JP6693065B2 - Steering control device - Google Patents

Description

  The present invention relates to a steering control device including at least a rotation monitoring unit to which electric power is supplied when a permission signal as a permission condition for traveling of a vehicle is in an off state.

  For example, Patent Document 1 describes a steering control device in which an ASIC is used as an evaluation unit that detects a rotation amount of a steering angle during a period in which an ignition switch (permission signal) of a vehicle is off.

  Further, Patent Document 2 describes a calculation unit that performs a process of amplifying an output value of a rotation angle sensor used for detecting a steering angle and an offset correction process.

European Patent No. 2050658 Japanese Patent Publication No. 2010-505680

  By the way, in general, when the permission signal is in the ON state, an accurate value for the steering angle is required. In this case, for example, it is considered effective to provide the calculation unit or the like at the input destination of the output value of the rotation angle sensor. However, in this case, when the permission signal is in the off state, the calculation unit outputs a more accurate detection value than necessary, and the power consumption increases as compared with the case where the calculation unit is not used.

  The present invention has been made in view of such circumstances, and an object thereof is to generate a highly accurate angle signal when the permission signal is in the ON state and to reduce power consumption when the permission signal is in the OFF state. It is to provide a steering control device capable of suppressing an increase.

Hereinafter, the means for solving the above problems and the effects thereof will be described.
1. The steering control device includes a control unit and at least a rotation monitoring unit to which electric power is supplied when a permission signal which is a permission condition for traveling of the vehicle is in an off state, and which corresponds to an angle within one rotation of the rotation shaft. And a high-precision signal output unit that outputs a high-precision signal, and a stop processing unit that stops power supply to the high-precision signal output unit on condition that the permission signal is in the off state. And the rotating shaft turns the steered wheels of the vehicle by rotating, and the rotation monitoring unit is a signal according to an angle within one rotation of the rotating shaft, and A low-accuracy signal output unit that outputs a signal with a lower accuracy than the high-accuracy signal output unit, and the rotation in an off period that is a period in which the permission signal is in an off state based on the output value of the low-accuracy signal output unit. Rotation amount detection process to detect the rotation amount of the shaft When the permission signal is in the ON state, the control unit controls the rotation of the vehicle based on the output value of the high precision signal output unit and the rotation amount detected by the rotation amount detection processing unit. A steering angle calculation processing unit that calculates the steering angle of the steering wheel is provided.

  In the above configuration, when the permission signal is in the off state, the rotation amount detection processing unit detects the rotation amount of the rotating shaft. When the permission signal is turned on, the control unit calculates the steered angle of the steered wheels of the vehicle based on the rotation amount detected by the rotation amount detection processing unit and the output value of the high precision signal output unit. To be done. Therefore, the turning angle calculated by the turning angle calculation processing unit can be determined by the accuracy of the high precision signal output unit.

  Moreover, since the high-accuracy signal output unit is configured to output a high-accuracy signal, it consumes more power than the low-accuracy signal output unit. In this respect, in the above configuration, when the permission signal is in the off state, the power supply to the high precision signal output unit is stopped and the rotation amount is detected based on the output value of the low precision signal output unit.

Therefore, in the above configuration, it is possible to generate a highly accurate angle signal when the permission signal is in the ON state and suppress an increase in power consumption when the permission signal is in the OFF state.
2. In the steering control device described in the above 1, the low-accuracy signal output unit is composed of a circuit independent of the high-accuracy signal output unit.

  In the case of the above configuration, the operating time of the entire high precision signal output unit can be reduced as compared with the case where the low precision signal output unit shares a part of the circuit of the high precision signal output unit. Therefore, it is possible to suppress the deterioration of the high-accuracy signal output section over time.

  3. In the steering control device according to the above item 1, the high-precision signal output unit may include a signal amplification amplifier that amplifies an output signal of a rotation angle sensor that detects a rotation angle of the rotation shaft, and an offset error of the signal amplification amplifier. The low-precision signal output unit includes a signal amplification amplifier that amplifies an output signal of a rotation angle sensor that detects a rotation angle of the rotation shaft, and the high-precision signal output. The signal amplification amplifier included in the unit and the signal amplification amplifier included in the low precision signal output unit are shared by the high precision signal output unit and the low precision signal output unit for single signal amplification. An amplifier, which includes a selective cutoff circuit that cuts off power supply to the compensation circuit in a state where power supply to the signal amplification amplifier is continued, and the stop processing unit is configured such that the permission signal is in an off state. On condition Rukoto, to cut off the power supply to the compensation circuit by operating the selective tripping circuit while continuing power supply to the signal amplification amplifier.

  In the above configuration, when the permission signal is in the off state, the stop processing unit operates the selective cutoff circuit to cut off the power supply to the compensation circuit, so that the power consumption can be reduced as compared with the case where the cutoff circuit is not cut off. Moreover, in the above configuration, since the high-precision signal output section and the low-precision signal output section share the signal amplification amplifier, it is easy to reduce the circuit scale of the steering control device.

4. In the steering control device according to any one of the above 1 to 3, the power supply to the control unit is cut off on condition that the permission signal is in an off state.
In the above configuration, the power supply to the control unit is cut off on the condition that the permission signal is in the off state, so that the power consumption can be reduced as compared to the case where the power supply is not cut off.

  5. In the steering control device according to the above 4, the control unit includes a storage unit that stores the turning angle calculated by the turning angle calculation processing unit, and the turning angle calculation processing unit turns off the permission signal. When the power supply is started by switching from the state to the ON state, the turning angle stored in the storage unit is updated based on the rotation amount detected by the rotation amount detection processing unit.

  In the above configuration, the turning angle when the permission signal is switched to the OFF state is stored in the storage unit, and when the permission signal is switched to the ON state, the steering angle stored in the storage unit is updated with the rotation amount. Therefore, even if the rotary shaft rotates while the permission signal is in the off state, the steered angle when the permission signal is switched to the on state can be calculated.

  6. In the steering control device according to any one of 1 to 5 above, the rotation amount detection processing unit detects a rotation amount of a unit rotation amount based on an output of the low-precision signal output unit, and determines a rotation direction thereof. The rotation direction detection processing unit that outputs a signal indicating the rotation of the specified rotation amount and the rotation direction that has been identified, and the integrated value of the unit rotation amount is updated based on the output value of the rotation direction detection processing unit. A counter, and the resolution by the unit rotation amount is lower than the resolution when the control unit grasps the rotation angle of the rotation shaft based on the output of the high precision signal output unit.

  In the above configuration, the resolution by the unit rotation amount detected by the rotation direction detection processing unit is lower than the resolution when the control unit grasps the rotation angle of the rotation shaft based on the output of the high precision signal output unit. Therefore, even if the input of the rotation direction detection processing unit is the low-accuracy signal output unit, the situation in which the input accuracy is insufficient does not occur.

1 is a system configuration diagram including a steering control device according to a first embodiment. FIG. FIG. 3 is a block diagram showing a part of processing of a microcomputer according to the same embodiment. The block diagram which shows the structure of the rotation monitoring part concerning the embodiment. FIG. 3 is a diagram showing a configuration of a low precision signal output unit according to the same embodiment. FIG. 3 is a diagram showing a configuration of a high precision signal output unit according to the same embodiment. (A)-(g) is a time chart which shows operation | movement of the compensation circuit concerning the embodiment. The figure which shows the structure of the high precision signal output part and low precision signal output part concerning 2nd Embodiment. The block diagram which shows the structure of the rotation monitoring part concerning the embodiment. The figure which shows the structure of the high precision signal output part and low precision signal output part concerning the modification of the said embodiment.

<First Embodiment>
Hereinafter, a first embodiment of the steering control device will be described with reference to the drawings.
As shown in FIG. 1, in the steering mechanism according to the present embodiment, the steering wheel (steering 10) is fixed to the steering shaft 12, and the rack shaft 20 reciprocates in the axial direction according to the rotation of the steering shaft 12. Move. The steering shaft 12 is configured by connecting a column shaft 14, an intermediate shaft 16, and a pinion shaft 18 in this order from the steering 10 side.

  The rack shaft 20 and the pinion shaft 18 are arranged with a predetermined crossing angle, and the first rack teeth 20a formed on the rack shaft 20 and the pinion teeth 18a formed on the pinion shaft 18 are meshed with each other. The first rack and pinion mechanism 22 is configured. Further, tie rods 24 are connected to both ends of the rack shaft 20, and the tips of the tie rods 24 are connected to a knuckle (not shown) to which steered wheels 26 are assembled. Therefore, the rotation of the steering shaft 12 due to the operation of the steering 10 is converted into an axial displacement of the rack shaft 20 by the first rack and pinion mechanism 22, and this axial displacement is transmitted to the knuckle through the tie rod 24. The steering angle of the steered wheels 26, that is, the traveling direction of the vehicle is changed.

  The rack shaft 20 is arranged at a predetermined crossing angle with the pinion shaft 28, and the second rack teeth 20b formed on the rack shaft 20 and the pinion teeth 28a formed on the pinion shaft 28 mesh with each other. The second rack and pinion mechanism 30 is configured.

  The pinion shaft 28 is connected to a rotating shaft 34a of a motor 34 via a speed reducing mechanism 32 such as a worm and wheel. Two rotation angle sensors, a first reference sensor 36a and a second reference sensor 36b, are provided near the rotation shaft 34a. Here, the first reference sensor 36a detects the rotation angle of the rotation shaft 34a with reference to the first angle, and the second reference sensor 36b detects the rotation angle of the rotation shaft 34a by the first angle. The second angle different from is detected. Here, in this embodiment, the first angle and the second angle are deviated from each other by “90 °”. Then, the output signal of the first reference sensor 36a is regarded as a sine wave signal (described as sin in the drawing), and the output signal of the second reference sensor 36b is regarded as a cosine wave signal (described as cos in the drawing).

  Output signals of the first reference sensor 36a and the second reference sensor 36b are captured by the rotation monitoring unit 38. The rotation monitoring unit 38 operates using the battery 54 as a power source. In this embodiment, the rotation monitoring unit 38 is composed of a dedicated integrated circuit (ASIC).

  A microcomputer (microcomputer 40) including a CPU and a memory that stores programs executed by the CPU controls a control amount (torque) of the motor 34 by operating an inverter 42 connected to the motor 34. To do. At this time, the microcomputer 40 detects the torque Trq applied to the pinion shaft 18 based on the torsion of the first reference sensor 36 a and the second reference sensor 36 b and the torsion bar 50 provided on the pinion shaft 18 via the rotation monitoring unit 38. The detected values of the torque sensor 52 and the vehicle speed sensor 56 for detecting the vehicle speed V are referred to.

FIG. 2 shows a part of the processing executed by the microcomputer 40.
The base value setting processing unit 60 sets the base value Ta1 * of the assist torque generated by the motor 34 based on the vehicle speed V and the torque Trq. On the other hand, the A / D converter 62 converts a sine wave signal, which is an output signal of the first reference sensor 36a, amplified by a process described below into digital data and outputs the digital data. The A / D converter 64 converts a cosine wave signal, which is an output signal of the second reference sensor 36b, amplified by a process described below into digital data and outputs the digital data. The steered angle calculation processing unit 68 calculates and outputs the steered angle θp of the steered wheels 26 based on the output values of the A / D converters 62 and 64.

  Here, the output signal of the first reference sensor 36a and the output signal of the second reference sensor 36b cannot uniquely determine the rotation angle of the rotation shaft 34a within one rotation. That is, for example, the output signal of the first reference sensor 36a cannot distinguish 0 ° and 180 °. On the other hand, according to the pair of output signals of the first reference sensor 36a and the second reference sensor 36b, the rotation angle within one rotation of the rotation shaft 34a can be uniquely determined. The turning angle calculation processing unit 68 calculates the rotation angle of the rotation shaft 34a within one rotation based on the output signals of the first reference sensor 36a and the second reference sensor 36b, and combines the rotation history of the rotation shaft 34a with the rotation history. The steering angle θp is calculated. That is, the rotation of the rotary shaft 34a moves the rack shaft 20 in the axial direction via the reduction mechanism 32 and the pinion shaft 28, and the steered angle θp of the steered wheels 26 changes as the rack shaft 20 moves in the axial direction. To do. In particular, the rotating shaft 34a rotates a plurality of times before the absolute value of the turning angle θp changes from zero to the maximum rotation angle. Therefore, there is no one-to-one correspondence between the rotation angle of the rotating shaft 34a and the turning angle θp, and it is necessary to use the rotation history of the rotating shaft 34a in determining the turning angle θp.

  The target turning angle setting processing unit 72 sets the target turning angle θp * based on the sum of the torque Trq detected by the torque sensor 52 and the base value Ta1 *. Here, the target turning angle θp * is set using the following model.

Trq + Ta1 * = K ・ θp * + C ・ θp * '+ J ・ θp *''(c1)
In the above formula, the viscosity coefficient C is a model of friction of the steering mechanism including the steering wheel 10, the steering shaft 12, the rack shaft 20, etc., and the inertia coefficient J is a model of the inertia of the steering mechanism. Is. On the other hand, the spring coefficient K is a model of the influence of the vehicle, and is determined by specifications such as suspension and hole alignment.

  The feedback processing unit 74 calculates and outputs a correction amount of the base value Ta1 * as an operation amount for feedback controlling the turning angle θp to the target turning angle θp *. The correction processing unit 76 corrects the base value Ta1 * by adding the correction amount of the feedback processing unit 74 to the base value Ta1 *, and sets this as the torque command value Ta * of the motor 34. The operation processing unit 78 operates the inverter 42 to control the torque of the motor 34 to the torque command value Ta *.

  As shown in FIG. 1, the rotation monitor 38 receives the IG signal when the ignition switch is turned on. The microcomputer 40 detects this when the IG signal switches from the ON state to the OFF state via the rotation monitoring unit 38. Then, the microcomputer 40 cuts off the power supply on condition that the IG signal is in the off state. That is, the microcomputer 40 executes necessary post-processing when the IG signal is turned off. The post-processing here includes storage processing of the turning angle θp in the nonvolatile memory 70 shown in FIG. The non-volatile memory 70 is a storage device that stores and holds data regardless of whether power is supplied. Then, when the post-processing is completed, the microcomputer 40 commands the rotation monitoring unit 38 to cut off the power supply. As a result, the power supply of the microcomputer 40 is cut off.

  The microcomputer 40 is activated when the IG signal is turned on. That is, the rotation monitoring unit 38 resumes the power supply to the microcomputer 40 when the IG signal is turned on. When the microcomputer 40 is activated in this manner, the microcomputer 40 acquires the rotation amount Δθ of the rotating shaft 34a when the IG signal is in the off state from the rotation monitoring unit 38, and the acquired amount is the A / D converter shown in FIG. Converted to digital data by 66. Then, the steering angle calculation processing unit 68 corrects the steering angle θp stored in the non-volatile memory 70 immediately before the power supply to the microcomputer 40 is cut off based on the output rotation amount Δθ. Know the angle θp.

FIG. 3 shows the configuration of the rotation monitoring unit 38.
The output signal of the first reference sensor 36a is amplified by the first reference low-precision signal output unit 80a, and then input to the first reference comparators 86a and 88a. The first reference comparator 86a determines whether or not the output signal of the first reference sensor 36a is a positive predetermined value or more, and the first reference comparator 88a determines that the output signal of the first reference sensor 36a is negative. It is determined whether or not the value is less than or equal to a predetermined value.

  The output signal of the second reference sensor 36b is amplified by the second reference low-precision signal output unit 80b, and then input to the second reference comparators 86b and 88b. The second reference comparator 86b is for determining whether or not the output signal of the second reference sensor 36b is a positive predetermined value or more, and the second reference comparator 88b is for the output signal of the second reference sensor 36b to be negative. It is determined whether or not the value is less than or equal to a predetermined value.

  The output signals of the first reference comparators 86a and 88a and the second reference comparators 86b and 88b are output to the rotation direction detection processing unit 90. The rotation direction detection processing unit 90 specifies which of the first quadrant to the fourth quadrant the rotation angle of the rotation shaft 34a is based on the output signal. Then, the rotation direction detection processing unit 90 determines that the rotation of the unit rotation amount (90 °) is performed every time the quadrant in which the rotation angle exists changes to the adjacent quadrant due to the change in the output signal. The rotation direction is specified based on the relationship between the quadrant existing before the change and the quadrant existing after the change.

  Then, the rotation direction detection processing unit 90 outputs to the counter 92 a signal indicating that the unit rotation amount has been rotated and the rotation direction. The counter 92 processes the unit rotation amount of the rotation shaft 34a as a vector amount based on the output signal of the rotation direction detection processing unit 90, and integrates them. That is, for example, when the unit rotation amount is rotated twice on the positive side, the counter value is “2”, and when the unit rotation amount rotations on the positive side and the negative side are performed once, the counter value is , "0".

The interface 94 outputs the counter value of the counter 92 to the microcomputer 40. This counter value is the rotation amount Δθ shown in FIG.
The output signal of the first reference sensor 36a is also input to the first reference high-accuracy signal output unit 100a, amplified by the high-accuracy signal output unit 100a, and output to the interface 94. Here, the high precision signal output unit 100a outputs a higher precision signal as a signal obtained by amplifying the output value of the first reference sensor 36a than the low precision signal output unit 80a.

  The output signal of the second reference sensor 36b is also input to the second reference high-accuracy signal output unit 100b, amplified by the high-accuracy signal output unit 100b, and output to the interface 94. Here, the high precision signal output unit 100b outputs a higher precision signal as a signal obtained by amplifying the output value of the second reference sensor 36b than the low precision signal output unit 80b.

  It should be noted that the interface 94 uses the IG signal in the ON state as a condition that the sine wave signal output from the first reference high precision signal output section 100a and the cosine wave output from the second reference high precision signal output section 100b. The signal is output to the microcomputer 40. On the other hand, in the microcomputer 40, the sine wave signal and the cosine wave signal are converted into digital data by the A / D converters 62 and 64 shown in FIG. The steering angle θp is calculated.

The power supply unit 96 steps down the voltage of the battery 54 to make it the operating voltage of the microcomputer 40, and applies it to the microcomputer 40 during the period when the IG signal is in the ON state.
The cutoff circuit 97 is a circuit that switches between power supply to the high-accuracy signal output units 100a and 100b and a cutoff state thereof.

When the IG signal is turned off, the stop processing unit 98 opens the cutoff circuit 97 to cut off the power supply to the high precision signal output units 100a and 100b.
FIG. 4 shows the configuration of the low precision signal output units 80a and 80b. In the present embodiment, the low-precision signal output units 80a and 80b are non-inverting amplifier circuits using the operational amplifier 82. That is, the output terminal and the inverting input terminal of the operational amplifier 82 are connected by the resistor 83, and the inverting input terminal is grounded via the resistor 84. The non-inverting input terminal of the operational amplifier 82 serves as the input terminal of the low precision signal output units 80a and 80b.

FIG. 5 shows the configuration of the high precision signal output units 100a and 100b.
As shown in FIG. 5, the high-accuracy signal output units 100a and 100b include a non-inverting amplifier circuit using an operational amplifier 102 as a signal amplification amplifier. That is, the output terminal and the inverting input terminal of the operational amplifier 102 are connected by the resistor 104, and the inverting input terminal is grounded via the resistor 106. The non-inverting input terminal of the operational amplifier 102 serves as the input terminal Tin of the high precision signal output unit 100a (100b). The operational amplifier 102 has the same specifications as the operational amplifier 82. The resistors 104 and 106 have the same specifications as the resistors 83 and 84, respectively.

  The high-accuracy signal output units 100a and 100b further include a compensation circuit 120 including a compensation unit 122 and a correction voltage generation unit 124. The compensation circuit 120 is a circuit that applies a voltage (correction voltage) that compensates for an offset voltage error of the operational amplifier 102 to the terminal TB of the operational amplifier 102. Here, the operational amplifier 102 has a potential difference “V (+) − V (−)” at the non-inverting input terminal with reference to the potential at the inverting input terminal, a gain Ga for the same potential difference, and a voltage Vb at the terminal TB. , And the output voltage Vout is expressed by the following equation (c2). However, in the following expression (c2), an offset voltage error ΔVo described later is ignored. In this embodiment, the gain Gb is set to a value much larger than 1.

Vout = Ga * {V (+)-V (-)}-Gb * Vb (c2)
The correction voltage generation unit 124 includes an operational amplifier 126 having the same specifications as the operational amplifier 102. The non-inverting input terminal of the operational amplifier 102 is connected to the input terminal Tin of the high precision signal output unit 100a (100b). The inverting input terminal of the operational amplifier 102 is connected to the inverting input terminal of the operational amplifier 102 via the switching element S1 and is connected to the input terminal Tin of the high precision signal output unit 100a (100b) via the switching element S2. The output terminal of the operational amplifier 126 is grounded via the switching element S3 and the capacitor C1, and is also grounded via the switching element S4 and the capacitor C2. Then, the charging voltage of the capacitor C1 is applied to the terminal TB of the operational amplifier 126, and the correction voltage that is the charging voltage of the capacitor C2 is applied to the terminal TB of the operational amplifier 102.

The compensating circuit 120 controls the reduction of the offset voltage superimposed on the output voltage Vout of the operational amplifier 102 by opening / closing the switching elements S1 to S4.
That is, the compensating unit 122 first sets the switching elements S1 and S4 in the open state and sets the switching elements S2 and S3 in the closed state. Thus, when the offset voltage error ΔVc of the operational amplifier 126 is used, the output voltage Vc (1) of the operational amplifier 126, that is, the charging voltage of the capacitor C1 is given by the following expression (c3).

Vc (1) = Ga · ΔVc / (1 + Gb) (c3)
Next, the compensator 122 puts the switching elements S1 and S4 into a closed state and puts the switching elements S2 and S3 into an open state. In this case, noting that the charging voltage of the capacitor C1 does not change, the output voltage Vc (2) of the operational amplifier 126 becomes the following expression (c4).

Vc (2)
= Ga · {V (+) − V (−) + ΔVc} −Gb · Ga · ΔVc / (1 + Gb)
= Ga · {V (+) − V (−)} + Ga · ΔVc / (1 + Gb)
… (C4)
The output voltage Vc (2) in the above equation (c4) is the charging voltage of the capacitor C2. Therefore, using the offset voltage error ΔVo of the operational amplifier 102, the output voltage Vout of the operational amplifier 102 is given by the following expression (c5).

Vout = Ga · {V (+) − V (−) + ΔVo} −Gb · Vc (2)
= (-Ga * Gb + Ga) * {V (+)-V (-)}
+ Ga · ΔVo- {Gb · Ga · ΔVc / (1 + Gb)}
… (C5)
The above expression (c5) can be approximated by the following expression (c6) when the gain Gb is much larger than 1.

Vout = −Ga · Gb · [V (+) − V (−) + {(− ΔVc + ΔVo) / Gb}]
… (C6)
As described above, the offset voltage error ΔVo of the operational amplifier 102 is reduced to “(−ΔVc + ΔVo) / Gb” which is sufficiently smaller than “V (+) − V (−)”.

  In the present embodiment, when the IG signal is in the off state, the stop processing unit 98 shown in FIG. 3 opens the cutoff circuit 97 to cut off the power supply to the operational amplifier 102 and the compensation circuit 120. On the other hand, when the IG signal is turned on, the stop processing unit 98 shown in FIG. 3 closes the cutoff circuit 97 to start power supply to the operational amplifier 102 and the compensation circuit 120. As a result, highly accurate signals are output from the highly accurate signal output units 100a and 100b.

  FIG. 6 shows the operation of the high precision signal output units 100a and 100b. Specifically, FIG. 6A shows the transition of the IG signal, FIG. 6B shows the transition of the open / close state of the cutoff circuit 97, and FIGS. 6C to 6F respectively. The transition of the open / close state of each of the switching elements S1 to S4 is shown. Further, FIG. 6G shows the transition of the on / off state of the microcomputer 40.

  As shown in FIG. 6, when the IG signal switches from the off state to the on state, the cutoff circuit 97 is closed. As a result, the compensating unit 122 of FIG. 5 alternately turns on the switching elements S2 and S3 and the switching elements S1 and S4. When the IG signal switches from the off state to the on state, the power supply unit 96 shown in FIG. 3 activates the microcomputer 40.

Here, the operation of the present embodiment will be described.
When the IG signal is in the ON state, the output signals of the high-accuracy signal output units 100a and 100b are sampled by the A / D converters 62 and 64 in the microcomputer 40, and the steering angle calculation processing unit 68 turns the steering signals. The angle θp is calculated. The turning angle θp is used to calculate the torque command value Ta * for the motor 34.

  When the IG signal is turned off, the microcomputer 40 executes post-processing such as storing the turning angle θp in the nonvolatile memory 70, and then the power supply is cut off. Even at this time, the power supply to the rotation monitoring unit 38 is continued. Then, the rotation monitoring unit 38 calculates the rotation amount Δθ of the rotation shaft 34a of the motor 34 as the counter value of the counter 92 based on the output signals of the low-precision signal output units 80a and 80b. Here, an offset error is superimposed on the output signals of the low-precision signal output units 80a and 80b. However, this error is slight in determining whether the rotation angle of the rotation shaft 34a is in the first quadrant to the fourth quadrant based on the outputs of the first reference comparators 86a and 88a and the second reference comparators 88b and 88b. It only gives an error. Therefore, although the rotation monitoring unit 38 may erroneously recognize the state in the first quadrant as being in the second quadrant, the rotation monitoring unit 38 is equal to the actual quadrant while the rotation shaft 34a rotates 90 degrees or more. Recognize that you are in the quadrant. Therefore, the counter value of the counter 92 sets the detection error of the rotation amount Δθ of the rotating shaft 34a to less than 90 °.

  Then, when the IG signal is switched to the ON state and the microcomputer 40 is activated, the microcomputer 40 takes in the rotation amount Δθ by the A / D converter 66 and sets the turning angle θp stored in the nonvolatile memory 70. It is updated with the rotation amount Δθ. Here, the turning angle calculation processing unit 68 of the microcomputer 40 analyzes the output signals of the high precision signal output units 100a and 100b at a resolution far higher than the resolution of the rotation amount Δθ. Therefore, after the steered angle θp stored in the non-volatile memory 70 is updated by the rotation amount Δθ, the steered angle θp is further corrected based on the latest output signals of the high-accuracy signal output units 100a and 100b. As a result, the turning angle θp can be set to a highly accurate value according to the resolution of the output signals of the high accuracy signal output units 100a and 100b.

Moreover, when the IG signal is off, the power supply to the high-accuracy signal output units 100a and 100b is cut off.
According to the present embodiment described above, the effects described below can be obtained.

  (1) The high-precision signal output units 100a and 100b and the low-precision signal output units 80a and 80b are provided, and power is supplied to the high-precision signal output units 100a and 100b on condition that the IG signal is in the off state. Shut off. This makes it possible to generate a highly accurate angle signal when the IG signal is in the on state and suppress an increase in power consumption when the permission signal is in the off state.

  (2) The low-accuracy signal output units 80a and 80b are configured by circuits independent of the high-accuracy signal output units 100a and 100b. As a result, the operating time of the high-accuracy signal output units 100a and 100b can be reduced as compared with the case where the low-accuracy signal output units 80a and 80b partially share the circuit of the high-accuracy signal output units 100a and 100b. Therefore, it is possible to suppress the aged deterioration of the high precision signal output units 100a and 100b.

  (3) The power supply to the microcomputer 40 is cut off on condition that the IG signal is in the off state. Therefore, power consumption can be reduced as compared with the case where the power is not cut off.

  (4) When the power supply to the microcomputer 40 is started by switching the IG signal from the off state to the on state, the turning angle calculation processing unit 68 is stored in the nonvolatile memory 70 based on the rotation amount Δθ. The steering angle θp was updated. As a result, even when the rotary shaft 34a rotates while the IG signal is in the off state, it is possible to calculate the turning angle θp when the IG signal is switched to the on state.

<Second Embodiment>
Hereinafter, a second embodiment of the steering control device will be described with reference to the drawings, focusing on differences from the first embodiment.

  FIG. 7 shows configurations of the low-precision signal output units 80a and 80b and the high-precision signal output units 100a and 100b according to the present embodiment. Note that, in FIG. 7, components corresponding to the circuits shown in FIG. 5 are denoted by the same reference numerals for convenience.

  As shown in FIG. 7, in the present embodiment, some parts are shared by the first reference low-accuracy signal output unit 80a and the first reference high-accuracy signal output unit 100a, and the second reference low-accuracy signal is output. Some components are shared by the output unit 80b and the second reference high-precision signal output unit 100b.

  More specifically, in the present embodiment, the low-precision signal output units 80a and 80b and the high-precision signal output units 100a and 100b share a non-inverting amplifier circuit as an amplifier for signal amplification, which includes the operational amplifier 102. It has become. Then, the selective cutoff circuit 128 cuts off the power supply to the compensation circuit 120 while continuing the power supply to the low precision signal output units 80a and 80b.

  As shown in FIG. 8, the selection cutoff circuit 128 is opened and closed by the stop processing unit 98. FIG. 8 shows the rotation monitoring unit 38 according to this embodiment. Note that, in FIG. 8, parts corresponding to the parts shown in FIG. 3 are denoted by the same reference numerals for convenience.

Here, the operation of the present embodiment will be described.
When the IG signal is turned off, the stop processing unit 98 switches the selection cutoff circuit 128 to the open state. In this case, the compensation circuit 120 does not operate. Therefore, among the circuits forming the high-accuracy signal output units 100a and 100b, the operational amplifier 102 is the only circuit that can continue to operate and operate. Therefore, only the low precision signal output units 80a and 80b are provided. In this case, as shown in FIG. 8, the output signals of the low-precision signal output units 80a and 80b are output not only to the first reference comparators 86a and 88a and the second reference comparators 86b and 88b but also to the interface 94. To be done. However, the interface 94 does not output the detection results of the first reference sensor 36a and the second reference sensor 36b to the microcomputer 40 when the IG signal is in the off state.

  On the other hand, when the IG signal is switched to the ON state, the stop processing unit 98 switches the selection cutoff circuit 128 to the closed state. In this case, since the compensation circuit 120 operates, the output signal of the operational amplifier 102 becomes a highly accurate signal with a reduced offset voltage. Then, this signal is output to the microcomputer 40 via the interface 94.

According to the present embodiment described above, in addition to the effects (1), (3), and (4) of the first embodiment, the following effects can be obtained.
(5) When the signal amplification amplifier (op amp 102, resistors 104 and 106) is shared by the high precision signal output units 100a and 100b and the low precision signal output units 80a and 80b, and the IG signal is in the off state, The selective cutoff circuit 128 was operated to cut off the power supply to the compensation circuit 120. As a result, power consumption can be reduced as compared with the case where the power is not cut off. Moreover, since the high-precision signal output units 100a and 100b and the low-precision signal output units 80a and 80b share the signal amplification amplifier, it is easy to reduce the circuit scale of the steering control device.

<Other embodiments>
Note that at least one of the items in the above-described embodiment may be changed as follows. In the following, there is a portion exemplifying the correspondence relationship between the matters described in the section “Means for solving the problem” and the matters in the above-mentioned embodiment by the reference numerals and the like. Is not intended to be limited. The permission signal described in the section “Means for solving the problem” corresponds to the IG signal. The rotation amount detection processing unit corresponds to the first reference comparators 86a and 88a, the second reference comparators 86b and 88b, the rotation direction detection processing unit 90, and the counter 92.

・ About the compensation circuit (120)
It is not limited to the example illustrated in FIG. 7. For example, the one illustrated in FIG. 9 may be used. In FIG. 9, members corresponding to those shown in FIG. 7 are designated by the same reference numerals for convenience. As shown in FIG. 9, the correction voltage generator 124 includes switching elements S5 to S7, an A / D converter 130, a gain adjuster 131, a register 132, an oscillator 134, and a D / A converter 136. Is equipped with. The A / D converter 130 converts the output voltage of the operational amplifier 102 applied via the switching element S7 into digital data. The gain adjuster 131 multiplies the output of the A / D converter 130 by a predetermined gain Gc. The register 132 holds the output of the gain adjuster 131. The oscillator 134 outputs a clock signal to the A / D converter 130 and the register 132. The D / A converter 136 converts the output of the register 132 into analog data and applies it to the terminal TB of the operational amplifier 102. The switching element S5 short-circuits the inverting input terminal and the non-inverting input terminal of the operational amplifier 102. The switching element S6 opens and closes between the non-inverting input terminal of the operational amplifier 102 and the input terminal Tin.

  Here, when the output voltage Vout of the operational amplifier 102 is set to (c2) above, the gain Gc is set to “1 / Gb”. The output voltage Vout of the operational amplifier 102 when the switching element S5 is in the closed state and the switching element S6 is in the open state is “Ga · ΔVo”. However, during this period, no voltage is applied to the terminal TB. After that, when the switching element S5 is in the open state and the switching element S6 is in the closed state, the output voltage Vout of the operational amplifier 102 is given by the following expression (c7).

Vout = Ga · {V (+) − V (−) + ΔVo} −Ga · ΔVo
= Ga · {V (+)-V (-)} (c7)
In FIG. 9, when the IG signal is in the off state, the power supply to the compensation circuit 120 is cut off.

  Incidentally, at this time, it is not essential that all of the compensation circuit 120 be built in the rotation monitoring unit 38. For example, the functions of the A / D converter 130, the gain adjuster 131, the register 132, and the oscillator 134 may be realized by the microcomputer 40.

・ About high-precision signal output section (100a, 100b)
In the first embodiment, the circuit shown in FIG. 9 may be used instead of the circuit shown in FIG. However, in this case, the low-accuracy signal output unit is as shown in FIG. 4, and is not the operational amplifier 102 and the resistors 104 and 106 in FIG.

  In the first embodiment, instead of using the operational amplifier 102 as the signal amplifying amplifier of the high precision signal output section with the same specifications as the operational amplifier 82 as the signal amplifying amplifier of the low precision signal output section, The specifications may be different from each other.

  Instead of using the operational amplifier 102 to configure the non-inverting amplifier circuit, an inverting amplifier circuit may be configured. At this time, in the low-precision signal output units 80a and 80b, the operational amplifier 82 may be used to configure a non-inverting amplifier circuit.

・ "Low precision signal output section (80a, 80b)"
Instead of using the operational amplifier 82 to configure the non-inverting amplifier circuit, an inverting amplifier circuit may be configured. At this time, in the high-precision signal output units 100a and 100b, the non-inverting amplifier circuit may be left as it is by using the operational amplifier 102, or the inverting amplifier circuit may be configured.

Note that a circuit may be provided that shuts off the power supply to the low-accuracy signal output units 80a and 80b on condition that the IG signal is turned on.
・ About the rotation monitor (38)
The rotation monitoring unit 38 is not limited to the ASIC. For example, it may be configured by hardware that executes software processing.

・ About the control unit (40)
In the above embodiment, the power supply to the microcomputer 40 is cut off on the condition that the IG signal is in the off state, but the present invention is not limited to this. For example, the microcomputer 40 may remain activated in the low power consumption mode compared to when the IG signal is in the on state. In this case, it is desirable that the microcomputer 40 does not have the ability to activate at least one of the A / D converters 62 and 64 and the turning angle calculation processing unit 68 in the low power consumption mode. .. In other words, if the microcomputer 40 does not have the ability to enter the startup state, the IG signal is turned off, and the microcomputer 40 cannot calculate the steering angle θp. Therefore, the rotation monitoring unit 38 detects the rotation amount Δθ. Is effective.

・ About the memory (70)
Not limited to the nonvolatile memory 70, for example, a backup volatile memory that continues power supply even when the main power supply of the microcomputer 40 is in an off state may be used.

-"Rotation axis (34a), rotation angle sensor (36a, 36b)"
The rotating shaft that steers the steered wheels 26 by rotating and whose rotation angle is the detection target of the rotation angle sensor is not limited to the rotation shaft 34a of the motor 34, but is, for example, the rotation angle of the pinion shaft 28. May be.

-"Rotation direction detection processing unit (90)"
The invention is not limited to the one in which the rotation direction of the unit rotation amount is specified based on the determination result of whether the sensor output value by the comparator is within a predetermined range. For example, an A / D converter having a lower resolution than the A / D converters 62, 64, 66 may be mounted on the rotation monitoring unit 38, and the rotation direction of the unit rotation amount may be specified based on the output value thereof.

・ "Controlling the vehicle using the turning angle θp"
It is not limited to steering assist control. For example, it may be skid prevention control of the vehicle. In this case, for example, an external electronic device other than the microcomputer 40 may execute the skid prevention control. In this case, when the IG signal is switched to the ON state, the microcomputer 40 may transmit the steering angle θp updated by the rotation amount Δθ to the external electronic device.

・ "Other"
The steering mechanism is not limited to the one illustrated in FIG. For example, the motor 34 may be connected to a speed reduction mechanism connected to the steering shaft 12. Further, for example, a steering angle ratio variable mechanism capable of variably controlling the ratio of the steering angle that is the rotation angle of the steering wheel 10 to the steered angle θp may be mounted. Further, a steer-by-wire system in which the steering 10 and the rack shaft 20 are separated may be used.

Note that the rack and pinion mechanism is not the only option.
The torque sensor 52 is not limited to the one that detects the torque applied to the pinion shaft 18. For example, the torque applied to the column shaft 14 may be detected.

  10 ... Steering, 12 ... Steering shaft, 14 ... Column shaft, 16 ... Intermediate shaft, 18 ... Pinion shaft, 18a ... Pinion teeth, 20 ... Rack shaft, 20a ... 1st rack tooth, 20b ... 2nd rack tooth, 22 ... First rack and pinion mechanism, 24 ... Tie rod, 26 ... Steering wheel, 28 ... Pinion shaft, 28a ... Pinion teeth, 30 ... Second rack and pinion mechanism, 32 ... Reduction mechanism, 34 ... Motor, 34a ... Rotating shaft, 36a ... 1st reference sensor, 36b ... 2nd reference sensor, 38 ... Rotation monitoring part, 40 ... Microcomputer, 42 ... Inverter, 50 ... Torsion bar, 52 ... Torque sensor, 54 ... Battery, 56 ... Vehicle speed sensor, 60 ... Base value Setting processing unit, 62, 64, 66 ... A / D converter, 68 ... Steering angle calculation processing unit, 70 ... Non-volatile memory, 72 ... Target steering angle setting process Section, 74 ... Feedback processing section, 76 ... Correction processing section, 78 ... Operation processing section, 80a, 80b ... Low precision signal output section, 83 ... Resistor, 82 ... Operational amplifier, 86a, 88a ... First reference comparator, 84 ... Resistors, 86b, 88b ... Second reference comparator, 90 ... Rotation direction detection processing section, 92 ... Counter, 94 ... Interface, 96 ... Power supply section, 97 ... Break circuit, 98 ... Stop processing section, 100a, 100b ... High accuracy Signal output unit, 102 ... Operational amplifier, 104, 106 ... Resistor, 120 ... Compensation circuit, 122 ... Compensation unit, 124 ... Correction voltage generation unit, 126 ... Operational amplifier, 128 ... Selective cutoff circuit, 130 ... A / D converter, 132 ... Register, 134 ... Oscillator, 136 ... D / A converter.

Claims (6)

A control unit,
At least a rotation monitoring unit to which electric power is supplied when the permission signal that is a permission condition for traveling of the vehicle is in an off state,
An output signal of a rotation angle sensor that detects the rotation angle of the rotation shaft is input and the output signal is amplified to obtain a signal corresponding to an angle within one rotation of the rotation shaft and having a high accuracy. High-accuracy signal output section to output,
A stop processing unit that stops power supply to the high-accuracy signal output unit on condition that the permission signal is in an off state,
The rotating shaft turns the steered wheels of the vehicle by rotating,
The rotation monitoring unit inputs the output signal of the rotation angle sensor, which receives the output signal to the high-accuracy signal output unit, and amplifies the output signal so that the rotation angle of the rotation shaft is within one rotation. The permission signal is in an off state based on the output value of the low-precision signal output unit that outputs a signal with a lower precision than the high-precision signal output unit and the output signal of the low-precision signal output unit. A rotation amount detection processing unit that detects a rotation amount of the rotating shaft in an off period that is a period,
When the permission signal is in the ON state, the control unit determines the steered angle of the steered wheels of the vehicle based on the output value of the high precision signal output unit and the rotation amount detected by the rotation amount detection processing unit. Equipped with a steering angle calculation processing unit to calculate ,
The high-precision signal output unit includes a signal amplification amplifier that amplifies an output signal of a rotation angle sensor that detects a rotation angle of the rotation shaft, and a compensation circuit that compensates an offset error of the signal amplification amplifier. ,
The steering control device, wherein the low-precision signal output unit includes a signal amplification amplifier that amplifies an output signal of a rotation angle sensor that detects a rotation angle of the rotation shaft .
A control unit,
At least a rotation monitoring unit to which electric power is supplied when the permission signal that is a permission condition for traveling of the vehicle is in an off state,
A high-accuracy signal output unit that outputs a high-accuracy signal that is a signal corresponding to the angle within one rotation of the rotating shaft;
A stop processing unit that stops power supply to the high-accuracy signal output unit on condition that the permission signal is in an off state,
The rotating shaft turns the steered wheels of the vehicle by rotating,
The rotation monitoring unit outputs a low-precision signal output unit that outputs a signal having a lower precision than that of the high-precision signal output unit, the low-precision signal output unit outputting the low-precision signal that is a signal corresponding to the angle of the rotation shaft within one rotation. A rotation amount detection processing unit that detects a rotation amount of the rotating shaft in an off period, which is a period in which the permission signal is in an off state, based on an output value of the output unit;
When the permission signal is in the ON state, the control unit determines the steered angle of the steered wheels of the vehicle based on the output value of the high precision signal output unit and the rotation amount detected by the rotation amount detection processing unit. Equipped with a steering angle calculation processing unit to calculate,
The high-precision signal output unit includes a signal amplification amplifier that amplifies an output signal of a rotation angle sensor that detects a rotation angle of the rotation shaft, and a compensation circuit that compensates an offset error of the signal amplification amplifier. ,
The low-precision signal output unit includes a signal amplification amplifier that amplifies an output signal of a rotation angle sensor that detects a rotation angle of the rotation shaft,
The signal amplification amplifier included in the high precision signal output unit and the signal amplification amplifier included in the low precision signal output unit are shared by the high precision signal output unit and the low precision signal output unit. One signal amplification amplifier,
A selection cutoff circuit for cutting off power supply to the compensation circuit in a state where power supply to the signal amplification amplifier is continued,
The stop processing unit cuts off the power supply to the compensation circuit in a state where the selection cutoff circuit is operated and the power supply to the signal amplification amplifier is continued, on condition that the permission signal is in the off state. steering control device for.   The steering control device according to claim 1, wherein the low-accuracy signal output unit is configured by a circuit independent of the high-accuracy signal output unit.   The steering control device according to claim 1, wherein the control unit cuts off power supply on condition that the permission signal is in an off state. The control unit includes a storage unit that stores the turning angle calculated by the turning angle calculation processing unit,
When the permission signal is switched from the off state to the on state to start the power supply, the turning angle calculation processing unit stores in the storage unit based on the rotation amount detected by the rotation amount detection processing unit. The steering control device according to claim 4, wherein the steered steering angle is updated. The rotation amount detection processing unit detects the rotation of the unit rotation amount based on the output of the low precision signal output unit, specifies the rotation direction, and detects the rotation of the unit rotation amount and the rotation direction. A rotation direction detection processing unit that outputs a signal that indicates, and a counter that updates the integrated amount of the unit rotation amount based on the output value of the rotation direction detection processing unit,
The resolution according to the unit rotation amount is lower than the resolution when the control unit grasps the rotation angle of the rotation shaft based on the output of the high-accuracy signal output unit. Steering control device.