JP2009101972A - Steering device, steering reaction force simulation device and steering reaction force setting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of unnatural feeling in steering feeling of an operator for operating a steering wheel when hysteresis is included in a steering reaction force characteristic in turning increase and turning back of the steering wheel. <P>SOLUTION: When a rotating direction of the steering wheel is changed with a steering reaction force command value Tp* on a second characteristic line (e.g. B and D), the steering reaction force command value Tp* is changed by inclination K1 which is larger than inclination K2 of the second characteristic line. When a steering angle θh attains an angle corresponding to an intersection with the second characteristic line when the steering reaction force command value Tp* is on a first characteristic line (e.g. A' and C), the steering reaction force command value Tp* is changed by the inclination K2. When the steering reaction force command value Tp* is on the first characteristic line, a value of the inclination K1 is gradually made smaller as the steering wheel rotates without changing the rotating direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steering device, a steering reaction force simulation device, and a steering reaction force setting method. More specifically, the present invention relates to a steering device and a steering reaction force simulation device that output a steering reaction force according to the operation of the steering wheel. The present invention relates to a steering reaction force setting method for setting a corresponding steering reaction force.

  Conventionally, as this type of steering device, as disclosed in Patent Document 1 below, a steering reaction force is set with hysteresis characteristics based on the steering angle of the steering wheel and the determination result of the steering wheel turning back and forth. Has been proposed. As shown in FIG. 9, the hysteresis characteristic is a first characteristic line (for example, characteristic lines A and C in FIG. 9) in which the steering reaction force Tp changes with the first inclination K1 with respect to the change in the steering angle θh. ), And a second characteristic line (for example, characteristic lines B and D in FIG. 9) in which the steering reaction force Tp changes with a second inclination K2 smaller than the first inclination K1 with respect to the change in the steering angle θh, And the steering reaction force Tp with respect to the steering angle θh is on the second characteristic line, and the steering reaction force Tp with respect to the steering angle θh has the second inclination When the steering reaction force Tp with respect to the steering angle θh is on the first characteristic line when changing from K2 to the first inclination K1, the steering angle θh corresponds to the intersection of the first characteristic line and the second characteristic line. When the angle is reached, whether the inclination of the steering reaction force Tp with respect to the steering angle θh is the first inclination K1. It is a characteristic that changes second inclination K2. In the steering reaction force characteristic shown in FIG. 9, the characteristic lines (straight lines) A and C of the inclination K1 correspond to the steering reaction force characteristic for generating hysteresis due to Coulomb friction. In the steering device of Patent Document 1, the steering reaction force is set with the hysteresis characteristic shown in FIG. 9 so that the steering reaction force characteristic when the steering wheel is turned back and forth is given hysteresis due to Coulomb friction.

Japanese Patent No. 3889916

  In the above steering device, by sufficiently increasing the value of the first inclination K1, a hysteresis approximating Coulomb friction is given to the relationship between the steering angle θh and the steering reaction force Tp by a spring element having a high rigidity (spring constant), Hysteresis characteristics that do not depend on the steering speed are reproduced. However, in the case of a vehicle in which the steering wheel and the tire are mechanically connected, as shown in FIG. 10, when the hysteresis occurs in the relationship between the steering angle θh and the steering reaction force Tp, the steering angle θh changes. On the other hand, the steering reaction force Tp changes nonlinearly. Here, FIG. 10 shows the result of measuring the characteristic of the steering reaction force Tp with respect to the steering angle θh in a vehicle in which the steering wheel and the tire are mechanically connected. On the other hand, in the above steering apparatus, when hysteresis is generated in the relationship between the steering angle θh and the steering reaction force Tp (when the steering reaction force Tp with respect to the steering angle θh is on the first characteristic line), the first The value of the inclination K1 is constant, and the steering reaction force Tp changes linearly with respect to the change in the steering angle θh. Therefore, the steering reaction force Tp when the hysteresis is generated differs from the vehicle in which the steering wheel and the tire are mechanically connected, and the steering feeling of the operator who operates the steering wheel is uncomfortable. . In the above steering apparatus, when the steering reaction force Tp with respect to the steering angle θh shifts from the first characteristic line to the second characteristic line, the amount of change in the steering reaction force Tp with respect to the steering angle θh changes abruptly. . This also causes an uncomfortable feeling in the steering feeling of the operator who operates the steering wheel.

  An object of the present invention is to prevent an uncomfortable feeling in the steering feeling of an operator who operates a steering wheel when a hysteresis is given to a steering reaction force characteristic when the steering wheel is further turned back and turned back.

  The steering device, the steering reaction force simulation device, and the steering reaction force setting method according to the present invention employ the following means in order to achieve the above-described object.

  A steering apparatus according to the present invention is a steering apparatus that outputs a steering reaction force corresponding to an operation of a steering wheel, and includes a steering angle detection unit that detects a steering angle of the steering wheel, and a steering wheel detection unit based on the detected steering angle. Target steering reaction force for setting a target steering reaction force with a hysteresis characteristic based on the determination result by the cutoff increase / return determination means and the detected steering angle Reaction force setting means, and steering reaction force output means for outputting a steering reaction force so that the set target steering reaction force is output, wherein the hysteresis characteristic is a steering reaction force against a change in steering angle. Includes a first characteristic that changes with a first inclination and a second characteristic that a steering reaction force changes with a second inclination with respect to a change in steering angle, and the steering reaction force with respect to the steering angle Rotating the handle when it is on the characteristics of 2 When the direction changes, the steering reaction force changes with a first inclination larger than the second inclination with respect to the change of the steering angle, and the steering reaction force with respect to the steering angle is on the first characteristic. When the steering angle reaches an angle corresponding to the intersection with the second characteristic, the steering reaction force changes with the second inclination with respect to the change of the steering angle, and the target steering reaction force The setting means is such that when the steering reaction force with respect to the steering angle is on the first characteristic, the first inclination is gradually reduced as the steering wheel rotates without changing its rotation direction. .

  In one aspect of the present invention, the target steering reaction force setting means sets the steering angle to an angle corresponding to the intersection with the second characteristic when the steering reaction force with respect to the steering angle is on the first characteristic. It is preferable that the first inclination at the time of reaching substantially coincides with the second inclination.

  In one aspect of the present invention, the target steering reaction force setting means is configured such that when the steering reaction force with respect to the steering angle is on the first characteristic and the steering wheel is in an increased state, the steering steering force is increased. It is preferable to gradually reduce the first inclination.

  In one aspect of the present invention, when the steering reaction force with respect to the steering angle is on the first characteristic and the steering wheel is in the turning back state, the target steering reaction force setting means is configured so that the steering wheel is turned back. It is preferable to gradually reduce the first inclination.

  The steering reaction force simulation device according to the present invention is a steering reaction force simulation device that outputs a steering reaction force according to an operation of a steering wheel, a steering angle detection unit that detects a steering angle of the steering wheel, and the detection A turn-up / back-off judging means for judging whether the steering wheel is turned up or down based on the steering angle, and a target having a hysteresis characteristic on the basis of the result of judgment by the turn-up / back-back judging means and the detected steering angle. Target steering reaction force setting means for setting a steering reaction force; and steering reaction force output means for outputting a steering reaction force so that the set target steering reaction force is output. A first characteristic in which the steering reaction force changes at a first inclination with respect to a change in the steering angle, and a second characteristic in which the steering reaction force changes at a second inclination with respect to a change in the steering angle. The steering reaction force against the angle is on the second characteristic. In this case, when the rotation direction of the steering wheel is changed, the steering reaction force changes with a first inclination larger than the second inclination with respect to the change in the steering angle, and the steering reaction force with respect to the steering angle becomes the first reaction force. When the steering angle reaches an angle corresponding to the intersection with the second characteristic when it is on the characteristic, the steering reaction force changes with the second inclination with respect to the change of the steering angle, The target steering reaction force setting means gradually decreases the first inclination as the steering wheel rotates without changing its rotation direction when the steering reaction force with respect to the steering angle is on the first characteristic. This is the gist.

  Further, the steering reaction force setting method according to the present invention is a steering reaction force setting method for setting a steering reaction force according to the operation of the steering wheel, and only whether the steering wheel is turned back or back based on the steering angle of the steering wheel. In the steering reaction force setting method that sets the steering reaction force with a hysteresis characteristic based on the determination result and the steering angle of the steering wheel, the hysteresis characteristic indicates that the steering reaction force is a first response to a change in the steering angle. A first characteristic that changes with a tilt of 1 and a second characteristic that a steering reaction force changes with a second slope with respect to a change in steering angle, and the steering reaction force with respect to a steering angle is the second characteristic. When the direction of rotation of the steering wheel changes when the characteristic is in the characteristic, the steering reaction force changes with the first inclination larger than the second inclination with respect to the change in the steering angle, and the steering reaction force with respect to the steering angle becomes Steer when it is on the first characteristic Is a characteristic in which the steering reaction force changes with the second inclination with respect to a change in the steering angle, and the steering reaction force with respect to the steering angle is The gist is to gradually decrease the first inclination as the handle rotates without changing its rotation direction when the first characteristic is satisfied.

  According to the present invention, when the steering reaction force with respect to the steering angle is on the first characteristic, the inclination of the first characteristic is gradually reduced as the steering wheel rotates without changing its rotation direction. When hysteresis is generated in the relationship between the steering angle and the steering reaction force, the steering reaction force can be changed nonlinearly with respect to the change in the steering angle. Then, when the steering reaction force with respect to the steering angle shifts from the first characteristic to the second characteristic, it is possible to suppress an abrupt change in the inclination of the steering reaction force with respect to the steering angle. Therefore, when the steering reaction force characteristics at the time of turning the steering wheel back and back are provided with hysteresis, it is possible to prevent the steering feeling of the operator who operates the steering wheel from feeling uncomfortable.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a steering device 20 according to an embodiment of the present invention, and shows a case where the present invention is applied to a steer-by-wire system. A steering device 20 according to the present embodiment is mounted on a vehicle, and as shown in the drawing, a steering wheel 22 that is operated by a driver (operator) and an angle (steering angle) of the steering wheel 22 are detected. The angle sensor 24, the torque sensor 26 for detecting the torque (steering reaction force) of the handle 22, and the steering reaction force of the handle 22 are simulated by applying a torque to the handle 22 according to the operation of the handle 22 by the driver. The output torque for changing the turning angle of the steering wheels 30 and 32 according to the reaction motor 40 and the steering angle of the handle 22 is transmitted to the rack 36 via the speed reducer 34 and output to the steering wheels 30 and 32. A steered motor 42 and an electronic control unit 50 that controls the entire apparatus are provided.

  The electronic control unit 50 is configured as a microprocessor centered on a CPU 52, and includes a ROM 54 that stores a processing program, a RAM 56 that temporarily stores data, and an input / output port (not shown). A steering angle θh from the steering angle sensor 24, a torque Th from the torque sensor 26, a vehicle speed V from the vehicle speed sensor 58, and the like are input to the electronic control unit 50 through an input port. Further, the electronic control unit 50 outputs drive signals to the reaction force motor 40 and the steering motor 42 through the output port.

  FIG. 2 is an explanatory diagram illustrating a control block when the electronic control unit 50 of the steering device 20 operates as the steering reaction force command value calculation block 60 for calculating the steering reaction force command value Tp *. As shown in the drawing, the steering reaction force command value calculation block 60 includes an additional switching / returning determination unit 62 that determines whether the steering wheel 22 is increased or decreased based on the input steering angle θh, and an additional switching / returning determination unit. And a steering reaction force command value calculation unit 66 for calculating the steering reaction force command value Tp * based on the determination result of 62, the steering angle θh, and the vehicle speed V. In the electronic control unit 50, the steering reaction force acting on the handle 22 is steered based on the steering reaction force command value Tp * calculated by the steering reaction force command value calculation block 60 and the torque Th detected by the torque sensor 26. The reaction force motor 40 is driven and controlled so that the reaction force command value Tp * is obtained. However, here, the reaction force motor 40 may be driven and controlled based only on the steering reaction force command value Tp * without using the torque sensor 26. The steering angle θh is detected by the steering angle sensor 24 with a predetermined resolution (minimum resolution) Δθh.

  The increase / return determination unit 62 in the steering reaction force command value calculation block 60 determines whether the handle 22 is in the increased state or the reverted state based on the steering angle θh detected by the steering angle sensor 24. Is done. More specifically, the sign of the difference between the steering angle θh input last time and the steering angle θh input this time, that is, whether it is increased or decreased is determined by positive / negative.

  In the steering reaction force command value calculation unit 66, the steering reaction force acting on the steering wheel 22 based on the determination result of the increase / cutback determination unit 62, the steering angle θh, and the vehicle speed V exhibits a hysteresis characteristic as illustrated in FIG. 3. The steering reaction force command value Tp * is calculated so as to hold. In FIG. 3, the horizontal axis is the steering angle θh, and the vertical axis is the steering reaction force Tp. The hysteresis characteristics illustrated in FIG. 3 are characteristic lines A and C (first characteristic lines) in which the steering reaction force Tp changes with a slope K1 with respect to changes in the steering angle θh, and steering with respect to changes in the steering angle θh. This is a characteristic including the characteristic lines B and D (second characteristic lines) in which the reaction force Tp changes with the inclination K2. In FIG. 3, the intercept of the characteristic line (straight line) B is T2, and the intercept of the characteristic line (straight line) D is -T2. Hereinafter, processing in which the steering reaction force command value calculation unit 66 calculates the steering reaction force command value Tp * will be described. The steering reaction force command value Tp * is calculated in the same way except that the sign differs between when the handle 22 is rotated to the right and when the handle 22 is rotated to the left. In the embodiment, the case where the handle 22 is rotated to the left will be described. For ease of explanation, a process for calculating the steering reaction force command value Tp * without using the vehicle speed V will be described.

  When the steering angle θh at the start of turning of the steering wheel 22 increases from the value 0, the steering reaction force is reached until the angle θ1 intersects with the characteristic line (straight line K2) B on the characteristic line (curve) A ′ shown in FIG. The command value Tp * is calculated to be a value on the characteristic line A ′. That is, when the characteristic line A ′ is expressed by the function f (θh), the steering reaction force command value Tp * is calculated by the following equation (1).

  As shown in FIG. 4, the characteristic line A ′ has a slope K1 when the steering angle θh is 0, which is larger than the slope K2 of the straight line B, and the slope K1 increases as the steering angle θh increases from 0. Is a curve in which the value of the slope K1 when the steering angle θh reaches the angle θ1 corresponding to the intersection with the straight line B coincides (or substantially coincides) with the inclination K2 of the straight line B. As the function f (θh) representing the curve A ′, for example, an upward convex monotonically increasing function that satisfies the following expressions (2) to (6) can be used.

  As an upwardly convex monotonously increasing function f (θh) that satisfies the expressions (2) to (6), for example, the following expression (7) can be used.

In Expression (7), a _f and b _f are constants and satisfy the following Expressions (8) and (9).

  When the steering angle θh is increased after exceeding the angle θ1, the steering reaction force command value Tp * is calculated by the following equation (10) so that the steering reaction force command value Tp * becomes a value on the straight line B with the inclination K2. Is calculated.

  Thus, when the steering reaction force command value Tp * for the steering angle θh is on the characteristic line A ′ (first characteristic line), the steering angle θh is the characteristic line A ′ and the characteristic line B (second characteristic line). ), The steering reaction force command value Tp * with respect to the steering angle θh shifts to the characteristic line B, and the steering reaction force command value Tp * with respect to the change in the steering angle θh. Changes with the slope K2. When the steering reaction force command value Tp * with respect to the steering angle θh is on the characteristic line A ′, if the handle 22 is in the increased state without changing its rotational direction, the handle 22 is increased. As the steering angle θh increases and approaches the angle θ1, the value of the inclination K1 gradually decreases. The value of the inclination K1 gradually decreases until the steering angle θh reaches the angle θ1, and the value of the inclination K1 when the steering angle θh reaches the angle θ1 becomes equal to the inclination K2 of the straight line B.

  When the steering wheel 22 is turned back from the state where the steering angle θh is larger than the angle θ1 and the rotation direction of the steering wheel 22 is changed, the characteristic line (straight line of inclination K2) on the characteristic line (curve) C shown in FIG. The steering reaction force command value Tp * is calculated to be a value on the characteristic line C until the angle θ3 intersecting with D is reached. As shown in FIG. 4, the characteristic line C here shows that the value of the inclination K1 when the steering angle θh is the angle θ2 is larger than the inclination K2 of the straight lines B and D, and the steering angle θh decreases from the angle θ2. As the value of the inclination K1 gradually decreases, the value of the inclination K1 when the steering angle θh reaches the angle θ3 corresponding to the intersection with the straight line D coincides with (or substantially coincides with) the inclination K2 of the straight line D. It is. As the curve C, for example, a curve obtained by rotating the curve A ′ by 180 ° about the origin and shifting it by a on the horizontal axis (θh direction) and b on the vertical axis (Tp direction) can be used. Therefore, for example, a downward convex monotonically increasing function −f (− (θh−a)) + b can be used as the function fc1 (θh) representing the characteristic line C, and the steering reaction force command is given by the following equation (11). The value Tp * can be calculated.

  Here, a and b satisfy the following expressions (12) and (13), respectively.

  In the equations (12) and (13), θ0 is an angle (see FIG. 4) at which the curve A ′ intersects the straight line D. Therefore, f (θ0) in the equation (13) is expressed by the following equation (14).

  When the steering wheel 22 is further turned back from the state where the steering angle θh is the angle θ3, the steering reaction force command is given by the following equation (15) so that the steering reaction force command value Tp * becomes a value on the straight line D of the inclination K2. The value Tp * is calculated.

  Thus, when the steering direction of the steering wheel 22 changes when the steering reaction force command value Tp * for the steering angle θh is on the characteristic line B (second characteristic line), the steering reaction force command for the steering angle θh. The value Tp * shifts to the characteristic line C (first characteristic line), and the steering reaction force command value Tp * changes with the inclination K1 larger than the inclination K2 of the characteristic lines B and D with respect to the change of the steering angle θh. (The inclination of the steering reaction force command value Tp * with respect to the steering angle θh increases). When the steering reaction force command value Tp * with respect to the steering angle θh is on the characteristic line C and the handle 22 is in the return state without changing its rotational direction, the handle 22 is turned back. As the steering angle θh decreases and approaches the angle θ3 corresponding to the intersection with the characteristic line D, the value of the slope K1 gradually decreases. The value of the inclination K1 gradually decreases until the steering angle θh reaches the angle θ3, and the value of the inclination K1 when the steering angle θh reaches the angle θ3 becomes equal to the inclination K2 of the straight line D. After the steering angle θh reaches the angle θ3, the steering reaction force command value Tp * with respect to the steering angle θh shifts to the characteristic line D, and the steering reaction force command value Tp * is changed with respect to the change in the steering angle θh. It changes with the inclination K2. Here, the characteristic line B of the inclination K2 corresponds to the steering reaction force characteristic at the time of further increase, and the characteristic line D of the inclination K2 corresponds to the steering reaction force characteristic at the time of return. The characteristic lines A, A ', and C of the inclination K1 correspond to the steering reaction force characteristic for applying the steering reaction force corresponding to the Coulomb friction. By increasing the value of the slope K1, it is possible to obtain a hysteresis approximating Coulomb friction by a spring element having a high rigidity (spring constant). Then, by setting the steering reaction force command value Tp * based on the steering angle θh and the determination result of the additional turning back, the current state in the hysteresis characteristic (the steering angle θh and the steering reaction force Tp are represented by the characteristic lines A, It is possible to reproduce the hysteresis characteristic due to Coulomb friction that does not depend on the steering speed while accurately grasping the position (B, C, D).

  Further, as shown in FIG. 5, when the steering reaction force command value Tp * is on the characteristic line A ′, the handle 22 is turned back from the state where the steering angle θh is smaller than the angle θ1, and the handle 22 is turned off. Is changed to the characteristic line (curve) C ′ shown in FIG. 5 until the angle θ5 intersecting with the characteristic line (straight line K2) D reaches the characteristic line C ′. Arithmetic so that it becomes the above value. As shown in FIG. 5, the characteristic line C ′ has a value of the inclination K1 when the steering angle θh is the angle θ4, which is larger than the inclination K2 of the straight lines B and D, and the steering angle θh decreases from the angle θ4. The value of the slope K1 gradually decreases with time, and the value of the slope K1 when the steering angle θh reaches the angle θ5 corresponding to the intersection with the straight line D matches (or almost matches) the slope K2 of the straight line D. It is a curve. As the curve C ′, for example, a curve obtained by rotating the curve A ′ by 180 ° about the origin and shifting it by c on the horizontal axis (θh direction) and d on the vertical axis (Tp direction) can be used. Therefore, as the function fc2 (θh) representing the characteristic line C ′, for example, a downward convex monotonically increasing function −f (− (θh−c)) + d can be used, and the steering reaction force is expressed by the following equation (16). The command value Tp * can be calculated.

  Here, c and d satisfy the following expressions (17) and (18), respectively.

  In the equations (17) and (18), θ4 ′ is an angle (see FIG. 5) at which the curve C ′ intersects the straight line B. Since the angle at which the curve A ′ and the curve C ′ intersect is θ4, the following equation (19) is established.

  Substituting Equation (17), Equation (18), and Equation (14) into Equation (19) yields the following Equation (20). The value of the angle θ4 ′ can be obtained by solving the following equation (20).

  Further, as shown in FIG. 6, when the steering reaction force command value Tp * is on the characteristic line C, the handle 22 is increased from the state where the steering angle θh is smaller than the angle θ2 and larger than the angle θ3. When the rotation direction of the steering wheel 22 is changed, the steering reaction force command value Tp * is changed until the angle θ9 intersects with the characteristic line (straight line K2) B on the characteristic line (curve) A ″ shown in FIG. Calculation is performed so that the value is on the characteristic line A ″. As shown in FIG. 6, the characteristic line A ″ indicates that the value of the inclination K1 when the steering angle θh is the angle θ8 is larger than the inclination K2 of the straight lines B and D, and the steering angle θh is from the angle θ8. As the value increases, the value of the inclination K1 gradually decreases, and the value of the inclination K1 when the steering angle θh reaches the angle θ9 corresponding to the intersection with the straight line B coincides with (or substantially coincides with) the inclination K2 of the straight line B. ) Curve. As this curve A ″, for example, a curve obtained by shifting the curve A ′ by g on the horizontal axis (θh direction) and h on the vertical axis (Tp direction) can be used. Accordingly, as the function fa1 (θh) representing the characteristic line A ″, for example, an upward convex monotonically increasing function f (θh−g) + h can be used, and the steering reaction force command value Tp can be expressed by the following equation (21). * Can be calculated.

  Here, g and h satisfy the following expressions (22) and (23), respectively.

  In Expressions (22) and (23), θ8 ′ is an angle at which the curve A ″ intersects the straight line D (see FIG. 6). Since the angle at which the curve A ″ and the curve C ′ intersect is θ8, the following equation (24) is established.

  Substituting Equation (22) and Equation (23) into Equation (24) yields the following Equation (25). The value of the angle θ8 ′ can be obtained by solving the following equation (25).

  As described above, when the steering reaction force command value Tp * with respect to the steering angle θh is on the characteristic line A ″, when the handle 22 is in the increased state without changing its rotation direction, the handle 22 is increased. Thus, as the steering angle θh increases and approaches the angle θ9 corresponding to the intersection with the characteristic line B, the value of the slope K1 gradually decreases. The value of the inclination K1 gradually decreases until the steering angle θh reaches the angle θ9, and the value of the inclination K1 when the steering angle θh reaches the angle θ9 becomes equal to the inclination K2 of the straight line B.

  As shown in FIG. 7, when the steering wheel 22 is increased from the state where the steering angle θh is the angle θ6 and the rotation direction of the steering wheel 22 changes when the steering reaction force command value Tp * characteristic line D is present. The steering reaction force command value Tp * is a value on the characteristic line A ′ ″ until the angle θ7 intersects with the characteristic line (straight line K2) B on the characteristic line (curve) A ′ ″ shown in FIG. Operate so that That is, the steering reaction force command value Tp * for the steering angle θh shifts from the characteristic line D to the characteristic line A ′ ″. As shown in FIG. 7, the characteristic line A ′ ″ indicates that the value of the inclination K1 when the steering angle θh is the angle θ6 is larger than the inclination K2 of the straight lines B and D, and the steering angle θh is the angle θ6. The value of the slope K1 gradually decreases as the value increases from the point of time, and the value of the slope K1 when the steering angle θh reaches the angle θ7 corresponding to the intersection with the straight line B coincides with (or substantially coincides with) the slope K2 of the straight line B. It is a curve. That is, when the steering reaction force command value Tp * with respect to the steering angle θh shifts from the characteristic line D to the characteristic line A ′ ″, the inclination of the steering reaction force command value Tp * with respect to the steering angle θh increases. As the curve A ′ ″, for example, a curve obtained by shifting the curve A ′ by i on the horizontal axis (θh direction) and j on the vertical axis (Tp direction) can be used. Accordingly, as the function fa2 (θh) representing the characteristic line A ′ ″, for example, an upwardly convex monotonically increasing function f (θh−i) + j can be used, and the steering reaction force command value is expressed by the following equation (26). Tp * can be calculated.

  Here, i and j satisfy the following expressions (27) and (28), respectively.

  In the present embodiment described above, the steering reaction force Tp with respect to the steering angle θh has the first characteristic line (for example, characteristic lines A, A ′, A ″, A ′ ″, C, C ′) for generating hysteresis. ), The steering wheel 22 rotates without changing its direction of rotation, and the steering angle θh corresponds to the intersection of the second characteristic line (for example, characteristic lines B and D) (for example, the angle θ1, The value of the slope K1 of the first characteristic line is gradually reduced as it approaches (θ3, θ5, θ7, θ9). Thus, when hysteresis due to Coulomb friction is generated in the relationship between the steering angle θh and the steering reaction force Tp, the steering angle is the same as in the case of a vehicle in which the steering wheel and the tire are mechanically connected (see FIG. 10). The steering reaction force Tp can be changed nonlinearly with respect to the change in θh. Then, when the steering reaction force Tp with respect to the steering angle θh shifts from the first characteristic line to the second characteristic, it is possible to suppress an abrupt change in the inclination of the steering reaction force Tp with respect to the steering angle θh. . Accordingly, it is possible to prevent the operator feeling the steering feeling of the steering wheel 22 from feeling uncomfortable and improve the steering feeling of the operator.

  Further, in this embodiment, when the steering reaction force Tp with respect to the steering angle θh is on the first characteristic line, the inclination K1 when the steering angle θh reaches an angle corresponding to the intersection with the second characteristic line is calculated. It is made to coincide with the inclination K2. Accordingly, when the hysteresis due to Coulomb friction is generated in the relationship between the steering angle θh and the steering reaction force Tp, the steering reaction force Tp is changed when the steering reaction force Tp shifts from the first characteristic line to the second characteristic. It can be changed more smoothly. Therefore, a smoother steering feeling can be obtained.

  In the above description, the steering reaction force command value Tp * is calculated without considering the vehicle speed V for easy explanation. However, in the steering device 20 according to the embodiment, the slopes K1 of the characteristic lines A, A ′, A ″, A ′ ″, C, C ′ and the slopes K2 of the characteristic lines B, D in FIGS. The steering reaction force command value Tp * can be calculated assuming that the intercepts T0 and -T0 are changed according to the vehicle speed V. Further, the inclination K2 is not necessarily a constant value and can be changed according to the steering angle θh.

  In the steering device 20 according to the embodiment, the reaction force motor 40 is driven and controlled based on the calculated steering reaction force command value Tp *. However, as shown in the control block illustrated in FIG. A value obtained by multiplying the steering angular velocity, which is a time derivative of θh, by a damper gain may be added to the steering reaction force command value Tp *, and the reaction force motor 40 may be driven and controlled based on this value. In this way, the convergence characteristic to the equilibrium point when the hand is released from the handle 22 can be improved.

  In the steering device 20 according to the embodiment, the steering reaction force is applied to the handle 22 by the torque of the reaction motor 40. However, the steering reaction force can be applied to the handle 22 using an actuator other than the motor.

  In the above description of the embodiment, the case where the present invention is applied to the vehicle-mounted steering device 20 has been described. However, the present invention can also be applied to a steering reaction force simulator used in a driving simulator or the like. In that case, the steering reaction force simulation apparatus according to the embodiment can be configured including the handle 22, the steering angle sensor 24, the reaction force motor 40, and the electronic control unit 50 described above.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

It is a figure showing a schematic structure of steering device 20 concerning an embodiment of the present invention. It is explanatory drawing which illustrates a control block when the electronic control unit 50 of the steering device 20 which concerns on embodiment of this invention operate | moves as the steering reaction force command value calculation block 60 which calculates steering reaction force command value Tp *. It is explanatory drawing which shows an example of the relationship between steering angle (theta) h and steering reaction force Tp. It is explanatory drawing explaining a mode that steering reaction force command value Tp * is calculated from steering angle (theta) h. It is explanatory drawing explaining a mode that steering reaction force command value Tp * is calculated from steering angle (theta) h. It is explanatory drawing explaining a mode that steering reaction force command value Tp * is calculated from steering angle (theta) h. It is explanatory drawing explaining a mode that steering reaction force command value Tp * is calculated from steering angle (theta) h. It is explanatory drawing which shows an example of the control block of a modification. It is explanatory drawing which shows an example of the relationship between steering angle (theta) h and steering reaction force Tp in a prior art example. It is a figure which shows the result of having measured the characteristic of the steering reaction force Tp with respect to steering angle (theta) h in the vehicle with which the steering wheel and the tire were connected mechanically.

Explanation of symbols

  20 Steering device, 22 Handle, 24 Steering angle sensor, 26 Torque sensor, 30, 32 Steering wheel, 34 Reducer, 36 Rack, 40 Reaction force motor, 42 Steering motor, 50 Electronic control unit, 52 CPU, 54 ROM, 56 RAM, 58 Vehicle speed sensor, 60 Steering reaction force command value calculation block, 62 Increase / return switching determination unit, 66 Steering reaction force command value calculation unit

Claims (6)

A steering device that outputs a steering reaction force according to the operation of a steering wheel,
Steering angle detection means for detecting the steering angle of the steering wheel;
An increase / return determination means for determining whether to increase or decrease the steering wheel based on the detected steering angle;
Target steering reaction force setting means for setting a target steering reaction force with hysteresis characteristics based on the determination result by the increase / decrease / return determination means and the detected steering angle;
Steering reaction force output means for outputting a steering reaction force so that the set target steering reaction force is output;
With
The hysteresis characteristic is
A first characteristic in which the steering reaction force changes with a first inclination with respect to a change in the steering angle; and a second characteristic in which the steering reaction force changes with a second inclination with respect to a change in the steering angle. ,
When the steering reaction force with respect to the steering angle is on the second characteristic and the steering direction changes, the first inclination in which the steering reaction force is greater than the second inclination with respect to the change in the steering angle. When the steering angle reaches an angle corresponding to the intersection with the second characteristic when the steering reaction force with respect to the steering angle is on the first characteristic, the steering is changed with respect to the change in the steering angle. The reaction force is a characteristic that changes with the second inclination,
The target steering reaction force setting means gradually decreases the first inclination as the steering wheel rotates without changing its rotation direction when the steering reaction force with respect to the steering angle is on the first characteristic. Steering device. The steering apparatus according to claim 1,
The target steering reaction force setting means has a first steering angle when the steering angle reaches an angle corresponding to an intersection with the second characteristic when the steering reaction force with respect to the steering angle is on the first characteristic. A steering device that makes the inclination substantially coincide with the second inclination. The steering apparatus according to claim 1 or 2,
The target steering reaction force setting means gradually increases the first inclination as the steering wheel is increased when the steering wheel is in the increased state when the steering reaction force with respect to the steering angle is on the first characteristic. Steering device to make it smaller. The steering apparatus according to any one of claims 1 to 3,
When the steering reaction force with respect to the steering angle is on the first characteristic and the steering wheel is in the return state, the target steering reaction force setting means gradually increases the first inclination as the steering wheel is turned back. Steering device to make it smaller. A steering reaction force simulation device that outputs a steering reaction force according to a steering operation,
Steering angle detection means for detecting the steering angle of the steering wheel;
An increase / return determination means for determining whether to increase or decrease the steering wheel based on the detected steering angle;
Target steering reaction force setting means for setting a target steering reaction force with hysteresis characteristics based on the determination result by the increase / decrease / return determination means and the detected steering angle;
Steering reaction force output means for outputting a steering reaction force so that the set target steering reaction force is output;
With
The hysteresis characteristic is
A first characteristic in which the steering reaction force changes with a first inclination with respect to a change in the steering angle; and a second characteristic in which the steering reaction force changes with a second inclination with respect to a change in the steering angle. ,
When the steering reaction force with respect to the steering angle is on the second characteristic and the steering direction changes, the first inclination in which the steering reaction force is greater than the second inclination with respect to the change in the steering angle. When the steering angle reaches an angle corresponding to the intersection with the second characteristic when the steering reaction force with respect to the steering angle is on the first characteristic, the steering is changed with respect to the change in the steering angle. The reaction force is a characteristic that changes with the second inclination,
The target steering reaction force setting means gradually decreases the first inclination as the steering wheel rotates without changing its rotation direction when the steering reaction force with respect to the steering angle is on the first characteristic. Steering reaction force simulation device. A steering reaction force setting method for setting a steering reaction force according to an operation of a steering wheel,
Based on the steering angle of the steering wheel, it is determined whether the steering wheel is increased or not,
In a steering reaction force setting method for setting a steering reaction force with hysteresis characteristics based on the determination result and the steering angle of the steering wheel,
The hysteresis characteristic is
A first characteristic in which the steering reaction force changes with a first inclination with respect to a change in the steering angle; and a second characteristic in which the steering reaction force changes with a second inclination with respect to a change in the steering angle. ,
When the steering reaction force with respect to the steering angle is on the second characteristic and the steering direction changes, the first inclination in which the steering reaction force is greater than the second inclination with respect to the change in the steering angle. When the steering angle reaches an angle corresponding to the intersection with the second characteristic when the steering reaction force with respect to the steering angle is on the first characteristic, the steering is changed with respect to the change in the steering angle. The reaction force is a characteristic that changes with the second inclination,
A steering reaction force setting method in which, when a steering reaction force with respect to a steering angle is on the first characteristic, the first inclination is gradually reduced as the steering wheel rotates without changing its rotation direction.

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