention]
In a conventional electric power steering device, when a driver tries to execute such reaction force control at all times during driving, a motor drive signal (PWM signal) generating means for driving an electric motor for generating auxiliary torque is provided as steering. In addition to arithmetic processing for converting a torque signal into an electric motor drive signal (PWM signal), for example, a correction amount corresponding to the vehicle behavior must always be arithmetically processed based on a vehicle speed signal, a yaw angular velocity signal, a lateral acceleration signal, etc. There is a problem that the time required for one cycle of control becomes longer and the steering feeling is lowered.
[0005]
On the other hand, in order to obtain a good steering feeling, a microprocessor having a fast calculation process must be used, which raises the problem of increasing the cost of the electric power steering apparatus.
[0006]
The present invention has been made to solve such problems, and a first object of the invention is to provide an electric power steering capable of executing or prohibiting reaction force transmission control at the driver's will by the driver operating a switch. To provide an apparatus.
[0007]
The second object is to execute or prohibit reaction force transmission control by the vehicle speed or road surface frictional resistance, and the electric power that can stabilize the vehicle behavior even with a relatively slow microprocessor. The object is to provide a steering device.
[0008]
[Means for Solving the Problems]
To solve the above problems, the present invention is concerned. 1st to 3rd The electric power steering apparatus includes a switch unit that allows or prohibits the output of the correction signal from the vehicle behavior determination unit for correcting the target torque signal from the target torque setting unit.
[0009]
According to this invention 1st to 3rd The electric power steering apparatus includes switch means for allowing or prohibiting output of the correction signal from the vehicle behavior determining means for correcting the target torque signal from the target torque setting means. The output of a correction signal for correcting the target torque signal by operating manually or automatically can be permitted or prohibited.
[0010]
Also, The first electric power steering device is provided The switch means includes a correction switch operated by the driver and switching means for switching permission / prohibition of output of the correction signal based on key information from the correction switch.
[0011]
this The first electric power steering device is provided Since the switch means includes a correction switch operated by the driver and a switching means for switching whether to permit or prohibit the output of the correction signal based on the key information from the correction switch, the driver manually operates the correction switch. The output of a correction signal for correcting the target torque signal can be permitted or prohibited at the driver's will.
[0012]
further, The second electric power steering device is provided The switch means includes vehicle speed comparison means for comparing a vehicle speed signal supplied from the vehicle speed sensor with a reference vehicle speed, and switching means for switching whether to permit or prohibit the output of the correction signal based on the vehicle speed comparison signal from the vehicle speed comparison means. When the vehicle speed signal is lower than the reference vehicle speed, the output of the correction signal is prohibited.
[0013]
this The second electric power steering device is provided The switch means includes vehicle speed comparison means for comparing a vehicle speed signal supplied from the vehicle speed sensor with a reference vehicle speed, and switching means for switching whether to permit or prohibit the output of the correction signal based on the vehicle speed comparison signal from the vehicle speed comparison means. Therefore, when the vehicle speed signal is lower than the reference vehicle speed, the output of the correction signal is prohibited, so that the time required for the control circulation process can be shortened in the low vehicle speed region below the reference vehicle speed.
[0014]
Also, The third electric power steering device is provided The switch means includes a friction coefficient estimation means for estimating a road surface friction coefficient, a friction coefficient comparison means for comparing the road surface friction coefficient estimated by the friction coefficient estimation means with a reference friction coefficient, and a friction comparison signal from the friction coefficient comparison means. Switching means for switching the allowance or prohibition of the output of the correction signal based on the above, and when the road surface friction coefficient exceeds the reference friction coefficient, the output of the correction signal is prohibited.
[0015]
this The third electric power steering device is provided The switch means includes a friction coefficient estimation means for estimating a road surface friction coefficient, a friction coefficient comparison means for comparing the road surface friction coefficient estimated by the friction coefficient estimation means with a reference friction coefficient, and a friction comparison signal from the friction coefficient comparison means. Switching means for switching the allowance or prohibition of the output of the correction signal based on the above, so if the road surface friction coefficient exceeds the reference friction coefficient, the output of the correction signal is prohibited. In the μ path, the time required for one cycle of control can be shortened.
[0016]
Further, the switch means according to the present invention is characterized by comprising display means for displaying a state in which the output of the correction signal is permitted.
[0017]
Since the switch means according to the present invention includes the display means for displaying the state where the output of the correction signal is allowed, the switch means can notify the driver of the state where the output of the correction signal is allowed.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
The present invention permits or prohibits the output of a correction signal for correcting the target torque signal by manually or automatically operating the switch means in accordance with the vehicle behavior, thereby obtaining an optimum steering feeling corresponding to the vehicle behavior. At the same time, while the output of the correction signal is prohibited, the time required for one cycle of control is shortened.
[0019]
FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present invention.
In FIG. 1, an electric power steering apparatus 1 includes a rack and pinion mechanism 5 including a steering wheel 2, a steering shaft 3, a hypoid gear 4, a pinion 5a and a rack shaft 5b, a tie rod 6, a front wheel 7 for steering wheels, and an auxiliary torque. An electric motor 8, a control means 13, an electric motor driving means 14, and an electric motor current detecting means 15 acting on the steering system are provided.
[0020]
The electric power steering device 1 detects a yaw angular velocity acting on the vehicle, outputs a yaw angular velocity signal Y converted into an electric signal corresponding to the yaw angular velocity, detects a front wheel turning angle, A turning angle sensor 10 for outputting a turning angle signal δ converted to an electrical signal corresponding to the turning angle of the front wheel, a vehicle speed sensor 11 for detecting a vehicle speed and outputting a vehicle speed signal V converted to an electrical signal corresponding to the vehicle speed, A steering torque sensor 12 that detects a steering torque acting on the steering wheel 2 and outputs a steering torque signal T converted into an electrical signal corresponding to the steering torque is provided.
The turning angle signal δ may be calculated from the steering angle of the steering shaft.
[0021]
The yaw angular velocity signal Y, the turning angle signal δ, and the steering torque signal T each have a magnitude and direction and are supplied to the control means 13.
As for the directions of the yaw angular velocity signal Y, the turning angle signal δ, and the steering torque signal T, the clockwise direction is positive (plus) and the counterclockwise direction is negative (minus).
[0022]
Furthermore, the electric power steering apparatus 1 includes a switch unit 16 including a correction switch that can be operated by the driver in the vicinity of the driver's seat, and a counting unit and a switching unit provided in the control unit 13.
[0023]
In addition, the electric power steering apparatus 1 includes a display unit 20 that notifies the driver that the switch unit 16 is operating.
[0024]
When the steering wheel 2 is steered, the manual steering torque applied to the steering shaft 3 is converted from the rotational force of the pinion 5a to the axial motion of the rack shaft 5b via the rack and pinion mechanism 5, and via the tie rod 6. The steering of the front wheel 7 is changed.
[0025]
In order to assist manual steering torque, when the electric motor 8 is driven in response to the steering torque signal T, the electric motor torque is converted into auxiliary torque (assist torque) boosted via the hypoid gear 4 and the steering shaft 3 It acts on the vehicle and reduces the driver's steering force.
[0026]
The control means 13 is composed of various calculation means, processing means, determination means, switch means, signal generation means, memory, etc. based on a microprocessor, and generates a target torque signal (IMO) corresponding to the steering torque signal T. An electric motor control signal VO (for example, an on signal, an off signal, and PWM) corresponding to a difference (negative feedback) between the target torque signal (IMO) and the electric motor torque signal IMF corresponding to the electric motor current IM detected by the electric motor current detecting means 15 A mixed signal of signals) is generated, and the driving of the motor driving means 14 is controlled so that this difference becomes zero quickly.
[0027]
Further, the control means 13 includes a slip angle difference estimating means and a correction means, and the front wheel slip angle and the rear wheel based on the yaw angular velocity signal Y, the turning angle signal δ, the vehicle speed signal V, and the vehicle dimension parameter (wheel base). The slip angle difference (angle difference signal) is estimated by calculation, the understeer correction amount and oversteer correction amount are determined based on the magnitude of this difference (angle difference signal), and the target torque signal (IMO) is determined based on this correction amount. Correct.
[0028]
Further, the control means 13 compares the direction (P) of the difference (angle difference signal) between the sliding angle of the front wheels and the sliding angle of the rear wheels (angle difference signal) and the direction (N) of the yaw angular velocity signal Y, thereby It is determined whether the behavior is an understeer area or an oversteer area.
[0029]
Further, the control means 13 outputs an output of an understeer correction amount or an oversteer correction amount for correcting the target torque signal automatically based on the manual operation of the driver switch or automatically based on the values of the vehicle speed (V) and the road surface friction coefficient (μ). Allow or ban.
[0030]
The motor driving means 14 is constituted by a bridge circuit composed of switching elements such as four power FETs (field effect transistors) and insulated gate / bipolar transistors (IGBTs), for example, and PWM (pulse width modulation) based on the motor control signal VO. ) Is output, and the motor 8 is PWM-driven in the forward or reverse rotation.
[0031]
The motor current detection means 15 detects the motor current IM converted into a voltage by a resistor or a hall element connected in series with the motor 8 and feeds back the motor torque signal IMF corresponding to the motor current IM to the control means 13. (Negative feedback).
[0032]
FIG. 2 is a block diagram of a basic main part of one embodiment of the electric power steering apparatus according to the present invention.
In FIG. 2, the control means 13 of the electric power steering apparatus 1 includes target torque signal setting means 21, difference calculation means 22, drive control means 23, vehicle behavior determination means 24, correction means 25, and switch means 16.
[0033]
The target torque signal setting means 21 stores in advance a steering torque signal T—target torque signal IMS characteristic data shown in FIG. 7 and a vehicle speed signal V—vehicle speed coefficient KT characteristic data shown in FIG. The target torque signal IMO obtained by multiplying the target torque signal IMS corresponding to the steering torque signal T detected by the steering torque sensor 12 and the vehicle speed coefficient KT corresponding to the vehicle speed signal V detected by the vehicle speed sensor 11 is supplied to the correcting means 25. Supply.
The target torque signal IMO is set so as to decrease as the vehicle speed signal V increases even if the torque signal T is the same, and the steering stability in the high vehicle speed region is ensured.
[0034]
The difference calculation means 22 includes a subtractor or a subtraction function, and a difference ΔI (= IMH−IMF) between the target torque signal IMH supplied from the correction means 25 and the motor torque signal IMF supplied from the motor current detection means 15. And the difference signal ΔI (= IMH−IMF) is supplied to the drive control means 23.
[0035]
The drive control means 23 includes a PID controller, an electric motor control signal generating means, etc., and after performing proportional (P), integral (I) and differential (D) control on the difference signal ΔI supplied from the difference calculating means 22, A PWM motor control signal VO corresponding to right steering or left steering of the steering wheel is generated based on a mixed signal obtained by mixing these proportional / integral / differential (PID) controlled signals, and the motor control signal VO is driven by motor driving means. 14.
[0036]
The vehicle behavior determination unit 24 includes a slip angle difference estimation unit, a direction determination unit, a selection unit, an understeer correction amount output unit, an oversteer correction amount output unit, and the like. The vehicle speed signal V supplied from the vehicle speed sensor 11 and the yaw angular velocity sensor 9 are provided. The difference between the front wheel slip angle (βf) of the vehicle and the rear wheel slip angle (βr) of the vehicle (angle difference βfr = βf−) from the yaw angular velocity signal Y supplied from the vehicle and the cut angle signal δ supplied from the cut angle sensor 10. βr) is calculated, understeer correction amount (DA) and oversteer correction amount (DO) are generated based on this angular difference βfr, and correction signal ID corresponding to understeer correction amount (DA) or oversteer correction amount (DO) is switched. Supply to means 16.
[0037]
FIG. 3 is a block diagram of the main part of the vehicle behavior determining means according to the present invention.
In FIG. 3, the vehicle behavior determination means 24 includes a vehicle speed coefficient generation means 26, a slip angle difference estimation means 30, a selection means 31, a direction determination means 32, an understeer correction amount output means 33, an oversteer correction amount output means 34, and a multiplication means 35. , Multiplication means 36, addition means 37, angle difference change amount calculation means 39, and angle difference change coefficient generation means 40.
[0038]
The vehicle speed coefficient generating means 26 includes a memory such as a ROM, stores characteristic data of the vehicle speed signal V and the vehicle speed coefficient KR shown in FIG. 9 in advance, and corresponds when the vehicle speed signal V is supplied from the vehicle speed sensor 11. The vehicle speed coefficient KR is read out and provided to the multiplication means 35 and the multiplication means 36.
[0039]
The slip angle difference estimation means 30 has a memory and a calculation function, and is based on a vehicle speed signal V, a yaw angular speed signal Y, a turning angle signal δ, and a vehicle dimension parameter L (for example, a wheel base) preset in the memory. The difference βfr (= βf−βr) between the front wheel slip angle (βf) and the rear wheel slip angle (βr) is calculated based on the angle difference signal βfr, the selection means 31, the direction determination means 32, and the angle difference change amount calculation means 39. To supply.
[0040]
[Expression 1]
βfr = Y * L / V−δ
[0041]
Note that the front wheel slip angle (βf) and the rear wheel slip angle (βr) represent the angle in the tire traveling direction with reference to the tire direction, so that when the handle is turned clockwise, the front wheel tire direction is On the other hand, the traveling direction of the tire is counterclockwise, and if the clockwise direction is positive (plus), the direction of the front wheel slip angle (βf) is negative (minus).
Similarly, the rear wheel slip angle (βr) is also negative (minus), and the direction (sign) of the angle difference signal βfr is the absolute value of the rear wheel slip angle (βr) | βr | is the absolute value of the front wheel slip angle (βf). Until | βf | or more (| βr | ≧ | βf |), it is expressed as negative (minus).
[0042]
Further, instead of the yaw angular velocity signal Y supplied to the direction determining means 32, a lateral acceleration G may be substituted.
[0043]
The selection means 31 has a soft control switch function, switches the switch based on the determination signal HO supplied from the direction determination means 32, and outputs the angle difference signal βfr supplied from the slip angle difference estimation means 30 to the understeer correction amount output. This is supplied to the means 33 or the oversteer correction amount output means 34.
[0044]
The direction determination unit 32 has a sign comparison function and is based on the direction signal P of the angular difference signal βfr supplied from the slip angle difference estimation unit 30 and the direction signal N of the yaw angular velocity signal Y supplied from the yaw angular velocity sensor 9. When the direction signal P and the direction signal N match (the same sign), for example, an H level determination signal HO is supplied to the selection means 31, and the direction signal P and the direction signal N are different (the signs are different). In this case, for example, an L level determination signal HO is supplied to the selection means 31.
[0045]
When the direction signal P of the angular difference signal βfr and the direction signal N of the yaw angular velocity signal Y are different (mismatch), for example, the yaw angular velocity Y is clockwise and the counterclockwise slip angle (βf) of the front wheel is rearward. When the wheel is larger than the counterclockwise slip angle (βr), the direction signal N of the yaw angular velocity signal Y is positive (+), and the direction signal P of the angular difference signal βfr is negative (−). The selection means 31 selects the understeer correction amount output means 33 by determining that the behavior is an understeer region (solid line display).
[0046]
On the other hand, when the direction signal P of the angular difference signal βfr and the direction signal N of the yaw angular velocity signal Y are the same (match), for example, the yaw angular velocity Y is clockwise and the counterclockwise slip angle (βr of the rear wheel) ) Is larger than the counterclockwise slip angle (βf) of the front wheel, the direction signal N of the yaw angular velocity signal Y is plus (+) and the direction signal P of the angular difference signal βfr is plus (+). The selection means 31 selects the oversteer correction amount output means 34 (denoted by a broken line) by determining that the vehicle behavior is an oversteer region.
[0047]
Understeer area with strong vehicle behavior means that the vehicle will not bend any further even if the steering wheel is further turned from the current steering state, and it is better to let the driver feel the reaction force and return the steering wheel. This is the steering area to notify.
[0048]
Since the reaction force correction is not necessary in the weak understeer region, the dead zone region of the understeer correction amount DA for the angular difference signal βfr is set large as shown in FIG.
[0049]
On the other hand, the strong oversteer region of the vehicle is a state where the vehicle may spin if it is as it is, and makes the driver feel a strong reaction force to facilitate counter-steering.
[0050]
The understeer correction amount output means 33 includes a memory such as a ROM, stores characteristic data of the absolute value | βfr | of the angle difference signal and the understeer correction amount DA shown in FIG. When the signal βfr is supplied, the corresponding understeer correction amount DA is read, and the understeer correction amount signal DA is supplied to the multiplication means 35.
[0051]
The oversteer correction amount output means 34 includes a memory such as a ROM, stores characteristic data of the absolute value | βfr | of the angle difference signal and the oversteer correction amount DO shown in FIG. When the signal βfr is supplied, the corresponding oversteer correction amount D0 is read, and the oversteer correction amount signal D0 is supplied to the multiplication means 36.
[0052]
Since the understeer correction amount DA and the oversteer correction amount DO have their own dead zones as shown in FIGS. 10 and 11, respectively, optimum correction according to the understeer state or the oversteer state can be performed. .
[0053]
The multiplication means 35 has a software-controlled multiplication function, multiplies the vehicle speed coefficient KR, the understeer correction amount signal DA, and the angle difference change coefficient KV, and performs an understeer correction amount signal IDA (= KR * KV * DA as a subtraction correction signal). ) Is supplied to the adding means 37.
[0054]
The understeer correction amount signal IDA corrects the understeer correction amount DA shown in FIG. 10 with the vehicle speed coefficient KR shown in FIG. 9, so that the understeer correction amount DA is not set to 0 in the low vehicle speed region and is not corrected in the medium to high vehicle speed region. It can be set to the same characteristic as the understeer correction amount DA.
[0055]
The multiplication means 36 has a software-controlled multiplication function, multiplies the vehicle speed coefficient KR, the oversteer correction amount signal DO and the angular difference change coefficient KV, and performs an oversteer correction amount signal IDO (= KR * KV * DO as a subtraction correction signal). ) Is supplied to the adding means 37.
[0056]
Since the oversteer correction amount signal IDO corrects the oversteer correction amount DO shown in FIG. 11 with the vehicle speed coefficient KR shown in FIG. 9, the oversteer correction amount DO is not set to 0 in the low vehicle speed region, and is not corrected in the medium to high vehicle speed region. It can be set to the same characteristic as the oversteer correction amount D0.
The oversteer correction amount D0 is set so that the dead zone is narrower and the inclination is smaller than the understeer correction amount DA.
[0057]
The adding means 37 has a software-controlled adding function, and an understeer correction amount signal IDA (= KR * KV * DA) supplied from the multiplying means 35 and an oversteer correction amount signal IDO (= KR) supplied from the multiplying means 36. * KV * DO) is added, and either the understeer correction amount signal IDA or the oversteer correction amount signal IDO is supplied to the switch means 16 shown in FIG. 2 as the correction signal ID.
[0058]
The angular difference change amount calculation means 39 has a differential calculation function, performs a differential calculation on the angle difference signal βfr supplied from the slip angle difference estimation means 30, and determines the angle difference change signal DV (= dβfr / dt) as the angular difference. This is supplied to the change coefficient generator 40.
[0059]
The angle difference change coefficient generation means 40 includes a memory such as a ROM, stores characteristic data of the angle difference change amount DV and the angle difference change coefficient KV shown in FIG. 12 in advance, and is supplied with an angle difference change amount signal DV. Then, the corresponding angular difference change coefficient KV is read out and supplied to the multiplication means 35 and the multiplication means 36.
[0060]
The angle difference change amount DV represents a change in the angle difference signal βfr, and thus represents a temporal change in the vehicle behavior. Therefore, an understeer correction amount signal IDA (= KR * KV * DA) corresponding to a sudden change in the vehicle behavior. Alternatively, the oversteer correction amount signal IDO (= KR * KV * DO) can be generated.
[0061]
Returning to FIG. 2, the switch means 16 automatically adjusts the correction amount ID supplied from the vehicle behavior determination means 24 based on the driver's manual switch operation or the value of the vehicle speed (V) and the road surface friction coefficient (μ). The supply to the correction means 25 is allowed (correction amount ID) or prohibited (correction amount ID = 0).
[0062]
FIG. 4 is a block diagram showing the principal part of an embodiment of the switch means according to the present invention.
In FIG. 4, the switch unit 16 includes a correction switch 17 that is manually operated by the driver, a counting unit 18, a switching unit 19, and a display unit 20.
The correction switch 17 is constituted by a push switch, for example, and is arranged in the vicinity of the driver's seat to generate a pulse signal for a predetermined time each time the driver operates, and supplies this pulse signal as key information J to the counting means 18.
[0063]
The counting means 18 has a counter function and a latch function, and counts the number of pulses of the key information J supplied from the correction switch 17. For example, the counting means 18 corresponds to odd numbered pulses (1, 3, 5,...) The count signal CH latched at the level is supplied to the switching means 19. The counting means 18 counts the number of pulses of the key information J and supplies the switching means 19 with a counting signal CH latched at L level corresponding to even numbered pulses (2, 4, 6,...), For example. .
However, the counting means 18 outputs an L-level counting signal CH based on an initial setting signal from a power-on reset circuit (not shown) when the apparatus is started, and sets the switching means 19 to a break state.
[0064]
Accordingly, when the first (odd number) key information J is supplied, the counting means 18 supplies the switching signal 19 with the H level counting signal CH, and the H level counting signal CH is the second (even number). Continue until key information J is supplied.
When the second (even number) key information J is supplied, the count signal CH becomes L level, and the L level count signal CH continues until the third (odd number) key information J is supplied.
[0065]
The switching means 19 has a switch function of a normal break contact configuration. When the H level count signal CH is supplied from the counting means 18, the switching means 19 is in a make state, and a correction amount ID (correction amount) supplied from the vehicle behavior determination means 24. : IDA, IDO) is allowed to be supplied to the correction means 25.
[0066]
On the other hand, the switching means 19 is in a break state when an L-level count signal CH is supplied from the counting means 18, and the correction means 25 for the correction amount ID (correction amounts: IDA, IDO) supplied from the vehicle behavior determination means 24. Prohibition of supply to
[0067]
When the apparatus is activated, the H level count signal CH is supplied to the switching means 18, the switching means 19 is set in the make state in advance, and the odd number key information J from the correction switch 17 is counted at the L level. An H-level count signal CH may be output for the signal CH and even-numbered key information J.
[0068]
As described above, the switch means 16 according to the present invention includes the correction switch 17 operated by the driver and the switching means 19 for switching permission / prohibition of the output of the correction signal ID based on the key information J from the correction switch 17. Thus, when the driver manually operates the correction switch 17, the output of the correction signal ID for correcting the target torque signal IMO can be permitted or prohibited by the driver's will.
[0069]
FIG. 13 is an operation waveform diagram of the switch means of FIG.
In FIG. 13, (a) is a pulse waveform of the key information J, (b) is a count signal CH waveform diagram when the count signal CH is set to L level when the apparatus is activated, and (c) is a count signal when the apparatus is activated. A count signal CH waveform diagram when the signal CH is set to H level is shown.
[0070]
(A) When the first (odd number) key information J is supplied after the apparatus is started in the figure, the count signal CH in (b) shifts from the L level set at the time of the apparatus activation to the H level. The count signal CH is kept at the H level until the th (even number) key information J is supplied.
On the other hand, when the first (odd number) key information J is supplied after the apparatus is started in FIG. 5A, the counting signal CH in FIG. 5C shifts from the H level set at the start of the apparatus to the L level. The count signal CH is kept at the L level until the second (even number) key information J is supplied.
[0071]
Subsequently, when the second (even number) key information J is supplied, the count signal CH in FIG. 5B shifts from the H level to the L level, and this state is the third (odd number) key information J. Until it is supplied.
On the other hand, the count signal CH in FIG. 8C shifts from the L level to the H level, and this state is held until the third (odd number) key information J is supplied.
[0072]
Similarly, for the odd-numbered key information J of 3, 5,..., The count signal CH in FIG. 5B holds the H level, and the count signal CH in FIG.
On the other hand, for even-numbered key information J of 4, 6,..., (B) the count signal CH in the figure holds the L level, and (c) the count signal CH in the figure holds the H level.
[0073]
In FIG. 4, the display unit 20 includes a display driving unit 27 and a display 28, and displays the display driving signal DL from the display driving unit 27 based on the H level counting signal CH supplied from the counting unit 18 (light emission). This is supplied to a display device 28 such as a diode) or an LCD (liquid crystal device), and the display device 28 visually displays a state in which the output of the correction signal ID is allowed.
[0074]
As described above, since the display means 20 for displaying the state in which the output of the correction signal ID is allowed is provided, it is possible to notify the driver of the state in which the output of the correction signal ID is allowed.
[0075]
FIG. 5 is a block diagram showing the principal part of another embodiment of the switch means according to the present invention.
In FIG. 5, the switch unit 50 includes a vehicle speed comparison unit 51, a switching unit 19, and a display unit 20.
The vehicle speed comparison means 51 has a comparison function, and uses a reference vehicle speed VK at which a preset vehicle speed V is a predetermined value (for example, 10 km / h) and a vehicle speed V supplied from the vehicle speed sensor 11 (see FIG. 2). In comparison, when the vehicle speed V is lower than the reference vehicle speed VK (V <VK), the L-level vehicle speed comparison signal VH is supplied to the switching means 19, and the vehicle speed V is equal to or higher than the reference vehicle speed VK (V ≧ VK). Is supplied with a vehicle speed comparison signal VH of H level to the switching means 19.
[0076]
The switching means 19 has a normal break contact switch function, similar to that shown in FIG. 4. When the vehicle speed comparison signal VH is supplied from the vehicle speed comparison means 51, the switching means 19 enters the make state and determines the vehicle behavior. The correction amount ID (correction amount: IDA, IDO) supplied from the means 24 is allowed to be supplied to the correction means 25.
[0077]
On the other hand, when the L-level vehicle speed comparison signal VH is supplied from the vehicle speed comparison means 51, the switching means 19 enters a break state and corrects the correction amounts ID (correction amounts: IDA, IDO) supplied from the vehicle behavior determination means 24. Supply to the means 25 is prohibited.
[0078]
Thus, the switch means 50 according to the present invention is based on the vehicle speed comparison means 51 for comparing the vehicle speed signal V supplied from the vehicle speed sensor 11 with the reference vehicle speed VK, and the vehicle speed comparison signal VH from the vehicle speed comparison means 51. And switching means 19 for switching whether to permit or prohibit the output of the correction signal ID. When the vehicle speed signal V is equal to or higher than the reference vehicle speed VK (V ≧ VK), the output of the correction signal ID is permitted and the target torque signal IMO is set. Since the subtraction correction is performed, the reaction force corresponding to the vehicle behavior is transmitted to the driver via the handle, and the driver is prevented from excessively turning the handle, thereby stabilizing the vehicle behavior.
[0079]
Further, when the vehicle speed signal V is lower than the reference vehicle speed VK (V <VK), the output of the correction signal ID is prohibited, so that the calculation process of the correction signal ID becomes unnecessary, and the control is required for one circulation process. Time can be shortened.
Therefore, fine control is possible and the steering feeling can be improved.
[0080]
FIG. 6 is a block diagram showing the principal part of another embodiment of the switch means according to the present invention.
In FIG. 6, the switch means 55 includes a friction coefficient estimation means 56, a friction coefficient comparison means 57, a switching means 19, and a display means 20.
[0081]
The friction coefficient estimating means 56 calculates and estimates the road surface friction coefficient (μ) between the tire and the road surface based on, for example, the vehicle speed signal V, the yaw acceleration signal Y, and the turning angle signal δ, and compares the road surface friction coefficient μ with the friction coefficient comparison. Supply to means 57.
[0082]
The friction coefficient comparison means 57 has a comparison function, and a reference friction in which the road surface friction coefficient μ supplied from the friction coefficient estimation means 56 and a preset road surface friction coefficient μ are predetermined values (for example, μ = 0.5). When the road surface friction coefficient μ is equal to or less than the reference friction coefficient μK (μ ≦ μK), an H level friction comparison signal μH is supplied to the switching means 19, and the road surface friction coefficient μ is the reference friction coefficient. If it exceeds μK (μ> μK), an L level friction comparison signal μH is supplied to the switching means 19.
[0083]
The switching means 19 has a switch function with a normal break contact configuration similar to that shown in FIG. 4, and when the H level friction comparison signal μH is supplied from the friction coefficient comparison means 57, it enters a make state and the vehicle behavior. The correction amount ID (correction amount: IDA, IDO) supplied from the determination unit 24 is allowed to be supplied to the correction unit 25.
[0084]
On the other hand, when the L-level friction comparison signal μH is supplied from the friction coefficient comparison means 57, the switching means 19 is in a break state, and the correction amount ID (correction amounts: IDA, IDO) supplied from the vehicle behavior determination means 24 is set. Supply to the correction means 25 is prohibited.
[0085]
As described above, the switch means 55 according to the present invention includes the friction coefficient estimation means 56 for estimating the road surface friction coefficient μ, and the friction coefficient for comparing the road surface friction coefficient μ estimated by the friction coefficient estimation means 56 and the reference friction coefficient μK. Comparing means 57 and switching means 19 for switching whether to permit or prohibit the output of the correction signal ID based on the friction comparison signal μH from the friction coefficient comparing means 57 are provided, and the road surface friction coefficient μ is equal to or less than the reference friction coefficient μK (μ In the case of ≦ μK), the output of the correction signal ID is allowed and the target torque signal IMO is subtracted and corrected. Therefore, the reaction force corresponding to the vehicle behavior is transmitted to the driver through the handle, and the driver cuts the handle too much. This suppresses this and stabilizes the vehicle behavior.
[0086]
Further, when the road surface friction coefficient μ exceeds the reference friction coefficient μK (μ> μK), the output of the correction signal ID is prohibited, so that the calculation process of the correction signal ID becomes unnecessary, and the control is circulated by that much. Can be shortened.
Therefore, fine control is possible and the steering feeling can be improved.
[0087]
Returning to FIG. 2, the correction means (subtraction means) 25 has a subtraction function, and a correction signal supplied from the vehicle behavior means 24 via the switch means 16 from the target torque signal IMO supplied from the target torque signal setting means 21. By subtracting and correcting ID (correction amounts: IDA, IDO), the target torque signal IMH obtained by correcting the target torque signal IMO with the correction signal ID corresponding to the vehicle behavior is supplied to the difference calculating means 22.
[0088]
【The invention's effect】
As described above, the electric power steering apparatus according to the present invention includes a switch unit that allows or prohibits output of a correction signal from a vehicle behavior determination unit for correcting a target torque signal from a target torque setting unit, Since the output of the correction signal for correcting the target torque signal can be permitted or prohibited by manually or automatically operating the switch means according to the behavior, the correction signal can be output only when the vehicle behavior corrects the target torque signal. The output can be allowed, and a good steering feeling can be obtained even if a microprocessor with a relatively slow calculation process is used.
[0089]
The switch means according to the present invention further comprises a correction switch operated by the driver, and a switching means for switching permission / prohibition of the output of the correction signal based on key information from the correction switch, and the driver manually operates the correction switch. By operating, it is possible to allow or prohibit the output of a correction signal that corrects the target torque signal at the driver's will, so it is possible to freely select the steering feeling according to the vehicle behavior according to the driving skill of the driver Can do.
[0090]
Further, the switch means according to the present invention comprises vehicle speed comparison means for comparing a vehicle speed signal supplied from a vehicle speed sensor with a reference vehicle speed, and permits or prohibits the output of a correction signal based on the vehicle speed comparison signal from the vehicle speed comparison means. Switching means, and when the vehicle speed signal falls below the reference vehicle speed, the correction signal is prohibited from being output. Therefore, the steering feeling is improved in the low vehicle speed range, and the vehicle behavior is stable in the medium and high vehicle speed range. Can be realized.
[0091]
Further, the switch means according to the present invention includes a friction coefficient estimation means for estimating a road surface friction coefficient, a friction coefficient comparison means for comparing a road surface friction coefficient estimated by the friction coefficient estimation means with a reference friction coefficient, and the friction coefficient comparison. Switching means for switching the allowance or prohibition of the output of the correction signal based on the friction comparison signal from the means, and the output of the correction signal is prohibited when the road surface friction coefficient exceeds the reference friction coefficient. The driver can be prevented from overcutting the steering wheel on a low μ road having a coefficient equal to or lower than the coefficient, and the steering feeling can be improved on a high μ road exceeding the reference friction coefficient.
[0092]
Furthermore, the switch means according to the present invention includes a display means for displaying a state in which the output of the correction signal is permitted, and notifies the driver of the state in which the output of the correction signal is permitted. It can be visually recognized that it is operating.
[0093]
Therefore, the driver senses the vehicle behavior from the reaction force as necessary, and the optimum steering feeling can be obtained according to the vehicle behavior, and the electric power that is economical and does not require a high-speed microprocessor for reaction force control. A power steering apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present invention.
FIG. 2 is a block diagram of a basic principal part of an embodiment of an electric power steering apparatus according to the present invention.
FIG. 3 is a block diagram of the main part of the vehicle behavior determining means according to the present invention.
FIG. 4 is a block diagram of the main part of an embodiment of the switch means according to the present invention.
FIG. 5 is a block diagram of the main part of another embodiment of the switch means according to the present invention.
FIG. 6 is a block diagram of the main part of another embodiment of the switch means according to the present invention.
FIG. 7 is a characteristic diagram of steering torque signal T-target torque signal IMS.
[Fig. 8] Vehicle speed signal V vs. vehicle speed coefficient KT characteristics
[Fig. 9] Vehicle speed signal V vs. vehicle speed coefficient KR characteristics
FIG. 10 is a graph showing the absolute value of the angle difference signal βfr | βfr | -understeer correction amount DA characteristic.
FIG. 11 is a graph showing the absolute value of the angle difference signal | βfr | —oversteer correction amount DO characteristic diagram;
FIG. 12 is an angle difference change amount DV−angle difference change coefficient KV characteristic diagram.
13 is an operation waveform diagram of the switch means of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 2 ... Steering wheel, 9 ... Yaw angular velocity sensor, 10 ... Cutting angle sensor, 11 ... Vehicle speed sensor, 12 ... Steering torque sensor, 13 ... Control means, 16, 50, 55 ... Switch means, 17 DESCRIPTION OF SYMBOLS ... Correction switch, 18 ... Counting means, 19 ... Switching means, 20 ... Display means, 21 ... Target torque signal setting means, 24 ... Vehicle behavior determination means, 25 ... Correction means, 51 ... Vehicle speed comparison means, 56 ... Friction coefficient estimation Means 57: Friction coefficient comparison means.

Claims (4)

A steering torque sensor for detecting steering torque of the steering system; an electric motor for adding auxiliary torque to the steering system; vehicle behavior determination means for determining vehicle behavior and outputting a correction signal; at least a steering torque signal from the steering torque sensor Target torque setting means for setting a target torque signal based on the target torque, and a correction means for correcting the target torque signal from the target torque setting means based on a correction signal from the vehicle behavior determination means. In an electric power steering device comprising control means for controlling,
Switch means for permitting or prohibiting the output of the correction signal from the vehicle behavior determining means for correcting the target torque signal from the target torque setting means;
Further, the switching means includes a correction switch that the driver operated electrostatic you comprising the, switching means for switching the allowable or disable output of the correction signal on the basis of the key information from the correction switch Dynamic power steering device. A steering torque sensor for detecting steering torque of the steering system; an electric motor for adding auxiliary torque to the steering system; vehicle behavior determination means for determining vehicle behavior and outputting a correction signal; at least a steering torque signal from the steering torque sensor Target torque setting means for setting a target torque signal based on the target torque, and a correction means for correcting the target torque signal from the target torque setting means based on a correction signal from the vehicle behavior determination means. In an electric power steering device comprising control means for controlling,
Switch means for permitting or prohibiting the output of the correction signal from the vehicle behavior determining means for correcting the target torque signal from the target torque setting means;
Furthermore, said switching means switching to switch the speed comparing means for comparing the vehicle speed signal supplied from the vehicle speed sensor as a reference vehicle speed, the allowable or disable output of the correction signal based on the vehicle speed comparison signal from the speed comparison means and means, and when said vehicle speed signal is below the reference vehicle speed, the correction signal to that electric power steering apparatus and inhibits the output of. A steering torque sensor for detecting steering torque of the steering system; an electric motor for adding auxiliary torque to the steering system; vehicle behavior determination means for determining vehicle behavior and outputting a correction signal; at least a steering torque signal from the steering torque sensor Target torque setting means for setting a target torque signal based on the target torque, and a correction means for correcting the target torque signal from the target torque setting means based on a correction signal from the vehicle behavior determination means. In an electric power steering device comprising control means for controlling,
Switch means for permitting or prohibiting the output of the correction signal from the vehicle behavior determining means for correcting the target torque signal from the target torque setting means;
Further, the switching means includes a friction coefficient estimating means for estimating a road surface friction coefficient, the friction coefficient comparison means for comparing the road surface friction coefficient and the reference friction coefficient The friction coefficient estimation means has estimated, from the friction coefficient comparison means and a switching means for switching allowable or disable output of the correction signal based on the friction comparison signal, when the road surface friction coefficient exceeds the reference coefficient of friction, to prohibit the output of the correction signal It said electrostatic power steering apparatus. It said switch means, the electric power steering apparatus according to any one of claims 1-3, characterized in that comprising a display means for displaying a state of permitting output of said correction signal.

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