JP2007223500A - Multi-axle vehicle and its steering control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a small-turn performance with a simple structure in a multi-axle vehicle having three or more axles, such as a 6-wheel vehicle and an 8-wheel vehicle. <P>SOLUTION: A multi-axle vehicle makes a turn by using intermediate driving wheels 34L, R and 36L, R disposed on one or more intermediate axles 24, 26 arranged between a foremost axle 22 and a rearmost axle 28. When making the turn, the vehicle controls a speed Vout of the intermediate driving wheels 34L, 36L at an outer side of the turn to be faster than a vehicle speed V<SB>0</SB>, and controls a speed Vin of the intermediate driving wheels 34R, 36R at an inner side of the turn to be slower than the vehicle speed V<SB>0</SB>. The vehicle controls the speeds Vout, Vin of the intermediate driving wheels at inner and outer sides according to the vehicle speed V<SB>0</SB>and a steering angle ψ of the steering wheels 32L, R and 34L, R so that the vehicle may make the turn with radii smaller than those when the vehicle makes the turn only by the steering wheels 32L, R and 34L, R. When making the turn, the vehicle uncouples the power transmission to the driving wheels 32L, R and 38L, R other than the intermediate driving wheels 34L, R and 36L, R to bring the driving wheels 32L, R and 38L, R into a free movement state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multi-axis vehicle having three or more axles such as a six-wheel vehicle and an eight-wheel vehicle, and more particularly to a steering control technique for turning the multi-axis vehicle with a small radius. The present invention is suitable, for example, for an eight-wheel vehicle having four axles with a substantially equal distance between the axes.

  Conventionally, a steering device for reducing the turning radius of a vehicle has been developed. Patent Document 1 discloses that braking is applied to a front turning inner wheel in a traveling direction in a four-wheel vehicle. Patent Document 2 also discloses that braking is applied to the rear turning inner wheel in the traveling direction in a four-wheel vehicle.

  By the way, in a multi-axis vehicle having three or more axles such as a six-wheel vehicle or an eight-wheel vehicle, rotation with a small radius is more difficult than a four-wheel vehicle. As an example, an eight-wheel vehicle having four axles will be described as an example.

  In an eight-wheel vehicle, normally, four wheels connected to the front two shafts including the first shaft and the second shaft are the steering wheels, and the four rear wheels including the third shaft and the fourth shaft are the non-steering wheels. It is. Turning is performed by changing the direction of the steering wheels of the front two axes. The turning center is the intersection of the extension line of the center axis of the inner ring of the first shaft that is the foremost steering wheel and the extension line of the middle line between the third axis and the fourth axis that are non-steering wheels. Due to the large span between the lines, the turning center is far away from the vehicle body and therefore the minimum turning radius is large. Even if the technology disclosed in Patent Documents 1 and 2 is applied to such an 8-wheel vehicle and braking is applied to the inner wheels of the front 2-axis or the rear 2-axis during turning, it is effective as in the case of a 4-wheel vehicle. The turning radius does not decrease.

  For an eight-wheel vehicle, a steering device based on another principle is disclosed on page 34 of Non-Patent Document 1, for example. According to this article, the steering device used in the Daimler Benz 8-wheel vehicle "Lux" developed in Germany in 1975, only steers the front two axes when steering at speeds below 30 km / h. Without turning the rear two axes to the opposite phase. Such a steering device that steers the front two axes and the rear two axes in opposite phases is called 8WS (Eight Wheel Steering System).

  By adopting 8WS, the turning center is closer to the vehicle body and the minimum turning radius is smaller than in the case of steering with only the front two axes.

JP-A-11-49019 (for example, claim 1) JP-A-11-49020 (for example, claim 1) Magazine "PANZER", July 2005 issue, Argonaut (for example, page 34)

  However, in 8WS, the structure of the steering device for turning the front two axes and the rear two axes in opposite phases is complicated, and a space for accommodating the steering mechanism in a place where the rear two axes of the vehicle body are disposed. Therefore, the capacity of the passenger seat and the cargo compartment at the rear of the vehicle body may be reduced. Therefore, the present inventors previously proposed in Japanese Patent Application No. 2005-244283 a means for suppressing such problems. The outline of the technical content disclosed by the present inventors in the above-mentioned patent application is that when a multi-axle vehicle having three or more axles performs a turning motion, the speed of the intermediate driving wheel outside the turning is changed to the inside of the turning. That is, the speed is controlled faster than the speed of the intermediate drive wheel.

  However, in a multi-axle vehicle having the configuration disclosed in the above patent application, there arises a problem that the turning radius increases as the friction coefficient between the wheels and the road surface increases. The present invention seeks to improve this problem as well.

  A first object of the present invention is to effectively improve the turning performance in a multi-axle vehicle having three or more axles such as a six-wheel vehicle and an eight-wheel vehicle.

  The second object of the present invention is to provide a multi-axle vehicle having three or more axles such as a six-wheel vehicle or an eight-wheel vehicle, even if the friction coefficient between the wheels and the road surface becomes high. Therefore, it is possible to suppress an increase in the turning radius.

  According to one aspect of the present invention, a multi-axle vehicle having three or more axles including a foremost axle, a last axle, and one or more intermediate axles is provided with one or more pairs provided on the one or more intermediate axles. An intermediate drive wheel, at least two pairs of steering wheels provided on the foremost axle and the last axle, and the speed of the intermediate drive wheel inside the turn and the speed of the outer intermediate drive wheel when performing a turning motion Depending on an external force acting on both or any one of the two or more pairs of steering wheels or a desired turning radius when performing a turning motion. A steering angle adjusting device that adjusts the steering angle of both or one of the two or more pairs of steering wheels so that the lateral force acting on both or one of the pairs of steering wheels is reduced. .

  According to this multi-axle vehicle, a turning motion is performed both when moving forward and backward using one or more pairs of intermediate drive wheels provided on one or more intermediate axles disposed between the front axle and the rear axle. be able to. The size of the turning radius can be controlled by controlling how the speeds of the intermediate driving wheel outside the turning and the intermediate driving wheel inside are different. Therefore, it is possible to turn with a smaller turning radius than when turning only with the steering wheel. Also, when performing a turning motion, the steering angle of both or one of the two or more pairs of steering wheels is set so that the lateral force acting on both or one of the two or more pairs of steering wheels becomes small. In a multi-axle vehicle having three or more axles such as a six-wheel vehicle or an eight-wheel vehicle, even if the coefficient of friction between the wheels and the road surface increases, the turning radius thereby increases. It is possible to suppress the increase.

  In a preferred embodiment according to one aspect of the present invention, when performing a turning motion, the lateral force acting on both or one of the two or more pairs of steering wheels causes the two or more pairs of steering wheels to move. A measuring means for measuring an external force acting on both or one of the pairs; and the steering angle adjusting device is configured so that the external force measured by the measuring means is minimized. The steering angle of both or either pair is adjusted.

  In an embodiment different from the above, when the steering angle adjusting device performs a turning motion, a lateral force acting on both or any one of the two or more pairs of steering wheels according to a desired turning radius. The geometrical calculation is performed so as to minimize the steering angle, and the steering angle of both or any one of the two or more pairs of steering wheels is adjusted precisely.

  In another embodiment different from the above, the steering angle adjusting device works on both or any one of the two or more pairs of steering wheels according to a desired turning radius when performing a turning motion. The steering angle of both or one of the two or more pairs of steering wheels is roughly variably adjusted so that the lateral force is as small as possible.

  In another embodiment different from the above, the steering angle adjusting device works on both or any one of the two or more pairs of steering wheels according to a desired turning radius when performing a turning motion. The steering angle of both or any one of the two or more pairs of steering wheels is variably adjusted intermittently so that the lateral force is as small as possible.

  In another embodiment different from the above, the steering angle adjusting device works on both or any one of the two or more pairs of steering wheels according to a desired turning radius when performing a turning motion. The steering angle of both or any one of the two or more pairs of steering wheels is variably adjusted based on the angle value set in advance in the left / right direction so that the lateral force is as small as possible. I have to.

  In another embodiment different from the above, the pair of wheels provided on the last axle are configured as fixed wheels when going straight, and are automatically steerable when turning.

  In addition to the intermediate drive wheel, when at least one pair of drive wheels is provided on the foremost axle or the rearmost axle, the steering control device applies to the drive wheels other than the intermediate drive wheel when performing a turning motion. The transmission of the driving force is cut off, so that the wheels provided on both the front axle and the rear axle can be controlled to be idle wheels. This prevents both the front and rear axle wheels from interfering with the turning motion by the intermediate drive wheels, thereby making it easier to turn with a small radius.

  In a preferred embodiment, the present invention is applied to an eight-wheeled vehicle including four axles having a substantially equal distance between the shafts, which is composed of a first axis, a second axis, a third axis, and a fourth axis in order from the front. Is done. In this 8-wheel vehicle, all four pairs of wheels are drive wheels, two pairs of wheels, the first and second axes, are steering wheels, and two pairs of wheels, the second and third axes, are intermediate. It is a drive wheel. Then, the two pairs of intermediate drive wheels can be used to turn with a small radius, and while the two pairs of intermediate drive wheels are turning, two pairs of driving of the first axis and the fourth axis are driven. The wheel is disconnected from the power transmission to the wheel.

  The present invention is applicable not only to such a 4-axis vehicle but also to a 3-axis vehicle or a vehicle having 5 or more axles.

  A steering control device for a multi-axis vehicle according to the present invention includes a steering angle detection unit that detects a steering angle of a steered wheel, a driving speed detection unit that detects a driving speed of the multi-axis vehicle, and a steering detected by the steering angle detection unit. Based on the angle and the driving speed detected by the driving speed detecting means, there can be provided intermediate driving wheel speed control means for controlling the speed of the inner intermediate driving wheel and the speed of the outer intermediate driving wheel. According to this configuration, the speed of the inner and outer intermediate driving wheels is controlled according to the current driving state such as the detected steering angle and vehicle speed (vehicle representative point speed) regardless of whether the vehicle is moving forward or backward. It is possible to perform a turning motion under turning conditions such as a turning radius and a yaw angular velocity suitable for the current driving state, and thus it is possible to obtain operability, maneuverability and stability during turning.

  When controlling the speed of the inner and outer intermediate driving wheels based on the current driving conditions (steering angle, driving speed, etc.) detected as described above, the vehicle turns only by steering with the steered wheels under the driving conditions. The target speed of each of the left and right intermediate drive wheels is determined so that the turning movement can be performed with a turning radius smaller than the turning radius (normal turning radius), and the inside and outside are used by using the respective target speeds. The speed of each of the intermediate drive wheels can be controlled. For example, in a preferred embodiment, the target turning radius is determined by multiplying the normal turning radius determined from the detected driving condition by a factor smaller than 1.0 (for example, about 0.8), and the smaller target turning radius. The target speed of each of the left and right intermediate drive wheels is determined so that the vehicle can turn. As a result, turning with a smaller turning radius is automatically realized when turning only with the steering wheel.

  In a preferred embodiment, the driving speed detecting means detects the speed of the left intermediate driving wheel and the speed of the right intermediate driving wheel, respectively. Then, the intermediate drive wheel speed control means, when performing the turning motion, of the detected left and right intermediate drive wheel speeds, one corresponding to the speed of the outer intermediate drive wheel is Based on one of the target speeds of the intermediate drive wheels, which corresponds to the target speed of the outer intermediate drive wheel, the respective speeds of the turning inner and outer intermediate drive wheels are controlled. According to this configuration, particularly when turning at an extremely low speed, even if the required time for detecting the wheel speed with a desired accuracy is lengthened and the control responsiveness is reduced, the higher speed of the left and right drive wheels Since the control is performed based on the detected speed of the driving wheel outside the turn, it is possible to alleviate the problem of a decrease in control responsiveness.

  In a preferred embodiment, the driving speed detecting means includes means for detecting the speed of the representative point of the multi-axis vehicle, and the intermediate driving wheel speed control means is configured to detect the representative point detected when performing the turning motion. Based on the speed, the speed of the inner and outer intermediate drive wheels is controlled so that the speed of the inner intermediate drive wheel is lower than the representative point speed and the outer intermediate drive wheel speed is higher than the representative point speed. . With this configuration, it is possible to perform a turning motion under turning conditions such as a turning radius and yaw angular velocity suitable for the detected representative point speed (current vehicle speed), and operability, maneuverability and stability during turning. Can be obtained.

  The multi-axle vehicle according to the present invention includes braking means for independently braking the left intermediate driving wheel and the right intermediate driving wheel, and the steering control device includes braking force control means for controlling the braking means. May be configured. The braking force control means can adjust the braking force applied to the left and right intermediate drive wheels when performing a turning motion. According to this configuration, the turning motion can be controlled as follows, for example, by adjusting the braking force applied to the left and right intermediate drive wheels regardless of whether the vehicle is moving forward or backward.

  That is, in a preferred embodiment, the inner and outer intermediate drive wheels are coupled via a differential gear. The braking force control means controls the braking means to apply a braking force to the inner intermediate driving wheels in order to make the inner and outer intermediate driving wheels different in speed when performing a turning motion. According to this configuration, by applying a braking force to the inner intermediate drive wheel, the speed of the inner intermediate drive wheel can be decreased, and at the same time, the speed of the outer intermediate drive wheel can be increased to reduce the turning radius.

  Further, in a preferred embodiment, the braking force control means includes an inner ring lock detecting means for detecting that the inner intermediate driving wheel is locked, and an inner intermediate driving wheel when the inner intermediate driving wheel is locked. And an inner ring unlocking means for controlling the braking means so as to relieve the braking of the wheel and to apply a braking force to the outer intermediate drive. According to this configuration, the wheel lock generated on the inner driving wheel can be released by applying a braking force to the outer intermediate driving wheel. As a result, it is possible to prevent an excessive lateral force from acting on the wheel during the turn and to prevent the turning radius from greatly varying depending on the road surface condition.

  Thus, the preferred embodiment of the multi-axis vehicle according to the present invention can reduce the turning radius while maintaining a stable traveling state by the action of the braking force control means described above.

  Further, the above-described braking force control means may be configured to control the time for braking the inner and outer intermediate driving wheels in order to control the braking force applied to the inner and outer intermediate driving wheels, respectively. . In that case, the braking force control means periodically repeats braking and non-braking alternately by the pulse width control method, and controls the speed of the inner and outer intermediate driving wheels to control the duty of the braking time within one cycle. It may be configured to control the length of each cycle to control the ratio and prevent locking of the intermediate drive wheels. By adopting such a pulse width control method, the speed control of the intermediate drive wheels is performed by adjusting the duty ratio, and the lock prevention is performed by adjusting the cycle, so that stable control can be realized.

  According to another aspect of the present invention, a steering control device for a multi-axis vehicle as described above is provided.

  According to the present invention, it is possible to effectively improve the turning performance in a multi-axle vehicle having three or more axles.

  Further, according to the present invention, even if the coefficient of friction between the wheels and the road surface is increased in a multi-axle vehicle having three or more axles, it is possible to suppress an increase in the turning radius.

  Hereinafter, a steering control device for a multi-axis vehicle according to an embodiment of the present invention will be described with reference to the drawings.

  First, an overview of steering control in a multi-axis vehicle according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the multi-axle vehicle 20 according to this embodiment has eight wheels including four axles including a first shaft 22, a second shaft 24, a third shaft 26, and a fourth shaft 28 in order from the front. It is a vehicle. The distance between the four axles 22, 24, 26, and 28 is substantially equal, the distance between the first and second axes 22, 24 is short, the distance between the second and third axes 24, 26 is long, and the third, The axle arrangement is not such that the distance between the four axes 26 and 28 is short. The present invention is not necessarily applied unless the axle arrangement is such that the distance between the shafts is substantially uniform, but this axle arrangement is preferable in order to obtain the effect of improving the turning performance according to the present invention.

  Two pairs of wheels 32L, 32R, 34L, and 34R provided on the front two shafts including the first shaft 22 and the second shaft 24 are directionally variable steering wheels coupled to an Ackermann link (not shown). On the other hand, two pairs of wheels 36L, 36R, 38L, and 38R provided on the rear two shafts including the third shaft 26 and the fourth shaft 28 are non-steering wheels that do not change direction. The two pairs of wheels 34L, 34R, 36L, 36R provided on the two intermediate shafts including the second shaft 24 and the third shaft 26 are drive wheels that receive a driving force from an engine (not shown). . Further, the left and right wheels 32L and 32R of the foremost first shaft 22 and the left and right wheels 38L and 38R of the last fourth shaft 28 can be switched between driving wheels and idle wheels by a clutch described later. . In this specification, in order to distinguish the drive wheels 34L, 34R, 36L, 36R of the intermediate two shafts 24, 26 from the drive wheels 32L, 32R, 38L, 38R of the first and fourth shafts 22, 28, “intermediate drive” is described. It is called a “ring”.

  When the steering wheel 32L, 32R, 34L, 34R is turned, the turning control device mounted on the multi-axle vehicle 20 according to this embodiment, according to the principle of the present invention, has the left intermediate drive wheels 34L, 36L. The rotational speeds of the right intermediate drive wheels 34R and 36R are controlled to different speeds. The course of the multi-axle vehicle 20 is forcibly changed due to the speed difference between the left intermediate drive wheels 34L, 36L and the right intermediate drive wheels 34R, 36R, so that the steering wheels 32L, 32R, 34L, 34R The multi-axis vehicle 20 turns with a smaller radius than when turning only by rudder.

  As an example, a more specific description will be given assuming that the vehicle turns to the right. In this case, the rotational speed is controlled so that the intermediate drive wheels 34L and 36L on the outer side (left side) of the turn travel at a high travel speed Vout, whereas the intermediate drive wheels 34R and 36R on the inner side (right side) of the turn travel at a low speed. The rotational speed is controlled so as to travel at the speed Vin. Here, the two intermediate drive wheels 34L, 36L outside the turn can be collectively regarded as one huge intermediate drive wheel 40L. Similarly, the two intermediate drive wheels 34R, 36R inside the turn are also In summary, it can be regarded as one huge intermediate drive wheel 40R. Accordingly, it can be considered that the outer and inner huge intermediate driving wheels 40L and 40R travel at different traveling speeds Vout and Vin, respectively, and the turning radius drawn by the intermediate driving wheels 34L and 36L (40L) on the outer sides of the turning is approximately The large radius Rout as shown in the figure is shown, and the turning radius drawn by the intermediate drive wheels 34R, 36R (40R) inside the turning is almost the small radius Rin as shown in the figure.

Here, when the representative point 30 of the multi-axis vehicle 20 is provided near the center of the length and width of the vehicle body of the multi-axis vehicle 20, the traveling speed V ₀ , turning radius R _0, and turning yaw angular velocity ω of the representative point 30. The following relational expression 100 is approximately established. In Expression 100, symbol H represents the distance between the left and right intermediate drive wheels 40L, 40R, and this distance H roughly corresponds to the width of the vehicle body (hereinafter, this distance H is referred to as "vehicle width"). .

ここで、代表点３０は車体の中央付近に配置されているから、代表点３０の旋回半径R₀は、次式１０２で表される。

Here, since the representative point 30 is arranged near the center of the vehicle body, the turning radius R ₀ of the representative point 30 is expressed by the following expression 102.

よって、次の関係式１０４が近似的に成立する。

Therefore, the following relational expression 104 is approximately established.

この実施形態に係る多軸車両２０では、左側の中間駆動輪３４Ｌ、３６Ｌと右側の中間駆動輪３４Ｒ、３６Ｒが夫々ディファレンシャルギアで連結され、それらのディファレンシャルギアの入力軸にトランスミッションの出力軸の回転速度が与えられる。この場合、多軸車両２０が直進走行する時の走行速度Vｄは下式１０６で与えられる。

In the multi-axle vehicle 20 according to this embodiment, the left intermediate drive wheels 34L and 36L and the right intermediate drive wheels 34R and 36R are connected by differential gears, respectively, and the rotation of the output shaft of the transmission is performed on the input shafts of these differential gears. Speed is given. In this case, the traveling speed Vd when the multi-axis vehicle 20 travels straight is given by the following formula 106.

上記の式１０４と式１０６から、V₀=Vdであり、代表点３０の走行速度V₀は、トランスミッションの出力軸の回転速度から読み取ることができる。

From the above equations 104 and 106, V ₀ = Vd, and the traveling speed V ₀ at the representative point 30 can be read from the rotational speed of the output shaft of the transmission.

When the travel speed (hereinafter referred to as “representative speed”) V _{0 of the} representative point 30 is a certain value, the travel speed (hereinafter referred to as “outer intermediate drive wheel speed”) Vout of the intermediate drive wheels 34L and 36L outside the turn. Is controlled to be a value larger than the representative speed V ₀ , the traveling speed Vin of the intermediate drive wheels 34R and 36R inside the turn (hereinafter referred to as “inner intermediate drive wheel speed”) Furthermore, it is determined to be a certain value lower than the representative speed V ₀ . Alternatively, if the braking force is applied to the inner drive wheels 34R, 36R inside the turn and the inner intermediate drive wheel speed Vin is controlled to a value lower than the representative speed V ₀ , the outer intermediate drive wheel speed Vout is automatically The value is automatically controlled to be higher than the representative speed V ₀ according to the equation 104.

By controlling in this way when pivoted the inner intermediate driven wheel speed Vin and the outer intermediate drive wheel speed Vout to different values, radius close to the turning radius R ₀ determined by the following equation 108 guided by Formula 100 and Formula 102, The multi-axis vehicle 20 turns.

ところで、上述した内側の中間駆動輪３４Ｒ、３６Ｒに制動力を加える制御において、中間駆動輪３４Ｒ、３６Ｒに制動をかけすぎてその車輪速度Vinがその目標値より低下してロックしそうになった場合、ディファレンシャルギアの作用で、外側中間駆動輪速度Voutがその目標値を超過してしまい、適正な半径と角速度での旋回ができないことになる。この問題を解決するため、この実施形態に係る多軸車両２０の操舵制御装置は、外側中間駆動輪速度Voutがその目標値を大きく超過してしまった場合（或は、内側中間駆動輪速度Vinが車輪ロックが生じそうなほどに低下した場合）には、外側の中間駆動輪３４Ｌ、３６Ｌに制動力を与えることで、ディファレンシャルギアから内輪側に加速トルクを与え、下がり過ぎた内側中間駆動輪速度Vinを上昇させて目標値へ戻すことができる。

By the way, in the control for applying the braking force to the inner intermediate driving wheels 34R and 36R described above, when the intermediate driving wheels 34R and 36R are excessively braked and the wheel speed Vin is lower than the target value, it is likely to be locked. Due to the action of the differential gear, the outer intermediate drive wheel speed Vout exceeds the target value, and turning with an appropriate radius and angular velocity cannot be performed. In order to solve this problem, the steering control device for the multi-axle vehicle 20 according to this embodiment is configured such that the outer intermediate driving wheel speed Vout greatly exceeds the target value (or the inner intermediate driving wheel speed Vin). Is lowered to the extent that the wheel lock is likely to occur), the braking force is applied to the outer intermediate drive wheels 34L and 36L, so that the acceleration torque is applied from the differential gear to the inner ring side, and the inner intermediate drive wheel is lowered too much. The speed Vin can be increased and returned to the target value.

  As described above, the steering control device for the multi-axle vehicle 20 according to this embodiment applies a braking force independently to each of the inner intermediate driving wheels 34R and 36R and the outer intermediate driving wheels 34L and 36L. Enables turning at a turning radius and angular velocity.

  Various variations can be adopted in the configuration of the speed sensor for detecting the intermediate drive wheel speeds Vin and Vout. In the multi-axle vehicle 20 according to this embodiment, as an example, a magnetic type having a configuration in which rotation of a magnetic gear attached to each intermediate drive wheel is captured and counted as a pulse signal by an electromagnetic pickup using a magnetic circuit or the like. Uses a rotation speed sensor. This magnetic rotational speed sensor has the advantage of being robust compared to an optical rotational speed sensor using an optical rotary encoder, but on the other hand it has a very high angular resolution structurally. Is difficult. Therefore, according to the magnetic rotational speed sensor, the lower the wheel speed, the longer the pulse signal generation interval, and the time required to count the number of pulse signals necessary to detect the speed with sufficient accuracy. The response time of the steering control device becomes longer. In order to alleviate this problem, the steering control device for the multi-axle vehicle 20 according to this embodiment includes speed detection devices attached to both the left intermediate drive wheels 34L and 36L and the right intermediate drive wheels 34R and 36R, respectively. In addition, when turning, depending on the turning direction (for example, based on the steering angle of the steered wheels), the intermediate drive wheels on the outer side out of the left intermediate drive wheels 34L and 36L and the right intermediate drive wheels 34R and 36R. (I.e., the drive wheel that rotates at a higher speed) is selected and the outer intermediate drive wheel speed Vout calculated based on the pulse signal from the speed detection device provided on the outer intermediate drive wheel is used. The steering control as described above is performed. Thereby, the fall of the control responsiveness at the time of low speed driving | operation can be reduced.

  Further, under road conditions such as slipperiness, the inner intermediate drive wheels are locked if an excessive braking force is applied to the inner intermediate drive wheels. Therefore, the steering control device for the multi-axis vehicle 20 according to this embodiment uses the inner intermediate drive wheel speed Vin to detect the locked state of the inner intermediate drive wheel. When the lock of the intermediate drive wheel is detected, the steering control device temporarily stops the braking of the inner intermediate drive wheel, and temporarily applies the braking force to the outer intermediate drive wheel, so that the differential The inner intermediate drive wheel is unlocked by the torque from the gear.

Various variations can be adopted in the configuration of the wheel brake. In the multi-axis vehicle 20 according to this embodiment, as an example, a dry air brake is used. In the case of a dry air brake, it is difficult to control the braking force linearly because the coefficient of friction inside the brake changes due to heat generated by the brake, and there is a response delay in the pressure transmission of the air piping. For this reason, if the braking force itself is feedback-controlled, the control may diverge. Therefore, the steering control device for the multi-axle vehicle 20 according to this embodiment has a configuration for ON / OFF control of the brake at an appropriate timing based on feedback from the rotation speed sensor. Specifically, the time T _on for exciting the solenoid valve for pressure increase the air pressure ((i.e., a time to ON of the brake, hereinafter,) referred to as "brake-on time", does not perform the excitation time T _off (that is, the time to turn off the brake, hereinafter referred to as “brake off time”) and the duty ratio S = T _on / (T _on + T _off ) and the ON-OFF cycle T = (T _on + T _off ) is automatically adjusted by feedback control.

  Next, the multi-axle vehicle 20 and the operation control device according to an embodiment of the present invention will be described more specifically.

  FIG. 2 is a plan view showing the configuration of the wheel drive mechanism of the multi-axle vehicle 20 according to the embodiment of the present invention.

  As shown in FIG. 2, an output shaft 52 of a transmission 50 driven by an engine (not shown) is connected to a distribution gear 54, and two output shafts 56 and 58 of the distribution gear 54 are respectively connected to a second shaft 24 and a third shaft. Connected to the differential gears 60 and 70 of the shaft 26. Here, a differential gear or a simple constant speed distribution gear can be used for the configuration of the distribution gear 54, but in this embodiment, the rotational speeds of the input shaft 52 and the two output shafts 56 are set to be simple. Suppose that equal constant speed distribution gears are used.

  The output shaft 56 of the distribution gear 54 is not only connected to and driven by the differential gear 60 of the second shaft 24, but also passes through the differential gear 60 of the second shaft 24 to input the first shaft driving clutch 64. The output shaft 66 of the first shaft drive clutch 64 is connected to the shaft 62 and is connected to the differential gear 68 of the first shaft 22. Similarly, the output shaft 58 of the distribution gear 54 is not only connected to the differential gear 70 of the third shaft 26, but also penetrates through the differential gear 70 of the third shaft 26 to input the input shaft of the fourth shaft drive clutch 74. 72 and the output shaft 76 of the fourth shaft driving clutch 74 is connected to the differential gear 78 of the fourth shaft 28.

  Accordingly, since the second shaft 24 and the third shaft 26 are always driven by the power from the distribution gear 54, the four intermediate drive wheels 34L, 34R, 36L, 36R coupled to the second shaft 24 and the third shaft 26 are used. Is always a drive wheel. In contrast, the wheels 32L and 32R coupled to the first shaft 24 are drive wheels when the first shaft drive clutch 64 is connected, but are idle when the first shaft drive clutch 64 is disconnected. It is a ring. Similarly, the wheels 38L and 38R coupled to the fourth shaft 28 are also drive wheels when the fourth shaft drive clutch 74 is connected, but are idle wheels when the fourth shaft drive clutch 74 is disconnected. It is.

  The steering control device for the multi-axle vehicle 20 according to this embodiment includes the first shaft drive clutch 64 and the fourth shaft during the turning motion as described above using the intermediate drive wheels 34L, 34R, 36L, 36R. Both the drive clutches 74 are disconnected, and all the wheels 32L, 32R, 38L, and 38R of the first shaft 22 and the fourth shaft 28 are set in the idle state as shown in FIG. Since these wheels 32L, 32R, 38L, and 38R in the idle state are not restricted by the rotational speed of the engine and can be freely rotated by the force received from the road surface, the turning motion by the intermediate drive wheels 34L, 34R, 36L, and 36R is performed. I do not disturb.

  FIG. 4 shows only a part necessary for the description of the present invention in the piping system of the air brake mounted on the multi-axle vehicle 20 according to this embodiment.

  As shown in FIG. 4, the brake cylinders 110 </ b> L, R to 116 </ b> L, R of the eight wheels are connected to any one of the two systems of brake piping 140, 150 that is the output of the brake valve 120 operated by one brake pedal 118. It is connected. When the driver depresses the brake pedal 118, the high-pressure air in the main pipe 160 supplied from an air tank (not shown) is supplied to all of the eight brake cylinders 110L, R to 116L, R to control all eight wheels. When power is applied and the driver removes his foot from the brake pedal 118, the high-pressure air in the eight brake cylinders 110L, R to 116L, R is released to the atmosphere through the brake valve 120 (see dotted arrows), The braking power of all 8 wheels disappears.

  In the piping to the four brake cylinders 112L, R, 114L, R for the four intermediate drive wheels of the second shaft and the third shaft, the automatic pressure increase control valves 122L, R, 124L, R, the automatic pressure increase check valve 142L, R, 144L, R, manual pressure increase check valves 152L, R, 154L, R and pressure reducing throttles 162L, R, 164L, R are provided. Independent of the air supply in response to the operation of the brake pedal 118 described above, the high pressure air in the main pipe 160 is also supplied to the four brakes for the intermediate drive wheels by opening and closing the automatic pressure increase control valves 122L, R, 124L, R. The cylinders 112L, R, 114L, and R are supplied. That is, by automatically exciting the automatic pressure increase control valves 122L, R, 124L, R corresponding to the four intermediate drive wheels, high pressure air is individually supplied to the brake cylinders 112L, R, 114L, R, and 4 The braking force can be individually applied to the two intermediate drive wheels.

  Hereinafter, the operation of the automatic pressure increase control valve will be described with reference to FIGS. 5 to 8 by taking a brake system for the second shaft right wheel 34R in the four intermediate drive wheels as an example.

  5 and 6 show the operation when the automatic pressure increase control valve 122R is opened and closed when the brake pedal 118 is not depressed.

  When the automatic pressure increase control valve 122R is excited and opened when the brake pedal 118 is not depressed, the high-pressure air from the main pipe 160 and the automatic pressure increase control valve 122R and the automatic pressure increase check as shown in FIG. The air flows into the brake cylinder 112R through the valve 142R (arrow 170), and a part thereof is released to the atmosphere through the decompression throttle 162R and the brake valve 120 (arrow 172). Since the piping resistance of the automatic pressure increase control valve 122R is sufficiently lower than that of the pressure reducing throttle, if the automatic pressure increase control valve 122R is continuously excited, substantially the same pressure as the high pressure air in the air tank can be applied to the brake cylinder 112R. Thereafter, when the automatic pressure increase control valve 122R is shut off, as shown in FIG. 6, the high-pressure air in the brake cylinder 112R is released to the atmosphere through the pressure reducing throttle 162R and the brake valve 120 (arrow 172).

  FIG. 7 shows the temporal relationship between the pressure change in the brake cylinder accompanying the excitation of the automatic pressure increase control valve and the braking force.

  As shown in FIG. 7, when the excitation of the automatic pressure increasing valve is turned on at time t0, the brake cylinder pressure starts to increase after the propagation delay time of air in the pipe (for example, about 20 to 30 milliseconds) (time t1). When the brake cylinder pressure becomes higher than a predetermined offset pressure, the brake is closed by overcoming the force of the built-in spring that attempts to open the spring inside the brake, and braking force starts to be generated (time t2).

  Thereafter, when the excitation of the automatic pressure increasing valve is turned off at time t3, the brake cylinder pressure starts to decrease after the propagation delay time of air in the pipe (time t4). This is because the high pressure air in the brake cylinder is released to the atmosphere through the decompression throttle and the brake valve, so that the pressure decreases. When the pressure in the brake cylinder falls below the offset pressure (time t5), the brake is released against the force of the built-in spring inside the brake, and the braking force disappears.

  FIG. 8 shows the transition of the braking force when the excitation of the automatic pressure increasing control valve is alternately turned on and off.

8, as can be seen from the comparison between the braking force mean value F1 and F3 when the different length of the on time T _on1 and T _on2, the average value of the braking force you wait on time T _on is raised, Approaches the maximum braking force. As can be seen from the comparison between the braking force mean value F1 and F2 when the on-time T _on1 and OFF time T _off1, Nobase the off time T _off1 decreases the average value of the braking force, approaches zero.

In this way, the average value of the braking force per unit time can be controlled by adjusting the on time _Ton and the off time _Toff as the pulse width of the exciting current. That is, the average value of the braking force per unit time can be controlled by adjusting the excitation timing of the automatic pressure increase control valve.

  Next, the steering control device mounted on the multi-axis vehicle 20 including the wheel drive mechanism having the above-described configuration will be described in detail.

  FIG. 9 shows a configuration of a portion of the steering control device 180 mounted on the multi-axis vehicle 20 that is directly related to steering control according to the principle of the present invention.

As shown in FIG. 9, the steering control device 180 includes an electronic control unit (hereinafter referred to as “ECU”) 192 using, for example, a programmed microcomputer. The ECU 192 determines the speed of the four intermediate drive wheels 34L, R, 36L, R from the rotational speed sensors 182L, R, 184L, R provided on the four intermediate drive wheels 34L, R, 36L, R, that is, Signals representing the 2-axis left wheel speed V _2L , the second-axis right wheel speed V _2R , the third-axis left wheel speed V _3L , and the third-axis right wheel speed V _3R are input. Further, the ECU 192 receives a steering wheel 32L, R, R, R from a steering angle sensor 186 provided on a steering handle (not shown) in the driver's seat of the multi-axis vehicle 20 or the four steering wheels 32L, R, 34L, R, and the like. A signal representing the steering angle ψ of 34L and R is input. The ECU 192 receives a signal representing the transmission output shaft rotational speed N ₀ from the rotational speed sensor 188 provided on the output shaft 52 of the transmission.

  Further, the ECU 192 is connected with a control selection switch 190 provided in the driver's seat. Control selection switch 190 is operated by the driver to provide ECU 192 with a selection signal for turning on or off steering control according to the principle of the present invention. When receiving a control ON command from the control selection switch 190, the ECU 192 uses the intermediate drive wheel in accordance with the principle of the present invention to perform a turn with a turning radius smaller than the turning radius that follows only the steering wheel steer. (Hereafter, this operation mode is referred to as “operation mode”). On the other hand, when a control-off command is received, the control for reducing the turning radius is not executed and the turning according to the steering wheel is performed. An operation mode for turning at a radius is selected (hereinafter, this operation mode is referred to as “normal mode”).

  The ECU 192 includes four automatic pressure increase control valves for individually turning on and off the braking force for the four intermediate drive wheels 34L, R, 36L, R, that is, the second axis left automatic pressure increase control valve 122L, the second axis Excitation signals are individually output to the right automatic pressure increase control valve 122R, the third axis left automatic pressure increase control valve 124L, and the third axis right automatic pressure increase control valve 124R. The ECU 192 also outputs a clutch control signal for connecting and disconnecting the first shaft drive clutch 64 and the fourth shaft drive clutch 74.

  The ECU 192 calculates the optimum speed of each of the intermediate drive wheels 34L, R, 36L, R during the turning motion based on the various input signals described above, and the actual of the intermediate drive wheels 34L, R, 36L, R The braking to the intermediate drive wheels 34L, R, 36L, R is controlled using the excitation signal so that the respective speeds become the respective optimum speeds. Particularly when the maneuvering mode is selected, the ECU 192, when turning, turns the intermediate drive wheels 34L, R so as to turn with a smaller turning radius than when turning only with the steering wheels 32L, R, 34L, R. , 36L, R to control the speed, and the first and fourth shaft drive clutches 64, 74 are disconnected so as not to interfere with the turning, and the first and fourth shaft wheels 32L, R, 38L, R Set to idle state.

  According to the above configuration, a turning moment can be generated between the pair of wheels 34L and 34R provided on the second shaft 24 and the pair of wheels 36L and 36R provided on the third shaft 26. The effect of reducing the turning radius of the multi-axle vehicle 20 can be expected on a road surface with a small friction coefficient such as earth and sand, that is, on a low μ road surface. However, on a road surface having a large friction coefficient such as a concrete road surface, that is, a high μ road surface, the pair of wheels 38L and 38R provided on the fourth shaft 28 that is neither a steering wheel nor a drive wheel are Since these wheels 38L, 38R cannot slip or rotate due to a large angle with respect to the traveling direction (that is, the turning direction), a large friction is generated between the wheels and the high μ road surface. Generate power. Moreover, since the fourth shaft 28 has a large distance to the center of the vehicle body (center of the multi-axis vehicle 20), the large frictional force generates a large moment that hinders the turning of the vehicle body (multi-axis vehicle 20). Become. Therefore, in the multi-axle vehicle 20 having the above-described configuration, the turning radius may vary greatly depending on the magnitude of the friction coefficient μ of the road surface.

  Therefore, as described above, as a means for preventing a large variation in the turning radius of the multi-axle vehicle 20 depending on the size of the friction coefficient μ of the road surface, the pair of wheels 38L provided on the fourth shaft 28 is provided. A method of turning the pair of wheels 38L and 38R is conceived so that the lateral force acting on the wheel 38R is reduced. That is, this is a method of automatically adjusting the steering angle on the fourth shaft 28 according to the lateral force of the pair of wheels 38L, 38R or a desired turning radius when the multi-axis vehicle 20 turns. This method basically measures the stress applied to the pair of wheels 38L, 38R by the lateral force of the pair of wheels 38L, 38R, and the fourth shaft 28 so that the measured stress is minimized. The steering angle is automatically adjusted.

  As a simplified version of the automatic adjustment method of the steering angle, there is a method of automatically adjusting the steering angle in the fourth shaft 28 in accordance with a desired turning radius. The fourth method uses a rough steering angle instead of an accurate steering angle. There is a method of sufficiently reducing the lateral force that hinders the turning moment by steering the shaft 28 and rotating the wheels 38L and 38R. Further, as a simplified version of the above-described automatic adjustment method of the steering angle, the fourth shaft 28 is steered at a rough steering angle on the basis of the so-called jumping steering angle value, and the turning moment is caused by the rotation of the wheels 38L and 38R. There is a method to sufficiently reduce the lateral force that hinders the movement. Furthermore, there is a method of steering the fourth shaft 28 based on one steering angle value. When this method is adopted, for example, when driving a specific large steering angle, such as when traveling on a rutted road, if the steering angle is switched to a large steering angle corresponding to the target small turning radius, the turning moment will be reduced. It is possible to sufficiently reduce the hindering lateral force.

  As for the steering angle on the fourth shaft 28, it is only necessary to secure an angle that allows the pair of wheels 38 </ b> L and 38 </ b> R to rotate. As compared with a case where no speed difference is given between the pair of wheels 36L and 36R provided on the third shaft 26, a smaller steering angle can be achieved.

  FIG. 10 is an explanatory diagram showing a state when the multi-axis vehicle 20 having a configuration in which a pair of wheels 38L and 38R provided on the fourth shaft 28 can steer is turning right.

  As described above, when the multi-axis vehicle 20 turns, the direction of the wheels 38L and 38R is changed to the traveling direction of the multi-axis vehicle 20 for the pair of wheels 38L and 38R provided on the fourth shaft 28, respectively. External force is applied. Therefore, when the directions of the wheels 38L and 38R are fixed, the above external force acts on the wheels 38L and 38R as a lateral force. As a result, for example, on a road surface having a large friction coefficient μ such as a concrete road surface, the lateral force increases, which acts as a moment of a large force that prevents the multi-axis vehicle 20 from turning. Is not a small trajectory of the expected turning radius, but draws a trajectory of a large turning radius that is a little straight ahead.

  Therefore, in FIG. 10, the wheels 38L and 38R provided on the fourth shaft 28 are configured to be steerable as shown in the figure, so that the multi-axis vehicle 20 is subjected to the external force received during turning or a desired turning radius. In this way, the turning radius of the multi-axle vehicle 20 is always tried to be reduced regardless of the friction coefficient μ of the road surface. 10, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 11 is an explanatory diagram of the configuration and operation of the steering mechanism for the fourth shaft 28 provided in the multi-axis vehicle 20 according to the embodiment of the present invention.

  The steering mechanism (of the fourth shaft 28) shown in FIG. 11 is provided on each of the left and right wheels 38L and 38R. However, in FIG. 11, the wheel on one side (for example, the left side) is shown for convenience of illustration and explanation. Only the steering mechanism of (38L) is described, and the description of the steering mechanism of the wheel (38R) on the other side (for example, the right side) is omitted.

  As shown in FIG. 11A, the steering mechanism includes a steering cylinder 75, a piston rod 77, and a steering arm 79. As the steering cylinder 75, for example, an actuator using fluid pressure such as a pneumatic cylinder or a hydraulic cylinder, an actuator using electric force such as an electric motor, or the like is employed. The driving of the steering cylinder 75 is controlled by a steering angle control device (indicated by reference numeral 212 in FIG. 15) described later. As shown in the drawing, one end side of the steering cylinder 75 is attached to the multi-axis vehicle 20 main body so as to swing (rotate) in a substantially horizontal direction via a rotation center 81 which is a fixed point of the multi-axis vehicle 20 main body. . The piston rod 77 performs a so-called reciprocating operation on the other end side of the steering cylinder 75, one end side thereof is immersed in the steering cylinder 75, and the other end side is attached to the steering arm 79 via the connection point 83. Yes. One end of the steering arm 79 is attached to the piston rod 77 so as to be rotatable in a substantially horizontal direction via a connection point 83, and the other end of the steering arm 79 has a turning center 85 that is a fixed point of the main body of the multi-axle vehicle 20. It is fixedly attached to the main body of the multi-axis vehicle 20 via

  FIG. 11B is an explanatory diagram showing the operation of the steering arm 79 and the piston rod 77 when the wheel (38L) is to be turned to the right in the steering mechanism. As shown in FIG. 11B, when the steering cylinder 75 is driven, the piston rod 77 moves in the direction of the arrow, that is, in the direction protruding from the steering cylinder 75, so that the steering arm 79 is clockwise around the connection point 83. And thereby the wheel (38L) is steered to the right.

  FIG. 11C is an explanatory diagram showing the operation of the steering arm 79 and the piston rod 77 when the wheel (38L) is to be steered leftward in the steering mechanism. As shown in FIG. 11C, when the steering cylinder 75 is driven, the piston rod 77 moves in the direction of the arrow, that is, in the direction of immersing into the steering cylinder 75, so that the steering arm 79 is turned around the connection point 83. The wheel (38L) is steered in the left-right direction by rotating clockwise.

  In other words, a steering arm 79 having a constant length and a telescopic steering cylinder 75 (which can be extended and retracted) with two points of the turning center 85 and the rotation center 81 fixed at positions on the multi-axis vehicle 20 as both ends. The piston rod 77) is connected via a connection point 83 to form a link structure (see FIG. 12).

  As is clear from the above description, in the link structure of the steering mechanism (of the fourth shaft 28) shown in FIG. 12, the steering cylinder 75 is driven to expand and contract the steering cylinder 75 (piston rod 77). The steering arm 79 can be turned around the turning center 85. When the multi-axle vehicle 20 tries to turn in a state where the steering cylinder 75 (piston rod 77) holds a certain length, that is, in a state where the link structure is fixed, a lateral force is applied from the road surface to the wheel (38L). However, the steering angle of the wheel (38L) is likely to change, but the fixed link structure acts to suppress a change in the direction of the wheel (38L).

  While the multi-axis vehicle 20 is turning, an external force acting on the wheel (38L) to change the direction of the wheel (38L) is, for example, a sensor for measuring a lateral bending strain in the steering arm 79, a steering wheel, or the like. It can be easily detected by attaching a force sensor or the like for measuring the force in the expansion / contraction direction acting on the cylinder 75 (piston rod 77) to an appropriate portion. The steering angle of the wheel (38L) is determined according to the state of the link structure of the steering mechanism (of the fourth shaft 28) shown in FIG. Therefore, the rotation angle of the steering arm 79 around the turning center 85, the angle formed by the steering arm 79 and the steering cylinder 75 (piston rod 77) around the connection point 83, the rotation angle of the steering cylinder 75 around the rotation center 81, The steering angle of the wheel (38L) can be detected by using a sensor that precisely measures any one physical quantity of the expansion / contraction length of the steering cylinder 75 (piston rod 77).

  If the resolution of the sensor employed is rough or the detection accuracy is poor, it is difficult to accurately detect the steering angle of the wheel (38L), but the steering angle of the wheel (38L) is roughly determined. It is possible to detect with accuracy (or with a jump value).

  FIG. 13 is an explanatory diagram showing an example of a sensor suitable for detecting a steering state when the multi-axis vehicle 20 is steered from the straight traveling direction to the left / right by an angle corresponding to one step.

  As shown in FIG. 13, the sensor includes an iron piece 87 attached to the end of the steering arm 79 on the side of the turning center 85, a straight switch 89, a left turn switch 91, and a right turn. And a switch 93. The straight switch 89 is positioned at the position of the main body of the multi-axle vehicle 20 facing the position of the iron piece 87 when the wheel (38L) is traveling straight, and the left turn switch 91 is an angle corresponding to one step from the straight traveling direction of the wheel (38L). Are attached to the positions of the main body of the multi-axle vehicle 20 facing the position of the iron piece 87 when turning left. The right turn switch 93 is attached to the position of the main body of the multi-axis vehicle 20 facing the position of the iron piece 87 when the wheel (38L) turns right by an angle corresponding to one step from the straight traveling direction.

  In the above configuration, for example, when the multi-axis vehicle 20 that has been traveling straight turns left by an angle corresponding to one step, the straight travel switch 89 that has been closed and outputs a predetermined electrical signal until then opens the contact. Since the output of the electrical signal is stopped, and instead the contact of the left turn switch 91 that has been opened is closed, a predetermined electrical signal is output from the left turn switch 91. A left turn is detected. The same applies to the case where the multi-axis vehicle 20 that has been traveling straight turns right by an angle corresponding to one step, and the case that the multi-axis vehicle 20 that has been turned right by an angle corresponding to one step proceeds straight.

  As the straight travel switch 89, the left turn switch 91, and the right turn switch 93, a mechanical limit switch, an optical shading detection switch, or the like may be employed instead of the electromagnetic proximity switch. Further, by using a sensor that accurately measures any one of the four types of physical quantities described above, it is possible to sufficiently cope with left / right turn detection of the multi-axis vehicle 20 by an angle corresponding to one stage.

  FIG. 14 is an explanatory diagram relating to the calculation principle of the fourth axis steering angle, that is, the formula (111) described later.

In FIG. 14, the turning center 42 of the multi-axis vehicle 20 is a line segment passing through the representative point 30 and perpendicular to the center line along the longitudinal direction of the multi-axis vehicle 20, and the wheels 38 </ b> L and 38 </ b> R about to turn. Is located at the intersection with the extension line of each axle. This is because it is necessary to minimize the magnitude of the lateral force acting on the wheels 38L and 38R to be turned. In the example shown in FIG. 14, since the multi-axis vehicle 20 is going to turn right, the fourth axis 28 when the multi-axis vehicle 20 is going straight and the turning center when the multi-axis vehicle 20 is going to turn right are shown. A relationship of θ _L > θ _R is established between angles θ _L and θ _R formed by line segments connecting the wheel 42 and the respective axles of the wheels 38L and 38R.

Next, the distance between the representative point 30 and the turning center 42 is a target value of the turning radius of the representative point 30 and is indicated by _R0 . Next, when the distance between the center lines along the diameter direction of the left and right wheels (for example, 38L and 38R) on the same axis of the multi-axis vehicle 20 is represented by W, the turning center 42 extends along the longitudinal direction of the multi-axis vehicle 20. The distance from the intersection of the line segment extending in parallel with the extended line of the fourth shaft 28 when the multi-axis vehicle 20 is traveling straight to the right wheel (38R) (of the fourth shaft) is R ₀ −W / 2. It is represented by On the other hand, from the intersection of a line segment extending in parallel along the longitudinal direction of the multi-axis vehicle 20 from the turning center 42 and an extension line of the fourth shaft 28 when the multi-axis vehicle 20 is traveling straight (on the fourth axis). The distance to the left wheel (38L) is represented by R ₀ + W / 2. Furthermore, if the distance between the line segment passing through the representative point 30 and the fourth axis 28 is A, θ _R is tan ⁻¹ (A / (R ₀ −W / 2)), and θ _L is tan. ^-1 (A / (R ₀ + W / 2)), respectively (shown by equation (111) below).

  FIG. 15 shows a functional configuration of a part that calculates the optimum speed of the intermediate drive wheel incorporated in the ECU 192. The calculation shown in FIG. 15 may be performed by a microprocessor executing a computer program in the ECU 192, or may be performed by a dedicated hardware logic circuit incorporated in the ECU 192.

In FIG. 15, the left optimum speed V _LS indicates the optimum wheel speed as a speed target value that is commonly applied to the two left intermediate drive wheels 34L and 36L. Similarly, right-optimal speed V _RS indicates the optimum wheel speed as the speed target value to be applied to common two right intermediate drive wheel 34R, the 36R.

As shown in FIG. 15, the steering angle ψ generated by the driver operating the steering wheel has a conversion function (for example, a conversion table) based on the structure of the Ackermann links of the steering wheels 32L, R, 34L, and R. The conversion calculation unit 200 converts the turning radius R. The converted turning radius R corresponds to the turning radius when turning with only the steered wheels 32L, R, 34L, R, and this is hereinafter referred to as "normal turning radius". The multiplication unit 202 multiplies the normal turning radius R by a predetermined reduction coefficient d to calculate a target value R _0S of the turning radius of the representative point 30 of the multi-axle vehicle 20. Here, the reduction coefficient d is a value smaller than 1.0, for example, 0.8 when the mobile mode is selected, and is 1.0 when the normal mode is selected. Therefore, the representative point turning radius target value R _0S is set to a radius smaller than the normal turning radius R in the maneuver mode, and is set to the same radius as the normal turning radius R in the normal mode.

In addition, the coefficient unit 204 multiplies the transmission output shaft rotational speed N ₀ by a predetermined coefficient k to calculate the speed V ₀ of the representative point 30. Here, the value of the coefficient k is a ratio k = V / N between the transmission output shaft rotational speed N when the vehicle is traveling straight and the speed V of the representative point 30 (speed measured by the vehicle speed meter). Can be obtained in advance.

At optimum speed calculating unit 206, the representative point turning radius target value R _0S, representative point velocity V _0, and the vehicle width H, the approximate calculation expression 110 below, and the left optimal speed V _LS and right optimal speed V _RS Calculated. Here, the left optimum speed V _LS is a speed target value that is commonly applied to the two left intermediate drive wheels 34L and 36L. Similarly, the right optimum speed is a speed target value that is commonly applied to the two right intermediate drive wheels 34R and 36R. The following expression 110 is derived from the above-described expression 108, in which the representative point turning radius R ₀ is positive when the turning center is on the right side of the vehicle body (V _LS = Vout, V _RS = Vin). When it is on the left side (V _LS = Vin, V _RS = Vout), it takes a negative value.

ECU１９２は、以上のようにして左右の最適速度V_ＬＳ、V_ＲＳを決定し、そして、左右の中間駆動輪速度V_L、V_Rが左右の最適速度V_ＬＳ、V_ＲＳに夫々なるように、左右の中間駆動輪の制動を制御する。

The ECU 192 determines the left and right optimum speeds V _LS and V _RS as described above, and the left and right intermediate drive wheel speeds V _L and V _R become the left and right optimum speeds V _LS and V _RS , respectively. Controls braking of the left and right intermediate drive wheels.

Further, the target value R _0S of the turning radius of the representative point 30 calculated by the multiplication unit 202 is output to the fourth axis steering angle target value calculation unit 208 together with the optimum speed calculation unit 206. In the fourth axis steering angle target value calculation unit 208, the distance A between the representative point 30 and the fourth axis 28, the distance W between the left and right wheels 38L and 38R on the fourth axis 28, and the turning of the representative point 30 From the radius target value R _0S , the steering angle target value θ _R of the fourth axis right wheel and the steering angle θ _{L of} the fourth axis left wheel are calculated by the following formula (111). The basis of the above formula (111) has already been described.

  FIG. 16 is a block diagram showing a configuration of a control system (control loop) for the fourth axis steering angle.

The control loop shown in FIG. 16 includes the steering angle target value θ _R for the right wheel of the fourth axis and the steering angle θ _{L of the} left wheel of the fourth axis that are output from the fourth axis steering angle target value calculation unit 208 shown in FIG. In response, for example, the fourth shaft steering mechanism (provided for each of the left and right wheels 38L, 38R) having the configuration shown in FIG. 11 is controlled. The control loop includes an adder 210, a steering angle control device 212, a fourth shaft steering mechanism 214, and a steering angle sensor 216. Here, as the steering angle sensor 216, for example, a sensor capable of accurately measuring the rotation angle of the steering arm 79 around the turning center 85 described above is employed. In reality, one control loop shown in FIG. 16 is provided for each of the left and right wheels (38L, 38R). However, in FIG. 16, for convenience of illustration and explanation, one control loop (fourth axis) is provided. Only the steering angle control loop of the right wheel 38R) will be described.

16, when the steering angle target value theta _R of the fourth shaft right wheel 38R is output through the adder 210 from the fourth axis steering angle target value calculation unit 208, a steering angle control device 212, the steering angle target value based on theta _R, the fourth (the right wheel 38R side) axis of the steering mechanism 214, and outputs a drive command signal. Upon receiving this drive command signal, the steering mechanism 214 causes the steering arm 79 to turn right as shown in FIG. 11B based on the drive command signal. The turning center 85 is turned to the position shown in FIG. The turning operation of the steering arm 79 is detected by the steering angle sensor 216, and a predetermined electrical signal is fed back to the adder 210 as a steering angle detection signal from the steering angle sensor 216. In the adder 210, the steering angle target value θ A difference between _R and the steering angle detection signal is calculated, and the difference is output to the steering angle control device 212.

In the steering angle control using the control loop shown in FIG. 16, if the steering angle detection accuracy and resolution of the steering angle sensor 216 are poor, the wheels (38L, 38R) provided on the fourth shaft 28 are rotated with an accurate steering angle. You cannot steer. However, in such a case, by reducing the control gain in the steering angle control device 212, the steering angle of the wheels (38L, 38R) is such that an external force applied to the wheels (38L, 38R) is applied to the wheels (38L). , 38R), and as a result, the lateral force applied to the wheels (38L, 38R) naturally converges to the steering angle. Therefore, there are still control deviation (between the steering angle target value theta _R and the steering angle detection signal) the wheel (38L, 38R) with poor control performance of the steering angle of the control loop shown in FIG. 16 However, a desirable steering angle is obtained by the force acting on the wheels (38L, 38R). Therefore, even if the steering angle detection accuracy and resolution of the steering angle sensor 216 are poor and the control deviation becomes large, there is no problem.

  Also, the steering angle necessary for steering the wheels (38L, 38R) may be an intermittent (jumped) value instead of a continuous value.

  In the multi-axle vehicle 20, a specific left turn angle and a right turn angle are set in advance (only one step), and the force acting on the wheels (38L, 38R) itself without performing strict steering angle control. It is also possible to use the effect of achieving a desired steering angle.

  When the multi-axis vehicle 28 is returned from the turning state to the straight traveling state, the steering cylinder 75 shown in FIG. 11 is controlled to bring the wheels (38L, 38R) into the straight traveling state. It is only necessary to mechanically lock the steering shafts of the wheels (38L, 38R) so as not to swing while the multi-axis vehicle 20 is traveling.

  FIG. 17 shows a flow of processing for controlling the braking of the left and right intermediate drive wheels, which is executed by the ECU 192 of the steering control device 180.

17, step 300 to 304, already described with reference to FIG. 15, the left and right of the optimum velocity _{V LS,} a process of determining the V _RS. In step 306, it is determined whether the motion to be performed by the multi-axle vehicle 20 is substantially straight, left turn, or right turn. As a result, in the case of left turn or right turn, braking control is performed in step 308 or 310. Done. Steps 306, 308, and 310 can be performed, for example, as described in the following (1) to (3).
(1) When V _LS ≒ V _RS The calculated left wheel speed V _LS is compared with the right optimum speed V _RS . If both speeds are almost equal, it is judged that the vehicle should go straight. In this case, automatic braking of the intermediate drive wheels 34L, R, 36L, R is not performed.
(2) In the case of V _LS >> V _{RS In} this case, it is determined that the vehicle should turn right. In this case, it is checked whether the average speed V _L of the intermediate drive wheels 34L, 36L on the left side (that is, the outside of the turn) is below the left optimum speed (target value) V _LS. The inner pressure boosting control valves 122R and 124R are excited to brake the right intermediate drive wheels 34R and 36R. As described above, if the right intermediate drive wheels 34R and 36R are braked, the left intermediate drive wheels 34L and 36L are automatically accelerated to approach the left optimum speed V _LS by the action of the differential gear.
(3) When V _LS << V _{RS In} this case, it is determined that the vehicle should turn left. In this case, it is checked whether the average speed V _R of the intermediate drive wheels 34R, 36R on the right side (that is, the outer side of the turn) is lower than the right optimum speed (target value) V _RS. The inner pressure boosting control valves 122L and 124L are excited to brake the left intermediate drive wheels 34L and 36L. As described above, when the left intermediate drive wheels 34L and 36L are braked, the right intermediate drive wheels 34R and 36R are automatically accelerated and approach the right optimum speed V _RS by the action of the differential gear.

  FIG. 18 shows an example of a change in wheel speed associated with excitation of the right side (turning inside) automatic pressure increase control valves 122R and 124R, taking a right turn as an example.

In the example shown in FIG. 18, the control selection switch 190 is off before time t1, and the normal mode is selected. At this time, the left intermediate drive wheels 34L and 36L and the right intermediate drive wheels 34R and 36R respectively rotate at the representative point speed V _{0 at} that time and the traveling speed determined by the action of the Ackermann link according to the steering angle ψ.

At time t1, the control selection switch 190 is turned on and the mobile mode is selected. If V _LS >> V _RS in the maneuvering mode, it is determined that a right turn should be performed, and the outer (left) intermediate driving wheel speed V _L is compared with the left optimum speed V _LS . In the illustrated example, at time t1, the outer (left) intermediate drive wheel speed V _L is lower than the left optimum speed V _LS , so the inner (right) automatic pressure increase control valves 122R and 124R are turned on. Is done. As a result, the inner (right) intermediate drive wheel speed V _R decreases, and at the same time, the outer (left) intermediate drive wheel speed V _L increases.

At time t2 the time from the start of excitation has elapsed T _on1, when the intermediate driving wheel speed V _L of the outer (left) to reach the left target speed V _LS, automatic pressure increase inside (right side) at that moment The excitation of the control valves 122R and 124R is turned off. However, due to a delay in the operation of the air brake, braking of the inner (right) intermediate drive wheels 34R and 36R is not immediately released, and the outer (left) intermediate drive wheel speed V _L slightly exceeds the target speed V _LS. Will do. Thereafter, when the braking of the inner (right) intermediate drive wheels 34R and 36R is released, the outer (left) intermediate drive wheel speed V _{L at} which the torque is reduced starts to gradually decrease. When the outer (left side) intermediate drive wheel speed V _L falls below the left target speed V _LS again at time t ₃ , the inner side (right side) again until it returns to the left target speed V _LS in the same manner as described above. The excitation of the automatic pressure increase control valves 122R and 124R is turned on.

  In this way, when turning in the maneuvering mode, it is checked whether the speed of the outer intermediate drive wheel, which is faster, is the optimum speed, and the total time for braking the inner intermediate drive wheel is increased or decreased according to the result. As a result, the speeds of the inner and outer intermediate drive wheels are controlled in the vicinity of the respective optimum speeds.

  By the way, when the road surface friction coefficient μ is low and the wheel to which the braking force is applied is locked, the ECU 192 of the steering control device 180 performs the following unlocking process.

  FIG. 19 shows a flow of processing for unlocking, which is executed by the ECU 192 of the steering control device 180.

As shown in FIG. 19, in step 320, the speeds Vin and Vout of the inner and outer intermediate driving wheels are controlled to the optimum speeds V _RS and V _LS by the method already described (depending on the turning direction). , V _RS or V _LS corresponds to the inner side or the outer side), and braking to the inner intermediate driving wheel is controlled. At the same time, it is checked in step 322 whether the braked inner intermediate drive wheel is locked.

If that is the inside of the intermediate drive wheel has locked is detected, in step 324, is energized on time T _on is the time obtained by braking the inner intermediate drive wheels, the minimum time T _min determined by the response time of the solenoid valves and piping Is also checked whether it was long or short. As a result, when the excitation on-time T _on is shorter than the minimum time T _min, since the friction coefficient of the inner road μ is estimated to be extremely low, the inner intermediate drive wheel locked while it is slipping, Continue turning.

On the other hand, in the determination of step 324, if the excitation on-time T _on is longer than the minimum time T _min may be able to prevent the lock if shorter excitation on-time T _on (braking time). Accordingly, in this case, in step 326, the braking of the inner intermediate driving wheel is released and the outer intermediate driving wheel is braked for a short time, thereby supplying the engine torque to the inner intermediate driving wheel through the differential gear. Thus, the inner intermediate driving wheel is forcibly driven to accelerate the rotation of the inner intermediate driving wheel and release the lock. Further, in step 328, in order to prevent the next lock, in order to reduce the braking time T _on the inner intermediate drive wheel, is target speed Vout _S of the outer intermediate drive wheel (which initially, in the case of right turn left the optimum speed V _LS, in the case of left turning equally set) to the right optimal speed V _RS, to change to a value lower than the predetermined step size Δv than its current value.

On the other hand, when the lock of the inner intermediate drive wheel is not detected in step 322, the target speed Vout _S of the outer intermediate drive wheel is set to the left optimum speed V _LS in the case of right turn and the left turn in step 330. If it is, the right optimum speed V _RS is checked whether it is set equal or lower. As a result, if they are set equal, control returns to step 320. On the other hand, when it is set low (that is, when it has been lowered by the above-mentioned step 328), it is not necessary to set it to the low value any longer, so the target speed Vout _S of the outer intermediate driving wheel is set to the increment Δv. Only return to higher values.

  As described above, when the inner intermediate driving wheel is locked, braking is applied to the outer intermediate driving wheel, the inner intermediate driving wheel is unlocked, and the duration of the subsequent braking of the inner intermediate driving wheel is increased. Reduced to prevent the next lock.

  The main points of the outer intermediate drive wheel speed control method and the inner intermediate drive wheel speed relaxation method in the steering control device 180 of this embodiment described above are as follows.

(1) Outer intermediate drive wheel speed control method Observe the wheel speed on the outer wheel side,
A) If the outer intermediate drive wheel speed falls below the target speed, increase the total time to brake the inner intermediate drive wheel,
B) If the outer intermediate drive wheel speed increases above the target speed, decrease the total time to brake the inner intermediate drive wheel, and
C) If the outer intermediate drive wheel speed is within the allowable range above and below the target speed, maintain the total time for braking the inner intermediate drive wheel as before.

(1) Inner intermediate drive wheel speed lock relaxation method
The time T _on to continue braking of A) an inner intermediate drive wheel has a reference value, which was the initial value,
B) When the lock on the inside intermediate drive wheels occurs, to shorten the time T _on to continue the braking of the inner intermediate drive wheels, also,
If the lock is generated in C) inside the intermediate drive wheel, the time T _on to continue braking of the inner intermediate drive wheel, increases the reference value as an upper limit.

  In performing the control as described above, the distortion of the wheel, the influence of the approximate expression or the gain change due to the complicated change of the road surface friction coefficient μ, the response delay due to the twist of the drive shaft or the backlash, etc. occur. In order to stabilize the operation while suppressing the control error of the system, a controller incorporating a control law with a good visibility including an integral operation is required. From this point of view, the control system incorporated in the ECU 192 of the steering control device 180 in this embodiment performs periodic ON-OFF control of the automatic pressure increase control valve by a pulse width modulation method. And a control system performs control of turning radius, and control control of inner ring lock using another independent variable.

That is, this control system periodically ON-OFF-controls the automatic pressure increasing control valve for braking the inner intermediate drive wheel, and the length of the ON-OFF cycle T (= T _on + T _off ). without changes, by operating the duty ratio S (= T _on / T) within one cycle, increase or decrease the amount of time for braking the inner intermediate drive wheel per unit time, whereby the outer intermediate Control drive wheel speed. The control system, without changing the duty ratio S, by operating the length of the ON-OFF period T, the time T _on to continue braking of the inner intermediate drive wheel is increased or decreased, whereby the inner The lock on the intermediate drive wheel is relaxed.

  FIG. 20 shows the configuration of this control system.

As shown in FIG. 20, in this control system 340, the optimum speed Vout _S of the outer intermediate drive wheel calculated as described above (the left optimum speed V _{LS for} the right turn and the right for the left turn) The speed deviation e _V is calculated using the optimum speed V _RS ) as the control target value and the outer intermediate drive wheel speed Vout as the feedback signal. By the control unit (e.g., a PID controller) 342 having a function of the integration operation in the interior, on the basis of the speed deviation e _V, the duty ratio S of ON-OFF drive the automatic pressure increase control valves for braking the inner intermediate drive wheel calculate. Here, when the integrated value of the speed deviation e _V increases, the computed duty ratio Sin to a large value, the duty ratio Sin smaller the integral value of the speed deviation e _V is also calculated to a small value.

In parallel with this operation, the lock detector 344 observes the inner intermediate driving wheel speed Vin, and when the value is zero, it is determined that the inner intermediate driving wheel is locked, and the inner intermediate driving wheel speed is determined. The ON / OFF drive cycle T of the automatic pressure increase control valve for driving wheel braking is reduced (while maintaining the ratio of the excitation on time _Ton and the excitation off time _Toff , for example, each is multiplied by a factor of 1 or less. Reduce those times).

Based on the duty ratio S from the controller 342 and the cycle T from the lock detector 344, the calculator 346 calculates the excitation on time T _on (braking time) and the excitation off time T _off (non-braking) in the next cycle. calculating a time), their time T _on, to ON-OFF drive the automatic pressure increase control valves for the inner intermediate drive wheel braking according T _off.

By the way, although not shown in FIG. 20, when the inner intermediate driving wheel is locked, the automatic pressure increase control valve for braking the outer intermediate driving wheel is shortened as described with reference to FIG. Drive with the time pulse to brake the outer intermediate drive wheels. As a result, the driving torque can be forced into the inner intermediate driving wheel to unlock the inner intermediate driving wheel. However, as described with reference to FIG. 19, when the value of the excitation on-time T _on becomes shorter than the minimum time T _min determined by the response of the solenoid valve and piping, friction coefficient of the road surface of the inner intermediate drive wheel Assuming that it is extremely low, a turning motion is performed with the locked inner intermediate drive wheel slipped as it is. In other words, if the friction coefficient μ of the road surface of the inner intermediate drive wheel is extremely low, there is a possibility that the inner intermediate drive wheel will run idle if the drive torque is forcibly applied. Omitted.

As described above with reference to FIGS. 15 to 20, in the control of the intermediate drive wheel by the steering control device in this embodiment, the average speed of the left second wheel and the third wheel is determined as the left intermediate drive wheel. The speed is V _L , the average speed of the right second wheel and the third wheel is the right intermediate drive wheel speed V _R, and the two wheels of the second and third axes on the left and right sides based on them. Are controlled together, but this is only an example. The above-described control may be performed separately and separately for each of the second axis and the third axis.

  In the multi-axis vehicle 20 according to the above-described embodiment, a configuration for adjusting the speeds of the left and right intermediate drive wheels to match the target speed, a publicly known document “Bosch Automotive Handbook Japanese Second Edition” (April 2003) ABS valve with pressure reducing and holding functions for TCS valve (automatic pressure increase control valve) and well-known antilock braking system (ABS) as introduced on page 606 of Sankaido (issued on the 22nd) And a technique for controlling and synchronizing the speeds of the left and right drive wheels of the differential gear.

  As mentioned above, although embodiment of this invention was described, this embodiment is only the illustration for description of this invention, and is not the meaning which limits the scope of the present invention only to this embodiment. The present invention can be implemented in various other modes without departing from the gist thereof. The present invention can be applied not only to an 8-wheel vehicle having 4 axles as described above, but also to a 6-wheel vehicle having 3 axles or a multi-axle vehicle having 5 or more axles.

  The pair of wheels (38L, 38R) provided on the fourth shaft 28 described above is a fixed wheel when traveling straight and can be automatically steered when turning, such as a caster. It can be used.

The top view for demonstrating the outline | summary of the steering control in the multi-axle vehicle 20 which concerns on one Embodiment of this invention. The top view which shows the structure of the wheel drive mechanism of the multi-axle vehicle 20 which concerns on one Embodiment of this invention. The multi-axis vehicle 20 which concerns on one Embodiment of this invention WHEREIN: The top view which shows the state which cut | disconnected the 1st, 4th axis drive clutch 64,74. The piping diagram which shows only a part required for description of this invention among the piping systems of the air brake mounted in the multi-axle vehicle 20 which concerns on one Embodiment of this invention. Explanatory drawing which shows operation | movement of an air brake when the automatic pressure increase control valve 122R is opened when the brake pedal 118 is not depressed. Explanatory drawing which shows the operation | movement of an air brake when the automatic pressure increase control valve 122R is closed when the brake pedal 118 is not depressed. The figure which showed the temporal relationship between the pressure change in a brake cylinder accompanying the excitation of an automatic pressure increase control valve, and braking force. The figure which showed transition of the braking force when the on / off of excitation of an automatic pressure increase control valve is repeated alternately. The block diagram which shows the structure of the part directly related to steering control of the steering control apparatus 180 mounted in the multi-axle vehicle 20 which concerns on one Embodiment of this invention. Explanatory drawing which shows the state when the multi-axle vehicle 20 of the structure which can steer a pair of wheel 38L, 38R provided in the 4th axis | shaft 28 turns right. The explanatory view of the composition of the steering mechanism of the 4th axis 28 with which multi-axle vehicle 20 concerning one embodiment of the present invention is provided, and the operation. The figure which showed the link structure comprised by the steering mechanism shown in FIG. Explanatory drawing which shows an example of the sensor suitable for detecting the steering state when the multi-axis vehicle 20 is steered by the angle for one step from the straight direction to the left / right. Explanatory drawing regarding the calculation principle of a 4th axis | shaft steering angle. The block diagram which shows the functional structure of the part which calculates the optimal speed of the intermediate drive wheel integrated in ECU192 of the steering control apparatus 180. FIG. The block diagram which shows the structure of the control system (control loop) of a 4th axis | shaft steering angle. The flowchart of the process for control of braking of an intermediate drive wheel performed by ECU192 of the steering control apparatus 180. FIG. The time chart which shows the example of a change of the wheel speed accompanying excitation of the right side (turning inner side) automatic pressure increase control valve 122R, 124R taking a right turn as an example. The flowchart of the process for lock release performed by ECU192 of the steering control apparatus 180. FIG. The block diagram which shows the structure of the control system for relaxation of the control of the outer side intermediate drive wheel speed, and the lock | rock of an inner side intermediate drive wheel incorporated in ECU192 of the steering control apparatus 180. FIG.

Explanation of symbols

20 Multi-axis vehicle 22 1st axis 24 2nd axis 26 3rd axis 28 4th axis 30 Representative point 32L, 32R, 34L, 34R Steering wheel 34L, 34R, 36L, 36R Intermediate drive wheel 42 Turning center R ₀ Representative point Turning radius V ₀ representative point speed Vout outer intermediate drive wheel speed Vin inner drive wheel speed 60 second shaft differential gear 64 first shaft drive clutch 68 first shaft differential gear 122L, 122R, 124L, 124R automatic Boost control valve 112L, 112R Second axis brake cylinder 114L, 114R Third axis brake cylinder 180 Steering control device 182L, 182R, 184L, 184R Intermediate drive wheel speed sensor 186 Steering angle sensor 188 Transmission output shaft speed sensor 192 Electronic Control Unit (ECU)
200 conversion calculation section 202 multiplying unit 204 coefficient unit 206 optimum speed calculating portion ψ steering angle R _0S turning radius of the optimal speed V _RS right intermediate drive wheel target value V _LS left intermediate drive wheel optimal speed V _RS right intermediate target speed of the optimum velocity V _L left target velocity Vin _S inside the intermediate driven wheel speed Vout _S outside the intermediate drive wheel speed V _R right intermediate drive wheel in the intermediate drive wheel of the drive wheel 340 the control system 342 controller 344 Lock detector 346 Calculator T _on Excitation on time (braking time)
T _off excitation off time (non-braking time)
T period

Claims (19)

In a multi-axle vehicle (20) comprising three or more axles including a foremost axle (22), a last axle (28) and one or more intermediate axles (24, 26),
A pair of intermediate drive wheels (34L, 34R, 36L, 36R) provided on the one or more intermediate axles (24, 26);
Two or more pairs of steering wheels (32L, 32R), (38L, 38R) provided on at least the foremost axle (22) and the last axle (28);
When performing a turning motion, the steering control device controls the speed (Vin) of the intermediate driving wheels (34R, 36R) inside the turning and the speed (Vout) of the outer intermediate driving wheels (34L, 36L) to different speeds. (180),
When performing a turning motion, the two pairs of the two or more pairs of steered wheels (32L, 32R), (38L, 38R) are applied depending on an external force acting on one or both of the pairs or a desired turning radius. The two or more pairs of steering wheels (32L, 32R), (38L, 38R) so that the lateral force acting on both or any one of the above steering wheels (32L, 32R), (38L, 38R) is reduced. A steering angle adjusting device that adjusts the steering angle of both or any one of the pair,
A multi-axis vehicle equipped with The multi-axle vehicle (20) according to claim 1,
When performing a turning motion, the two or more pairs of steering wheels (32L, 32R) are caused by a lateral force acting on both or one of the two or more pairs of steering wheels (32L, 32R), (38L, 38R). ), (38L, 38R), further comprising a measuring means for measuring an external force acting on one or both of the pairs,
The steering angle adjusting device steers both or any one of the two or more pairs of steering wheels (32L, 32R), (38L, 38R) so that the external force measured by the measuring means is minimized. A multi-axis vehicle that adjusts the angle. The multi-axle vehicle (20) according to claim 1,
When the steering angle adjusting device performs a turning motion, the steering angle adjusting device works on both or any one of the two or more pairs of steering wheels (32L, 32R) and (38L, 38R) according to a desired turning radius. The geometrical calculation is performed so that the lateral force is minimized, and the steering angle of either or both of the two or more pairs of steering wheels (32L, 32R) and (38L, 38R) is precisely set. A multi-axis vehicle that adjusts to The multi-axle vehicle (20) according to claim 1,
When the steering angle adjusting device performs a turning motion, the steering angle adjusting device works on both or any one of the two or more pairs of steering wheels (32L, 32R) and (38L, 38R) according to a desired turning radius. A multi-axis in which the steering angle of both or any one of the two or more pairs of steering wheels (32L, 32R), (38L, 38R) is roughly variably adjusted so that the lateral force is as small as possible. vehicle. The multi-axle vehicle (20) according to claim 1,
When the steering angle adjusting device performs a turning motion, the steering angle adjusting device works on both or any one of the two or more pairs of steering wheels (32L, 32R) and (38L, 38R) according to a desired turning radius. The steering angle of both or any one of the two or more pairs of steering wheels (32L, 32R), (38L, 38R) is intermittently variably adjusted so that the lateral force is as small as possible. Axle vehicle. The multi-axle vehicle (20) according to claim 1,
When the steering angle adjusting device performs a turning motion, the steering angle adjusting device works on both or any one of the two or more pairs of steering wheels (32L, 32R) and (38L, 38R) according to a desired turning radius. The steering angles of both or one of the two or more pairs of steering wheels (32L, 32R), (38L, 38R) are set in advance in the left / right direction so that the lateral force is as small as possible. A multi-axis vehicle that is variably adjusted based on the angle value. The multi-axle vehicle (20) according to claim 1,
A multi-axle vehicle configured such that a pair of wheels (38L, 38R) provided on the last axle (28) are fixed wheels when going straight and can be automatically steered when turning. In the multi-axle vehicle (20) according to any one of claims 1 to 7,
In addition to the intermediate drive wheels (34L, 34R, 36L, 36R), at least one pair of drive wheels (32L, 32R, 38L, 38R) provided on the foremost axle or the last axle are provided,
The steering control device (180)
Drive wheels (32L, 32R) other than the intermediate drive wheels so that the wheels (32L, 32R, 38L, 38R) provided on both the foremost axle and the last axle become idle wheels when performing a turning motion. , 38L, 38R), a multi-axle vehicle having power transmission control means (192, 64, 74) that cuts off transmission of driving force to. In the multi-axle vehicle (20) according to any one of claims 1 to 7,
It is provided with four axles consisting of a first axis (22), a second axis (24), a third axis (26), and a fourth axis (28) in order from the front, with an approximately equal distance between the axes,
Two pairs of wheels (34L, 34R, 36L, 36R) provided on the second shaft (24) and the third shaft (26) correspond to the intermediate drive wheels,
A multi-axis vehicle in which one or more pairs of wheels (32L, 32R, 34L, 34R) provided on one or more axles including at least the first shaft (22) correspond to the steering wheels. In the multi-axle vehicle (20) according to any one of claims 1 to 9,
The steering control device (180)
Steering angle detection means (186) for detecting the steering angle (ψ) of the steering wheel;
Driving speed detecting means (188, 204, 182L, 182R, 184L, 184R) for detecting the driving speed (V ₀ , V _L , V _R ) of the multi-axis vehicle;
Based on the steering angle (ψ) detected by the steering angle detection means and the driving speeds (V ₀ , V _L , V _R ) detected by the driving speed detection means, the inner intermediate drive wheels Intermediate drive wheel speed control means (200, 202, 206) for controlling the speed (Vout) and the speed (Vin) of the outer intermediate drive wheel;
A multi-axis vehicle having The multi-axle vehicle (20) according to claim 10,
The intermediate drive wheel speed control means (200, 202, 206) is configured such that the steering angle (ψ) detected by the steering angle detection means and the driving speed (V ₀ , V _L ) detected by the driving speed detection means. , based on the V _R), said to allow a swirling motion in the turning radius in the case of pivoting by the steering wheel only piercer rudder (R) is smaller than the turning radius (R _0S), the target speed of the left intermediate wheel ( V _LS ) and a target speed (V _RS ) of the right intermediate drive wheel, and based on at least one of the left and right intermediate drive wheel target speeds (V _LS , V _RS ), A multi-axis vehicle that controls the speed (Vout, Vin) of each of the outer intermediate drive wheels. The multi-axle vehicle (20) according to claim 11,
The driving speed detecting means detects intermediate driving wheel speed detecting means (182L, 182R, 184L, 184R) for detecting the speed (V _L ) of the left intermediate driving wheel and the speed (V _R ) of the right intermediate driving wheel, respectively. )
The intermediate drive wheel speed control means, when performing a turning motion, the outer intermediate drive of the speeds (V _L , V _R ) of the left and right intermediate drive wheels detected by the intermediate drive wheel speed detection means. One corresponding to the wheel speed (Vout) and one of the target speeds (V _LS , V _RS ) of the left and right intermediate drive wheels corresponding to the target speed (Vout _S ) of the outer intermediate drive wheel And a multi-axis vehicle that controls the respective speeds (Vout, Vin) of the inner and outer intermediate drive wheels based on the above. The multi-axle vehicle (20) according to claim 10,
The driving speed detecting means includes means (188, 204) for detecting the speed (V ₀ ) of the representative point (30) of the multi-axis vehicle (20),
When the intermediate drive wheel speed control means performs a turning motion, the speed (Vin) of the inner intermediate drive wheel is determined based on the speed (V ₀ ) of the representative point detected by the driving speed detection means. The speeds (Vout) of the inner and outer intermediate drive wheels are lower than the representative point speed (V ₀ ) and the outer intermediate drive wheel speed (Vout) is higher than the representative point speed (V ₀ ). , Vin) is a multi-axis vehicle. In the multi-axle vehicle (20) according to any one of claims 1 to 9,
Brake means (112L, 114L, 112R, 114R) for independently braking the left intermediate drive wheel (34L, 36L) and the right intermediate drive wheel (34R, 36R), respectively,
The steering control device (180) is
A multi-axis vehicle having braking force control means (192, 122L, 124L, 122R, 124R) that controls the braking means to adjust the braking force applied to the left and right intermediate drive wheels, respectively, when performing a turning motion. . The multi-axle vehicle (20) according to claim 14,
The inner and outer intermediate drive wheels (34L, 36L, 34R, 36R) are coupled via a differential gear (60, 70);
When the braking force control means performs a turning motion, the braking means controls the braking means to apply a braking force to the inner intermediate driving wheels in order to make the speeds of the inner and outer intermediate driving wheels different (308, 310) Multi-axis vehicle. The multi-axle vehicle (20) according to claim 14,
The braking force control means is
An inner ring lock detecting means (344) for detecting that the inner intermediate driving wheel is locked;
When the lock of the inner intermediate driving wheel is detected by the inner ring lock detecting means, the braking of the inner intermediate driving wheel is relaxed and the braking means is controlled to apply a braking force to the outer intermediate driving. Inner ring unlocking means (346);
A multi-axis vehicle having The multi-axle vehicle (20) according to claim 14,
The braking force control means is
Braking time control means (342, 344, 346) for controlling the time for braking the inner and outer intermediate driving wheels, respectively, in order to control the braking force applied to the inner and outer intermediate driving wheels, respectively;
A multi-axis vehicle having The multi-axle vehicle (20) according to claim 17,
The braking force control means is
In order to control the speed of the inner and outer intermediate driving wheels by repeating the braking and non-braking periodically by the pulse width control method, the duty ratio of the braking time within one cycle is controlled, and the inner Pulse width control means (342, 344, 346) for controlling the length of each cycle in order to prevent the intermediate driving wheel from being locked;
A multi-axis vehicle having One or more pairs provided on the one or more intermediate axles (24, 26), comprising three or more axles including a front axle (22), a rear axle (28), and one or more intermediate axles (24, 26) Multi-axle vehicle (34L, 34R, 36L, 36R) and at least one pair of steering wheels (32L, 32R, 34L, 34R) provided on the foremost axle or the last axle ( 20) In the steering control device (180) for
When the multi-axis vehicle performs a turning motion, the speed (Vin) of the intermediate driving wheels (34R, 36R) inside the turning and the speed (Vout) of the outer intermediate driving wheels (34L, 36L) are controlled to different speeds. Intermediate drive wheel speed control means,
A multi-axis vehicle steering control device.

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