Follow-me type self-propelled vehicle

Abstract

The system can detect the target even when the distance to the target is short. [Solution] A self-propelled transport vehicle 1 that travels in pursuit of a target T, comprising: a vehicle body 11; a pair of distance sensors 17 and 18 disposed on the vehicle body 11, each having a non-detection distance; a position determination unit that determines the position of the target T based on the detection results of the pair of distance sensors 17 and 18; and a travel control unit that performs travel control based on the determined position of the target T, wherein the pair of distance sensors 17 and 18 are disposed at a distance of more than twice the non-detection distance and are arranged at an inward inclination relative to each other.

Description

Technical Field

[0001] The present invention relates to a following type self-propelled vehicle.

Background Art

[0002] Conventionally, as a following type self-propelled vehicle, there is one that detects a following target by a pair of left and right ultrasonic sensors (see Patent Document 1). This following type self-propelled vehicle (following type traveling work vehicle) includes a following target detection means for detecting a following target by a pair of left and right ultrasonic sensors, and a traveling control means for controlling traveling based on the detection result from the following target detection means. In this following type self-propelled vehicle, by using a pair of left and right ultrasonic sensors for detecting a following target, the position of the following target can be detected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional following type self-propelled vehicle, there is a problem that when the distance to the following target is too close, the following target cannot be detected.

[0005] Therefore, an object of the present invention is to provide a following type self-propelled vehicle that can detect a following target even when the distance to the following target is close.

Means for Solving the Problems

[0006] To achieve the above objective, the present invention provides a self-propelled vehicle that follows a target, comprising: a vehicle body; a pair of distance sensors disposed on the vehicle body, each having a non-detection distance; a position determination unit that determines the position of the target based on the detection results from the pair of distance sensors; and a driving control unit that performs driving control based on the determined position of the target, wherein the pair of distance sensors are disposed at a distance of at least twice the non-detection distance and are arranged at an inward inclination relative to each other.

[0007] Furthermore, in order to achieve the above objective, the present invention provides a self-propelled vehicle that follows a target, comprising: a vehicle body; a pair of distance sensors disposed on the vehicle body, each having an undetectable distance; a position determination unit that determines the position of the target based on the detection results from the pair of distance sensors; and a driving control unit that performs driving control based on the determined position of the target, wherein the pair of distance sensors are disposed at both left and right ends of the vehicle body and are arranged at an inclination toward each other. [Effects of the Invention]

[0008] The self-propelled vehicle that follows a target according to the present invention can detect the target even when the distance to the target is short. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing a self-propelled transport vehicle according to one embodiment of the present invention. [Figure 2] These are a plan view and a side view of a self-propelled transport vehicle. [Figure 3] This is a control block diagram showing the control configuration of a self-propelled transport vehicle. [Figure 4] This is an explanatory diagram showing the required detection range and the layout of a pair of distance sensors. [Figure 5] This is a flowchart illustrating the follow-me driving operation of a self-propelled transport vehicle. [Modes for carrying out the invention]

[0010] The following describes an autonomous transport vehicle using a follow-type autonomous vehicle according to one embodiment of the present invention, with reference to the attached drawings. This autonomous transport vehicle detects the position of the object to be followed using a pair of distance sensors and travels by following (tracking) the object. In particular, this autonomous transport vehicle is designed so that the position of the object to be followed can be detected even when the distance to the object is short, by adjusting the layout of the pair of distance sensors. In this embodiment, it is assumed that the autonomous transport vehicle follows a farm worker and transports harvesting containers, supporting the farm worker's harvesting work (for example, harvesting grapes or apples). Furthermore, the left / right, front / back and up / down directions will be defined and explained as shown in each figure.

[0011] (Configuration of the self-propelled transport vehicle) As shown in Figures 1 and 2, the self-propelled transport vehicle 1 comprises a vehicle body 11 consisting of a loading platform 11a and a mechanism housing 11b disposed below the loading platform 11a, a pair of crawlers 12, 12 disposed on the left and right sides of the mechanism housing 11b, a drive mechanism 13 housed in the mechanism housing 11b that drives the pair of crawlers 12, 12, and a control mechanism 14 housed in the mechanism housing 11b that controls the drive mechanism 13.

[0012] Furthermore, the self-propelled transport vehicle 1 is equipped with operation switches 15, 15 and indicator lights 16 located at the front upper end of the cargo bed 11a, and a pair of (two) distance sensors 17, 18 located in front of the cargo bed 11a for detecting the target vehicle T to be followed. The self-propelled transport vehicle 1 is an example of a follow-type self-propelled vehicle. In this embodiment, the pair of distance sensors 17, 18 and the control mechanism 14 constitute a position detection means for detecting the position of the target vehicle T to be followed.

[0013] The vehicle body 11 is composed of a cargo bed 11a for loading cargo and a mechanism housing 11b located below the cargo bed 11a, which has a smaller lateral dimension than the cargo bed 11a. The lateral dimension of the cargo bed 11a is approximately 70 cm, and as a result, the lateral dimension of the vehicle body 11 and the self-propelled transport vehicle 1 is approximately 70 cm. In this embodiment, the lateral dimension of the vehicle body 11 and the self-propelled transport vehicle 1 is more than twice the undetectable distance of the distance sensors 17 and 18.

[0014] The cargo bed 11a is formed in a cage shape as a whole and has a grid-like floor frame 21 on which cargo is placed, frame frames 22, 22, 22 erected upward from the left, right and rear ends of the floor frame 21, and a plate-shaped front plate 23 erected upward from the front end of the floor frame 21. Operation switches 15, 15, indicator lights 16, and a pair of distance sensors 17, 18 are arranged on the front plate 23.

[0015] Each crawler 12, 12 is equipped with a drive wheel 31 (sprocket wheel) and a plurality of wheels 32, and a crawler belt 33 stretched over the drive wheel 31 and the plurality of wheels 32. By rotating the drive wheel 31, the crawler belt 33 moves, causing the self-propelled transport vehicle 1 to move.

[0016] As shown in Figure 3, the drive mechanism 13 has a pair of motors 41 and 42 that drive each drive wheel 31 of a pair of crawlers 12, 12 via a drive shaft (not shown). Each motor 41 and 42 is configured to be able to rotate independently in both forward and reverse directions, and by rotating each drive wheel 31 with each motor 41 and 42, each crawler 12, 12 can be individually driven forward / backward.

[0017] As shown in FIGS. 1 and 2, a pair of distance sensors 17 and 18 are distance detection devices for detecting the distance from a following target T, respectively, and are disposed at both left and right ends of the front plate 23 and at both left and right ends of the front end of the vehicle body 11. Further, the pair of distance sensors 17 and 18 are transmission-reception integrated ultrasonic distance sensors that transmit ultrasonic waves and receive reflected waves reflected from the following target T, respectively. For example, the half-angle is 80°, and it has a non-detection distance (non-detection range) of 30 cm in the vicinity. And the layout of each of the distance sensors 17 and 18 is set in consideration of a required detection range E1 (see FIG. 4) required to detect the position of the following target T. Here, referring to FIG. 4, the required detection range E1 and the layout of each of the distance sensors 17 and 18 with respect thereto will be described.

[0018] (Required Detection Range and Layout of a Pair of Distance Sensors) As shown in FIG. 4, the required detection range E1 of the self-propelled transport vehicle 1 is, for example, in the left-right direction, a range of 70 cm in length from the position of the right end of the vehicle body 11 to the position of the left end, and in the front-back direction, a range of 20 cm or more and 200 cm or less from the front end of the vehicle body 11. That is, in order to perform following travel with respect to the following target T located in front of the vehicle body 11, it is required to be able to detect the position in the front range of the vehicle body 11. Since it is necessary to approach and stop up to the range where the human hand of the following target T can reach, it is required that the vehicle body 11 (self-propelled transport vehicle 1) can detect the position up to a position closer than the non-detection distance of the distance sensors 17 and 18.

[0019] On the other hand, the pair of distance sensors 17 and 18 are disposed at both left and right ends of the vehicle body 11. As a result, the separation distance (center-to-center distance) of the pair of distance sensors 17 and 18 is 70 cm, and each of the distance sensors 17 and 18 is located at both left and right ends of the required detection range E1. Further, the pair of distance sensors 17 and 18 are inclined inwardly with respect to each other by 40° in the horizontal direction. That is, the right distance sensor 17 is disposed by being inclined 40° to the left from the state facing the front, and the left distance sensor 18 is disposed by being inclined 40° to the right from the state facing the front.

[0020] With these layouts, as shown in FIG. 4, the portion where the detectable ranges E2 and E3 of the respective distance sensors 17 and 18 overlap becomes the position detectable range E4. In this case, the widest possible range in the required detection range E1 can be made the position detectable range E4. That is, by arranging the pair of distance sensors 17 and 18 to tilt inward in relation to each other by an angle that is half of the half-angle, the front range of the vehicle body 11 can be made the wide position detectable range E4. Also, by arranging the pair of distance sensors 17 and 18 at a distance of more than twice the non-detection distance of the distance sensors 17 and 18 and tilting them inward in relation to each other, the center portion in the left-right direction within a range closer than the non-detection distance of the distance sensors 17 and 18 can be made the position detectable range E4.

[0021] (Control Configuration of Self-Propelled Transport Vehicle) Next, referring to FIG. 3, the control configuration of the self-propelled transport vehicle 1 will be described. As shown in FIG. 3, the control mechanism 14 includes a pair of motor drivers 51 and 52 that control a pair of motors 41 and 42, and a control unit 53 that connects the motor drivers 51 and 52.

[0022] The control unit 53 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash ROM, etc. It receives operation signals and detection results from the operation switches 15, 15 and the distance sensors 17, 18, and controls the drive mechanism 13, the indicator lights 16, and the distance sensors 17, 18. Also, by executing a predetermined program, the control unit 53 functions as a distance acquisition unit 61, a position determination unit 62, and a travel control unit 63.

[0023] The distance acquisition unit 61 operates each distance sensor 17, 18 to receive detection results from each distance sensor 17, 18, and acquires distance information from each distance sensor 17, 18 to the tracking target T based on these detection results. Specifically, it receives the ultrasonic transmission time (transmission timing) and reflected wave reception time (reception timing) as detection results from each distance sensor 17, 18, and calculates the distance from each distance sensor 17, 18 to the tracking target T from the received transmission time, reception time and ultrasonic velocity.

[0024] The position determination unit 62 determines the position information of the target object T based on the distance information from each distance sensor 17, 18 to the target object T and the information on the placement positions of each distance sensor 17, 18. That is, the position of the target object T (position in the left, right, front, and rear directions) is calculated using trigonometry from the distance information from each distance sensor 17, 18 to the target object T, the placement positions of each distance sensor 17, 18, and the distance between the centers of the pair of distance sensors 17, 18 (the above-mentioned separation distance). In this embodiment, the position of the target object T is detected by the pair of distance sensors 17, 18, the distance acquisition unit 61, and the position determination unit 62.

[0025] The driving control unit 63 determines a target movement position based on the position information of the target vehicle T, and controls the driving of the self-propelled transport vehicle 1 based on the target movement position. Specifically, the driving control unit 63 first determines the tracking distance based on the speed of the target vehicle T, and then determines the target movement position to be a position shifted by the determined tracking distance backward from the position of the target vehicle T in the direction of travel. Once the target movement position is determined, the driving control unit 63 controls each motor 41, 42 via each motor driver 51, 52 to drive each crawler 12 so that the center of the front end of the vehicle body 11 is at the target movement position. The speed of the target vehicle T is calculated, for example, based on the current position information and past position information of the target vehicle T that have been determined.

[0026] (Explanation of follow-me driving operation) Next, with reference to Figure 5, the follow-me driving operation of the self-propelled transport vehicle 1 will be explained. This follow-me driving operation is performed at predetermined intervals (every 0.1 seconds), and by continuously performing the follow-me driving operation at predetermined intervals, follow-me driving towards the target vehicle T is achieved.

[0027] As shown in Figure 5, in follow-me driving operation, first, the distance acquisition unit 61 activates each distance sensor 17 and 18 (S1), and receives detection results (transmission time and reception time) from each distance sensor 17 and 18 (S2). After receiving detection results from each distance sensor 17 and 18, distance information from each distance sensor 17 and 18 to the target T to be followed is calculated based on the received detection results (S3). That is, the distance from each distance sensor 17 and 18 to the target T to be followed is calculated from the received transmission time, reception time and ultrasonic speed.

[0028] Once the distance information from each distance sensor 17, 18 to the tracked target T is calculated, the position determination unit 62 determines the position information of the tracked target T based on the calculated distance information and the information on the placement positions of each distance sensor 17, 18 (S4). That is, the position of the tracked target T (position in the left, right, front, and back directions) is calculated using trigonometry from the distance information from each distance sensor 17, 18 to the tracked target T, the placement positions of each distance sensor 17, 18, and the distance between the centers of the pair of distance sensors 17, 18.

[0029] Once the position information of the target vehicle T is determined, the driving control unit 63 determines the target movement position based on the determined position information of the target vehicle T (S5). That is, it calculates the speed of the target vehicle T and determines the tracking distance based on the speed of the target vehicle T. Then, the target movement position is determined to be a position shifted by the determined tracking distance backward from the position of the target vehicle T in the direction of travel.

[0030] Once the target movement position is determined, the driving control unit 63 controls each motor 41 and 42 via each motor driver 51 and 52 so that the front center position of the vehicle body 11 is at the target movement position, and drives each crawler 12 to move (S6). This causes the self-propelled transport vehicle 1 to move in accordance with the target T.

[0031] (Effects and Effects of the Embodiment) As described above, according to the configuration of the embodiment, by arranging the pair of distance sensors 17 and 18 at a distance of more than twice the undetectable distance (more than the sum of the undetectable distances of the pair of distance sensors 17 and 18) and arranging them at an inward inclination relative to each other, as shown in Figure 4, the range of the half-angle of the pair of distance sensors 17 and 18 can be brought closer to the vehicle body 11, while the intermediate position of the pair of distance sensors 17 and 18 can be excluded from the undetectable distance of each distance sensor 17 and 18. This makes it possible to make the central part of the range of the self-propelled transport vehicle 1 that is closer than the undetectable distance of the distance sensors 17 and 18 a wide position detection range E4. Therefore, even when the distance between the self-propelled transport vehicle 1 and the target vehicle T is short, the position of the target vehicle T can be detected. As a result, the self-propelled transport vehicle 1 can follow the target vehicle T as closely as possible, for example, it can follow the target vehicle T until it is within reach of a person's hand, and can stop when it is within reach of a person's hand. Furthermore, since the position of a nearby tracking target T can be detected without changing to a distance sensor with a wider detectable range E2 and E3, or by adding distance sensors, the position of a nearby tracking target T can be detected with a simple configuration.

[0032] Furthermore, by arranging the pair of distance sensors 17 and 18 at both the left and right ends of the vehicle body 11, the pair of distance sensors 17 and 18 can be spaced as far apart as possible, making the range closer to the undetectable distance of the distance sensors 17 and 18 in the self-propelled transport vehicle 1 a wider range of position detection range E4.

[0033] Furthermore, by arranging the pair of distance sensors 17 and 18 at an angle of half the half-angle inward relative to each other, the forward range of the vehicle body 11 can be widened to create a position-detectable range E4. This makes it possible to maximize the position-detectable range E4 within the required detection range E1. In addition, since areas other than the forward range of the vehicle body 11 can be excluded from the position-detectable range E4 as much as possible, the generation of noise (detection of objects other than the target T being tracked) can be suppressed.

[0034] (Regarding other embodiments) Although embodiments of the present invention have been described above, these embodiments do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. The present invention can be implemented with appropriate modifications without departing from its spirit.

[0035] For example, in the above embodiment, the pair of distance sensors 17 and 18 were arranged at both the left and right ends of the vehicle body 11, but this is not limited to this configuration as long as the pair of distance sensors 17 and 18 are arranged at a distance of at least twice the non-detection distance. In other words, one or both of the pair of distance sensors 17 and 18 may be arranged with a lateral displacement from the left and right ends of the vehicle body 11.

[0036] Furthermore, in the above embodiment, the left-right dimension of the vehicle body 11 (cargo bed 11a) was set to approximately 70 cm, and the distance between the pair of distance sensors 17 and 18 (center-to-center distance) was set to 70 cm. However, the configuration is not limited to the left-right dimension of the vehicle body 11 being the same as the distance between the pair of distance sensors 17 and 18. For example, as shown in Figure 4, the left-right dimension of the vehicle body 11 may be greater than the distance between the pair of distance sensors 17 and 18, or the left-right dimension of the vehicle body 11 may be smaller than the distance between the pair of distance sensors 17 and 18.

[0037] Furthermore, in the above embodiment, the right distance sensor 17 was positioned tilted 40° to the left, and the left distance sensor 18 was positioned tilted 40° to the right. However, the tilt angle of the pair of distance sensors 17 and 18 (the tilt angle relative to the state facing directly forward) is not limited to half of the half-angle of the distance sensors 17 and 18, but may be greater than or less than half of the half-angle. However, if the vehicle body 11 enters the position detection range E4, it will become noise in the position detection of the target T being followed. Therefore, it is preferable to set the tilt angle of the pair of distance sensors 17 and 18 to be less than or equal to the value obtained by subtracting half of the half-angle from 90° so that the vehicle body 11 does not enter the position detection range E4.

[0038] Furthermore, the configuration is not limited to having the same tilt angle for the pair of distance sensors 17 and 18; the pair of distance sensors 17 and 18 may be arranged tilted at different angles to each other.

[0039] Furthermore, although the above embodiment included only two distance sensors 17 and 18, the system is not limited to this configuration. In other words, it may also include one or more distance sensors in addition to the pair of distance sensors 17 and 18, for a total of three or more distance sensors 17 and 18.

[0040] Furthermore, in the above embodiment, the distance sensors 17 and 18 were configured to be integrated transmitting and receiving ultrasonic sensors, but the system is not limited to this, as long as the distance sensor has a non-detection range. For example, the distance sensors 17 and 18 may be configured to be optical distance sensors (LiDAR) such as infrared sensors, or electromagnetic wave sensors that utilize electromagnetic waves such as millimeter waves.

[0041] Furthermore, while the above embodiment illustrates the self-propelled transport vehicle 1 following a farm worker to support harvesting work, it is not limited to this. For example, the self-propelled transport vehicle 1 may be configured to follow a golf player while transporting golf bags, etc., to support movement within a golf course. Alternatively, for example, the self-propelled transport vehicle 1 may be configured to follow a factory worker to support pickup work in a factory.

[0042] Furthermore, although the present invention was applied to a self-propelled transport vehicle 1 capable of transporting cargo in the above embodiment, it is not limited to this. In other words, the present invention may also be applied to a follow-type self-propelled vehicle that does not have the function of transporting cargo. [Explanation of Symbols]

[0043] 1: Self-propelled transport vehicle, 11: Vehicle body, 17, 18: Distance sensors, 62: Position determination unit, 63: Driving control unit, T: Target to follow

Claims

1. A self-propelled vehicle that follows a target vehicle, The car body and, A pair of distance sensors, each having a non-detection distance, are arranged on the vehicle body, A position determination unit determines the position of the target to be tracked based on the detection results from the pair of distance sensors, The system includes a driving control unit that performs driving control based on the determined position of the target to be followed, The following type self-propelled vehicle is characterized in that the pair of distance sensors are arranged at a distance of more than twice the non-detection distance and are arranged at an inward angle relative to each other.

2. The self-propelled vehicle following the lead of vehicle 1, characterized in that the pair of distance sensors are arranged at an angle of half the angle of half-angle, tilting inward from each other.

3. A self-propelled vehicle that follows a target vehicle, The car body and, A pair of distance sensors, each having a non-detection distance, are arranged on the vehicle body, A position determination unit determines the position of the target to be tracked based on the detection results from the pair of distance sensors, The system includes a driving control unit that performs driving control based on the determined position of the target to be followed, The following-type self-propelled vehicle is characterized in that the pair of distance sensors are arranged at both left and right ends of the vehicle body and are arranged at an inward angle relative to each other.

4. The self-propelled vehicle that follows vehicles according to claim 3, characterized in that the left-right dimension of the vehicle body is at least twice the undetectable distance.

5. The self-propelled vehicle following the lead of vehicle 3, characterized in that the pair of distance sensors are arranged at an angle of half the angle of half-angle, tilting inward from each other.

6. The following type self-propelled vehicle according to any one of claims 1 to 5, characterized in that the distance sensor is an integrated transmit / receive distance sensor.

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