JP2014024434A - Carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve travel stability, by preventing a situation of disturbing a route when turning for traveling in a curve such as particularly cornering, with a simple constitution having no steering mechanism.SOLUTION: A pair of front wheels Wf, a pair of intermediate wheels Wc, and a pair of rear wheels Wr are provided in a longitudinal direction of a chassis 1, and the respective wheels are provided so that its wheel shaft 2 is orthogonal to the longitudinal direction of the chassis 1, and the intermediate wheels Wc comprise: a rubber tire 4; and the front wheels Wf and the rear wheels Wr are constituted of an omnidirectional wheel of annularly arranging a plurality of laterally rotating rollers 6 for freely rotating in a lateral direction, and a driving part 7 is respectively provided in the respective wheels, and a control part 20 is provided with maximum driving torque command means 21 for distributing maximum driving torque of the intermediate wheels Wc by reducing more than maximum driving torque of the front wheels and the rear wheels in the front wheels Wf, the intermediate wheels Wc and the rear wheels Wr on the outside in a turning radius direction when turning for traveling in a curve of the chassis 1.

Description

  The present invention relates to an unmanned transport vehicle mainly for transporting various articles, and more particularly to a transport vehicle having six or more wheels and suitable for transporting heavy objects.

  Conventionally, as this type of transport vehicle, for example, there is one disclosed in Japanese Patent Laid-Open No. 2003-34262 (Patent Document 1). This transport vehicle is a six-wheeled vehicle provided with a pair of front wheels, a pair of intermediate wheels and a pair of rear wheels, each having the same tread in the front-rear direction of the chassis, and each wheel can independently turn. It can be steered by electric steering. However, this transport vehicle has a drawback that the structure is complicated because there is a steering mechanism that adjusts the steering angle by allowing each wheel to turn independently.

  Therefore, as a simple configuration without a steering mechanism, for example, it is a vehicle technology that moves a robot that performs various operations, but it is conceivable to use the technology described in US Pat. No. 5,323,867 (Patent Document 2). . As shown in FIG. 9, a pair of front wheels Wf, a pair of intermediate wheels Wc, and a pair of rear wheels Wr having the same tread in the front-rear direction of the chassis 100 are provided at predetermined intervals, and the wheel shafts 101 are provided. Are provided so as to be orthogonal to the front-rear direction R of the chassis 100. The intermediate wheel Wc includes a rubber tire 103, and a plurality of roll rollers 104 that freely rotate the front wheels Wf and the rear wheels Wr other than the intermediate wheel Wc in a lateral direction perpendicular to the straight traveling direction of the wheels are provided. It consists of omnidirectional wheels arranged in a ring. A pair of motors 105 is mounted on the chassis 100 so that the left and right wheel groups can be driven in synchronization via the speed reduction mechanism 106, the chain transmission mechanism 107 and the belt transmission mechanism 108. Thereby, the motor 105 is controlled by a control unit (not shown) so that the chassis 100 moves forward and backward.

JP 2003-34262 A US Pat. No. 5,323,867

  However, when the transport vehicle has a configuration without the latter steering mechanism, particularly when the transport vehicle is used outdoors, there is a problem that traveling stability is poor due to a change in road surface conditions. This is because, for example, when the road surface is wet with rain, or when it is slippery due to snow or ice burn, the course is likely to be disturbed during cornering and other cornering turns. That is, as shown in FIG. 10, at the time of this turning, the motor 105 is controlled so that the number of rotations is larger than that of the inner wheel group (right side) in the turning radius direction with respect to the outer wheel group (left side). However, since the wheels on the outer side in the turning radius direction rotate synchronously, the maximum driving torque becomes uniform, so that the maximum driving torque Tc of the intermediate wheel Wc on the outer side in the turning radius direction and the cornering force Fa in the lateral direction are increased. This is because the resultant force Tt exceeds the grip limit of the tire (the tire friction circle on the snowy road surface in FIG. 10) and the course is disturbed by losing the lateral grip of the vehicle body.

  The present invention has been made in view of the above points, and has a simple structure without a steering mechanism, and prevents a situation in which the course is disturbed particularly during cornering and turning, thereby improving running stability. The purpose is to provide a transport vehicle.

  In order to achieve such an object, the transport vehicle of the present invention is a transport vehicle provided with at least a pair of front wheels, a pair of intermediate wheels, and a pair of rear wheels in the front-rear direction of the chassis. The shaft is provided so as to be orthogonal to the front-rear direction of the chassis, the intermediate wheel is provided with rubber tires, and the front and rear wheels other than the intermediate wheel can be freely moved in the lateral direction perpendicular to the straight direction of the wheel. A plurality of roll rollers that rotate in a circular pattern are arranged in an omnidirectional wheel, each of the wheels is provided with a drive unit that can independently output the commanded maximum drive torque, and each drive unit is controlled. The control unit for moving the chassis forward and backward and turning is provided, and the control unit is provided with maximum drive torque command means for allocating and commanding the maximum drive torque to each drive unit.

  Thus, when the chassis is driven, the control unit instructs each drive unit about the required rotation speed and rotation direction of each wheel, and distributes the maximum drive torque from the maximum drive torque command means. To move the chassis forward and backward. For this reason, it is possible to travel with a simple configuration without a steering mechanism. In this case, for example, when moving forward and backward, the rotational speed is equally distributed to the left and right wheel groups. Further, in so-called in-situ turning with the center between the pair of intermediate wheels as the turning center, the rotational speed is equally distributed to the left and right wheel groups and the rotation directions of the left and right wheel groups are reversed. In addition, when turning on a curve that is a turn other than the turn on the spot, for example, in cornering of a right turn or a left turn, the number of rotations is increased with respect to the wheel group on the outer side in the turn radius direction than the wheel group on the inner side in the turn radius direction. To distribute. Therefore, the radius of rotation can be changed freely. In this turning, since individual maximum drive torque can be commanded from the maximum drive torque command means to each drive unit, the number of control combinations is increased as compared with the conventional case. Therefore, for example, if the maximum driving torque of the intermediate wheel is reduced and distributed below the maximum driving torque of the front and rear wheels on the outer side in the turning radius direction, the torque limit of the front and rear wheels on the outer side in the turning radius is increased. The limit can be suppressed, the lateral grip of the intermediate wheel can be increased, the course can be prevented from being disturbed, and the running stability can be improved. In this turning, the front and rear wheels have a plurality of roll rollers that rotate freely in the lateral direction perpendicular to the straight direction of the wheels. Since it rotates, it can follow a rotation difference and can obtain smooth running.

  Then, if necessary, the maximum drive torque command means is configured to set the maximum drive torque of the intermediate wheel at the front wheel, the intermediate wheel, and the rear wheel on the outer side in the turning radial direction at the time of turning at least a curve of the chassis. It is configured to be distributed by being reduced from the maximum driving torque. As a result, for example, when the road surface is wet with rain or is slippery due to snow or ice burn, the course is likely to be disturbed during cornering when turning on a curve. The maximum drive torque of the front wheel and the rear wheel is reduced and distributed, so the torque limit of the front and rear wheels on the outside in the turning radius direction can be increased to suppress the torque limit of the intermediate wheel, and the lateral direction of the intermediate wheel The grip can be increased, and the lateral grip of the chassis can be secured. Therefore, the disturbance of the course can be prevented and the running stability can be improved.

Further, if necessary, the maximum driving torque of the intermediate wheel on the outer side in the turning radius direction is the friction circle determined by the combined torque of the maximum driving torque of the intermediate wheel and the cornering force corresponding to the slipperiness of the road surface. The configuration is set so as to fit inside.
Here, the friction circle is a pie chart in which the boundary value of the magnitude of the force in the front-rear direction and the left-right direction generated in the intermediate wheel corresponding to the slipperiness of the road surface is a perfect circle or an ellipse in each direction. Is. Inside this friction circle, the intermediate wheel does not slip against the road surface, but outside this friction circle, the intermediate wheel exceeds the limit of the road surface friction and the intermediate wheel slips.
As a result, the combined force of the maximum driving torque of the intermediate wheel and the cornering force in the lateral direction can be within the friction circle (grip limit) of the intermediate wheel, and the lateral grip of the vehicle body can be secured. Therefore, it is possible to reliably prevent the course from being disturbed and improve the running stability.

Further, if necessary, the control unit calculates the maximum driving torque of the intermediate wheel on the outer side in the turning radius direction based on a predetermined relationship corresponding to the slipperiness of the road surface and the chassis speed. Torque calculating means; and front and rear wheel maximum driving torque calculating means for calculating the maximum driving torque of the front and rear wheels on the outer side in the turning radius based on the maximum driving torque of the intermediate wheel calculated by the intermediate wheel maximum driving torque calculating means. And the maximum drive torque command means distributes and commands the maximum drive torque calculated by the intermediate wheel maximum drive torque calculation means and the front and rear wheel maximum drive torque calculation means.
As a result, the maximum driving torque of the front wheels, intermediate wheels, and rear wheels on the outer side in the turning radius direction is automatically calculated according to the speed of the chassis.

Furthermore, if necessary, the maximum drive torques distributed to the front, intermediate, and rear wheels on the outer side in the turning radius direction are Tf, Tc, Tr, respectively, and the front wheels, When the standard maximum driving torque distributed to the intermediate wheel and the rear wheel is Tfs, Tcs, Trs, respectively, and the value reduction value of the maximum driving torque with respect to the standard maximum driving torque of the intermediate wheel is Tcd,
Tcd = Tcs−Tc
Tf = Tfs + (1/2) Tcd
Tr = Trs + (1/2) Tcd
The configuration is set to
Since the decrease value Tcd of the maximum driving torque of the intermediate wheel is equally distributed to the front and rear wheels by (½), the track becomes smoother and the travel stability can be further improved.

If necessary, the front wheel, the intermediate wheel, and the rear wheel are supported on the chassis via a suspension mechanism.
As a result, even if the road surface is uneven, it is possible to follow this, that is, even if the chassis is lifted by the unevenness of the road surface, the suspension mechanism operates and the wheel follows the running surface, and the wheel is lifted. Therefore, the driving force can be reliably transmitted to the traveling surface. In particular, on snowy roads, it is possible to cope with unevenness due to snow in addition to dealing with the above-mentioned slipping, so that the running stability can be further improved.

  According to the present invention, the wheel shafts of the respective wheels are provided so as to be orthogonal to the front-rear direction of the chassis, and a plurality of rollovers that freely rotate the wheels other than the intermediate wheels in the lateral direction orthogonal to the straight traveling direction of the wheels. Since the rollers are composed of omnidirectional wheels arranged in an annular shape, when the chassis is driven, the controller determines the number of rotations and the direction of rotation of the wheels, and allocates and commands the maximum drive torque from the maximum drive torque command means. Control each drive unit to move the chassis forward and backward. For this reason, it can be made to drive | work by a simple structure without a steering mechanism. In this case, at the time of turning such as cornering, the rotation is distributed to the outer wheel group in the turning radius direction while increasing the number of rotations compared to the inner wheel group in the turning radius direction, and each wheel on the outer side in the turning radius direction. By appropriately changing the distribution ratio of the maximum drive torque of the vehicle, for example, if the maximum drive torque of the intermediate wheel is reduced and distributed from the maximum drive torque of the front and rear wheels on the outer side in the turning radius direction, The torque limit of the intermediate wheel can be suppressed by increasing the torque limit of the wheel, the lateral grip of the intermediate wheel can be increased, and the running stability can be improved by preventing the disturbance of the course.

It is a perspective view which shows the conveyance vehicle which concerns on embodiment of this invention. It is a top view which shows the conveyance vehicle which concerns on embodiment of this invention. It is a perspective view which shows the structure of the intermediate wheel of the conveyance vehicle which concerns on embodiment of this invention. It is a perspective view which shows the structure of the front-and-rear wheel of the conveyance vehicle which concerns on embodiment of this invention. It is a graph which shows the relationship between the centrifugal force and speed used in control of the control part of the conveyance vehicle which concerns on embodiment of this invention. It is a graph which shows the relationship between the maximum drive torque and speed of an intermediate wheel used in control of the control part of the conveyance vehicle which concerns on embodiment of this invention. An example of the control in the snowy road surface of the conveyance vehicle which concerns on embodiment of this invention is shown, (a) shows the relationship between the maximum drive torque and cornering force when the speed of an intermediate wheel is comparatively slow (A in FIG. 6). FIG. 4B is a diagram showing the relationship between the maximum driving torque and the cornering force when the intermediate wheel has a relatively high speed (B in FIG. 6). It is a figure which shows the distribution state of the maximum drive torque of each wheel at the time of the cornering of the conveyance vehicle which concerns on embodiment of this invention. It is a top view which shows an example of the vehicle which can be used for the conventional conveyance vehicle. The conventional vehicle cornering disadvantages are shown, (a) is a diagram showing the relationship between the maximum driving torque of the intermediate wheel and the cornering force, (b) is a diagram showing the distribution state of the maximum driving torque of each wheel.

Hereinafter, a transport vehicle according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected and demonstrated to the same thing as the above. The transport vehicle according to the embodiment is an automatic guided vehicle that travels by wireless communication with a base station.
As shown in FIGS. 1 to 4, a transport vehicle C according to an embodiment of the present invention includes a chassis 1 formed of a metal frame, and a pair of treads that are the same in the front-rear direction of the chassis 1. A front wheel Wf, a pair of intermediate wheels Wc, and a pair of rear wheels Wd are provided. Each wheel Wf, Wc, Wd is supported to the chassis 1 via a suspension mechanism 10 described later, and the wheel shaft 2 of each wheel Wf, Wc, Wd is provided so as to be orthogonal to the front-rear direction R of the chassis 1. It has been.

  As shown in FIG. 3, the intermediate wheel Wc has a rubber tire 4 mounted on the outer periphery of a wheel 3 having a wheel shaft 2. Further, the front wheel Wf and the rear wheel Wd other than the intermediate wheel Wc are composed of omnidirectional wheels as shown in FIG. This is formed on a wheel 5 having a wheel shaft 2 by arranging a plurality of rubber roll rollers 6 that freely rotate in a lateral direction perpendicular to the straight traveling direction of the wheels in a ring shape. Each roll roller 6 is rotatably supported on a rotating shaft (not shown) provided on the outer periphery of the wheel 5. The rubber tire 4 is used for the intermediate wheel Wc in order to obtain a reaction force against the centrifugal force by gripping the road surface with the tire 4 during turning such as cornering. Each wheel Wf, Wc, Wd is formed in a size with the same diameter.

  Each wheel Wf, Wc, Wd is provided with a drive unit 7 capable of independently outputting the maximum drive torque commanded to each wheel Wf, Wc, Wd. The drive unit 7 is constituted by an electric motor having a driver functioning according to a command of a control unit 20 described later, which is called an in-wheel motor, and the rotation shaft thereof is directly connected to the wheel shaft 2.

  As shown in FIGS. 3 and 4, the suspension mechanism 10 that supports the wheels Wf, Wc, and Wd is an independent suspension mechanism, which is a so-called double wishbone suspension mechanism. Specifically, the suspension mechanism 10 includes a holding portion 11 that holds the driving portion 7, a support portion 12 that is fixed to the chassis 1, and both ends that are pivotally supported between the holding portion 11 and the support portion 12. And a pair of upper and lower links 13 (A) and 13 (B) that form a link mechanism. Each link 13 includes a pair of left and right arms 14 that are pivotally supported at both ends. In addition, the suspension mechanism 10 is provided with a pair of dampers 16 having a coil spring 15 between the support portion 12 and the lower link 13. Mounting members 17 are provided on both upper sides of the support portion 12, and each damper 16 is pivotally supported between the mounting member 17 and the corresponding arm 15 of the lower link 13 (B). It is erected.

Further, as shown in FIG. 2, the transport vehicle C is provided with a control unit 20 that controls each drive unit 7 to move the chassis 1 forward and backward. The control unit 20 includes a CPU, performs wireless communication with the base station, and performs control such as controlling each drive unit 7 individually.
The control unit 20 includes a rotation command unit 24 that commands each drive unit 7 to determine the rotation speed and rotation direction of each wheel, and a maximum drive torque command unit 21 that allocates and commands the maximum drive torque of each wheel. ing. The maximum drive torque command means 21 determines the maximum drive torque Tc of the intermediate wheel Wc at the front wheel Wf and the rear wheel Wd in the front wheel Wf, the intermediate wheel Wc, and the rear wheel Wd on the outer side in the turning radius when the vehicle turns at least in a curve. The maximum drive torques Tf and Tr are distributed to be reduced. As shown in FIG. 7, the maximum driving torque Tc of the intermediate wheel Wc on the outer side in the turning radial direction corresponds to the maximum driving torque Tc of the intermediate wheel Wc and the combined torque Tt of the cornering force Fa corresponding to the slipperiness of the road surface. It is set so as to be within a predetermined friction circle (30, 31, 32 in FIG. 7 described later).

  Specifically, the control unit 20 calculates the maximum driving torque of the intermediate wheel that calculates the maximum driving torque Tc of the intermediate wheel Wc on the outer side in the turning radius direction based on a predetermined relationship corresponding to the slipperiness of the road surface and the chassis speed. Front and rear wheels for calculating the maximum drive torques Tf and Tr of the front wheel Wf and the rear wheel Wd on the outer side in the turning radius based on the means 22 and the maximum drive torque Tc of the intermediate wheel Wc calculated by the intermediate wheel maximum drive torque calculation means 22 A maximum driving torque calculating means 23, and the maximum driving torque commanding means 21 distributes and commands the maximum driving torque calculated by the intermediate wheel maximum driving torque calculating means 22 and the front and rear wheel maximum driving torque calculating means 23.

In the intermediate wheel maximum drive torque calculating means 22, the maximum drive torque Tc of the intermediate wheel Wc is determined, for example, as follows.
When the total mass of the vehicle body mass plus the load mass is m, the speed of the chassis 1 is v, the angular speed of the chassis 1 is ω, the radius of rotation is r, and the centrifugal force generated in the chassis 1 is F, r = v / ω Because
F = mrω ² = mvω ² / ω = mvω
It becomes a relationship. This relationship is shown in the graph of FIG. Note that m (MIN) was set when there was no load, and m (MAX) was set when the load was mounted on the vehicle.

  Then, the maximum drive torque Tc of the intermediate wheel Wc is determined so as to resist this centrifugal force F. In this case, the slipperiness of the road surface is taken into consideration. As shown in FIG. 6, the maximum driving torque of the intermediate wheel Wc is Tc, and the standard maximum driving torque of the intermediate wheel Wc distributed without decreasing the maximum driving torque of the intermediate wheel Wc is Tcs (100%). A correlation diagram in which the output ratio (%) of the maximum drive torque Tc to the standard maximum drive torque Tcs of the intermediate wheel Wc is associated with the slipperiness of the road surface and the speed (vω) of the chassis 1 is obtained in advance. The intermediate wheel maximum drive torque calculating means 22 calculates the maximum drive torque Tc of the intermediate wheel Wc based on this correlation diagram.

The slipperiness of the road surface is set in advance by checking the road surface condition. For example, as shown in FIG. 6, the road surface is a dry road surface, a wet road surface, or a snowy road surface. Alternatively, it is also possible to detect slipping of the wheels with respect to the road surface using the traction control of the ABS device, and to give the ease of slipping of the road surface in real time based on this slip detection.
7A and 7B show examples of the output ratio (%) of the maximum drive torque Tc at the intermediate wheel Wc at the points A and B of the speed (vω) of the chassis 1 on a snowy road surface. In the figure, 30 indicates a tire friction circle on a snowy road surface, 31 indicates a tire friction circle on a wet road surface, and 32 indicates a tire friction circle on a pavement dry road surface.

The front and rear wheel maximum drive torque calculating means 23 sets the maximum drive torque distributed to the front wheel Wf, the intermediate wheel Wc and the rear wheel Wd on the outer side in the turning radius direction to Tf, Tc and Tr, respectively, and reduces the maximum drive torque of the intermediate wheel Wc. The standard maximum driving torque distributed to the front wheel Wf, the intermediate wheel Wc, and the rear wheel Wd without being made Tfs, Tcs, Trs, respectively, and the decrease value of the maximum driving torque with respect to the standard maximum driving torque Tcs of the intermediate wheel Wc is Tcd. When
Tcd = Tcs−Tc
Tf = Tfs + (1/2) Tcd
Tr = Trs + (1/2) Tcd
It is calculated by the relational expression.

  Therefore, according to the conveyance vehicle C which concerns on this embodiment, it is made to drive | work as follows. The transport vehicle C is driven by wireless communication with the base station. In this traveling, the control unit 20 commands the required rotation speed and rotation direction of each wheel from the rotation command unit 24, and distributes and commands the maximum drive torque from the maximum drive torque command unit 21 to command each drive unit. 7 is controlled to move the chassis 1 forward and backward. For this reason, it is possible to travel with a simple configuration without a steering mechanism. In this case, for example, when moving forward and backward, the rotational speed is equally distributed to the left and right wheels Wf, Wc, and Wd. Further, in the so-called in-situ turning with the center P (FIG. 2) between the pair of intermediate wheels Wc as the turning center, the rotational speeds are equally distributed to the left and right wheel groups, and the rotation directions of the left and right wheel groups are mutually determined. Reverse. In addition, when turning on a curve that is a turn other than the turn on the spot, for example, in cornering of a right turn or a left turn, the number of rotations is increased with respect to the wheel group on the outer side in the turn radius direction than the wheel group on the inner side in the turn radius direction. To distribute.

  At the time of this curve traveling, in the control unit 20, the intermediate wheel maximum drive torque calculation means 22 determines the maximum drive torque Tc of the intermediate wheel Wc on the outer side in the turning radius direction in advance corresponding to the slipperiness of the road surface and the chassis speed. The front and rear wheel maximum drive torque calculation means 23 calculates based on the determined relationship, and the front wheel Wf on the outer side in the turning radius direction based on the maximum drive torque Tc of the intermediate wheel Wc calculated by the intermediate wheel maximum drive torque calculation means 22 and The maximum driving torque Tf, Tr of the rear wheel Wd is calculated, and the maximum driving torque command means 21 calculates the maximum driving torque Tf, Tc, Tr calculated by the intermediate wheel maximum driving torque calculating means 22 and the front and rear wheel maximum driving torque calculating means 23. To distribute and command.

As a result, as shown in FIGS. 6 to 8, the maximum driving torque Tc of the intermediate wheel Wc on the outer side in the turning radius direction is such that the maximum driving torque Tc of the intermediate wheel Wc and the combined torque Tt of the cornering force Fa are easy to slip on the road surface. It is set so as to be within the friction circle determined corresponding to the height. Further, in the front wheel Wf, the intermediate wheel Wc, and the rear wheel Wd on the outer side in the turning radius direction, the maximum drive torque of the intermediate wheel Wc is distributed to be smaller than the maximum drive torque of the front wheel Wf and the rear wheel Wd.
For this reason, as shown in FIG. 8, for example, when the road surface is wet with rain or is slippery due to snow or ice burn, the course is likely to be disturbed during so-called cornering at the time of cornering turning. Then, the maximum driving torque Tc of the intermediate wheel Wc on the outer side in the turning radius direction and the combined force Tt of the cornering force Fa in the lateral direction are within the friction circle (grip limit) of the intermediate wheel Wc, and the torque limit of the front and rear wheels Wd on the outer side in the turning radius direction. Since the torque limit of the intermediate wheel Wc is reduced and the lateral grip of the intermediate wheel Wc can be increased, the lateral grip of the chassis 1 can be secured, slippage is suppressed, and the course is prevented from being disturbed. Thus, the running stability can be improved. In this turning, the front wheel Wf and the rear wheel Wd are arranged in a plurality of roll rollers 6 that freely rotate in a lateral direction perpendicular to the straight traveling direction of the wheels. Since it rotates freely in the direction, it is possible to follow the difference in rotation and obtain smooth running.
Further, since the decrease value Tcd of the maximum driving torque Tc of the intermediate wheel Wc is equally distributed (1/2) to the front and rear wheels Wd on the outer side in the turning radius direction, the track becomes smoother and the running stability is further increased. It is possible to improve the performance.

  Thus, it becomes possible to deal with any road surface by appropriately changing the rotation speed of each wheel and the distribution ratio of the maximum driving torque. In particular, when turning, since individual maximum drive torque can be commanded from the maximum drive torque command means 21 to each drive unit 7, the number of control combinations is increased as compared with the conventional case. To do. Therefore, for example, it is possible to prevent a situation where the course is disturbed particularly during cornering and the like when turning, thereby improving the running stability.

  In this traveling, the front wheel Wf, the intermediate wheel Wc, and the rear wheel Wd are supported by the chassis 1 via the suspension mechanism 10. Therefore, even if the road surface is uneven, it can follow this. In other words, even if the chassis 1 is lifted due to the unevenness of the road surface, the suspension mechanism 10 is operated so that the wheels Wf, Wc, Wd follow the running surface, and the wheels Wf, Wc, Wd can be prevented from lifting. The driving force can be reliably transmitted to the traveling surface. In particular, on snowy roads, it is possible to cope with unevenness due to snow in addition to dealing with the above-mentioned slipping, so that the running stability can be further improved.

  In the above embodiment, the distribution of the maximum drive torque by the control unit 20 is not limited to the above-described distribution, and may be changed as appropriate. Of course, a maximum driving torque difference may be provided between the front and rear wheels Wf and Wd during acceleration or braking. Moreover, although the function of the control part 20 was mounted in the chassis 1, it is not necessarily limited to this, You may make it instruct | indicate by radio | wireless communication and may change suitably. Furthermore, in the above embodiment, the treads of the front wheel Wf, the intermediate wheel Wc, and the rear wheel Wd are the same. However, the tread is not necessarily limited to this, and the tread may be different and may be appropriately changed. Absent. Furthermore, the number of wheels is not limited to the above six wheels, and may be eight wheels, ten wheels, or the like. In this case, it is desirable that the intermediate wheel Wc be paired. Of course, the number of wheels may be increased in the axle direction.

C carrier 1 chassis Wf front wheel Wc intermediate wheel Wr rear wheel 2 wheel shaft 3 wheel 4 rubber tire 5 wheel 6 rollover roller 7 drive unit 10 suspension mechanism 11 holding unit 12 support unit 13 link 14 arm 15 coil spring 16 damper 20 control unit 21 Maximum drive torque command means 22 Intermediate wheel maximum drive torque calculation means 23 Front and rear wheel maximum drive torque calculation means 24 Rotation command means Tf, Tc, Tr Maximum drive torque of wheels on the outer side in the turning radius 30 Tire friction circle 31 on snowy road surface Wet road surface Tire friction circle of 32 Tire friction circle of pavement dry road surface

Claims (6)

A transport vehicle provided with at least a pair of front wheels, a pair of intermediate wheels, and a pair of rear wheels in the front-rear direction of the chassis,
Each wheel is provided such that its wheel axis is orthogonal to the front-rear direction of the chassis, the intermediate wheel is provided with a rubber tire, and the front wheels and rear wheels other than the intermediate wheel are arranged in a straight direction of the wheel. It comprises omnidirectional wheels in which a plurality of roll rollers that rotate freely in a transverse direction orthogonal to each other are arranged in an annular shape, and each of the wheels is provided with a drive unit capable of independently outputting a maximum drive torque, A control unit for controlling each drive unit to move the chassis forward and backward and turn is provided, and the control unit is provided with a maximum drive torque command means for allocating and commanding the maximum drive torque to each drive unit. Transport vehicle.   The maximum drive torque command means reduces the maximum drive torque of the intermediate wheel to the maximum drive torque of the front wheel and the rear wheel at the front, intermediate and rear wheels on the outer side in the turning radius when turning at least a curve of the chassis. 2. The transport vehicle according to claim 1, wherein the transport vehicle is distributed.   The maximum driving torque of the intermediate wheel on the outer side in the turning radius direction is set so that the maximum driving torque of the intermediate wheel and the combined torque of the cornering force are within the friction circle determined according to the slipperiness of the road surface. The conveyance vehicle according to claim 2, wherein:   The control unit calculates the maximum driving torque of the intermediate wheel on the outer side in the turning radius direction based on a predetermined relationship corresponding to the slipperiness of the road surface and the chassis speed; and Front and rear wheel maximum drive torque calculating means for calculating the maximum drive torque of the front and rear wheels on the outer side in the turning radius based on the maximum drive torque of the intermediate wheel calculated by the intermediate wheel maximum drive torque calculating means, and the maximum drive torque 4. The transport vehicle according to claim 3, wherein the command means distributes and commands the maximum drive torque calculated by the intermediate wheel maximum drive torque calculation means and the front and rear wheel maximum drive torque calculation means. The maximum driving torques distributed to the front, intermediate and rear wheels on the outside in the turning radius direction are Tf, Tc and Tr, respectively, and the maximum driving torque of the intermediate wheels is not reduced and the front wheels, intermediate wheels and rear wheels are reduced. When the standard maximum driving torque distributed in the above is Tfs, Tcs, Trs, and the decrease value of the maximum driving torque with respect to the standard maximum driving torque of the intermediate wheel is Tcd,
Tcd = Tcs−Tc
Tf = Tfs + (1/2) Tcd
Tr = Trs + (1/2) Tcd
The transport vehicle according to claim 3 or 4, wherein the transport vehicle is set as follows.   6. The transport vehicle according to claim 1, wherein the front wheel, the intermediate wheel, and the rear wheel are supported by a chassis via a suspension mechanism.

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