Steering control device

Abstract

The present invention relates to a steering control device. A servo controller (400) operates a basic command value of assist torque, i.e., a basic assist command (Tb*), so that a steering operation torque (Ts) follows a target steering operation torque (Ts*). An estimated load torque operation section (20) operates an estimated load torque (Tx). A target steering operation torque operation section (30) operates the target steering operation torque (Ts*) using a map (33) that defines a relationship between the estimated load torque (Tx) and the target steering operation torque (Ts*). The estimated load torque operation section (30) operates the estimated load torque (Tx) based on the steering operation torque (Ts) or the target steering operation torque (Ts*), and an estimated load operation assist command (Tbx*) that corresponds to an operation result of only proportional integral control operation in control operation in the servo controller (400).

Description

[0001] Cross-references to related applications

[0002] This application is based on Japanese Application No. 2021-094147, filed on June 4, 2021, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to steering control devices. Background Technology

[0004] Conventionally, there are known techniques in steering devices that control the auxiliary torque output of a motor, where a target steering torque is calculated based on an estimated load torque, and a servo controller calculates basic auxiliary commands to make the steering torque follow the target steering torque. For example, in the steering control device disclosed in Patent Document 1, the target generation unit calculates the target steering torque (Ts) * ) and basic auxiliary commands (Tb * The estimated load torque (road reaction force in Patent Document 1) is calculated by adding the values ​​of the estimated load torque and the target torque generator. The target torque generator uses a mapping that specifies the value of the target steering torque for the estimated load torque to calculate the target steering torque.

[0005] In addition, in the steering control device disclosed in Patent Document 2, the servo controller (an auxiliary controller in Patent Document 2) generates basic auxiliary commands through PID control so that the steering torque follows the target steering torque.

[0006] Patent Document 1: Japanese Patent No. 6314752

[0007] Patent Document 2: Japanese Patent No. 6252027

[0008] The target steering torque is obtained by interpolation using a mapping. If the estimated load torque, which is the input to the mapping, changes during steering, the output change is constant relative to the input change within the interpolation interval, but the gradient changes at the inflection point of the mapping, so the time rate of change of the output changes drastically.

[0009] For example, when the mapping is adapted to achieve the desired steering feel and action, the gradient change at the mapping inflection point can sometimes be large, especially in the small signal region where the estimated load torque is close to zero. If the gradient change is large at the mapping inflection point, the differential output of the servo controller changes when passing through that point, resulting in a change in the basic auxiliary command. Moreover, during the calculation of the target steering torque in the next operation cycle using the feedback basic auxiliary command, impulse noise is generated, which excites the motor and may produce a rattling sound. Summary of the Invention

[0010] The purpose of this disclosure is to provide a steering control device that prevents clicking noise caused by impulse noise even when the gradient change at the inflection point of the mapping between the estimated load torque and the target steering torque is large.

[0011] This disclosure relates to a steering control device that controls the auxiliary torque output of a motor connected to a steering control system mechanism that generates steering torque, and includes a servo controller, an estimated load torque calculation unit, and a target steering torque calculation unit.

[0012] The servo controller calculates the basic instruction value of the auxiliary torque, which is also the basic auxiliary instruction, so that the steering torque follows the target steering torque.

[0013] The estimated load torque calculation unit calculates the load torque, which acts on the steering shaft of the steering system mechanism and varies according to steering input; that is, the estimated load torque. The target steering torque calculation unit calculates the target steering torque using a mapping that defines the relationship between the estimated load torque and the target steering torque.

[0014] The estimated load torque calculation unit calculates the estimated load torque based on the steering control torque or target steering control torque and the estimated load calculation auxiliary instruction. This estimated load calculation auxiliary instruction is equivalent to the calculation result of the proportional-integral control calculation in the control calculation of the servo controller.

[0015] Therefore, in this disclosure, even when the gradient change is large at the mapping inflection point in the small signal region, there will be no steep pulses overlapping with the basic auxiliary command. Thus, steering vibrations such as clicking noises can be prevented, resulting in low-vibration, smooth operation. This increases the degrees of freedom during adaptation. Furthermore, the low-pass filter in the load torque estimation unit can be changed from a second-order filter to a first-order filter, simplifying the computational processing. Attached Figure Description

[0016] The foregoing objects, other objects, features, and advantages of this disclosure will become more apparent from the accompanying drawings and from the following detailed description. In the drawings:

[0017] Figure 1 This is a schematic diagram of an electric power steering system.

[0018] Figure 2 This is a schematic structural diagram of the ECU (Electronic Steering Control Unit) according to the first embodiment.

[0019] Figure 3 This is a magnified view of the small-signal region of the estimated load torque-target steering torque mapping.

[0020] Figure 4 This diagram illustrates the underlying principles behind problems arising from mapping operations.

[0021] Figure 5 Yes Figure 4 Supplementary timing diagrams,

[0022] Figure 6 This is a block diagram of the servo controller according to the first embodiment.

[0023] Figure 7 This is a timing diagram showing the actual vehicle behavior of a comparative example (typical PID control).

[0024] Figure 8 This is a timing diagram illustrating the actual vehicle movements in this embodiment.

[0025] Figure 9 This is a schematic structural diagram of the ECU (Engine Control Unit) according to the second embodiment. Detailed Implementation

[0026] Several embodiments of the steering control device will be described based on the accompanying drawings. The ECU, serving as the "steering control device," is applied to the electric power steering system of a vehicle and calculates the output commands of the motor. In the following embodiments, examples applied to an electric power steering system are primarily shown. In the electric power steering system, the steering control device outputs auxiliary torque commands to the steering assist motor. The following first and second embodiments are collectively referred to as "this embodiment."

[0027] [Structure of Electric Power Steering System]

[0028] Reference Figure 1 The structure of the electric power steering system is explained. Furthermore, the auxiliary torque Ta and the basic auxiliary command Tb are discussed. * Symbol reference Figure 2 The electric power steering system 1 is a system that assists the driver in operating the steering wheel 91 using the driving torque of the motor 80. The steering wheel 91 is fixed to one end of the steering shaft 92, and an intermediate shaft 93 is provided at the other end of the steering shaft 92. The steering shaft 92 and the intermediate shaft 93 are connected by a torsion bar of the torque sensor 94, forming a steering control shaft 95. The torque sensor 94 detects the steering torque Ts based on the torsion angle of the torsion bar.

[0029] A gearbox 96, comprising a pinion 961 and a rack 962, is located at the end of the intermediate shaft 93 opposite to the torque sensor 94. When the driver turns the steering wheel 91, the pinion 961 rotates together with the intermediate shaft 93, and the rack 962 moves left and right as the pinion 961 rotates. Steering tie rods 97, located at both ends of the rack 962, are connected to the tires 99 via steering knuckle arms 98. The steering tie rods 97 reciprocate left and right, pulling or pushing the steering knuckle arms 98, thereby changing the direction of the tires 99.

[0030] Motor 80 is, for example, a three-phase AC brushless motor, which outputs an auxiliary torque Ta to assist the steering force of the steering wheel 91 based on the drive voltage Vd output from ECU 10. In the case of a three-phase AC motor, the drive voltage Vd refers to the voltage of each of the U-phase, V-phase, and W-phase. The rotation of motor 80 is transmitted to intermediate shaft 93 via a reduction mechanism 85 consisting of worm gear 86 and worm wheel 87. Furthermore, the rotation of intermediate shaft 93 caused by steering operation of steering wheel 91 and reaction force from the road surface is transmitted to motor 80 via reduction mechanism 85.

[0031] also, Figure 1 The electric power steering system 1 shown is a column-assisted type that transmits the rotation of the motor 80 to the steering control shaft 95, but the ECU 10 of this embodiment can also be applied to a rack-assisted type electric power steering system. Furthermore, in other embodiments, a multi-phase AC motor other than a three-phase motor or a brushed DC motor can be used as the steering control assist motor.

[0032] Here, the mechanism that transmits the steering force from the steering wheel 91 to the tire 99 is collectively referred to as the "steering control system mechanism 100". The ECU 10 controls the steering torque Ts generated by the steering control system mechanism 100 by controlling the auxiliary torque Ta output by the motor 80 connected to the steering control system mechanism 100. In addition, the ECU 10 acquires the vehicle speed V detected by the vehicle speed sensor 11 located at a specified part of the vehicle.

[0033] The ECU 10 operates using power from an on-board battery (not shown). Based on the steering torque Ts detected by the torque sensor 94 and the vehicle speed V detected by the vehicle speed sensor 11, it calculates the basic auxiliary torque command value, i.e., the basic auxiliary command Tb. * In this embodiment, the basic auxiliary instruction Tb is not included. * Add a correction torque while maintaining the original output of the basic auxiliary command Tb. * This is the commanded value of the auxiliary torque Ta.

[0034] By applying the basic auxiliary command Tb to the motor 80 * The calculated drive voltage Vd causes the motor 80 to output an auxiliary torque Ta, which in turn causes the steering system mechanism 100 to generate a steering torque Ts. Furthermore, the various calculations and processing in the ECU 10 can be either software processing based on programs pre-stored in physical memory devices such as ROM executed by the CPU, or hardware processing based on dedicated electronic circuits.

[0035] [ECU Structure]

[0036] (First Implementation)

[0037] Reference Figure 2 The structure of the ECU 10 according to the first embodiment will be described. The ECU 10 includes: a load torque estimation calculation unit 20, a target steering torque calculation unit 30, a deviation calculator 39, a servo controller 400, and a current feedback ("FB" in the figure) unit 70, etc.

[0038] The load torque estimation calculation unit 20 estimates the target steering control torque Ts. * And the auxiliary instruction Tbx for load estimation calculation * This is used to calculate and estimate the load torque Tx. In other words, relative to Patent Document 1... Figure 3 In terms of structure, it replaces the basic auxiliary instruction Tb * The auxiliary instruction Tbx for load estimation calculation is used. * The estimated load torque Tx is the load torque acting on the steering shaft 95 of the steering system mechanism 100 and varying according to steering operation. The signs of the estimated load torque Tx and steering torque Ts are defined according to the rotation direction of the steering shaft 95: torque in one direction of rotation is positive, and torque in the opposite direction is negative.

[0039] The load torque estimation calculation unit 20 includes an adder 21 and a low-pass filter (LPF) 22 in the figure. The adder 21 takes the estimated load calculation auxiliary instruction Tbx fed back from the servo controller 400. * The target steering torque Ts fed back from the target steering torque calculation unit 30 * Add. The load estimation operation uses the auxiliary instruction Tbx. * This is equivalent to the result of the proportional-integral control operation in the servo controller 400, excluding the derivative control operation. (Refer to...) Figure 6 The auxiliary instruction Tbx for load estimation calculation will be discussed later. * Details.

[0040] The low-pass filter 22 extracts components of a specified frequency band, such as below 10 Hz, from the summed torques. The load torque estimation unit 20 outputs the frequency components extracted by the low-pass filter 22 as the estimated load torque Tx.

[0041] The target steering torque calculation unit 30 uses the estimated load torque Tx and the target steering torque Ts as specified. * The mapping of the relationship 33 is used to calculate the target steering torque Ts. *The target steering torque calculation unit 30 includes: a sign determination unit (“sgn” in the figure) 31, an absolute value determination unit (“|u|” in the figure) 32, a mapper 33, and a multiplier 34. The sign determination unit 31 determines the sign of the estimated load torque Tx, that is, the sign corresponding to the rotation direction of the steering shaft 95. The absolute value determination unit 32 calculates the input u, that is, the absolute value of the estimated load torque Tx.

[0042] Mapping 33 is represented as the mapping of the estimated load torque Tx in the positive region, i.e., the mapping of its absolute value. In the negative region of the estimated load torque Tx, it becomes a mapping symmetrical about the origin of the positive region. Target steering torque Ts * It is positively correlated with the estimated load torque Tx, and increases in a logarithmic manner as the estimated load torque Tx increases.

[0043] Specifically, for each vehicle speed V, the target steering torque Ts is represented by a connection for a specific value of the estimated load torque Tx. * The polyline representation of the value at multiple points is mapped 33, and the target steering torque Ts for any estimated load torque Tx is obtained through interpolation operations on mapping 33. * The higher the vehicle speed V, the greater the target steering torque Ts for the same estimated load torque Tx. * The larger the value, the more likely it is to be mapped to the horizontal axis of 33, which is also the range of the estimated load torque Tx, approximately 0–30 [Nm], and the target steering torque Ts. * The range is approximately 0–6 [Nm].

[0044] Figure 3 express Figure 2 The small-signal region in mapping 33, where the estimated load torque Tx is close to 0, is amplified as shown. This mapping 33 adapts the small-signal region to obtain the desired steering feel and action. The result of this adaptation is that at the inflection point where the estimated load torque Tx is 0.3 [Nm], the target steering torque Ts... * The rate of change increases, and the curvature is greater. At other inflection points, the second derivative value is negative, while at this inflection point, the second derivative value is positive. Furthermore, at the inflection point where the estimated load torque Tx is 1 [Nm], the target steering torque Ts... * The rate of change decreases sharply, and the curvature is significant. (Refer to...) Figure 4 , Figure 5 The effects of greater curvature at such inflection points will be discussed later.

[0045] Return to Figure 2 The target steering torque Ts is obtained by mapping the absolute value of the estimated load torque Tx to the multiplier 34. *The absolute value is multiplied by the sign corresponding to the estimated load torque Tx. The target steering torque Ts output by the target steering torque calculation unit 30. * The data is input into the deviation calculator 39 and fed back to the estimated load torque calculation unit 20.

[0046] Deviation Calculator 39 calculates the target steering torque Ts * The difference between the steering torque and the steering torque Ts is the steering torque deviation ΔT (=Ts) * -Ts). Input steering torque deviation ΔT to servo controller 400. Servo controller 400 calculates basic auxiliary instruction Tb. * So that the steering torque Ts follows the target steering torque Ts * . Reference Figure 6 The detailed structure of the servo controller 400 in this embodiment will be described later.

[0047] The current feedback unit 70 applies a drive voltage Vd to the motor 80 to provide a basic auxiliary command Tb, particularly to the steering control shaft 95, which is located closer to the tire 99 than the torque sensor 94. * The corresponding auxiliary torque. Current feedback control is a well-known technique in the field of motor control, so a detailed explanation is omitted.

[0048] Next, refer to Figure 4 , Figure 5 The principle behind the problems arising from the mapping calculations in the target steering torque calculation unit 30 is explained. Figure 4 This shows the estimated load torque Tx and target steering torque Ts. * The mapping pattern is illustrated in the diagram. As shown by the dashed arrow, consider the case where the estimated load torque Tx increases monotonically, and the action point on the mapping moves from point A to point B. Here, it is assumed that the basic auxiliary command Tb... * Feedback is sent to the load torque estimation calculation unit 20.

[0049] If the estimated load torque Tx increases linearly, the target steering torque Ts * and the differential D(Ts) of the target steering torque * Changes such as Figure 5 As shown in the time waveform. In this case, the differential D(Ts) of the target steering torque. * That is, the gradient change of the mapping is not an impulse but a step-like change. However, when the basic auxiliary command Tb, which contains the differential control component of the steering torque deviation ΔT, is fed back from the servo controller 400 to the load torque estimation calculation unit 20, it is... * When the loop is closed, the following phenomenon occurs.

[0050] exist Figure 4 When the estimated load torque Tx changes from time n to the next time (n+1), the signal from the servo controller 400 mainly consists of a relatively large step change in the derivative control component. At this time, if the estimated load torque Tx increases, the steering torque deviation ΔT increases, and the derivative of the steering torque deviation D(ΔT) is positive. Furthermore, as described later, the derivative gain Kd in the PID control formula is negative, so the basic auxiliary command Tb... * The trend is towards decreasing.

[0051] Thus, at the next time step (n+2), based on the reduced basic auxiliary instruction Tb * The calculated estimated load torque Tx decreases. Then, the target steering torque Ts is calculated based on this estimated load torque Tx. * It becomes smaller compared to the previous value at time (n+1). Therefore, the differential D(Ts) of the target steering torque is smaller. * The derivative of the previous step change changes in the opposite direction, resulting in a pulse. This serves as the basic auxiliary instruction Tb. * Impulse noise appears.

[0052] Thus, especially if the gradient change is large at the inflection point of the mapping in the small signal region, due to the basic auxiliary instruction Tb * The vibration of motor 80 due to pulse noise may produce a clicking sound. Here, by taking a larger number of mapped points and adapting to make the changes smoother, it is possible to eliminate the sound and vibration. However, this requires trial and error during repeated adaptation and sound and vibration evaluation, thus limiting the adaptation process. Therefore, in this embodiment, the objective is to estimate both the load torque Tx and the target steering torque Ts. * The gradient change at the inflection point of the mapping is large, which also prevents the clicking sound caused by the generation of impulse noise.

[0053] Figure 6 The structure of a servo controller 400 according to a first embodiment for solving this problem is shown. The servo controller 400 includes: a proportional-integral control arithmetic unit 420, a derivative control arithmetic unit 50, a final adder 58, and a final limit arithmetic unit 59. Figure 6 The structure is shown after performing an equivalent transformation of the servo control calculation in a discrete manner. The servo controller 400 of the first embodiment calculates the auxiliary instruction Tbx for load estimation using proportional-integral control calculation. * Furthermore, the calculation results based on differential control operations are compared with the estimated load calculation using the auxiliary instruction Tbx. * The basic auxiliary instruction Tb for addition operations * In other words, the load estimation calculation is performed using the auxiliary instruction Tbx via a servo controller 400.* and basic auxiliary commands Tb * both sides.

[0054] The proportional-integral control arithmetic unit 420 includes a proportional control arithmetic unit 430, an integral control arithmetic unit 440, an adder 48, and an accumulation processing unit 490. The proportional control arithmetic unit 430 and the integral control arithmetic unit 440 are similar to those in Patent Document 2. Figure 4 The disclosed auxiliary controller structure is also based on proportional and integral control calculations performed on the steering torque deviation ΔT.

[0055] The delay element 45 retrieves the previous value of the steering torque deviation ΔT. In the proportional control calculation unit 430, the steering torque deviation ΔT, after the previous value has been subtracted by the subtractor 463, is multiplied by the proportional gain Kp by the gain multiplier 473. In the integral control calculation unit 440, the steering torque deviation ΔT, after the previous value has been added by the adder 464, is multiplied by the integral gain Ki by the gain multiplier 474.

[0056] Adder 48 outputs the target torque TM obtained by adding the proportional control and integral control components according to each control cycle. Here, the proportional control quantity alone is insufficient for estimating the load, and the integral control quantity alone has a large delay relative to the road reaction force, so it cannot be used. Accumulation processing unit 490 performs accumulation processing on the target torque TM and calculates the current value Tbx of the auxiliary command used for estimating the load. * n Although accumulation processing is synonymous with integral processing, the term "accumulation" is used here to distinguish it from integral control. Furthermore, while there are differences depending on the operational configuration of the proportional-integral control arithmetic unit, the output signal is generally a signal subjected to proportional-integral control.

[0057] The cumulative processing unit 490 includes an adder 491, a delay element 492, and a limit arithmetic unit 494. The adder 491 adds the current value of the torque TM to the value being processed, along with the previous value Tbx from the estimated load calculation auxiliary instruction input via the delay element 492. * n-1 The limiting arithmetic unit 494 limits the addition result of the adder 491 to a limit value that can be used as an auxiliary torque output. This addresses the integral saturation problem, i.e., the phenomenon where, after a series of deviations have occurred and the integral has taken a value larger than the allowable output, the output delay decreases when the sign of the deviation reverses.

[0058] The differential control calculation unit 50 includes a pseudo-differential calculation unit 54 and a gain multiplier 57. The pseudo-differential calculation unit 54 calculates the steering torque deviation differential D(ΔT) through pseudo-differential calculation. The discrete-valued pseudo-differential "D" is equivalent to (s / (τs+1)) in terms of the transfer function of a continuous system. 2 The operation function is ...

[0059] The current value Tbx of the auxiliary instructions used by the final adder 58 for load estimation operations * n Add the current value Kd·D(ΔT) of the output of the differential control arithmetic unit 50. n The final limiting unit 59, like the limiting unit 494, limits the addition result of the final adder 58. This limitation is unrelated to integral saturation, but corresponds to the limitations for overheat protection and fail-safe conditions.

[0060] The following is a formula for servo control. The steering torque deviation ΔT is expressed by formula (1).

[0061] ΔT=Ts*-Ts…(1)

[0062] The basic auxiliary instruction Tb is represented by equation (2). * .exist Figure 6 In the structure, the proportional gain Kp, integral gain Ki, and derivative gain Kd are all set to negative values.

[0063] [Number 1]

[0064]

[0065] To discretize equation (2), we substitute the bilinear transformation expressed by equation (3) into equation (2) and rearrange, resulting in equations (4.1) and (4.2). In equation (3), ts represents the computation period. Furthermore, in... Figure 6 In this context, the (ts / 2)Ki set is denoted as "Ki".

[0066] [Number 2]

[0067]

[0068]

[0069] Tb* n =Tbx* n +Kd·D(ΔT) n …(4.2)

[0070] As described above, in this embodiment, the servo controller 400 feeds back an auxiliary instruction Tbx for load estimation calculation that does not contain a differential control component to the load estimation torque calculation unit 20. * Therefore, the accompanying target steering torque Ts * The step change of gradient change and the basic auxiliary instruction Tb for feedback * The difference is smaller compared to the previous situation. Therefore, step changes are less likely to cycle in the closed loop and are less likely to appear as impulse noise. As a result, the excitation vibration of motor 80 can be suppressed.

[0071] Additionally, in the feedback of basic auxiliary command Tb * In the case of load torque calculation unit 20, the low-pass filter 22 is a second-order filter to remove the high-frequency components of servo control. However, since it does not contain differential control components, a first-order filter can be used to simplify the calculation process.

[0072] Next, refer to Figure 7 , Figure 8 The timing diagrams are used to illustrate the actual vehicle behavior in the comparative example and this embodiment when the steering wheel is turned left or right to change the steering torque Ts from positive to negative and from negative to positive. In the comparative example, a basic auxiliary command Tb is fed back from the servo controller performing normal PID control to the load torque estimation calculation unit 20. * Equation (5) represents the discrete form of a typical PID control.

[0073] [Number 3]

[0074]

[0075] exist Figure 7 , Figure 8 In the middle, from top to bottom, are shown the steering control angular velocity ω, steering control torque Ts, and target steering control torque Ts. * Steering torque deviation differential D(ΔT) and basic auxiliary command Tb * Furthermore, in this embodiment, the auxiliary instruction Tbx for load estimation calculation is shown at the bottom. * .

[0076] exist Figure 7 In the comparative example shown, the target steering torque Ts * In the small signal region near 0, through mapping ( Figure 3 When the bend is large, the target steering torque Ts * The change becomes larger. At this point, the differential control component of the fourth term in equation (5) changes stepwise. This stepwise change is also reflected in the basic auxiliary instruction Tb accumulated through equation (5). * .

[0077] If this basic auxiliary command Tb * Feedback to the estimated load torque calculation unit 20 will affect the target steering torque Ts in the next calculation. * This prevents change. The result is a change in the target steering torque Ts. * The changes produce a step, as shown in (*1) and (*2), the differential of steering torque deviation D(ΔT), and thus the basic auxiliary command Tb. * It becomes pulse-like, exciting motor 80.

[0078] The vibration caused by the pulsed current also affects the steering angular velocity ω calculated from the motor rotation angle, as shown in (*3), causing a change in the waveform. Furthermore, if we consider the direction of the vibration, it is opposite to the intended direction of motor rotation at 80°. Therefore, it acts as a reverse blockage through the gear backlash and clearance, easily causing a clicking sound.

[0079] exist Figure 8 In the embodiment shown, even if the target steering torque Ts * The target steering torque Ts is obtained by mapping the large bend point. * The changes are significant, due to the auxiliary instruction Tbx used in load estimation calculations. * It does not contain differential control components, so the stepwise changes are also smaller.

[0080] Therefore, the estimated load calculated using equation (4.1) is processed by the auxiliary instruction Tbx. * This becomes an instruction without impulse noise. Furthermore, the auxiliary instruction Tbx is used to calculate the load based on this estimated value. * The calculated estimated load torque Tx is used to calculate the target steering torque Ts. * The basic auxiliary instruction Tb determined in the loop system * This results in a command without pulse noise. Therefore, no clicking sound is generated in this embodiment, achieving low-noise and smooth actuator operation.

[0081] (Second Implementation)

[0082] Reference Figure 9 The structure of the ECU 10X in the second embodiment will be described mainly based on the differences from the first embodiment. Structures that are essentially the same as those in the first embodiment will be given the same reference numerals and their descriptions will be omitted. In the ECU 10X of the second embodiment, the servo controller 40B and the PI controller 40X are provided separately, instead of the servo controller 400 of the first embodiment.

[0083] The servo controller 40B calculates the basic auxiliary instruction Tb using PID control. *The structure of the servo controller 40B can, for example, be similar to that of Patent Document 2. Figure 4 The same applies. The PI controller 40X uses proportional-integral control operations, which do not involve derivative control operations, to estimate the load using the auxiliary instruction Tbx. * The auxiliary instruction Tbx is used for load estimation calculation. * This is equivalent to the result of only the proportional-integral control operation in the control calculation of the servo controller 40B. The structure of the PI controller 40X is similar to... Figure 6 The proportional-integral control calculation unit 420 is the same. Even with this separate structure, the same effect as the first embodiment can be obtained.

[0084] (Other implementation methods)

[0085] (a) The load torque estimation calculation unit 20 can also replace the target steering control torque Ts * The load torque Tx is estimated based on the steering torque Ts.

[0086] (b) Target steering torque Ts * Not only can the torque be calculated based on the estimated load torque Tx, but it can also include the steering torque corresponding to other state variables such as steering angle and steering angular velocity, or be corrected based on other state variables. For example, Japanese Patent No. 6387657 discloses a structural example of adding a steering reference correction torque to the estimated load torque.

[0087] This disclosure is not limited to such implementations and can be implemented in various ways without departing from its spirit.

[0088] The controller and method described in this disclosure can also be implemented by a special-purpose computer consisting of a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the controller and method described in this disclosure can also be implemented by a special-purpose computer consisting of a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the controller and method described in this disclosure can also be implemented by one or more special-purpose computers consisting of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. Furthermore, the computer program can also be stored as instructions to be executed by the computer on a non-transferable tangible recording medium that can be read by the computer.

[0089] This disclosure has been described in accordance with embodiments. However, this disclosure is not limited to these embodiments and structures. This disclosure also includes various modifications and variations within the same scope. In addition, various combinations and arrangements, and even other combinations and arrangements containing only one element, more or fewer elements, also fall within the scope and spirit of this disclosure.

Claims

1. A steering control device that controls the auxiliary torque output by a motor and suppresses the increase of gradient changes in the target steering torque generated at inflection points within a mapped signal region, wherein the motor is connected to a steering system mechanism that generates the steering torque, and the mapping defines the relationship between the estimated load torque and the target steering torque. The aforementioned steering control device includes: The servo controller calculates basic auxiliary instructions to make the steering torque follow the target steering torque. The basic auxiliary instructions are the basic instruction values ​​of the auxiliary torque. The load torque estimation calculation unit calculates the estimated load torque, which is the load torque acting on the steering shaft of the steering system mechanism and varying according to steering input; and The target steering torque calculation unit calculates the target steering torque using the aforementioned mapping. The estimated load torque calculation unit calculates the estimated load torque based on the steering torque or the target steering torque and the estimated load calculation auxiliary instruction. The estimated load calculation auxiliary instruction is equivalent to the calculation result of the proportional-integral control calculation in the control calculation of the servo controller.

2. The steering control device according to claim 1, wherein, The aforementioned servo controller calculates the auxiliary instructions for estimating the load using proportional-integral control calculations, and adds the calculation result based on differential control calculations to the auxiliary instructions for estimating the load to calculate the basic auxiliary instructions.

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