Controller of electric driven truck

Abstract

To provide a controller of an electric driven truck which suppresses influence of lateral deviation due to roll-over of a free-rolling wheel.SOLUTION: A controller of an electric driven truck is given in which: one of a front wheel 211 and a rear wheel 212 is a free-rolling wheel; and power of an electric motor 311 can be transferred to the other of the front wheel 211 and the rear wheel 212 as a drive wheel. When direction of travel is switched where rotation direction of the drive wheel at the time of resuming the traveling after stopping the electric driven truck 1 is opposite to the direction before travel stop, the electric driven truck 1 is stopped in a state that a wheel center line Ax13 connecting a grounding point Pg of the free-rolling wheel with a steering shaft Ax12 in a plan view of the electric driven truck 1 is slanted to traveling direction Dr of the electric driven truck 1 after resuming travel.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a control device for an electric trolley.

Background Art

[0002] There exists a trolley equipped with a swivel wheel as a traveling wheel, where the orientation of the wheel can freely change around a vertical steering axis.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a trolley equipped with swivel wheels, when switching the traveling direction between forward and reverse, lateral vibration occurs in the vehicle body due to the trail of the swivel wheels.

[0005] This lateral vibration is caused by the swivel wheel rotating (i.e., reversing) around the steering axis. For example, when the trolley enters the forward direction towards the stop position and stops facing forward, and then exits the stop position in the reverse direction, during the exit process, the steering axis moves left and right with respect to the ground contact point of the swivel wheel, causing the lateral vibration. When the trolley is loaded with goods, there is a concern that the shaking due to the lateral vibration will be transmitted to the goods, resulting in the collapse of the load. Furthermore, when stopping the trolley in a narrow place such as a loading / unloading location of goods or inside an elevator car, there is also a concern that the trolley will contact surrounding people or objects due to the lateral vibration.

[0006] It is difficult to predict in advance the timing and direction (whether it is clockwise or counterclockwise) of the reversal of the swivel wheel. Therefore, it is also difficult to predict the timing and direction of the lateral vibration generated in the trolley due to the reversal of the swivel wheel, and it is also difficult to suppress the occurrence of the lateral vibration by control.

[0007] In view of such a situation, an object of the present invention is to provide a control device for an electric trolley that can suppress or mitigate the influence of lateral vibration caused by the reversal of a castor by causing the reversal of the castor to occur at a controlled or predicted timing and direction.

Means for Solving the Problems

[0008] To solve the above problems, a control device for an electric trolley according to an embodiment of the present invention is a control device for an electric trolley configured to be capable of transmitting the power of an electric motor to a driving wheel, which is the other of the front wheels and the rear wheels, and having a castor on one of the front wheels and the rear wheels. The control device includes a switching determination means for determining whether or not the rotation direction of the driving wheel when restarting travel after the trolley has stopped traveling is at the time of a traveling direction change that is opposite to that before the traveling stop, and a switching stop means for stopping the trolley in a state where a wheel center line connecting the contact point of the castor and the steering axis in a plan view of the trolley is inclined with respect to the traveling direction of the trolley after the restart of travel, when it is determined by the switching determination means that it is at the time of the traveling direction change.

Effects of the Invention

[0009] According to one aspect of the present invention, at the time of a traveling direction change of an electric trolley, when restarting travel after stopping, the reversal of the castor can be caused to occur at a controlled or predicted timing and direction, and the influence of lateral vibration caused by the reversal of the castor can be suppressed or mitigated.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a side view showing the electric trolley (hereinafter simply referred to as "electric trolley") 1 according to an embodiment of the present invention as viewed from the right side with respect to the traveling direction, and FIG. 2 is a rear view showing the electric trolley 1 as viewed from the rear. With reference to FIGS. 1 and 2, the configuration of the electric trolley 1 will be described.

[0013] The electric trolley 1 can be used for the movement of people or the transportation of goods. For example, by attaching a chair part to the electric trolley 1, it can be used as an electric wheelchair, or by attaching a loading platform part, it can be used as an electric transport vehicle. In this embodiment, the case of using it as an electric transport vehicle will be described.

[0014] The electric trolley 1 includes, as basic components, a vehicle body 11, wheels 21, and a drive device 31. In FIG. 1, the direction indicated by the arrow Dl is the front-rear direction of the electric trolley 1, and the direction indicated by the arrow Dv is the vertical direction of the electric trolley 1. The direction perpendicular to both the front-rear direction Dl and the vertical direction Dv, that is, the direction indicated by the arrow Dw in FIG. 2 is the vehicle width direction of the electric trolley 1. The front-rear direction Dl coincides with the traveling direction of the electric trolley 1, and the direction indicated by the arrow Df in FIG. 1, that is, the direction from the left side to the right side with respect to the paper surface is the forward direction of the electric trolley 1.

[0015] The vehicle body 11 includes a vehicle body main body portion 111 and a loading platform portion 112. The loading platform portion 112 includes a pair of left and right side members 112a extending in the front-rear direction Dl of the electric trolley 1, and a plurality of cross members 112b extending in the vehicle width direction Dw. The side members 112a are arranged at both left and right ends of the loading platform portion 112, and the cross members 112b are spanned between these pair of side members 112a to connect the left and right side members 112a to each other. The number of the cross members 112b can be appropriately changed. For example, the cross members 112b include a first cross member arranged at the front end of the loading platform portion 112, a second cross member arranged at the rear end, and an appropriate number of third cross members arranged in the middle. In addition to the left and right side members 112a, by arranging intermediate reinforcing members, it is also possible to configure the loading platform portion 112 by combining the side members 112a, the cross members 112b, and the reinforcing members in a lattice shape. The loading platform portion 112 is attached above the vehicle body main body portion 111, and forms a substantially flat and horizontal loading surface (hereinafter referred to as "loading surface") on its upper part.

[0016] The electric trolley 1 has, as wheels 21, a pair of left and right wheels provided in the front part of the electric trolley 1, that is, front wheels 211, and a pair of left and right wheels provided in the rear part of the electric trolley 1, that is, rear wheels 212. And as the front wheels 211, a left front wheel 211a and a right front wheel 211b are provided, and as the rear wheels 212, a left rear wheel 212a and a right rear wheel 212b are provided. As shown in FIG. 2, the left front wheel 211a and the left rear wheel 212a are located below the left side member 112a, and the right front wheel 211b and the right rear wheel 212b are located below the right side member 112a. In this way, the wheels 21 are provided in pairs, one pair in the front and one pair in the rear, for a total of four, and the electric trolley 1 supports the vehicle body 11 on the road surface or floor surface on which the electric trolley 1 travels by these four wheels 21 (front wheels 211, rear wheels 212).

[0017] In this embodiment, the front wheels 211 (211a, 211b) are smaller in diameter than the rear wheels 212 (212a, 212b). In the electric cart 1, the rotation axis or wheel axis Ax11 of the front wheels 211 is disposed below the rotation axis or wheel axis Ax21 of the rear wheels 212. When traveling on a flat floor surface or road surface, the upper surface of the vehicle body 11, that is, the loading surface of the loading section 111, is parallel to the floor surface or road surface.

[0018] Furthermore, in this embodiment, while the rear wheels 212 are provided as drive wheels, the front wheels 211 are provided as driven wheels and are constituted by swivel wheels. That is, the front wheels 211 are rotatable about the wheel axis Ax11 when the electric cart 1 travels, and rotate about the vertical steering axis Ax12 when the course of the electric cart 1 is changed, and their direction can be changed over the entire circumference, that is, 360°. Here, as shown in FIG. 1, a deviation called a trail T is formed between the wheel axis Ax11 and the steering axis Ax12 of the front wheels 211. The direction in which the trail T is defined is a direction perpendicular to both the wheel axis Ax11 and the steering axis Ax12, and coincides with the direction defining the direction of the wheels 211. In this embodiment, the direction of the wheels 211, which are swivel wheels, is defined as the direction along a straight line (hereinafter referred to as the "wheel center line") Ax13 connecting the steering axis Ax12 and the ground contact point Pg of the front wheels 211 in a plan view of the electric cart 1 as viewed from above.

[0019] The drive device 31 is composed of electric motors 311 (311a, 311b). The electric motors 311a and 311b are respectively provided for the left rear wheel 212a and the right rear wheel 212b, and are supported by a bracket (not shown) with respect to the vehicle body main body 111. As shown in FIG. 2, the first electric motor 311a on the left side is configured to be able to transmit power to the left rear wheel 212a, and the second electric motor 311b on the right side is configured to be able to transmit power to the right rear wheel 212b with an appropriate reduction ratio. Further, the electric motors 311a and 311b can be independently controlled in terms of current, and can independently and individually transmit power to the left rear wheel 212a and the right rear wheel 212b respectively. Specifically, it is possible to rotate the left rear wheel 212a and the right rear wheel 212b at the same speed, or reduce the rotational speed of one wheel lower than that of the other wheel, or rotate one wheel in the opposite direction to the other wheel at the same or different speeds.

[0020] In this embodiment, the electric cart 1 is provided with an automatic control system and can automatically travel on the floor surface or the road surface along a preset route. The electric cart 1 is provided with an operation switch (not shown) that can be manually operated by an operator handling luggage. When the electric cart 1 is instructed by the operator to start running via this operation switch, it starts running along the set route.

[0021] As shown in FIG. 2, the automatic control system includes various sensors 201, 202,... as detection units in addition to the controller 101 which is a calculation unit. The automatic control system further includes a storage unit 301 that stores in advance map information and route information regarding the set route. The sensors provided as the detection unit include a position sensor 201 and an external sensor 202. The controller 201 can grasp the current position of the electric cart 1 on the map or the set route based on the output information from the position sensor 201, and can grasp the situation around the electric cart 1 based on the output information from the external sensor 202. In this embodiment, the controller 101 grasps or detects the left and right situations of the electric cart 1, particularly the presence or absence of obstacles existing on the left and right sides of the electric cart 1, based on the output information from the external sensor 202.

[0022] Here, in a carriage equipped with swivel wheels, when switching the traveling direction between forward and backward (that is, when switching the traveling direction), lateral shaking due to the trail of the swivel wheels occurs in the vehicle body. This will be schematically described with reference to FIG. 7.

[0023] FIG. 7 shows, as an example of a situation where lateral shaking occurs, a situation where the carriage 1' enters in the forward direction with respect to the stop position, stops traveling at the stop position (time t1), and then exits the stop position in the backward direction Dr.

[0024] The carriage 1' which is a comparative example has free wheels provided on the front wheels 211a and 211b which are driven wheels, while the rear wheels 212a and 212b are driving wheels, similar to the electric carriage 1 according to the present embodiment. After stopping traveling at time t1, traveling is restarted and the vehicle starts moving in the backward direction Dr. Through times t2 and t3, at time t4, the direction of the front wheels 211 (211a, 211b) switches by 180° from the forward direction to the backward direction. In the following description, the operation in which the direction of the free wheels switches by 180° is referred to as "inversion" of the free wheels. FIG. 7(a) shows a case where lateral shaking due to the inversion of the front wheels 211 occurs to the right with respect to the forward direction of the vehicle 1', and FIG. 7(b) shows a case where the lateral shaking occurs to the left. In FIG. 7, the arrows D11 and D12 indicate the displacement (that is, rocking) of the vehicle body 11 when the lateral shaking occurs to the right, and the arrows D21 and D22 indicate the displacement of the vehicle body 11 when the lateral roll occurs to the left.

[0025] In the situation shown in FIG. 7, the lateral shaking is generated by the front wheels 211 rotating (that is, inverting) about the steering axis Ax12, and is generated by the steering axis Ax12 moving left and right with respect to the ground contact point Pg of the front wheels 211 in the process of exiting in the direction indicated by the arrow Dr (times t2, t3). Specifically, when the inversion of the front wheels 211 occurs in the direction in which the steering axis Ax12 passes on the right side of the ground contact point Pg, that is, in the clockwise direction in the plan view of the carriage 1', the lateral roll occurs to the right (FIG. 7(a)). On the other hand, when the inversion of the front wheels 211 occurs in the direction in which the steering axis Ax12 passes on the left side of the ground contact point Pg, that is, in the counterclockwise direction in the plan view of the carriage 1', the lateral roll occurs to the left (FIG. 7(b)).

[0026] FIG. 7 shows, as an example, a case where inversions occur simultaneously and in the same direction in the left and right front wheels 211a and 211b, respectively. However, the timing at which the inversion occurs is not necessarily simultaneous between the left and right, and the direction of inversion is not necessarily the same between the left and right. Inversions may occur in only one of the left and right front wheels 211a and 211b, or the direction of inversion may be different between the left and right. And when the inversions of the front wheels 211a and 211b occur successively between the left and right, for example, when an inversion occurs in the right front wheel 211b following or during the inversion of the left front wheel 211a, lateral shakes due to the inversion occur multiple times (when the inversions of the front wheels 211a and 211b occur once each on the left and right, a total of 2 times) within a short period of time. In a situation where lateral shakes occur multiple times, when the directions of inversion are different between the left and right, the influence of the lateral shakes can become more prominent.

[0027] As described above, when a lateral shake occurs in the carriage 1', if there is a load on the loading platform, there is a concern that the shake or vibration due to the lateral movement is transmitted to the load, causing the load to collapse. Further, when the carriage 1' is stopped in a narrow place such as a loading and unloading location of a load or inside an elevator car, there is also a concern that after restarting the travel, the carriage 1' contacts surrounding people or objects due to the lateral movement. It is difficult to predict in advance the timing and direction of the inversion of the free wheels, and it is also difficult to predict the timing and direction of the lateral shake generated in the carriage 1' due to the inversion of the free wheels.

[0028] In contrast, in the present embodiment, by a specific operation performed when stopping the travel of the electric carriage 1, after restarting the travel, the inversion of the front wheel 211, which is a free wheel, is caused to occur at a controlled or predicted timing and direction, and the influence of the lateral shake generated by the inversion of the front wheel 211 is suppressed or mitigated.

[0029] FIGS. 5 and 6 schematically show the operations performed by the electric carriage 1 according to the present embodiment in a plan view as seen from above the electric carriage 1. FIG. 5 shows the operations from stopping the travel to restarting the travel, and FIG. 6 shows the operations after restarting the travel in time series, respectively.

[0030] In this embodiment, when stopping the traveling of the electric cart 1, it is determined whether or not it is at the time of switching the traveling direction in which the rotation direction of the drive wheels (rear wheels 212) after resuming traveling is opposite to that before stopping the traveling. At the time of switching the traveling direction, for example, as in the example shown in FIG. 7, the electric cart 1 is caused to enter the forward direction Df with respect to a stop position such as a loading / unloading location of a load or inside an elevator car, stopped at the stop position, and then traveling is resumed, and the case where it exits the stop position in the backward direction Dr corresponds. And when it is at the time of switching the traveling direction, as shown in FIGS. 5(a) and 5(b), the electric cart 1 is stopped in a state where the wheel center line Ax13 of the front wheels 211, which are swivel wheels, is inclined with respect to the traveling direction Dr of the electric cart 1 after resuming traveling.

[0031] In this embodiment, at the time of stopping the traveling, the direction of the electric cart 1 itself (that is, the direction of the vehicle body 11) is inclined with respect to the traveling direction Dr after resuming traveling, thereby inclining the direction of the front wheels 211. FIG. 5(b) shows the direction (leftward) in which the electric cart 1 is inclined by an arrow D1, and the angle formed by the longitudinal center line Actr of the electric cart 1 with respect to the traveling direction Dr after resuming traveling is indicated by a symbol θt. The traveling direction Dr after resuming traveling is defined in the direction along the dotted line Al in FIG. 5(b).

[0032] And at the time of resuming traveling after stopping, the inclination of the electric cart 1 is released, and the direction of the electric cart 1 is made to coincide with the traveling direction Dr after resuming traveling. In other words, as shown in FIG. 5(c), the electric cart 1 is swiveled in the direction indicated by an arrow D2, and the direction of the electric cart 1 is returned so that the longitudinal center line Actr of the electric cart 1 is along the traveling direction Dr after resuming traveling. At this time, the front wheels 211 do not return to a state where the wheel center line Ax13 is parallel to the vehicle body center line Actr, but are inclined in a direction opposite to that when the electric cart 1 itself was inclined previously. Thereby, the front wheels 211 maintain an inclined state with respect to the traveling direction Dr after resuming traveling at the time of resuming traveling.

[0033] Furthermore, in the present embodiment, control for actively suppressing the influence of lateral vibration caused by the reversal of the front wheels 211 after resuming travel (hereinafter referred to as "oscillation suppression control") is implemented. Specifically, after resuming travel, until the electric trolley 1 travels a predetermined distance, the lateral vibration caused by the reversal of the front wheels 211 is offset by the sway of the vehicle body 11 in the opposite phase. For example, as shown in FIG. 6(a), when lateral sway occurs in the right direction, a leftward sway is superimposed on the vehicle body 11 of the electric trolley 1. FIG. 6(a) shows the case where the reversal of the front wheels 211 occurs in the direction in which the steering axis Ax12 passes through the right side of the ground contact point Pg with respect to the forward direction Df of the electric trolley 1 (that is, in the right direction), and the direction of reversal is indicated by the arrow Ds3, and the direction of lateral vibration is indicated by the arrow D3, respectively. In this case, in the present embodiment, a sway in the direction opposite to the arrow D3 is generated in the vehicle body 11 of the electric trolley 1. This sway can be formed by increasing the rotational speed of one of the left and right drive wheels 212a, 212b, which is provided on the side opposite to the turning direction Dy2 (FIG. 5(c)) of the vehicle body 11 when the direction of the electric trolley 1 is restored at the time of resuming travel, that is, the left rear wheel 212a, compared to the other wheel, that is, the right rear wheel 212b.

[0034] Thereafter, when the rotation of the front wheels 211 about the steering axis Ax12 progresses (FIG. 6(b)), and the wheel center line Ax13 reaches a position along the traveling direction Dr and the reversal is completed (FIG. 6(c)), the oscillation suppression control is stopped and the vehicle shifts to normal mode driving.

[0035] FIGS. 3 and 4 are flowcharts showing the basic flow of control when the traveling direction of the electric trolley 1 is switched. FIG. 3 shows the control (hereinafter referred to as "stop control") in the phase until the electric trolley 1 approaches the stop position and stops traveling, and FIG. 4 shows the control (hereinafter referred to as "resume travel control") in the phase after the electric trolley 1 resumes traveling, the front wheels 211 are reversed, and the electric trolley 1 shifts to normal traveling. In the present embodiment, the resume travel control includes the content of the oscillation suppression control described above. Both the stop control and the resume travel control are implemented by the controller 101.

[0036] In this embodiment, a "control device for an electric trolley" is constituted by a controller 101, a position sensor 201, an external sensor 202, and a memory unit 301. The controller 101 is configured as an electronic control unit equipped with a microcomputer, and each of the means (excluding the "travel route storage means") constituting the "control device for an electric trolley" is realized software-wise by the controller 101 operating according to a computer program. The "travel route storage means" according to this embodiment is constituted by the memory unit 301.

[0037] In the flowchart shown in FIG. 3, in S101, various control information such as output information from the position sensor 201 and the external sensor 202 is acquired.

[0038] In S102, it is determined whether or not it is at the time of changing the traveling direction. In this embodiment, it is determined whether or not the electric trolley 1 has stopped traveling and whether or not the rotation direction of the drive wheels (rear wheels 212) after resuming traveling is opposite to that before the traveling stop. In this embodiment, it is determined whether or not the traveling direction of the electric trolley 1 is opposite before and after the traveling stop. This determination can be made, for example, based on the output information from the position sensor 201 to specify the current position of the electric trolley 1, and by collating the specified current position with the set route of the electric trolley 1 to determine whether or not the position where the electric trolley 1 is scheduled to stop involves a change in the traveling direction before and after the traveling stop. If it is determined that it is at the time of changing the traveling direction, the process proceeds to S103, and otherwise, this control is terminated. By the process of S102, the "determination means at the time of switching" according to this embodiment is realized.

[0039] In S103, it is determined whether or not there is an obstacle (not limited to an object, including a person) around the electric vehicle 1. This determination is based on the output information from the external sensor 202. If there is an obstacle around the electric trolley 1, particularly near the left and right of the electric trolley 1, this control is terminated, and if not, the process proceeds to S104.

[0040] In S104, it is determined whether the electric cart 1 has reached the stop position. If it has reached the stop position, the process proceeds to S105. If it is approaching the stop position and has not yet reached, the process returns to S103, and while continuously monitoring the surrounding situation, the subsequent processing is awaited until the stop position is reached.

[0041] In S105, an operation to adjust the direction of the front wheels 211, which are swivel wheels, in other words, an operation to incline the wheel center line Ax13 of the front wheels 211 with respect to the traveling direction Dr after resuming travel (hereinafter referred to as the "angle-giving adjustment operation") is performed. In the present embodiment, after reaching the stop position, the rotation speed of the left front wheel 211a by the first electric motor 311a and the rotation speed of the right front wheel 211b by the second electric motor 311b are made different from each other, thereby inclining the direction of the electric cart 1 itself. Specifically, at the stop position, the left front wheel 211a and the right front wheel 211b are rotated at the same speed in opposite directions to perform a super-reliable turning. Here, the angle θt formed by the center line Actr in the front-rear direction of the electric cart 1 after the angle-giving adjustment operation with respect to the traveling direction Dr after resuming travel is set to 5° or less. By the process of S105, the "first switching stop means" and the "second switching stop means" according to the present embodiment are realized.

[0042] In S106, the travel of the electric cart 1 is stopped. Thereafter, the controller 101 waits for an instruction to resume travel from an operator handling the load based on the output signal from the operation switch.

[0043] In the flowchart shown in FIG. 4, in S201, it is determined whether it is at the time of resuming travel. This determination is based on the output signal from the operation switch. If an instruction to resume travel is given by the operator via the operation switch, it is considered to be at the time of resuming travel, and the process proceeds to S202. If an instruction to resume travel has not been given, the subsequent processing is awaited until an instruction to resume travel is given.

[0044] In S202, an operation to return the direction of the electric cart 1 (hereinafter referred to as "vehicle body position return operation") is performed. Specifically, the center line Actr in the front-rear direction of the electric cart 1 inclined with respect to the traveling direction Dr after resuming travel is aligned with the traveling direction Dr after resuming travel, and the direction of the electric cart 1 is returned. When the direction of the electric cart 1 is inclined, that is, when the angle application adjustment operation is performed, the left front wheel 211a and the right front wheel 211b are rotated at the same speed in opposite directions to perform a super reliable turning in the direction opposite to the inclination. By the process of S202, the "pre-travel preliminary operation means" according to the present embodiment is realized.

[0045] In S203, swing suppression control is performed. Specifically, among the left and right drive wheels 212a and 212b, for one wheel provided on the side opposite to the turning direction Dy2 of the vehicle body 11 when the direction of the electric cart 1 is returned by the vehicle body position return operation. For example, when the turning direction Dy2 of the vehicle body 11 when the direction of the electric cart 1 is returned is rightward (Fig. 5(c)), the rotational speed of the left rear wheel 212a, which is the drive wheel on the side opposite to the rightward direction, is increased compared to the other wheel, that is, the right rear wheel 212b. By the process of S203, the "swing suppression means" according to the present embodiment is realized.

[0046] In S204, after resuming travel, it is determined whether the electric cart 1 has traveled a predetermined distance, in other words, whether the travel distance after resuming travel is equal to or greater than the predetermined distance. If the travel distance after resuming travel is equal to or greater than the predetermined distance, the process proceeds to S205. If it is less than the predetermined distance, the process returns to S203, and the swing suppression control is continued until the predetermined distance is reached.

[0047] In S205, the swing suppression control is terminated, and the process shifts to normal travel in which the left and right drive wheels 212 are rotated at a rotational speed corresponding to the travel speed of the electric cart 1.

[0048] The electric cart 1 and its control device according to the present embodiment have the above configuration. Hereinafter, the effects obtained by the present embodiment will be described.

[0049] First, when switching the traveling direction, the electric trolley 1 is stopped in a state where the wheel center line Ax13 of the front wheel 211, which is a swivel wheel in plan view of the electric trolley 1, is inclined with respect to the traveling direction Dr after resuming travel. Thereby, it becomes possible to cause the front wheel 211 to reverse in a controlled or predicted timing and direction after resuming travel. Specifically, when resuming travel in the direction opposite to that before stopping, it becomes possible to quickly reverse the front wheel 211 and shift it in the direction corresponding to the traveling direction Dr after resuming travel.

[0050] Furthermore, it becomes possible to align the timing and direction of reversal of the front wheels 211a and 211b on the left and right sides with each other between these two front wheels 211a and 211b.

[0051] In this way, when stopping during travel at the time of switching the traveling direction, by inclining the front wheel 211 with respect to the traveling direction Dr after resuming travel, it becomes possible to suppress or mitigate the influence of lateral vibration caused by the reversal of the front wheel 211 after resuming travel.

[0052] Second, when inclining the front wheel 211, by inclining the direction of the electric trolley 1 itself, it is not necessary to separately provide a dedicated mechanism for inclining the front wheel 211, which can reduce the manufacturing cost, suppress an increase in the weight of the electric trolley 1, and promote weight reduction of the electric trolley 1.

[0053] Third, when stopping during travel at the time of switching the traveling direction, by making the rotational speeds of the left driving wheel (left wheel 212a) driven by the left first electric motor 311a and the right driving wheel (right wheel 212b) driven by the right second electric motor 311b different from each other, when inclining the direction of the electric trolley 1 itself, it becomes possible to easily change its direction and to incline the direction of the electric trolley 1 within a short moving distance. Here, by inclining the direction of the electric trolley 1 by super reliable turning, it becomes possible to incline the direction of the electric trolley 1 without accompanying movement in the front-rear direction Dl.

[0054] Fourthly, when the orientation of the electric trolley 1 itself is inclined, by setting the angle formed by the center line Actr in the longitudinal direction of the electric trolley 1 with respect to the traveling direction Dr after the restart of travel to 5° or less, it becomes possible to appropriately avoid a situation where the electric trolley 1 is excessively inclined and contacts surrounding obstacles. And if the angle is 5° or less, the time required to incline the orientation of the electric trolley 1 is relatively short, and it becomes possible to suppress a situation that bothers the user or operator of the electric trolley 1.

[0055] Fifthly, after stopping and before restarting travel, the orientation of the electric trolley 1 is returned so that the center line Actr in the longitudinal direction of the electric trolley 1 is along the traveling direction Dr after the restart of travel. In other words, so that the orientation of the electric trolley 1 matches the traveling direction Dr after the restart of travel, thereby making it possible to smoothly restart travel.

[0056] Sixthly, after the restart of travel and until the electric trolley 1 travels a predetermined distance, the rotational speeds of the left and right drive wheels (left wheel 212a, right wheel 212b) are made different from each other, and the rotational speed of the drive wheel (left wheel 212a) provided on the side opposite to the direction Dy2 in which the electric trolley 1 is turned during return is increased compared to the rotational speed of the other drive wheel (right wheel 212b). By doing so, it becomes possible to cancel out the lateral shake caused by the reversal of the front wheel 211 after the restart of travel with a shake of the opposite phase, and suppress the rocking or vibration generated in the electric trolley 1 due to the lateral shake.

[0057] Seventhly, when the surrounding situation is monitored by the external sensor 202 and an obstacle is detected around the electric trolley 1, an operation of tilting the direction of the electric trolley 1 (angle application adjustment operation) is prohibited, so that a situation where the electric trolley 1 collides with an obstacle can be avoided. Here, when an obstacle is detected around the electric trolley 1, the operation of tilting the direction of the electric trolley 1 is not necessarily prohibited uniformly. When an obstacle is detected only on either the left or right side of the electric trolley 1, the direction of the electric trolley 1 may be tilted in the direction where there is no obstacle. Even if obstacles are detected on both the left and right sides of the electric trolley 1, if there is sufficient margin to tilt between the electric trolley 1 and an obstacle on either side, within the range of the margin, the direction of the electric trolley 1 may be tilted in the direction in which the front wheel 211 or the vehicle body 11 moves away from the obstacle close to the electric trolley 1. Thereby, while avoiding a collision of the electric trolley 1 with an obstacle, it is possible to suppress or mitigate the influence of lateral vibration generated in the electric trolley 1 after resuming travel within a possible range.

[0058] In this embodiment, while the rear wheel 212 of the electric trolley 1 is a driving wheel and the front wheel 211 is a driven wheel, and it is configured by a castor wheel, it is not limited to this. It is also possible to configure it such that the front wheel 211 is a driving wheel and the rear wheel 212 is a driven wheel, and it is configured by a castor wheel.

[0059] Furthermore, in this embodiment, an operation of returning the direction of the electric trolley 1, that is, a vehicle body position return operation of releasing the tilt of the electric trolley 1 (the operation shown in S202 of the flowchart in FIG. 4) is to be performed after an instruction to resume travel. However, the timing of performing the vehicle body position return operation is not limited to this. For example, it is also possible to perform it after an operation of tilting the direction of the electric trolley 1 (angle application adjustment operation) and before stopping the travel. In this case, during the stop, the center line Actr in the front-rear direction of the electric trolley 1 becomes in a state along the traveling direction Dr after resuming travel, and it is possible to avoid a situation where the stopped electric trolley 1 hinders passage or work.

[0060] Moreover, the operation of imparting and adjusting the angle can be performed not only after the electric cart 1 reaches the stop position but also before reaching the stop position. For example, when switching the traveling direction, while the electric cart 1 is approaching the stop position from just before the stop position, by making the rotational speed of the left front wheel 211a by the first electric motor 311a and the rotational speed of the right front wheel 211b by the second electric motor 311b different from each other, the direction of the electric cart 1 is inclined, and the wheel center line Ax13 of the front wheels 211 is inclined with respect to the traveling direction Dr after resuming travel.

[0061] Furthermore, in this embodiment, the determination of whether or not it is at the time of switching the traveling direction is automatically performed by collating the current position of the electric cart 1 and the set route, but this determination may be made by a manual operation using a switch or the like by the user of the electric cart 1 or the work vehicle. For example, in an application example of an electric wheelchair in which a seat portion is attached to the electric cart 1, an operation switch for designating that it is at the time of switching the traveling direction is installed on the operation portion of the electric wheelchair.

Explanation of Signs

[0062] 1... Electric cart, 11... Vehicle body, 21... Wheels, 211... Front wheels, 212... Rear wheels, 111... Vehicle body main body portion, 112... Loading platform portion, 31... Driving device, 311... Electric motor, 101... Controller, 201... Position sensor, 202... External sensor, 301... Storage unit, Ax11... Wheel axis of the front wheels, Ax12... Steering axis of the front wheels (swivel wheels), Ax13... Wheel center axis, Ax21... Wheel axis of the rear wheels, Actr... Center line in the longitudinal direction of the vehicle body.

Claims

1. A control device for an electric trolley configured to include a castor on one of a front wheel and a rear wheel and to be able to transmit the power of an electric motor to a drive wheel which is the other of the front wheel and the rear wheel, switching determination means for determining whether or not the rotation direction of the drive wheel when restarting travel is in the case of a travel direction change where the direction is opposite to that before the travel stop after the trolley has stopped traveling; a first switching stop means for stopping the trolley in a state where a wheel center line connecting a contact point of the castor and a steering axis in a plan view of the trolley is inclined with respect to the traveling direction of the trolley after the restart of travel, when it is determined by the switching determination means that it is in the case of a travel direction change. A control device for an electric trolley, comprising:

2. The control device for an electric trolley according to claim 1, wherein the first switching stop means inclines the direction of the trolley after stopping with respect to the traveling direction of the trolley after the restart of travel.

3. The electric trolley further includes a first electric motor disposed so as to be able to transmit power to the left wheel and a second electric motor disposed so as to be able to transmit power to the right wheel, with the left wheel and the right wheel provided as the drive wheels, The control device for an electric trolley according to claim 2, wherein the first switching stop means inclines the direction of the trolley after stopping by making the rotational speed of the left wheel by the first electric motor different from the rotational speed of the right wheel by the second electric motor.

4. The control device for an electric trolley according to claim 3, wherein the direction of the trolley after stopping is a direction in which the angle formed by the center line in the front-rear direction of the trolley with respect to the traveling direction of the trolley after the restart of travel is 5° or less.

5. After the trolley is stopped in a state where the direction of the trolley is inclined with respect to the traveling direction of the trolley after the restart of travel by the first switching stop means, until the travel is restarted, the center line in the front-rear direction of the trolley is along the traveling direction of the trolley after the restart of travel. The control device for an electric trolley according to claim 3, further comprising pre-travel preparation operation means for returning the direction of the trolley.

6. After the restart of travel, until the trolley travels a predetermined distance, the rotational speed of one of the left wheel and the right wheel provided on the side opposite to the turning direction of the trolley when the direction of the trolley is returned by the pre-travel preparation operation means is increased more than the rotational speed of the other wheel. The control device for an electric trolley according to claim 5, further comprising rocking suppression means.

7. The electric trolley control device further comprises an external sensor configured to be able to detect the situation around the vehicle. When the first switching stop means stops the trolley during the traveling direction switching, if the external sensor detects an obstacle on at least one of the left and right sides of the vehicle, the first switching stop means inclines the direction of the trolley in the direction in which the free wheel separates from the obstacle closest to the trolley. The control device for an electric trolley according to claim 2.

8. The electric trolley control device further comprises an external sensor configured to be able to detect the situation around the vehicle. When the first switching stop means stops the trolley during the traveling direction switching, if the external sensor detects an obstacle on either the left or right side of the trolley, the first switching stop means inclines the direction of the trolley in the direction in which the free wheel separates from the obstacle. if the external sensor detects obstacles on both the left and right sides of the trolley, the first switching stop means prohibits the operation of inclining the direction of the trolley. The control device for an electric trolley according to claim 2.

9. The electric trolley control device further comprises a traveling route storage means for storing the preset traveling route of the trolley, and a traveling control means for automatically controlling the electric motor so that the trolley travels along the traveling route stored in the traveling route storage means. The control device for an electric trolley according to any one of claims 1 to 8.

10. A control device for an electric trolley having a free wheel on one of the front wheels and the rear wheels and configured to be able to transmit the power of an electric motor to the driving wheel which is the other of the front wheels and the rear wheels, a switching determination means for determining whether or not the rotation direction of the driving wheel when restarting traveling after the trolley has stopped traveling is at the time of traveling direction switching which is opposite to that before the traveling stop, and a second switching stop means for stopping the trolley in a state where the wheel center line connecting the contact point of the free wheel and the steering axis in the plan view of the trolley is inclined with respect to the center line in the front-rear direction of the trolley when the switching determination means determines that it is at the time of traveling direction switching. The control device for an electric trolley.

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