Vehicle motion control device and vehicle motion control method

Abstract

To provide a vehicle motion controller which can restrict the occurrence of sudden vehicle behavior arising in an own vehicle during travel, by setting a self-vehicle speed that takes into account not only information in the vicinity of an own vehicle but also remote information.SOLUTION: A vehicle motion controller comprises: a vicinity information acquisition part for acquiring vicinity information of a vehicle; a remote information acquisition part for acquiring remote information of the vehicle; and a speed planning part for generating a speed command value that is a travel target of the vehicle, on the basis of the vicinity information and the remote information.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle motion control device for controlling the motion of a vehicle, and a vehicle motion control method. [Background technology]

[0002] As one type of vehicle motion control technology represented by driving assistance and autonomous driving, a technology is known that generates a driving trajectory consisting of information such as a driving route and a driving speed as a driving target of the vehicle, and controls the power train, brakes, steering, etc. so that the vehicle drives along the driving trajectory. For example, the simplest driving route control is lane keeping control, which sets the driving route to the center of the lane.

[0003] Furthermore, a more advanced driving route control technology is disclosed in Patent Document 1. For example, claim 1 of Patent Document 1 describes a vehicle control device including "a speed distribution setting unit that sets a speed limit distribution that specifies an upper limit value of an allowable relative speed around a surrounding vehicle detected by the surrounding vehicle detection unit, and a control unit that controls the speed and / or steering of the vehicle so as to satisfy the speed limit distribution set by the speed distribution setting unit, and the speed distribution setting unit sets different speed limit distributions depending on whether information about the driving state of the surrounding vehicles can be acquired by the vehicle information receiving unit or not" and claim 2 describes a vehicle control device that "reduces the speed limit in the speed limit distribution when information about the driving state of the surrounding vehicles cannot be acquired."

[0004] Thus, Patent Document 1 discloses a vehicle control device that targets vehicle motion control by setting a limit value for the relative speed between the vehicle itself and surrounding vehicles traveling therearound, changing the setting depending on whether or not information about the driving conditions of the surrounding vehicles can be obtained, and lowering the speed limit if information about the driving conditions of the surrounding vehicles cannot be obtained, thereby preventing the vehicle from suddenly decelerating or steering due to the behavior of the surrounding vehicles, which would cause anxiety to the driver. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-142303 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the vehicle control device in Patent Document 1 does not improve the ride quality and comfort of the occupants by setting the vehicle speed taking into consideration distant curves that cannot be detected by the vehicle sensor. For this reason, when using the vehicle control device in this document, after setting the vehicle speed taking into consideration only information about the surroundings (vicinity) of the vehicle detected by the vehicle sensor, if a curve ahead is detected at a position moving forward a predetermined distance, it becomes necessary to significantly reduce the vehicle speed from the set speed, which can cause the vehicle behavior to become unstable.

[0007] Therefore, the present invention aims to provide a vehicle motion control device and a vehicle motion control method that suppress the occurrence of unstable vehicle behavior by setting the speed of the vehicle taking into account not only information in the vicinity of the vehicle but also information from far away. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the vehicle motion control device of the present invention is a vehicle motion control device that includes a nearby information acquisition unit that acquires nearby information of the vehicle, a distant information acquisition unit that acquires distant information of the vehicle, and a speed planning unit that generates a speed command value that becomes the driving target of the vehicle based on the nearby information and the distant information. Effect of the Invention

[0009] According to the vehicle motion control device or vehicle motion control method of the present invention, a speed command value is generated taking into consideration both information about the vicinity of the vehicle and information about the distant area, thereby making it possible to suppress unstable behavior of the vehicle, such as sudden braking. Note that problems, configurations, and effects other than those described above will become clear from the description of the embodiments below. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a functional block diagram of the in-vehicle system according to the first embodiment. [Diagram 2] FIG. 2 is a functional block diagram of a travel trajectory generation unit according to the first embodiment. [Diagram 3] FIG. 4 is a functional block diagram of a speed planning unit according to the first embodiment. [Figure 4] 4 is a flowchart showing an outline of processing by a traveling speed generating unit according to the first embodiment. [Diagram 5] FIG. [Figure 6A] 13 is a graph showing a path command value when conventional control is used when traveling along path A. [Figure 6B] Graph of speed command value when using conventional control when traveling along route A. [Figure 6C] 13 is a distant route graph when the control of the first embodiment is used when traveling along the travel route A. [Figure 6D] 13 is a graph showing a speed command value when the control of the first embodiment is used when traveling along a travel route A. [Figure 7] FIG. 11 is a functional block diagram of a speed planning unit according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the vehicle motion control device of the present invention will be described with reference to the drawings. The same reference numerals are used to designate substantially the same or similar components, and descriptions of duplicated components may be omitted. Also, descriptions of well-known technologies may be omitted. EXAMPLES

[0012] First, a vehicle motion control device 2 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 6D.

[0013] <In-vehicle system 1> 1 is a functional block diagram of an in-vehicle system 1 having a vehicle motion control device 2 of this embodiment. The in-vehicle system 1 is a system that is mounted on a vehicle and performs vehicle motion control such as driving assistance and automatic driving, and as shown in the figure, has an external communication device 11, a GNSS (Global Navigation Satellite System) 12, a map information storage unit 13, a sensor 14, an HMI (human machine interface) unit 15, the vehicle motion control device 2, a powertrain system 6, a brake system 7, and a steering system 8. Each of these will be described in turn below.

[0014] <Information sources for vehicle motion control device 2> The exterior vehicle communication device 11 performs vehicle-to-vehicle communication between the vehicle itself and another vehicle, or road-to-vehicle communication between the vehicle itself and a roadside unit, by wireless communication, and transmits and receives information about the vehicle and the surrounding environment.

[0015] The GNSS 12 receives radio waves transmitted from artificial satellites such as quasi-zenith satellites and GPS (Global Positioning System) satellites, and acquires information such as the position of the vehicle.

[0016] The map information storage unit 13 stores general road information used in navigation systems, road information including information on curves such as road width and road curvature, information on road surface conditions and traffic conditions, information on the driving conditions of other vehicles, information on the vehicle and the surrounding environment, etc. The information on the vehicle and the surrounding environment is updated successively by information acquired through vehicle-to-vehicle communication and road-to-vehicle communication via the exterior communication device 11.

[0017] The sensor 14 is an external environment recognition sensor such as an image sensor, a millimeter wave radar, a lidar, etc. that detects information on the vehicle and the surrounding environment, and a sensor that detects information on the driver's operation, the vehicle speed, acceleration, jerk, angular velocity, steering angle of the wheels, etc. The information on the vehicle and the surrounding environment detected by the external environment recognition sensor is, for example, information on various objects present around the vehicle, such as obstacles, signs, lane boundaries, lane outer lines, buildings, pedestrians, and other vehicles. The sensor 14 also recognizes lane boundaries, lane outer lines, etc., based on the difference in brightness between the white lines in the image data captured by the image sensor and the road surface, for example.

[0018] The HMI unit 15 displays on the display and provides audio guidance from the speaker the information required by the user from information received through user input operations such as selection of a driving mode and setting of a destination, information acquired by the external communication device 11, the GNSS 12, and the sensor 14, and information recorded in the map information storage unit 13. The HMI unit 15 also generates an alarm to alert the user.

[0019] Here, the driving modes include, for example, a comfort mode, an economy mode, a sports mode, etc., and the driving mode is set arbitrarily by the user, or is set in advance by the user, or is set by the operation management unit 3 described later based on the driving situation information, and the vehicle speed, acceleration, jerk, etc. are set. In other words, the upper limit value of the vehicle behavior changes depending on the driving mode. In addition, the driving modes include a minimum time mode that minimizes the travel time and a minimum distance mode that minimizes the travel distance.

[0020] <Vehicle motion control device 2> As shown in Fig. 1, the vehicle motion control device 2 has an operation management unit 3, a travel trajectory generation unit 4, and a travel control unit 5. Specifically, the vehicle motion control device 2 has a calculation device such as a CPU (Central Processing Unit), a main storage device such as a semiconductor memory, an auxiliary storage device, and hardware such as a communication device, and is an ECU (Electronic Control Unit) that controls the vehicle in an integrated manner, and realizes various functions of the operation management unit 3 and the like by executing a program loaded into the main storage device on the calculation device. In this embodiment, for convenience of explanation, the operation management unit 3, the travel trajectory generation unit 4, and the travel control unit 5 have separate configurations, but they do not necessarily have to have separate configurations, and when these units are used in an actual vehicle, various functions of these units may be realized by a higher-level controller.

[0021] The operation management unit 3 generates information on the position of the vehicle, information on various objects present around the vehicle (information on the vehicle and surrounding environment, etc.), and information on the behavior of the vehicle, such as lateral acceleration, yaw rate, and lateral jerk, based on information acquired by the external communication device 11, the GNSS 12, and the sensor 14, and map information recorded in the map information storage unit 13. The operation management unit 3 periodically transmits the information on the position of the vehicle, information on various objects, and information on the behavior of the vehicle to other vehicles and roadside devices via the external communication device 11, and also transmits the information to the map information storage unit 13, thereby successively updating the map information stored in the map information storage unit 13. Furthermore, the operation management unit 3 sets information on the route from the current position of the vehicle to the destination, based on the information on the position of the vehicle, information on various objects, information on the behavior of the vehicle, and information received by the HMI unit 15 (for example, a driving mode and a destination). Note that, hereinafter, information generated or set by the operation management unit 3 may be referred to as "driving situation information."

[0022] As shown in FIG. 2, the traveling trajectory generation unit 4 has an information acquisition unit 41, a route planning unit 42, a speed planning unit 43, and an information output unit 44. In the traveling trajectory generation unit 4, the route planning unit 42 generates a route (hereinafter referred to as a "route command value P") that is a traveling target when the vehicle travels on a road based on the traveling situation information transmitted from the operation management unit 3 and acquired by the information acquisition unit 41. Here, the route command value P is a command value generated based on, for example, information in the vicinity of the vehicle acquired by the sensor 14 or the like, or information obtained by combining distant map information recorded in the map information storage unit 13 or the like with the aforementioned nearby information, but the method of generating the route command value P is not limited. Then, the speed planning unit 43 generates a speed (hereinafter referred to as a "speed command value") that is a traveling target when the vehicle travels on a road based on the route command value P and the traveling route information, and the information output unit 44 outputs a traveling trajectory composed of information such as the route command value P and the speed command value. The speed planning unit 43 will be described in detail later.

[0023] The driving control unit 5 sets target driving force, target braking force, target steering angle, etc., and controls the powertrain system 6, brake system 7, and steering system 8 so that the vehicle follows the driving trajectory output from the driving trajectory generation unit 4.

[0024] <Controlled Objects of Vehicle Motion Control Device 2> The powertrain system 6 controls the driving force generated by the internal combustion engine, the electric motor, etc., based on the operation by the driver or the target driving force output from the cruise control unit 5.

[0025] The brake system 7 controls the braking force generated by the brake calipers and the like based on the operation by the driver or a target braking force output from the cruise control unit 5.

[0026] The steering system 8 controls the steering angle of the wheels based on the operation by the driver or the target steering angle output from the cruise control unit 5.

[0027] <Speed ​​Planning Division 43> Next, the speed planning unit 43 will be described in detail with reference to Fig. 3. Fig. 3 is a functional block diagram of the speed planning unit 43. The speed planning unit 43 generates a speed command value for the vehicle based on the vehicle's position and speed, upper limit value of the behavior, route command value P, etc., and has an information acquisition unit 43a, a distant route generation unit 43b, a distant speed generation unit 43c, a traveling speed generation unit 43d, and an information output unit 43e. Each of these will be described in order below.

[0028] The information acquisition unit 43a acquires driving situation information from the traffic management unit 3 and also acquires a route command value P from the route planning unit 42, and outputs them to each unit in the speed planning unit 43.

[0029] The long distance route generating unit 43b generates a route (hereinafter referred to as a "long distance route F") to a long distance (for example, 200 m ahead of the vehicle) that cannot be detected by the sensor 14, based on a surrounding map included in the driving situation information acquired from the information acquiring unit 43a. When the route planning unit 42 generates the route command value P, it is necessary to take into consideration the avoidance of a collision between the vehicle and surrounding vehicles, and therefore the calculation load is large, and it is not possible to generate a route command value P corresponding to a long distance. Therefore, in this embodiment, the long distance route generating unit 43b generates a long distance route F with a small calculation load, thereby compensating for long distance route information that cannot be handled by the route command value P. Here, the long distance route F generated by the long distance route generating unit 43b may be a route having the same start point as the route command value P or a route having the same start point as the end point of the route command value P, and the definition of the long distance route F is not limited.

[0030] Based on the driving situation information from the information acquisition unit 43a and the distant route F from the distant route generation unit 43b, the distant speed generation unit 43c generates a speed (hereinafter referred to as "distant speed") at which a physical quantity related to the vehicle behavior occurring when the host vehicle travels on the distant route F is within a specified value. Here, the specified value may be a predetermined value determined in advance in consideration of ride comfort, etc., or a vehicle limit value based on a road surface friction coefficient acquired by the sensor 14, etc., and the definition of the specified value is not limited. In addition, the speed at which the physical quantity related to the vehicle behavior is within the specified value may be a speed assuming a steady circular turn obtained by calculating the square root of a value obtained by dividing a specified value of the lateral acceleration by the curvature of the travel route, a speed obtained by integrating a specified value of the longitudinal acceleration, a legal maximum speed on a general road, or an arbitrarily set speed limit, and the method of calculating the speed at which the physical quantity related to the vehicle behavior is within the specified value is not limited.

[0031] The travel speed generating unit 43d generates a speed command value when the host vehicle travels along the route command value P based on the travel situation information and the route command value P from the information acquiring unit 43a, and the far speed from the far speed generating unit 43c. Here, when the distance of the far route F is approximately the same as the distance of the route command value P, the travel speed generating unit 43d may generate a speed command value only from the route command value P, and the type of input value for the travel speed generating unit 43d to generate the speed command value is not limited. In addition, when the computation load of the vehicle motion control device 2 is very high or the accuracy of the far route F is very low, the travel speed generating unit 43d may lower the priority of using the far route F or generate a speed command value without using the far route F, and the method of selecting the input value used by the travel speed generating unit 43d to generate the speed command value is not limited.

[0032] The information output unit 43e outputs the speed command value from the traveling speed generation unit 43d to the information output unit 44.

[0033] <Processing of the traveling speed generating unit 43d> Next, an outline of the process of the traveling speed generating unit 43d will be described with reference to the flowchart of FIG.

[0034] First, in step S1, the traveling speed generating unit 43d acquires the traveling situation information and the route command value P from the information acquiring unit 43a, and acquires the far-distance speed from the far-distance speed generating unit 43c.

[0035] Next, in step S2, the driving speed generation unit 43d generates a speed (hereinafter referred to as the "nearby speed") at which physical quantities related to the vehicle behavior occurring when driving only along the route command value P are within specified values, based on the driving condition information acquired in step S1 and the route command value P.

[0036] In step S31, the travel speed generating unit 43d determines whether the nearby speed is higher than the far speed in the overlapping range of the route command value P and the far route F, based on the far speed acquired in step S1 and the nearby speed generated in step S2. If the nearby speed is higher than the far speed (step S31, YES), the process proceeds to step S32, and if the nearby speed is equal to or lower than the far speed (step S31, NO), the process proceeds to step S33. Here, the range in which the magnitudes of the nearby speed and the far speed are compared may be the entire overlapping range of the route command value P and the far route F or only the end point of the route command value P, and the definition of the range in which the magnitudes of the nearby speed and the far speed are compared is not limited.

[0037] In step S32, the travel speed generator 43d selects a relatively slow distant speed, whereas in step S33, the travel speed generator 43d selects a relatively slow nearby speed.

[0038] In step S4, a speed command value is generated based on the selected distant speed or nearby speed, which is a speed at which physical quantities related to the vehicle behavior occurring when the host vehicle travels along the route command value P and the distant route F beyond it are within specified values.

[0039] In step S5, the speed command value generated in step S4 is output to the information output unit 43e.

[0040] <Route A> Next, the route command value P and the speed command value that are generated moment by moment while the host vehicle V is traveling along the travel route A in FIG. 5 will be described with reference to FIG. 6A to FIG. 6D.

[0041] FIG. 5 is a plan view of a route A along which a host vehicle V travels. n 5 shows an example of a route command value P and a distant route F set within a range of a travelable area R of the vehicle V. In this travelable area R, an inflection point I exists at the start point of a right turn, and the section up to the inflection point I is defined as a straight road S, and the section after the inflection point I is defined as a curve C. n In this case, since the sensor 14 of the host vehicle V can only detect the straight road S area within the drivable area R, the route command value P generated by the route planning unit 42 of the host vehicle V is linear, as illustrated by the arrow in the figure. However, as the host vehicle V moves forward and approaches the inflection point I, the sensor 14 detects the curve C, and the route command value P changes to a curved shape.

[0042] 6A is a graph of the curvature of the path command value P when the conventional control is used for the host vehicle V in FIG. 5, and FIG. 6B is an example of a speed command value generated based on the path command value P in FIG. 6A. FIG. 6C is a graph of the curvature of the distant path F when the control of this embodiment is used for the host vehicle V in FIG. 5, and FIG. 6D is a speed command value when the control of this embodiment is used for the host vehicle V in FIG. 5. Each graph shows the time T n From time T n+4 In each figure, the dashed lines indicate time T n The dotted line indicates the time T n+1 The dashed line indicates the time T n+2 The long dashed line indicates the time T n+3 The long dashed line indicates the time T n+4 Indicates the value of.

[0043] As shown in FIG. 6A, the vehicle V is in the position of FIG. 5 for a time T n The curvature of the path command value P is 0 (straight line). nIn the conventional control, in which the speed command value is generated based only on the path command value P, the speed command value is generated based on a specified value mainly related to the longitudinal motion of the host vehicle V, such as the longitudinal acceleration. n As shown by the speed command value (dashed line), a speed command value for increasing the speed is generated.

[0044] Then, when the host vehicle V moves forward and approaches the curve C, at time T n+2 From time T n+4 As shown in the route command value P in FIG. 6, a route command value P corresponding to the curvature of the curve C is generated, and a speed command value (see FIG. 6B) for rapid deceleration is generated based on a specified value including the lateral movement of the host vehicle V, such as the lateral acceleration, in accordance with the curvature of the route command value P.

[0045] As described above, in the conventional control illustrated in FIGS. 6A and 6B, the change in the speed command value becomes large before and after the time when the sensor 14 detects the curve C, so that the deceleration within the specified value of the longitudinal acceleration cannot follow the sudden deceleration specified by the speed command value, and abrupt speed changes that impair the ride quality and comfort of the passengers may occur.

[0046] On the other hand, in the speed control of this embodiment, as explained in the flowchart of FIG. n From this point on, a speed command value is generated taking into consideration the curvature of the distant route F including the curve C shown in Fig. 6C in addition to the curvature of the route command value P shown in Fig. 6A. As a result, as shown in Fig. 6D, the speed command value generated at one time and the speed command value generated at the next time always substantially match each other, so that not only is the speed change gentler than in conventional control, but the physical quantities related to the vehicle behavior can be kept within specified values ​​that do not impair the ride quality and comfort of the occupants.

[0047] Therefore, it can be seen that this embodiment not only makes it possible to make the speed change gentler, but also makes it possible to keep the physical quantities related to the vehicle behavior within the specified values. In other words, by adopting the speed control of this embodiment, the occurrence of unstable vehicle behavior due to sudden braking, etc. can be suppressed compared to the conventional method, and therefore the ride comfort of the occupants is improved. EXAMPLES

[0048] Next, a vehicle motion control device 2 according to a second embodiment of the present invention will be described with reference to Fig. 7. Note that a duplicated description of points common to the first embodiment will be omitted.

[0049] Fig. 7 is a functional block diagram of the speed planning unit 43 of the embodiment 2. The speed planning unit 43 of the embodiment shown here is obtained by changing the travel speed generating unit 43d to a travel speed candidate generating unit 43f and adding a travel speed selecting unit 43g to the speed planning unit 43 of the embodiment 1 shown in Fig. 3.

[0050] Based on the driving condition information and route command value P from the information acquisition unit 43a, and the distant speed from the distant speed generation unit 43c, the driving speed candidate generation unit 43f generates multiple speed command values ​​such that physical quantities related to the vehicle behavior occurring when traveling along either or both of the route command value P and the distant route F are within specified values, and outputs the generated speed command values ​​to the driving speed selection unit 43g.

[0051] The travel speed selection unit 43g selects one as a speed command value based on the current travel mode (shortest time mode, economy mode, etc.) indicated by the travel status information from the information acquisition unit 43a and the multiple speed command value candidates from the travel speed candidate generation unit 43f, and the information output unit 43e outputs it to the travel control unit 5. For example, when the travel status information indicates the shortest time mode, the speed command value candidate with the shortest travel time is selected from the multiple speed command value candidates generated by the travel speed candidate generation unit 43f, and when the travel status information indicates the economy mode, the speed command value candidate with the smallest energy consumption is selected from the multiple speed command value candidates. That is, the travel speed selection unit 43g selects the speed command value with the shortest travel time from the multiple speed command value candidates, or selects the speed command value with the smallest energy consumption from the multiple speed command value candidates.

[0052] In this way, the vehicle motion control device of the second embodiment not only provides the same effects as those of the first embodiment, but also makes it possible to control the vehicle motion in accordance with the selected driving mode.

[0053] The present invention is not limited to the above-mentioned embodiment, and various modifications are included. For example, the above-mentioned embodiment is specifically described in order to easily explain the present invention, and is not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with a part of the configuration of another embodiment. Also, a configuration of another embodiment can be added to a configuration of one embodiment. Also, a part of the configuration of each embodiment can be deleted, a part of another configuration can be added, and a part of another configuration can be replaced with a part of another configuration. [Explanation of symbols]

[0054] 1. In-vehicle systems 11 External communication device 12 GNSS 13 Map information storage unit 14 Sensors 15 HMI units 2 Vehicle motion control device 3. Operation Control Unit 4. Trajectory generation unit 41 Information Acquisition Department 42 Route Planning Section 43 Speed ​​Planning Department 43a Information acquisition section 43b Distant path generation unit 43c Far velocity generation section 43d Travel speed generating unit 43e Information output section 43f Travel speed candidate generation unit 43g Travel speed selection section 44 Information output section 5. Driving control unit 6 Powertrain System 7. Brake System 8. Steering System C Curve I inflection point P Path command value F Distant Route R Drivable area S straight road V Vehicle

Claims

1. A neighborhood information acquisition unit that acquires neighborhood information of a vehicle; A remote information acquisition unit that acquires remote information of the vehicle; a speed planning unit that generates a speed command value that is a travel target of the vehicle based on the near information and the far information; a route planning unit that generates a route command value that is a route that is a travel target of the vehicle based on the neighborhood information; a far path generating unit that generates a far path, which is a path farther than the path command value, based on the far distance information; Equipped with The vehicle motion control device according to the present invention, characterized in that the speed planning unit selects and outputs a lower speed command value from among a speed command value based on the route command value and a speed command value based on the distant route.

2. 2. The vehicle motion control device according to claim 1, The vehicle motion control device is characterized in that the speed planning unit generates a speed command value such that the route command value and a physical quantity related to the vehicle behavior occurring when traveling on the distant route are within a specified value.

3. The vehicle motion control device according to claim 1 or 2, A vehicle motion control device characterized in that the speed planning unit changes the priority of information used to generate the speed command value or selects information used to generate the speed command value based on the magnitude of the calculation load or the accuracy of the remote information.

4. The vehicle motion control device according to claim 1 or 2, The vicinity information is information about the surroundings of the vehicle acquired from a sensor that detects the surrounding environment of the vehicle, The vehicle motion control device is characterized in that the remote information is information about the surroundings of the vehicle obtained from a map information storage unit that records map information.

5. acquiring information about the vicinity of a vehicle; acquiring distant information of the vehicle; generating a speed command value that is a travel target of the vehicle based on the near information and the far information; generating a route command value that is a route to be traveled by the vehicle based on the vicinity information; generating a long distance route that is a route farther than the route command value based on the long distance information; a speed command value based on the route command value and a speed command value based on the remote route, the speed command value being a lower speed and being outputted in the step of generating the speed command value.

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