JPH02218909A - Position detecting apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a position detection device suitable for detecting the steering angle of an automobile, etc., and more specifically, it combines an analog sensor and a digital sensor to simplify the configuration and improve detection accuracy. The present invention relates to a position detection device that aims to improve.

(Prior art) In a steering device that steers the rear wheels independently of the front wheels and a steering device in which the steering wheel and steering wheel are mechanically separated, the steering angle of the rear wheels and the steering wheel is is detected and feedback control is performed. Such a steering device generally includes a steering sensor for detecting steering wheel operation on the steering wheel, and
The steering mechanism is equipped with an electric motor that drives the rear wheels (steering wheels) and a steering angle detector that detects the steering angle of the steering wheels, and the electric motor is energized based on the output signals of the steering angle detector and the steering sensor. to steer the rear wheels (steering wheels). In this type of steering device, the steering angle detector is generally composed of a differential transformer or a potentiometer, and detects the linear displacement of an operating rod or the like interposed between the steering wheel and the electric motor.

However, the above-mentioned steering angle detector has a problem in that its characteristics tend to change due to environmental conditions such as temperature, fluctuations in power supply voltage, etc., and detection accuracy is relatively low.

Therefore, in recent years, such steering devices have been equipped with an electric motor in which a rotary encoder is incorporated as a steering angle detector, as described in Japanese Utility Model Application Publication No. 60-43473. , one has been proposed that detects the steering angle of steered wheels based on the output of an encoder.

(Problem to be Solved by the Invention) However, in the above-mentioned vehicle steering system, the steering angle from the neutral position is detected by counting the pulse signals output by the encoder that accompany the steering. The numerical value, that is, the steering angle, must be stored in a memory device that does not require a memory retention operation when the ignition key switch is turned off, and non-volatile memory such as EFROM is essential, increasing manufacturing costs, and its control is also difficult. The problem was that it became complicated.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a position detection device that can detect the relative position of members, such as the steering angle, with high accuracy without using a nonvolatile memory.

(Means for Solving the Problems) As shown in FIG. 1, the present invention detects the relative positions of two relatively moving members with a predetermined position as a reference, and outputs a detection signal representing the relative positions. In a position sensing device,
an analog sensor that outputs an analog signal of a potential according to the relative position of the two members; a first digital sensor that outputs a predetermined number of pulse signals for a unit movement distance according to the relative movement of the two members; , a second digital sensor that outputs a pulse signal at least at the predetermined position in response to relative movement of the two members; and an output signal of the analog sensor is within a predetermined range; a predetermined position determining means that outputs a reference signal when outputting a pulse signal; and counting the number of pulse signals output by the first digital sensor based on the time when the predetermined position determining means outputs the reference signal. pulse signal counting means for outputting a signal representing the number of pulse signals from the predetermined position, and before the predetermined position determining means outputs the reference signal, the number of pulse signals from the predetermined position is Detecting the position by outputting a position detection signal and, after the predetermined position determining means outputs the reference signal, selecting means outputting a position detection signal from a predetermined position based on the output signal of the pulse signal counting means. The point is to do it.

(Operation) According to the position detection device according to the present invention, a predetermined position is searched from the output signals of the analog sensor and the second digital sensor, and until the predetermined position is detected, the position detection device searches for the predetermined position based on the output signal of the analog sensor. A detection signal representing a position based on a predetermined position is output, but after the predetermined position is detected, the pulse signal output by the first digital sensor is counted to generate a detection signal representing a position based on the predetermined position. Output. Therefore, when the power is disconnected, there is no need to memorize and retain the count value of the pulse signal output by the digital sensor, which simplifies the configuration and control method, and also makes it possible to detect the position based on the digital signal. Detection accuracy can be improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

2 to 9 show a position detection device according to an embodiment of the present invention applied to a rear wheel steering control device of a vehicle with front and rear wheel steering, and FIG. 2 is a schematic diagram of the rear wheel steering control device of a vehicle. 3(a) and 3(b) are sectional views showing the front wheel steering mechanism, FIGS. 4(a) and 4(b) are sectional views showing the rear wheel steering mechanism, and FIGS. 5 and 6 are block diagrams, Figure 7 is a flowchart.
FIGS. 8 and 9 are timing charts.

In FIG. 2, 11 is a steering handle, and the steering handle 11 is connected via a steering shaft 12 and the like to a rack-and-pinion type steering gear mechanism housed in a front gear housing 13F. As shown in FIG. 3(a) later, the steering shaft 1
2 is rotatably inserted into the column 18, and this column 1
8 is provided with an analog type first front wheel steering angle sensor 14 and a digital type second front wheel steering angle sensor 15. In the steering gear mechanism, a pinion that rotates together with the steering shaft 12 meshes with a rack extending in the vehicle width direction, and both ends of this rack are connected to tie rods 16FL.
, 16FR are connected to the left and right front wheels 17FL, 17FR via steering linkages such as the front wheels 17FL, 16FR, etc.
The steering wheel operation of the steering handle 11 is transmitted to 17FR. These front wheels are 17FL.

17FR and rear wheels 17RL and 17RR, which will be described later, are provided with vehicle speed sensors 19FL and 19FR, respectively.

19RL and 19RR (hereinafter represented by numbers without subscripts) are provided, and these vehicle speed sensors 19 are connected to a controller 20, which will be described later. In addition, in FIG. 2, 21 is a power unit.

The first front wheel steering angle sensor 14 includes a substantially cylindrical movable iron core 22 and a differential transformer 23, as shown in FIG. 3(a). The differential transformer 23 includes a bracket 2 formed by joining two substantially cylindrical members 27a and 27b to the column 18.
A holder 24 is attached via 7, and this holder 24
A primary coil for excitation, two secondary coils for detection, and a tertiary coil for compensation (hereinafter, each coil is collectively referred to as 25) are housed inside. The movable iron core 22 has an inner circumference screwed onto the outer circumference of a collar 26 fitted to the steering shaft 12 so as to be movable in the axial direction, and an outer circumference attached to the holder 24.
It is spline-fitted to the inner periphery of the steering shaft 12 so as to be movable in the axial direction but prohibited from rotating, and is displaced in the axial direction as the steering shaft 12 rotates. This first front wheel steering angle sensor 14 is
Each coil 25 of the differential transformer 23 is connected to the controller 20 and outputs a detection signal of a potential corresponding to the position of the movable iron core 22 representing the steering angle of the steering handle 11. That is, in the differential transformer 23, an alternating current signal is applied to the negative coil to excite the primary coil, and each secondary coil differentially sends a detection signal to the controller 20 in accordance with the position of the movable iron core 22. Output.

The second front wheel steering angle sensor 15 includes a holding member 28 fitted to a collar 26 on the right side of the movable iron core 22 in the figure, a rotating magnetic body 29 attached to the outer circumference of this holding member 28, and a bracket. 27, and a main body 30 fixed to the member 27a. As shown in FIG. 3(b), the rotating magnetic body 29 includes a multi-pole section 29a in which a large number of magnets (for example, 60 poles) are arranged at equal intervals in the rotational direction, and at least one magnetic pole (for example, two poles). ) are arranged in the rotational direction.
b, and these magnetic pole parts 29a.

29b are coaxially joined in the axial direction via a spacer portion 29c. In the minority magnetic pole portion 29b, one magnetic pole is arranged corresponding to the neutral position (straight traveling position) of the steering handle 11. The main body 30 has three magnetically sensitive elements 30a1 and 30a.
2, 30b, and these magnetic sensing elements 30al, 30
a2 and 30b are connected to the controller 20. Note that the magnetically sensitive element is not limited to a coil, but can also be constructed from a Hall element, an MR element, or the like. This main body 30 includes two magnetically sensitive elements 30al.

30a2 is spaced apart from each other by a predetermined distance in the direction of rotation, and the multiple magnetic pole portions 29
The first magnetic pole part 29a is arranged opposite to the
The encoder 31 includes a magnetically sensitive element 30b.
is arranged to face the minority magnetic pole portion 29b, and constitutes the second encoder 32 together with the minority magnetic pole portion 29b.

The first encoder 31 generates pulse signals af and bf with a predetermined phase difference by detecting changes in the magnetic field caused by the multiple magnetic pole portion 29a by magnetic sensing elements 30al and 30a2, respectively, as the rotating magnetic body 29 rotates (Fig. 8.9). Similarly, the second encoder 32 outputs a pulse signal Sf to the controller 20 when the magnetic sensing element 30b detects a change in the magnetic field caused by the minority magnetic pole portion 29b. As will be described later, the pulse signals af and bf are used as the basis for calculating the steering angle and determining the direction, and the pulse signal Sf is used as the basis for determining the neutral position.

Referring again to FIG. 2, 13R is a gear housing provided at the rear of the vehicle body, and the rear wheel steering mechanism 33 is accommodated within this gear housing 13R. Rear wheel steering mechanism 33
As shown in FIGS. 4(a) and 4(b), the housing 13
R so that it can slide in the vehicle width direction, and both ends are the left and right rear wheels 17
R.L.

A rod 34 connected to 17RR via a steering linkage such as tie rods 16RL and 16RR, a motor 35 configured coaxially with the rod 34 within the housing 13R, and a first rear wheel that detects the axial displacement of the rod 34. It has a steering angle sensor 36 and a second rear wheel steering angle sensor 37 that detects the rotation angle of the output shaft 38 of the motor 35.

In the motor 35, a field magnet 39 is fixed to the inner wall of the housing 13R, and a rotor 40 is arranged between the field magnet 39 and the rod 34 so as to be rotatable coaxially with the rod 34. The rotor 40 is a cylindrical output shaft 3 through which a rod 34 is inserted.
The output shaft 38 is constructed by coaxially and integrally fixing a laminated iron core 41 with a skew groove formed on the outer periphery of the 8 and a multi-wound armature winding 42. is supported by the inner peripheral wall of the gear housing 13R via a bearing 43, and the outer peripheral portion at the left end in the figure is coupled to a pole nut 45 of a pole screw mechanism 44, which will be described later. The armature winding 42 is connected to the controller 20 via a commutator 46 fixed to the outer periphery of the output shaft 38 on the right side in the figure and a brush 48 slidably supported in a holder 47 and in elastic contact with the commutator 46. wired.

In the pole screw mechanism 44, a substantially cylindrical pole nut 45 coupled to the output shaft 38 of the motor 35 is supported by a pole bearing 49 on the inner peripheral wall of the housing 13R. This pole nut 45 has a ball groove formed in its inner circumferential wall, and the rod 34 has a ball groove formed in a range corresponding to its moving distance, and the pole nut 45 has a ball groove formed between the ball groove and the ball groove of the rod 34. A large number of circulating poles are interposed and screwed to the rod 34 so as to be removable. This pole screw mechanism 44 has a pole nut 45.
are driven by the output shaft 38 of the motor 35 to rotate together, and the rotational movement of the pole nut 45 and the axial linear movement of the rod 34 are mutually converted and reversibly transmitted. Note that the rod 34 is supported by the housing 13R with only rotational movement allowed, and rotational movement is prohibited.

Like the first front wheel steering angle sensor 14 described above, the first rear wheel steering angle sensor 36 detects a movable iron core 50 that is displaced integrally with the rod 34 and a potential depending on the position of the movable iron core 50. It has a differential transformer 51 that outputs a signal. Figure 4 (
As also evaluated in b), the movable iron core 50 is connected to the rod 34
A mounting rod 53 is attached to a stay 52 fixed at right angles to the end of the
, and is displaced parallel to and integrally with the rod 34. In the differential transformer 51, coils 55 wound in a substantially cylindrical shape, such as a primary coil and two secondary coils, are disposed in a hollow holder 54 that is integrally arranged in parallel with the housing 13R. A movable iron core 50 is loosely inserted into. This differential transformer 51 also has a coil 55 connected to the controller 20, and differentially outputs a detection signal of a potential corresponding to the position of the movable iron core 50 to the controller 20.

Like the second front wheel steering angle sensor 15 described above, the second rear wheel steering angle sensor 37 includes a holding member 57 fixed to the outer circumference of the pole nut 45 of the pole screw mechanism 44 with a lock nut 56, and a holding member 57 fixed to the outer circumference of the pole nut 45 of the pole screw mechanism 44. The main body 59 is attached to the housing 13R and connected to the controller 20. The rotating magnetic body 58 includes a large number magnetic pole part 58a in which a large number of magnetic poles (for example, 60 poles) are arranged at equal intervals in the rotational direction, and a small number magnetic pole part 58b in which at least one magnetic pole (for example, 2 poles) is arranged in the rotational direction. These magnetic pole parts 58a and 58b are coaxially joined in the axial direction via a spacer part 58c. In the minority magnetic pole portion 58b, one magnetic pole is connected to the rear wheel 17RL, 1
It is arranged corresponding to the neutral position of 7RR. Main body 59
has three magnetically sensitive elements 59al, 59a2, 59b, and these magnetically sensitive elements 59al.

59a2 and 59b are connected to the controller 20. As mentioned above, the magnetic sensing element is a Hall element or an MR element.
It is also possible to configure it from elements and the like. In this main body 59, two magnetically sensitive elements 59al and 59a2 are arranged facing the multi-magnetic pole part 58a with a predetermined distance in the rotational direction to constitute a first encoder 60, and similarly, a magnetically sensitive element 59b A second
The encoder 61 is configured as follows. first encoder 6
0 is a magnetic sensing element 59a1.0 as the rotating magnet rotates.
59a2 detects the change in the magnetic field caused by the multi-pole portion 58a, and outputs pulse signals ar and br (see FIG. 8.9) having a phase difference of about 90 degrees to the controller 20, and similarly, the second The magnetically sensitive element 59b of the encoder 61 detects a change in the magnetic field caused by the minority magnetic pole portion 58b and outputs a pulse signal sr to the controller 20. As will be described later, as shown in FIGS. 8 and 9, the pulse signals ar and br output from the encoders ao and at described above are guided to the D flip-flop configured in the controller 20, and the D flip-flop converts the signal A high potential signal dr is output when ar precedes signal br, and a low potential signal dr is output when signal br precedes signal ar, and the rotation direction of the rotating magnetic body 58 is determined according to the phase difference between these signals a and b. is determined.

The controller 20 includes a control circuit 62 as shown in FIG.
and a drive circuit 63, and a current sensor 64 (described later) in the drive circuit 63 is connected to the control circuit 62 along with the aforementioned sensors 14, 15, 19, 36°37. A motor 35 is connected.

The control circuit 62 includes a constant voltage circuit 65, a microcomputer circuit 66, and human interface circuits 67 and 68.
, 69, 70.71. The constant voltage circuit 65 is
It is connected to a battery (not shown) via a fuse, etc., and supplies power at a constant voltage to each circuit. The input interface circuits 67, 68, 69, 70, 71 are connected to the respective corresponding sensors 14, 15, 36, 37, 19, and are also connected to the microcomputer circuit 66 via a data bus. There is. The human power interface circuit 67 connected to the first front wheel steering angle sensor 14 includes an oscillation circuit,
Consisting of an amplifier circuit, a rectifier circuit, an A/D converter, etc., it outputs an AC signal to the secondary coil, shapes the signal generated by the secondary coil, converts it into a digital signal representing the steering angle value, and converts it into a digital signal representing the steering angle value. Output to computer circuit 66. The input interface circuit 68 to which the second front wheel steering angle sensor 15 is connected includes a direction determination circuit 72F1 counter 7 having a D flip-flop, as shown in FIG.
3F and an AND gate 74H.

As shown in FIG. 8.9, the direction determination circuit 72F receives the signals af and bf at the input terminals of the D flip-flop, determines the steering direction of the steering wheel 11 based on the phases of the signals af and bf, and outputs the signal. When af precedes signal bf (hereinafter assumed to be rightward steering), the potential is high, and signal bf becomes signal af.
When the vehicle is further ahead (assuming leftward steering), a low potential signal df is output.

The counter 73F receives the above-mentioned signal df and signals af, b.
At least one of f is input to the input terminal, and the reset terminal is connected to the output terminal of the AND gate, and when the signal df is at a high potential, the signal af is input.

The number of pulses of bf is added and counted, and when the potential of signal df is low, the number of pulses of signals af and bf is subtracted and counted, and
When a high potential signal (neutral position detection signal Rf) is input from the AND gate 74F to the reset terminal, the count value is reset. AND gate 74F has the above-mentioned signal S at its input terminal.
A determination signal Cf is input from the microcomputer circuit 62 along with f, and when these signals Sf and Cf are both at high potential, a high potential detection signal Rf is output to the counter 73F and the microcomputer circuit 66. As will be described later, the determination signal Cf input to the AND gate 74F indicates that the steering angle of the steering wheel 11 is at the neutral position when the output signal of the first front wheel steering angle sensor 15 is within a predetermined value range. It has a high potential when it is within a predetermined range based on
Further, the output signal Rf of the AND gate 74F has a high potential when in the neutral position. The counter 73F is reset each time the signal Rf is input from the AND gate 74F to the reset terminal.

The human power interface circuit 69 connected to the first rear wheel steering angle sensor 36 includes an oscillation circuit, an amplifier circuit, a rectifier circuit, and an A/D converter, similar to the human power interface circuit 67 of the first front wheel steering angle sensor 14 described above. etc. This input interface circuit 69 also outputs an alternating current signal to excite the primary coil of the first rear wheel steering angle sensor 36, and also shapes and exchanges the signal induced in the secondary coil into a digital signal to output it to the microcomputer. Output to circuit 66. The input interface circuit 70 to which the second rear wheel steering angle sensor 37 is connected also includes, as shown in FIG. 6, a direction determination circuit 72R1 having a D flip-flop, a counter 73R, an AND gate 74R, and the like. This input interface circuit 70 also connects to the rear wheel 17RL, similar to the aforementioned human power interface circuit 68.

When 17RR is in the neutral position, the counter 73R is reset by the high potential detection signal Rr output by the AND gate 74R, and when the signal dr is at a high potential, the counter 73R adds the number of pulses of one of the signals ar and br. This counter 73 counts the number of pulses by subtracting it when the potential is low.
R outputs a digital signal representing the steering angle value to the microcomputer circuit 66.

The input intertube ace circuit 71 to which the vehicle speed sensors 19 are connected includes a waveform shaping circuit, a counter, etc., and outputs a signal representing the vehicle speed to the microcomputer circuit 66 based on the output signal of each vehicle speed sensor 19. Further, a human power interface circuit 75 to which the current sensor 64 is connected includes an amplifier circuit, an A/D converter, and the like, and exchanges the output signal of the current sensor 64 into a digital signal and outputs the digital signal to the microcomputer circuit 66.

The microcomputer circuit 66 includes a CPU, ROM%R
Each interface circuit 67, 68, 69 is equipped with AM, clock, etc., and according to the program stored in the ROM.
．． 70, 71. The signals input from each sensor through 75 are processed to determine the duty factor of the current flowing to the motor 35, and pulse width modulation signals (PWM signals) g, h, i representing this duty factor are processed. , j to the drive circuit 63.

The drive circuit 63 includes a booster circuit 76 and a gate drive circuit 7.
7, a current sensor 64, a relay circuit 78, a switch circuit 79, etc. are provided, and the gate drive circuit 77 is connected to the battery, and the switch circuit 79 is connected to the battery via the relay circuit 78. The switch circuit 79 is
Four field effect transistors (FETs) Ql, Q2.
Q3゜Q4 are connected in a bridge shape, and these FETs
Ql, Q2. Q3. The gate of Q4 is connected to a gate drive circuit 77. The drains of FETQI and Q2 are connected to the battery, and the sources are connected to FETQ3. Q4 is also connected to the drain of FETQ3. The source of Q4 is grounded (one terminal of the battery) via the current sensor 64,
FET QI.

A motor 35 is connected between the source-drain connection portion of Q3 and the source-drain connection portion of FET Q2°Q4. The booster circuit 76 boosts the voltage of the battery and outputs it to the gate drive circuit 77, and the gate drive circuit 77 receives the PWM signal g input from the microcomputer circuit 66.

Each FETQ1 of the switch circuit 79 based on h, t, j
．． Q2. Q3. A drive signal is output to the gate of Q4. The current sensor 64 detects the current applied to the motor 35 and sends a detection signal of this current to the aforementioned interface circuit 75.
Output to. In the switch circuit 79, a duty factor drive signal corresponding to a PWM signal signal is inputted to the gate of FETQI, and similarly, a PWM signal is inputted to the gate of FETQ2.
M signal, FETQ: M) Gate 1.1: PWM signal t
, the duty factor drive signal of the PWM signal j is manually applied to the gates of FETQ4.

Next, the operation of this embodiment will be explained with reference to FIG.

The steering control device for this front and rear wheel steering device controls the motor 35 by executing a series of processes shown in the flowchart of FIG. 7 in a microcomputer circuit 66.

First, when the ignition key is operated and the key switch is placed in the ON position, the microcomputer circuit 6
6 etc., the microcomputer circuit 66
is activated. Then, in step P1, the microcomputer circuit 66 is initialized, and data stored in internal registers etc. are erased and addresses are designated.Subsequently, in step P2, other defined Interrupt processing is performed according to the subroutine. Then, in the next step P3, the flag F4 is set to 0.

Next, in step P4, the front wheel steering angle θFl is read from the output signal of the first front wheel steering angle sensor 14, and in step P5, it is determined whether the front wheel steering angle θFl is within a predetermined range εF with respect to the neutral position. to judge. In step P5, if it is determined that the front wheel steering angle θF1 is within the predetermined range εF, the aforementioned determination signal Cf is output to the AND gate 74F in step P6. Similarly,
In step P7, the rear wheel steering angle θR1 is read from the output signal of the first rear wheel steering angle sensor 36, and in step P8, it is determined whether the rear wheel steering angle θR1 is within a predetermined range cR based on the neutral position. However, if it is determined in step P8 that the rear wheel steering angle θR1 is within the predetermined range εF, a determination signal Cr is output to the AND gate 74R in step P9.

Subsequently, in step PIO, the value of the flag F4 is determined, and if the flag F4 is O, the processes of step pH and step P12 are performed, and if the flag F4 is 1, the processes from step P13 to step P19 are performed. In step pH, the front wheel steering angle θF1 read from the output signal of the first front wheel steering angle sensor 14 is selected as the front wheel steering angle θF, which is the reference for control, and similarly, in step P12, the rear wheel steering angle θR, which is the reference, is selected. The rear wheel steering angle θR1 read from the output signal of the first rear wheel steering angle sensor 36 is selected as the rear wheel steering angle θR1.

Further, in step P13, the front wheel steering angle θF2 is read from the output signal of the second front wheel steering angle sensor 15, and in step P14, the front wheel steering angle θF1 is read from the output signal of the first front wheel steering angle sensor 14. It is determined whether the absolute value of the deviation (IθF1-θF21) between the front wheel steering angle θF2 and the front wheel steering angle θF2 read from the output signal of the second front wheel steering angle sensor 15 is less than or equal to a predetermined value δF. In this step P14, if it is determined that the absolute value of the above-mentioned deviation (θF1-θF2) exceeds the predetermined value δF, a process for ensuring safety is performed in accordance with a subroutine for safety defined elsewhere in step P15. If the absolute value of the deviation (θF1-θF2) is less than or equal to the predetermined value δF, step P1B is performed. Step P13 described above. Similarly to P14, in step P16, the rear wheel steering angle θR2 is read from the output signal of the second rear wheel steering angle sensor 37, and in step P17, the deviation (θR1 - θR2) of each rear wheel steering angle θR1, θR2 is calculated. It is determined whether the absolute value of is less than or equal to a predetermined value δR. Then, in step P17, if it is determined that the absolute value of the deviation (θR1-θR2) exceeds the predetermined value δR, step P17 is performed.
15 to ensure safety, and the deviation (θR1-θ
If the absolute value of R2) is determined to be less than or equal to the predetermined value δR, step P18. Perform the process of P19.

In step P18, the front wheel steering angle θF2 read from the output signal of the second front wheel steering angle sensor 15 described above is selected as the front wheel steering angle θF, which is the basis of electric motor control. The rear wheel steering angle θR2 read from the output signal of the second rear wheel steering angle sensor 37 is selected as the rear wheel steering angle θR, which is the basis of electric motor control. Then, in the following steps, step P11゜PI
3 or step P18. The electric motor is controlled based on the front wheel steering angle θF and the rear wheel steering angle θR selected in P19.

In the following step P20, the vehicle speed V is read from the output signal of the vehicle speed sensor 19. Then, in step P21, a map search is performed for the steering angle ratio k from the vehicle speed-steering angle ratio data table using the vehicle speed V as an address. This vehicle speed-steering angle ratio data table is based on the patent application filed in 1986 by the applicant.
As described in the specification of No. 2-189705, etc.
The steering angle ratio k is defined to be positive (same phase) in a high vehicle speed range and negative (opposite phase) in a low vehicle speed range. Next, step P2
In step P23, the rear wheel target steering angle θRT is calculated by multiplying the front wheel steering angle θF by the steering angle ratio k, and in step P23, the rear wheel steering angle θR is subtracted from the rear wheel target steering angle θRT to calculate the deviation Δ.
Calculate θR. In the next step P24, the deviation -
A map search is performed for the steering force of the rear wheels using the deviation ΔθR as an address from the steering force table. This steering force is caused by the motor 35
In step P24, the steering force is defined to have a predetermined characteristic with respect to the deviation ΔθR so that it increases when the deviation ΔθR is large. Then, in the subsequent step P25, output control, that is, energization control of the motor 35 is performed. This step P25
Now, one duty factor of the PWM signals g, h, i, and j described above is set to the above-mentioned steering force to drive the motor 35, and processes such as braking the motor 35 are performed.

Next, in step P26, the value of flag F4 is determined, and if it is determined that flag F4 is 1, step P26 is performed.
Repeat the series of processes from 4, and also set the flag F.
If it is determined that 4 is 0, the process of step P27 is performed. In step P27, the above-mentioned AND gate 7
It is determined whether both 4F and 74R have output high potential signals, in other words, whether the neutral positions of both the front wheels and the rear wheels have been detected. And this step P27
If it is determined that the two AND gates 74F and 74R both output high potential signals, the flag F4. and set 1 to 1, and also two AND gates 74
If it is determined that one or both of F and 74R is not outputting a high potential signal, a series of processes from step P4 are repeatedly executed. That is, flag F
Reference numeral 4 is used to switch between using a signal from an analog sensor as a steering angle signal and when using a signal from a digital sensor as a steering angle signal, and is controlled to switch both front and rear at the same time.

As described above, in this rear wheel steering control device, the steering angle of the front wheels is detected by the analog type first front wheel steering angle sensor 14 and the digital type second front wheel steering angle sensor 15,
Front wheel steering angle θ detected by first front wheel steering angle sensor 14
F1 is within a predetermined value range based on the neutral position and the second
The front wheel steering angle sensor 15 outputs a signal when the front wheel steering angle sensor 15 outputs a signal.
It is determined that L and 17FR are in the neutral position. Then, until the neutral position is determined, the front wheel steering angle θF1 detected by the first front wheel steering angle sensor 14 is selected and the front wheel steering angle θ
Control is performed based on F1, and after the neutral position is determined, the front wheel steering angle θF is detected by the second front wheel steering angle sensor 15.
2 is selected and control is performed based on the front wheel steering angle θF2.

That is, when the ignition is turned on, the analog sensor determines the steering angle until neutrality is determined, and once neutrality is determined, the steering angle from the digital sensor is used. Therefore, the steering angles of the front wheels 17FL and 17FR can be detected with high precision, improving the reliability of control, and there is no need to memorize the steering angles when the ignition key switch is turned off, reducing manufacturing costs and controlling methods. can be simplified. Similarly, the rear wheel steering angle is determined by the analog type first rear wheel steering angle sensor 3.
6 and a digital second rear wheel steering angle sensor 37, and determines the neutral position of the rear wheels from the output signals to the rear wheel steering angle sensors 36 and 37. Until the neutral position is determined, Control is performed based on the rear wheel steering angle read from the output signal of the first rear wheel steering angle sensor 36 and, after the neutral position is determined, from the output signal of the second rear wheel steering angle sensor 37. conduct.

Therefore, the rear wheel steering angle can be detected with high precision, improving the flexibility of control, and there is no need to use a memory device that does not require memory retention, reducing manufacturing costs and simplifying the control method. I can figure it out.

Although the above-mentioned embodiment shows an application to a rear wheel steering control device of a vehicle, it goes without saying that this position detection device can also be used for other purposes such as detecting the table position of a machine tool. None.

(Effects of the Invention) As explained above, according to the position detection device according to the present invention, an analog sensor outputs an analog signal of a potential according to the position, and a predetermined number of pulse signals for a unit movement distance according to the movement. a first digital sensor that outputs a pulse signal and a second digital sensor that outputs a pulse signal at least at a predetermined position; The reference point for determining a predetermined position is when the digital sensor outputs a pulse signal, and until the predetermined position is determined, the analog sensor is used, and after the predetermined position is determined, the first
The position is detected by a digital sensor. For this reason,
There is no need to install a storage device that does not require memory retention operation,
It simplifies the control method and reduces manufacturing costs, and the position can be detected with high precision using a digital sensor.
Control reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a position detection device according to the present invention. 2 to 9 show a position detection device according to an embodiment of the present invention applied to a rear wheel steering control device of a vehicle, and FIG. 2 is a schematic diagram of the rear wheel steering control device of a vehicle, and FIG. Diagram (a)
is a sectional view of a position detection device provided as a front wheel steering angle sensor that detects the front wheel steering angle, FIG. 3(b) is a partially enlarged view of FIG. 3(a), and FIG. 4(a) is a rear wheel steering angle. Sectional view of a position detection device provided as a rear wheel steering angle sensor for detecting a steering angle, No. 4
Figure (b) is a partially enlarged view of Figure 4 (a), Figure 5 is a block diagram of the control system, Figure 6 is a block diagram showing the part in Figure 5 in detail, Figure 7 is a flowchart, and Figure 7 is a flowchart. 8 and 9 are timing charts. 11... Steering handle 12... Steering shaft 13F 13R... Gear housing 14... First
front wheel steering angle sensor 15...second front wheel steering angle sensor 17FL, 17FR. 17RL, 17RR...Wheel 18...Column 20...Controller 31...First encoder 32...Second encoder 34...Rod 36...First rear wheel steering angle sensor 7...Second rear wheel steering angle sensor 5...Pole nut 0...First encoder...Second encoder 2...Control circuit 6...Microcomputer circuit 2F, 72R...・Direction determination circuit 3F, 73R... Counter 4F, 74R... AND gate patent

Claims (1)

[Scope of Claims] A position detection device that detects the relative position of two relatively moving members with a predetermined position as a reference, and outputs a detection signal representing the relative position, comprising: an electric potential corresponding to the relative position of the two members; a first digital sensor that outputs a predetermined number of pulse signals for a unit movement distance according to the relative movement of the two members; a second digital sensor that outputs a pulse signal at the predetermined position; and an output signal of the analog sensor is within a predetermined range;
and a predetermined position determining means that outputs a reference signal when the second digital sensor outputs a pulse signal; pulse signal counting means for counting the number of pulse signals from the predetermined position and outputting a signal representing the number of pulse signals from the predetermined position, and before the predetermined position discriminating means outputs the reference signal, the analog sensor Outputs a position detection signal from a predetermined position based on the output signal, and after the predetermined position determining means outputs the reference signal, outputs a position detection signal from a predetermined position based on the output signal of the pulse signal counting means. A position detection device characterized in that a position detection device detects a position using a selection means that selects a position.