Vehicle system and control method

Abstract

To provide a control method for preventing cargo collapse and damage to goods transported by tracked vehicles. [Solution] In a control method for a tracked vehicle 2 traveling on a path 5 on which magnetic tape 51 is laid, the magnetic intensity measured by the magnetic sensor array 4F·R provided by the tracked vehicle 2 is processed to detect a lifting state in which either the front or rear side of the tracked vehicle 2 leaves the road surface. Upon detection of the lifting state, mitigation control is performed to mitigate the impact that may occur when the lifting state is resolved.

Description

Technical Field

[0001] The present invention relates to a vehicle system and a control method for automatically driving an endless track vehicle (crawler vehicle) equipped with crawlers.

Background Art

[0002] Conventionally, as a system for automating logistics within facilities such as factories and warehouses, a system in which a magnetic tape is laid along a route is known. In this system, a transport vehicle travels while detecting the magnetic tape so as to follow the magnetic tape (see, for example, Patent Document 1).

[0003] In recent years, there have been attempts to apply vehicles for autonomous driving introduced in factories and warehouses to agricultural lands such as construction sites and orchards. For example, a crawler vehicle can also handle uneven ground such as construction sites and orchards. If autonomous driving of vehicles can be realized in agricultural lands such as construction sites and orchards, the burden on workers engaged in on-site work can be reduced, and work efficiency can be improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the system of crawler vehicles has the following problems. While crawler vehicles can travel on a route with unevenness such as bumps and steps, an impact occurs when crossing a step or the like, which may cause troubles such as vehicle malfunctions, collapse or damage of the loaded goods.

[0006] This invention has been made in view of the aforementioned conventional problems, and aims to provide a system and control method for preventing cargo collapse and damage to goods transported by crawler vehicles. [Means for solving the problem]

[0007] One aspect of the present invention is a vehicle system in which a tracked vehicle travels along a path laid out of magnetic components that exert a magnetic force around it, One or more magnetic measuring circuits attached to the tracked vehicle to measure the magnetic intensity acting from the aforementioned magnetic components, A detection circuit for detecting when either the front or rear side of the tracked vehicle lifts off the road surface, The system comprises a control circuit for controlling the movement of the tracked vehicle, The detection circuit detects the levitation state by processing the magnetic intensity measured by at least one of the one or more magnetic measurement circuits. The vehicle system is configured such that, upon detection of the lifted state by the detection circuit, the control circuit performs mitigation control to mitigate the impact that may occur when the original lifted state is resolved as a result of transitioning to a new lifted state in which either the front or rear side leaves the road surface, or when the original lifted state is resolved as a result of transitioning to a state in which both the front and rear sides are in contact with the road surface.

[0008] One aspect of the present invention is a control method for a tracked vehicle that travels along a path on which magnetic components that exert a magnetic force on the surroundings are laid, The aforementioned tracked vehicle is equipped with one or more magnetic measuring circuits to detect the magnetic components and measure the magnetic intensity acting from the magnetic components. By processing the magnetic intensity measured by at least one of the one or two or more magnetic measurement circuits mentioned above, a lifting state in which either the front or rear side of the tracked vehicle is separated from the road surface is detected. The control method involves detecting the lifted state and then executing mitigation control to reduce the impact that may occur when either the front or rear side leaves the road surface, resulting in the elimination of the original lifted state, or when both the front and rear sides come into contact with the road surface. [Effects of the Invention]

[0009] This invention relates to a tracked vehicle that automatically travels using magnetic components laid along a path. The tracked vehicle according to this invention is equipped with one or more magnetic measurement circuits that measure the magnetic intensity acting from the magnetic components. In this invention, the levitation state of the tracked vehicle is detected by processing the magnetic intensity measured by at least one of the magnetic measurement circuits. When the levitation state is detected, mitigation control is performed to mitigate the impact that may occur as the levitation state is resolved.

[0010] According to the vehicle system and control method of the present invention, when a lift-up state occurs in which either the front or rear side of a tracked vehicle leaves the road surface, the impact associated with the resolution of the lift-up state can be mitigated. Therefore, the present invention reduces the likelihood of any problems occurring due to the lift-up state. [Brief explanation of the drawing]

[0011] [Figure 1] An explanatory diagram of the route the vehicle travels in Example 1. [Figure 2] A perspective view of the vehicle (tracked vehicle) that carries the transport box in Example 1. [Figure 3] A block diagram showing the configuration of the vehicle in Example 1. [Figure 4] A block diagram showing the configuration of the vehicle's driving control system in Example 1. [Figure 5] A block diagram showing the configuration of the magnetic sensor array in Example 1. [Figure 6] An explanatory diagram showing how a vehicle travels along a magnetic tape in Example 1. [Figure 7] A graph showing an approximate curve of the magnetic intensity distribution represented by the magnetic measurement values ​​of magnetic sensors A1 to A12 in Example 1. [Figure 8] An explanatory diagram showing how the vehicle crosses the ridge in Example 1. [Figure 9] This graph shows the changes in the magnetic intensity (maximum value) measured by the front magnetic sensor array, the changes in the magnetic intensity (maximum value) measured by the rear magnetic sensor array, and the changes in the magnetic intensity difference, which is the difference between the magnetic intensity (maximum value) measured by the front magnetic sensor array and the magnetic intensity (maximum value) measured by the rear magnetic sensor array, when the vehicle crosses a ridge in Example 1. [Figure 10] An explanatory diagram showing how a vehicle crosses a valley in Example 1. [Figure 11] This graph shows the changes in the magnetic intensity (maximum value) measured by the front magnetic sensor array, the changes in the magnetic intensity (maximum value) measured by the rear magnetic sensor array, and the changes in the magnetic intensity difference, which is the difference between the magnetic intensity (maximum value) measured by the front magnetic sensor array and the magnetic intensity (maximum value) measured by the rear magnetic sensor array, when the vehicle crosses a valley in Example 1. [Figure 12] An explanatory diagram showing how the vehicle drives onto a step in Example 1. [Figure 13] This graph shows the changes in the magnetic intensity (maximum value) measured by the front magnetic sensor array, the changes in the magnetic intensity (maximum value) measured by the rear magnetic sensor array, and the changes in the magnetic intensity difference, which is the difference between the magnetic intensity (maximum value) measured by the front magnetic sensor array and the magnetic intensity (maximum value) measured by the rear magnetic sensor array, when the vehicle drives over a step in Example 1. [Figure 14] An explanatory diagram showing how a vehicle descends a step in Example 1. [Figure 15]In Example 1, a graph showing the change in magnetic intensity (maximum value) measured by the front magnetic sensor array, the change in magnetic intensity (maximum value) measured by the rear magnetic sensor array, and the change in magnetic intensity difference, which is the difference between the magnetic intensity (maximum value) measured by the front magnetic sensor array and the magnetic intensity (maximum value) measured by the rear magnetic sensor array, when the vehicle descends a step. [Figure 16] In Example 1, a flowchart showing the control flow of a crawler vehicle. [Figure 17] In Example 1, a graph showing the lifting period and the leaving period during which relaxation control is applied when crossing a ridge. [Figure 18] In Example 1, a graph showing that no lifting period and leaving period during which relaxation control is applied are set when crossing a valley. [Figure 19] In Example 1, a graph showing the lifting period and the leaving period during which relaxation control is applied when climbing onto a step. [Figure 20] In Example 1, a graph showing the lifting period and the leaving period during which relaxation control is applied when descending a step. [Figure 21] In Example 1, a flowchart showing the flow of other control of a crawler vehicle.

Mode for Carrying Out the Invention

[0012] The magnetic component in the present invention may be any component that acts on the surrounding magnetic field. For example, a magnetic component made of a permanent magnet can be considered. Examples of magnetic components include a continuous strip-shaped magnetic tape laid along a path and fragmented magnetic markers arranged along a path.

[0013] Embodiments of the present invention will be specifically described below using the following examples. (Example 1) This example relates to a vehicle system that automatically drives a crawler vehicle (an endless track vehicle) using a magnetic tape laid along a path, and one of the technical features is in the control method of the crawler vehicle. This content will be described using FIGS. 1 to 21.

[0014] This example shows a route 5 (Figure 1) set in an environment with uneven terrain and steps, such as a construction site or orchard. This route 5 is difficult to travel on with a four-wheeled vehicle. Therefore, in this example, a crawler-type vehicle 2 (hereinafter referred to as vehicle 2) equipped with crawlers (caterpillars(R)) is used to travel on route 5.

[0015] Vehicle 2 automatically travels along the route 5 while detecting the magnetic tape 51 laid out along the route 5. The magnetic tape 51 is an example of a magnetic component that exerts magnetism on its surroundings, with one side of its surface being the north pole and the other being the south pole. In this example, the magnetic tape 51 is laid so that the top surface (front side) is the north pole and the bottom surface (back side) is the south pole.

[0016] Vehicle 2 (Figures 1-3) is equipped with annular rubber belts, called crawlers 21L and R, on both sides of the vehicle body 2B. Vehicle 2 measures 1 m in length and 1.2 m in width. Vehicle body 2B measures 0.8 m in length and 0.7 m in width. The top surface of vehicle body 2B forms a loading platform on which a transport box 200 or the like can be placed. Rod-shaped magnetic sensor arrays 4F and R are mounted on the front and rear of vehicle body 2B, respectively, along the vehicle width direction (lateral direction). The vehicle system 1 in this example is a system comprising magnetic sensor arrays 4F and R positioned at intervals in the longitudinal direction of vehicle 2, a detection circuit 30 for detecting the lifting state of vehicle 2, and a control circuit 20 for controlling the movement of vehicle 2.

[0017] The vehicle 2's driving control system is electrically configured around a control circuit 20 (Figures 3 and 4). The control circuit 20 is electrically connected to a left motor 24L that rotates the left crawler 21L, a right motor 24R that rotates the right crawler 21R, a speed sensor 26L that measures the driving speed of the left crawler 21L, a speed sensor 26R that measures the driving speed of the right crawler 21R, and a detection circuit 30. The front magnetic sensor array 4F and the rear magnetic sensor array 4R are electrically connected to the control circuit 20 via the detection circuit 30. In Figure 3, the motors 24 and speed sensors 26 are not shown.

[0018] Vehicle 2 can change the orientation of its body 2B (vehicle orientation, yaw angle) according to the difference in the driving speed of the left and right crawlers 21L and R. By setting a difference in driving speed while driving the left and right crawlers 21L and R in the same direction, vehicle 2 can be made to travel along an arc-shaped trajectory. By driving the left and right crawlers 21L and R in opposite directions, a spin turn is also possible, which changes the orientation of the body 2B without changing its position.

[0019] The control circuit 20 (Figure 4) is composed of a CPU that performs various calculations, memory elements such as ROM and RAM, etc. The control circuit 20 is equipped with an I / O circuit that performs communication with external circuits. The control circuit 20 communicates with external circuits such as the detection circuit 30, motor 24, and speed sensor 26 via the I / O circuit.

[0020] The control circuit 20 acquires the detection processing results of the magnetic tape 51 from both the front magnetic sensor array 4F and the rear magnetic sensor array 4R. The detection processing results acquired by the control circuit 20 via the detection circuit 30 include the lateral deviation of the vehicle 2 relative to the magnetic tape 51.

[0021] The control circuit 20 identifies the longitudinal orientation deviation of the vehicle 2 relative to the longitudinal direction of the magnetic tape 51 based on a comparison of the lateral deviation measured by the front magnetic sensor array 4F and the lateral deviation measured by the rear magnetic sensor array 4R. The control circuit 20 controls the orientation of the vehicle 2 (vehicle orientation) to bring the lateral deviation measured by the front magnetic sensor array 4F closer to a predetermined value such as zero, and to eliminate the above-mentioned orientation deviation. Through this control by the control circuit 20, automatic driving of the vehicle 2 along the magnetic tape 51 is realized.

[0022] The magnetic sensor array 4 (Figure 5) is an example of a magnetic measurement circuit mounted on the underside of the vehicle 2 to measure the magnetic intensity acting from the magnetic tape 51. The magnetic sensor array 4 includes a signal acquisition unit 41 that acquires magnetic measurement values ​​from 12 magnetic sensors An (where n is an integer from 1 to 12), a detection processing unit 43 that incorporates a CPU (not shown), and an output unit 45 that outputs the detection processing results. The front magnetic sensor array 4F and the rear magnetic sensor array 4R have the same specifications and will be described as magnetic sensor array 4 as appropriate.

[0023] The magnetic sensor array 4 is rod-shaped, with 12 magnetic sensors An arranged along its longitudinal direction at 5 cm intervals. In this example, the magnetic sensors An employ the known MI effect (Magneto Impedance Effect) to detect magnetism. The direction of magnetic force measured by each magnetic sensor An is the same. The magnetic sensor array 4 is mounted on the vehicle 2 so that it can measure the magnetic intensity acting in the vertical direction.

[0024] The detection processing unit 43 (Figure 5) of the magnetic sensor array 4 is an arithmetic circuit that performs detection processing to detect the magnetic tape 51. The detection processing unit 43 is composed of a CPU that performs various calculations, memory elements such as ROM and RAM, etc., although it is not shown in the figure. The detection processing unit 43 acquires 12 magnetic measurement values ​​from the magnetic sensor An at a frequency of 3 kHz and performs detection processing.

[0025] The crawler-type (continuous track) vehicle 2 has a running characteristic in which the gap between the vehicle body 2B and the road surface does not fluctuate significantly. Therefore, when running on a flat road surface, the distance between the road surface and the magnetic sensor array 4F·R does not deviate significantly from the design specification value of the sensor mounting height. In normal running conditions where no lift-up occurs, the maximum value of the magnetic intensity measured by the magnetic sensor array 4F·R (hereinafter referred to as the magnetic intensity measured by the magnetic sensor array 4F·R) is almost constant. In addition, in normal running conditions, the magnetic intensity measured by the front magnetic sensor array 4F and the magnetic intensity measured by the rear magnetic sensor array 4R at the same measurement point are almost equal, so the difference in magnetic intensity between the front and rear is almost zero.

[0026] For example, when the vehicle 2 is automatically driven using the magnetic tape 51 as shown in Figure 6, the 12 magnetic measurements (magnetic intensity acting in the vertical direction) from the magnetic sensor An form a magnetic intensity distribution in the vehicle width direction, as illustrated by the approximate curve in Figure 7. As described above, since the front surface of the magnetic tape 51 is the north pole, a peak in magnetic intensity appears at a position directly above the magnetic tape 51.

[0027] The detection processing unit 43 (Figure 5) detects the magnetic tape 51 by detecting the peak in the distribution of magnetic intensity in the vehicle width direction, as illustrated in Figure 7. The detection processing unit 43 identifies the position of this peak in the vehicle width direction as the position directly above the magnetic tape 51. The detection processing unit 43 then identifies the lateral deviation of the vehicle 2 relative to the magnetic tape 51. The detection processing unit 43 outputs the detection processing result to an external source via the output unit 45.

[0028] The detection processing results of the detection processing unit 43 include a statement that the magnetic tape 51 was detected, the lateral deviation of the vehicle 2 relative to the magnetic tape 51, and the maximum value of the magnetic intensity. The maximum value of the magnetic intensity is the peak of the approximation curve in Figure 7, which represents the distribution of magnetic intensity in the vehicle width direction. The detection processing results are input to the detection circuit 30. The lateral deviation from the detection processing results is input to the control circuit 20 via the detection circuit 30 and used for driving control as described above.

[0029] The detection circuit 30 uses the detection processing results of the magnetic sensor array 4F·R to detect when the front or rear of the vehicle 2 is lifted off the road surface. There are two types of lifted states: when the front of the vehicle 2 is lifted off the road surface, and when the rear of the vehicle 2 is lifted off the road surface. As will be described in more detail later, the detection circuit 30 in this example detects the lifted state of the vehicle 2 without distinguishing between whether the lifted state is at the front or the rear.

[0030] As described above, Route 5 in this example includes steps and undulations that are difficult for four-wheeled vehicles to traverse. When crawler-type vehicle 2 travels, for example, when it goes over a step or crosses a ridge, one of the front or rear sides of vehicle 2 lifts off the road surface. This behavior of crawler-type vehicles is unique and differs from the behavior of four-wheeled vehicles.

[0031] The lifted state of the front of vehicle 2 is resolved as the lifted state of the rear of vehicle 2 transitions due to the effects of gravity, such as the front-to-rear weight balance of vehicle 2. The lifted state of the rear of vehicle 2 is resolved, for example, when vehicle 2 passes over an uneven surface. When the lifted state is resolved, if the front or rear of the lifted crawler 21 lands forcefully on the road surface, an impact may occur. This impact is undesirable as it may induce problems with vehicle 2 itself or cause the transported goods to shift or be damaged.

[0032] The following describes the behavior of vehicle 2 (Figures 8, 10, 12, and 14) and the changes in the magnetic intensity (maximum value) measured by the magnetic sensor array 4F·R (Figures 9, 11, 13, and 15) for the following cases: (1) crossing a ridge, (2) crossing a valley, (3) going up a step, and (4) going down a step. Note that the magnetic tape 51 (see Figure 6) is not shown in Figures 8, 10, 12, and 14, but these figures show vehicle 2 traveling along the magnetic tape 51.

[0033] (1) When crossing a ridge For example, when vehicle 2 travels over a ridge 501, which is a convex undulation as shown in Figure 8, a lift-up state occurs at the front of the vehicle, followed by a lift-up state at the rear of the vehicle as the front lift-up state is resolved. Figure 8 shows the position and attitude of vehicle 2 between times t11 and t14. Note that times t12 and t13 are approximately the same time, before and after the resolution of the front lift-up state.

[0034] Vehicle 2 approaches the ridge 501 at time t11, and thereafter, until time t12, the front of vehicle 2 is lifted away from the road surface 500. At time t13, this front lift is resolved, and in response, the rear of vehicle 2 also lifts away from the road surface 500. The transition from the front lift to the rear lift can occur as the front-to-rear weight balance of vehicle 2 changes as the vehicle moves forward. At this time, if the front of vehicle 2 lands forcefully on the road surface 500, an impact may occur.

[0035] After the transition to the rear-side lifted state, when vehicle 2 moves forward and passes over the ridge 501, the rear of vehicle 2 lands on the road surface 500 and the rear-side lifted state is resolved (time t14). During the rear-side lifted state from time t13 to time t14, the tilt of vehicle 2 is approximately equal to the slope of the road surface 500 in front. Therefore, there is little risk of an impact occurring when the rear-side lifted state is resolved at time t14.

[0036] When vehicle 2 crosses ridge 501 (Figure 8), the magnetic intensity (maximum value) measured by the magnetic sensor array 4F·R changes as shown in Figure 9, for example. The maximum value of the magnetic intensity is the peak in the distribution of magnetic intensity in the vehicle width direction (see, for example, Figure 7), and is detected by the detection processing unit 43. In the following description, the maximum value of the magnetic intensity measured by the magnetic sensor array 4 is simply referred to as the magnetic intensity measured by the magnetic sensor array 4.

[0037] As shown in Figures 8 and 9, until time t11, when the crawler 21L and R are not lifting and the vehicle 2 is in a normal driving state, the magnetic intensity measured by the front magnetic sensor array 4F and the magnetic intensity measured by the rear magnetic sensor array 4R are approximately equal and relatively large values. In the following explanation, the magnetic intensity detected when the distance between the magnetic sensor array 4 and the road surface 500 is as per the design specifications is referred to as the reference intensity R.

[0038] The magnetic intensity measured by the front magnetic sensor array 4F gradually decreases from time t11 when the front of the vehicle begins to lift, and reaches its minimum at time t12, just before this lifting condition is resolved. When the front of the vehicle is resolved (time t13), the magnetic intensity measured by the front magnetic sensor array 4F returns to the reference intensity R. Thereafter, until the entire vehicle 2 passes the ridge 501 (time t14), the front of the vehicle 2 remains in contact with the road surface 500, and the front magnetic sensor array 4F remains in close proximity to the road surface 500. Therefore, until time t14, the magnetic intensity measured by the front magnetic sensor array 4F is maintained at the reference intensity R.

[0039] As shown in Figures 8 and 9, the magnetic intensity measured by the rear magnetic sensor array 4R is maintained at the reference intensity R from time t11, when the front lift-up state occurs, until time t12, when this lift-up state is maintained. At time t13, when the front lift-up state is resolved, the rear of the vehicle 2 transitions to a lift-up state where it is separated from the road surface 500, and the magnetic intensity measured by the rear magnetic sensor array 4R rapidly decreases to its minimum.

[0040] Subsequently, as vehicle 2 moves forward while its rear end remains lifted, the distance between the rear magnetic sensor array 4R and the road surface 500 gradually decreases, and the magnetic intensity measured by the magnetic sensor array 4R gradually increases. At time t14, when the entire vehicle 2 passes over the ridge 501, the magnetic intensity measured by the rear magnetic sensor array 4R returns to the standard intensity R as the rear end is released. After time t14, vehicle 2 returns to a normal driving state, and the magnetic intensity measured by the rear magnetic sensor array 4R is maintained at the standard intensity R.

[0041] As shown in Figures 8 and 9, the difference in magnetic intensity between the front magnetic sensor array 4F and the rear magnetic sensor array 4R (absolute value; bottom graph in Figure 9; difference in magnetic intensity between front and rear) is kept at zero until time t11 when vehicle 2 approaches the ridge 501. After time t11, the difference in magnetic intensity between front and rear gradually increases until time t12, when the distance between the front magnetic sensor array 4F and the road surface 500 gradually increases.

[0042] During the transition period from the front floating state to the rear floating state, between times t12 and t13, as described above, the magnetic intensity measured by the front magnetic sensor array 4F rapidly increases from its minimum value to the reference intensity R, while the magnetic intensity measured by the rear magnetic sensor array 4R rapidly decreases from the reference intensity R to its minimum value. Between times t12 and t13, the difference in magnetic intensity between the front and rear undergoes a V-shaped change, first rapidly decreasing to near zero, and then rapidly increasing again. Note that in Figure 9, for illustrative purposes, times t12 and t13 are shown to be far more separated than they actually are, but as described above, times t12 and t13 are almost the same time. Therefore, the period during which the difference in magnetic intensity between the front and rear decreases is very short and instantaneous.

[0043] From time t13 onward, vehicle 2 moves forward while its rear end remains lifted, and the magnetic intensity difference decreases as the distance between the rear magnetic sensor array 4R and the road surface 500 gradually decreases. Then, at time t14, when the vehicle returns to its normal driving state, the magnetic intensity difference becomes zero, and from time t14 onward, the magnetic intensity difference is maintained at zero.

[0044] (2) When crossing a valley For example, when vehicle 2 travels across a concave valley 502 as shown in Figure 10, normal driving conditions are maintained until time t15 when vehicle 2 reaches the valley 502. At time t16, the front of vehicle 2 comes into contact with the front slope of the two opposing slopes on either side of the valley, and the rear of vehicle 2 comes into contact with the other slope. At this time, the middle part of vehicle 2 is lifted off the road surface 500, but both the front magnetic sensor array 4F and the rear magnetic sensor array 4R are close to the road surface 500. Subsequently, when vehicle 2 moves forward, at time t17, the entire vehicle 2 passes through the valley 502 and returns to normal driving conditions. When vehicle 2 travels across the valley 502, the front and rear of vehicle 2 do not lift off the ground, and there is little risk of impact.

[0045] As shown in Figures 10 and 11, when vehicle 2 travels across valley 502, both the front magnetic sensor array 4F and the rear magnetic sensor array 4R remain close to the road surface 500, so the measured magnetic intensity remains at the reference intensity R. While vehicle 2 is crossing valley 502, the magnetic intensity difference, which is the difference between the magnetic intensity measured by the front magnetic sensor array 4F and the magnetic intensity measured by the rear magnetic sensor array 4R, is maintained at approximately zero.

[0046] (3) When going over a step For example, when vehicle 2 drives onto a step 505 as shown in Figure 12, at time t21, after vehicle 2 reaches the step 505, the front of the vehicle drives onto the step 505, causing the front to rise and the vehicle 2 to tilt. As the vehicle continues to move forward, the front of the vehicle will lift up. When the center of vehicle 2 passes over the step 505 (time t22), the front of the vehicle 2 lands on the road surface 500 due to the weight balance between the front and rear of the vehicle 2, and the lifted state of the front is resolved (time t23). When the lifted state of the front is resolved in this way, an impact may occur if the front of vehicle 2 lands on the road surface 500 with force.

[0047] When vehicle 2, which has climbed onto step 505, is on the higher step (time t23), the rear of vehicle 2 will be lifted up until the entire vehicle has passed step 505 (time t24). After time t24, when the entire vehicle 2 has passed step 505, it will return to its normal running state.

[0048] As shown in Figure 12, when vehicle 2 drives onto the step 505, the magnetic intensity measured by the magnetic sensor array 4F·R changes as shown in Figure 13. Until time t21, when vehicle 2 is in a normal driving state, the magnetic intensity measured by the front magnetic sensor array 4F and the rear magnetic sensor array 4R are both at the reference intensity R.

[0049] When the front of the vehicle lifts up (time t21), the tilt of the vehicle 2 gradually increases as the vehicle 2 moves forward, and the distance between the front magnetic sensor array 4F and the road surface 500 gradually increases. As a result, the magnetic intensity measured by the front magnetic sensor array 4F gradually decreases, reaching a minimum just before the front lift-up condition is resolved (time t22). When the front lift-up condition is resolved (time t23), the magnetic intensity measured by the front magnetic sensor array 4F returns to the reference intensity R. Thereafter, until the entire vehicle 2 passes over the step 505 (time t24), the front of the vehicle 2 remains in contact with the road surface 500, and the magnetic intensity measured by the front magnetic sensor array 4F is maintained at the reference intensity R.

[0050] As shown in Figures 12 and 13, the magnetic intensity measured by the rear magnetic sensor array 4R is maintained at the reference intensity R from time t21, when the front lift-up state occurs, until time t22, when this lift-up state is maintained. At time t23, when the front lift-up state is resolved, the rear of the vehicle 2 transitions to a lift-up state where it is separated from the road surface 500, and the magnetic intensity measured by the rear magnetic sensor array 4R rapidly decreases to its minimum.

[0051] When the rear of the vehicle is lifted up while driving over the step 505, the vehicle 2 is on the higher step, while the rear of the vehicle 2 faces the road surface 500 of the lower step. This is a rear-side lift state in which the gap between the rear magnetic sensor array 4R and the road surface 500 is maintained at a constant level. This rear-side lift state continues until time t24 when the entire vehicle 2 passes over the step 505. Therefore, after the rear-side lift state occurs at time t23, the magnetic intensity measured by the rear magnetic sensor array 4R is maintained at a nearly constant minimum value until the entire vehicle 2 passes over the step 505 and the rear-side lift state is resolved (time t24). Then, when the rear-side lift state is resolved (time t24), the magnetic intensity measured by the rear magnetic sensor array 4R increases rapidly and returns to the reference intensity R.

[0052] As shown in Figures 12 and 13, the difference in magnetic intensity between the front magnetic sensor array 4F and the rear magnetic sensor array 4R (absolute value; bottom graph in Figure 13; difference in magnetic intensity between front and rear) is kept at zero until time t21 when the vehicle 2 reaches the step 505. Then, until time t22 when the distance between the front magnetic sensor array 4F and the road surface 500 gradually increases due to the occurrence of a lifting state at the front, the difference in magnetic intensity between front and rear gradually increases.

[0053] During the transition period from the front floating state to the rear floating state, between times t22 and t23, as described above, the magnetic intensity measured by the front magnetic sensor array 4F rapidly increases from its minimum value to the reference intensity R, while the magnetic intensity measured by the rear magnetic sensor array 4R rapidly decreases from the reference intensity R to its minimum value. Between times t22 and t23, the difference in magnetic intensity between the front and rear undergoes a V-shaped change, first rapidly decreasing to near zero, and then rapidly increasing again. Note that in Figure 13, for illustrative purposes, times t22 and t23 are shown to be far more separated than they actually are, but as described above, times t22 and t23 are almost the same time. Therefore, the period during which the difference in magnetic intensity between the front and rear decreases is very short and instantaneous.

[0054] From time t23 onward, while vehicle 2 moves forward with its rear end floating, the maximum value of the magnetic intensity difference remains constant. When the entire vehicle 2 passes over the step 505 and returns to a normal driving state (time t24), the magnetic intensity difference becomes zero, and thereafter, a magnetic intensity difference of zero is maintained.

[0055] (4) When going down a step For example, when vehicle 2 descends a step 506 as shown in Figure 14, after vehicle 2 reaches step 506 (time t25), the front of vehicle 2 faces the road surface 500 of the lower step with a gap between them, causing the front to lift up. When the center of vehicle 2 passes step 506 (time t26), the weight balance between the front and rear causes vehicle 2 to tilt downwards, and the front of vehicle 2 lands on the road surface 500, eliminating the lifted state at the front (time t27). When the lifted state at the front is eliminated in this way, an impact may occur if the front of vehicle 2 lands on the road surface 500 with force.

[0056] When the front of vehicle 2 makes contact with the lower step's road surface 500, vehicle 2 tilts downwards and its rear end lifts up. As vehicle 2 moves forward, the downward tilt of vehicle 2 decreases, but the rear end remains lifted up until the entire vehicle 2 passes over the step 506 (time t28). Once the entire vehicle 2 has passed over the step, the rear of vehicle 2 lands on the lower step's road surface 500, and the rear end lifts up. When the rear end lifts up in this way, an impact may occur if the rear of vehicle 2 lands forcefully on the lower step's road surface 500.

[0057] As vehicle 2 descends the step 506 as shown in Figure 14, the magnetic intensity measured by the magnetic sensor array 4F·R changes, for example, as shown in Figure 15. Until time t25, when vehicle 2 is in a normal driving state, the magnetic intensity measured by the front magnetic sensor array 4F and the rear magnetic sensor array 4R are both at the reference intensity R.

[0058] The magnetic intensity measured by the front magnetic sensor array 4F decreases sharply to its minimum at time t25 when the vehicle transitions to a lifted state at the front, and remains at this minimum until just before this lifted state is resolved (time t26). At time t27, when the lifted state at the front is resolved, the magnetic intensity measured by the front magnetic sensor array 4F rapidly returns to the standard intensity R. After that, since the front of the vehicle 2 remains in contact with the road surface 500, the magnetic intensity measured by the front magnetic sensor array 4F is maintained at the standard intensity R.

[0059] As shown in Figures 14 and 15, the magnetic intensity measured by the rear magnetic sensor array 4R is maintained at the reference intensity R from time t25, when the front lift-up state occurs, until time t26, when this lift-up state is maintained. Subsequently, when the front lift-up state is resolved (time t27), the rear of the vehicle 2 transitions to a lift-up state where it separates from the road surface 500, and the magnetic intensity measured by the rear magnetic sensor array 4R rapidly decreases to its minimum.

[0060] The lift at the rear of the vehicle 2 when descending the step 506 is caused by the downward tilt of the front of the vehicle 2. This lift at the rear continues until the entire vehicle 2 passes over the step 506 and the entire vehicle 2 lands on the lower step (time t28). As the vehicle 2 transitions from a lift at the front to a lift at the rear, the magnetic intensity measured by the rear magnetic sensor array 4R decreases sharply to a minimum, and then the downward tilt of the front of the vehicle 2 gradually eases as the vehicle 2 moves forward. Until the entire vehicle 2 passes over the step 506 and the lift at the rear is eliminated (time t28), the magnetic intensity measured by the rear magnetic sensor array 4R gradually increases and changes to approach the reference intensity R.

[0061] As shown in Figures 14 and 15, the magnetic intensity difference (absolute value; bottom graph in Figure 15; front-to-rear magnetic intensity difference) between the front magnetic sensor array 4F and the rear magnetic sensor array 4R is kept at zero until time t25 when the vehicle 2 reaches the step 506. Then, after time t25, when the front of the vehicle 2 crosses the step 506 and the front magnetic sensor array 4F faces the road surface 500 of the lower step with a gap between them, the front-to-rear magnetic intensity difference rapidly expands and reaches its maximum. This expanded magnetic intensity difference is kept approximately constant until time t26 when the transition from the front-to-rear lift-up state to the rear-to-rear lift-up state occurs.

[0062] During the transition period from the front floating state to the rear floating state, between times t26 and t27, as described above, the magnetic intensity measured by the front magnetic sensor array 4F rapidly increases from its minimum value to the reference intensity R, while the magnetic intensity measured by the rear magnetic sensor array 4R rapidly decreases from the reference intensity R to its minimum value. Between times t26 and t27, the difference in magnetic intensity between the front and rear undergoes a V-shaped change, first rapidly decreasing to near zero, and then rapidly increasing again. Note that in Figure 15, for illustrative purposes, times t26 and t27 are shown to be far more separated than they actually are, but as described above, times t26 and t27 are almost the same time. Therefore, the period during which the difference in magnetic intensity between the front and rear decreases is very short and instantaneous.

[0063] At time t27, after transitioning to a lifted state at the rear, the magnetic intensity difference gradually decreases as vehicle 2 moves forward. When the rear of vehicle 2 reaches the corner of step 506 and the rear magnetic sensor array 4R approaches the road surface 500 of the upper step, vehicle 2 is still tilted downwards at the front, but the magnetic intensity measured by the rear magnetic sensor array 4R becomes the reference intensity R, and the difference in magnetic intensity between the front and rear becomes zero. Subsequently, when the entire vehicle 2 passes over step 506 and the entire vehicle 2 lands on the road surface 500 of the lower step (time t28), the rear magnetic sensor array 4R approaches the road surface 500 of the lower step, and thereafter the magnetic intensity difference is maintained at zero.

[0064] Next, the control method of the vehicle system 1 in this example will be explained using the flowchart in Figure 16. The control shown in the figure is for when vehicle 2 automatically travels along the magnetic tape 51. The detection circuit 30 detects when vehicle 2 is floating, and the control circuit 20 executes the driving control of vehicle 2. According to the control shown in the flowchart, it is possible to mitigate the impact that may occur when vehicle 2 crosses a ridge or passes over a step.

[0065] In this example, the detection circuit 30 and the control circuit 20 work in coordination to control the movement of vehicle 2. For the sake of explanation, the detection circuit 30 and the control circuit 20 have been described separately in the above explanation. However, in actual circuit configurations, the detection circuit 30 may be integrated into the control circuit 20, considering hardware cost and the need for coordinated operation. Below, the control content will be explained mainly with respect to the control circuit 20, based on the configuration in which the detection circuit 30 is integrated into the control circuit 20.

[0066] While vehicle 2 automatically travels along the magnetic tape 51, the control circuit 20 accumulates the distance traveled by vehicle 2 (S101) and determines whether the front and rear magnetic sensor arrays 4F and R can detect the magnetic tape 51 (S102). Here, the shock mitigation control is based on the premise that the magnetic tape 51 can be detected. Therefore, if both the front and rear magnetic sensor arrays 4F and R can detect the magnetic tape 51 (S102: YES), the control circuit 20 executes the processing from step S103 onwards. If the magnetic tape 51 is not correctly detected, the processing from step S103 onwards is not executed, and the system waits until the magnetic tape 51 is correctly detected (S102: NO → Return).

[0067] If both the front and rear magnetic sensor arrays 4F and R can detect the magnetic tape 51 (S102: YES), the control circuit 20 performs a threshold determination regarding the magnetic intensity difference, which is the difference (absolute value) between the magnetic intensity measured by the front magnetic sensor array 4F and the magnetic intensity measured by the rear magnetic sensor array 4R (S103). The magnetic intensity measured by the magnetic sensor array 4 is the maximum value of the magnetic intensity distribution represented by the magnetic measurement values ​​from the magnetic sensors A1 to A12 of the magnetic sensor array 4 (see Figure 7; the peak of the approximation curve of the magnetic intensity distribution).

[0068] In step S103, the threshold determination determines whether the above magnetic intensity difference exceeds a preset threshold Th. The magnetic intensity difference subject to threshold determination is not the difference between the magnetic intensity measured by the front magnetic sensor array 4F and the magnetic intensity measured by the rear magnetic sensor array 4R (see the bottom graphs in Figures 9, 11, 13, and 15). The magnetic intensity difference subject to threshold determination is the filter output value obtained by applying a high-cut filter that blocks high-frequency components to the difference between the magnetic intensity measured by the front magnetic sensor array 4F and the magnetic intensity measured by the rear magnetic sensor array 4R.

[0069] The magnitude of the threshold Th is set, for example, as shown in Figures 17 to 20, with respect to the magnetic intensity difference after applying the high-cut filter. The graphs in Figures 17 to 20 are graphs of the magnetic intensity difference obtained by applying the above high-cut filter to the difference (magnetic intensity difference) between the magnetic intensity measured by the front magnetic sensor array 4F and the magnetic intensity measured by the rear magnetic sensor array 4R.

[0070] The graph in Figure 17 shows the magnetic intensity difference when vehicle 2 crosses a ridge (Figure 8), and is obtained by applying a high-cut filter to the magnetic intensity difference shown in the bottom graph of Figure 9. Unlike the graph before applying the high-cut filter (bottom graph of Figure 9), the graph in Figure 17 does not show a V-shaped change at time t12-t13. As mentioned above, time t12-t13 is almost the same, and the V-shaped change at the bottom of Figure 9 is instantaneous. Therefore, the instantaneous V-shaped change at time t12-t13 disappears when the high-cut filter is applied.

[0071] The graph in Figure 18 shows the difference in magnetic intensity when a vehicle crosses a valley (Figure 10), and is obtained by applying a high-cut filter to the difference in magnetic intensity shown in the bottom graph of Figure 11. The graph in Figure 11 shows a nearly constant difference in magnetic intensity and has few high-frequency components. Therefore, the graph in Figure 18 after applying the high-cut filter is almost the same as the bottom graph in Figure 11.

[0072] The graph in Figure 19 shows the magnetic intensity difference when vehicle 2 drives over a step (Figure 12), and is obtained by applying a high-cut filter to the magnetic intensity difference shown in the bottom graph of Figure 13. The V-shaped change at time t22~t23 in the bottom graph of Figure 13 disappears when a high-cut filter is applied.

[0073] The graph in Figure 20 shows the difference in magnetic intensity when a vehicle descends a step (Figure 14), and is obtained by applying a high-cut filter to the difference in magnetic intensity shown in the bottom graph of Figure 15. The V-shaped change at time t26~t27 in the bottom graph of Figure 15 disappears when a high-cut filter is applied.

[0074] The downward-pointing triangles in Figures 17 to 20 indicate the points at which impacts may occur. For example, when crossing a ridge (Figure 8), as shown in Figure 17, an impact may occur at point t13 when the vehicle 2 transitions from a front-to-rear lift state to a rear-to-back lift state due to a change in the front-to-rear weight balance. For example, when driving over a step 505 (Figure 12), as shown in Figure 19, an impact may occur at point t23 when the vehicle 2, which has tilted forward after driving over the step, returns to a horizontal position. For example, when descending a step (Figure 14), as shown in Figure 20, impacts may occur at two points: at point t27 when the front of the vehicle 2 lands on the lower step's surface, and at point t28 when the rear of the vehicle 2 lands on the lower step's surface. Note that when crossing a valley (Figure 10), neither the front nor the rear of the vehicle lifts up, so there is little risk of an impact occurring. Therefore, Figure 18 does not include the downward-pointing triangle mark that indicates the point at which impact needs to be suppressed.

[0075] The control circuit 20 identifies the lift-up period when the magnetic intensity difference is greater than the threshold Th set as shown in Figures 17 to 20. This lift-up period is a time interval in which either the front or rear of the vehicle 2 is lifted and an impact may occur. The control circuit 20 identifies the lift-up period by determining the threshold in step S103 in Figure 16.

[0076] The control circuit 20 detects the vehicle 2's lift-up state when the magnetic intensity difference exceeds the threshold Th (S103: YES) and executes mitigation control to suppress the impact (S104). In this example, the mitigation control is a control that reduces the speed of the vehicle 2. Under mitigation control, the vehicle 2 moves forward slowly, thereby preparing for any impact that may occur when the lift-up state on the front or rear side is resolved. The mitigation control during the lift-up period (S104) reduces the momentum when the vehicle 2 lands on the road surface at time t13 (Figure 17), time t23 (Figure 19), and time t27 (Figure 20), thereby suppressing the impact.

[0077] The control circuit 20 further sets a program control flag to 1 (S105) and resets the accumulated travel distance to zero (S106). The setting of the flag value in step S105 and the reset of the travel distance to zero in step S106 are repeatedly performed during the above-mentioned levitation period (see Figures 17 to 20) (S102:YES → S103:YES). Therefore, when the magnetic intensity difference falls below the threshold Th and the levitation period ends (S103:NO), step S114 is executed with the flag value at 1 and the travel distance at zero.

[0078] The control circuit 20 determines whether the flag value is 1 (S114) if the magnetic intensity difference is less than or equal to the threshold Th (S103: NO). The case where the magnetic intensity difference is less than or equal to the threshold Th includes the case after the lift-up period in step S104 described above has passed, and the case before the lift-up period has started. As described above, if the lift-up period has passed, the flag value is 1 and the distance traveled is zero. On the other hand, if the lift-up period has not started, the flag value is the initial value of zero, while the distance traveled is the distance that vehicle 2 has traveled. In this case, the flag value is zero and not 1 (S114: NO), so the control circuit 20 applies normal control to vehicle 2 instead of relaxation control (S135).

[0079] On the other hand, after the lift-up period in step S104 to which the relaxation control is applied, if the magnetic intensity difference falls below the threshold Th (S103: NO), the flag value is 1 (S114: YES), and the control circuit 20 performs a threshold determination regarding the distance traveled (S115). The control circuit 20 continues to perform relaxation control during the departure period (S115: YES) after the lift-up period has ended, i.e., until the vehicle 2 has traveled the threshold distance and passed over the ridge or step (S116). With the relaxation control during the departure period following the lift-up period, at time t28 (Figure 20) when descending a step (Figure 14), the force with which the rear of the vehicle 2 lands on the road surface can be mitigated, thereby reducing the impact. Subsequently, when the distance traveled reaches the threshold (S115: NO), the flag value is reset (S126), and normal control is performed (S135). Figures 17 to 20 illustrate the timing at which the relaxation control in step S116 is terminated, indicated as time point te.

[0080] As described above, the vehicle system 1 in this example can detect the lifting state of the front or rear of the crawler-type vehicle 2, which is a characteristic behavior of the vehicle, and by applying mitigation control to the vehicle 2, it is possible to suppress the impact that may occur due to the lifting state. By suppressing the impact, it is possible to prevent cargo collapse or damage to goods transported by the vehicle 2, thereby improving safety.

[0081] In this example, the control that reduces the speed of vehicle 2 is presented as a mitigation control. As a mitigation control, instead of, or in addition to, the control that reduces the speed, other methods can be employed, such as a control that suppresses the difference in rotational speed between the left and right crawlers 21L and R to prevent excessive turning (changes in vehicle orientation), or a control that softens the suspension to reduce the impact on the transported goods.

[0082] In this example, the lifting state of the front or rear of the vehicle 2 is detected by utilizing the magnetic intensity measured by two magnetic sensor arrays 4F·R, which are positioned differently in the front-to-rear direction on the vehicle 2. Alternatively, the lifting state of the front may be detected when the magnetic intensity measured by the front magnetic sensor array 4F falls below a predetermined threshold. Similarly, the lifting state of the rear may be detected when the magnetic intensity measured by the rear magnetic sensor array 4R falls below a predetermined threshold.

[0083] Alternatively, a magnetic sensor array 4 may be installed in the middle section of the vehicle 2 in the longitudinal direction. By utilizing the magnetic intensity detected by the magnetic sensor array 4 located in the middle section, it is possible to detect the lifting state of the middle section of the vehicle 2 when the vehicle 2 crosses the valley 502 (Figure 10). When the lifting state of the middle section occurs, mitigation control may be applied.

[0084] This example shows a case where magnetic tape, which is an example of a magnetic component, is laid along the path. Instead of magnetic tape, individual magnetic markers may be laid along the path as magnetic components. In this case, when a magnetic marker is detected by the front magnetic sensor array 4F, the lifting state of the front side may be detected when the magnetic intensity measured by the magnetic sensor array 4F falls below a predetermined threshold. Similarly, when a magnetic marker is detected by the rear magnetic sensor array 4R, the lifting state of the rear side may be detected when the magnetic intensity measured by the magnetic sensor array 4R falls below a predetermined threshold. Furthermore, when using magnetic markers as magnetic components and attempting to detect the lifting state of the front or rear side by threshold processing related to the difference in magnetic intensity between the front and rear, it is preferable to match the span (distance) of the front and rear magnetic sensor arrays 4F and R in the vehicle 2 with the distance between two adjacent magnetic markers. In this case, the front and rear magnetic sensor arrays 4F and R can simultaneously detect the magnetic marker, making it possible to obtain the difference in magnetic intensity between the front and rear. The magnetic markers detected simultaneously by the front and rear magnetic sensor arrays 4F·R may be two adjacent magnetic markers, or two adjacent magnetic markers separated by one or more other magnetic markers.

[0085] In this example, a threshold determination (step S103 in Figure 16) is performed based on the difference in magnetic intensity before and after applying the high-cut filter (Figures 17 to 20), and relaxation control is performed when the difference in magnetic intensity before and after exceeds the threshold Th (S104 in the same figure). Alternatively, according to the process in Figure 21, a threshold determination (S103 in Figure 21) based on the difference in magnetic intensity before and after applying the high-cut filter (see the bottom graphs in Figures 9, 11, 13, and 15) can be adopted. The flowchart in Figure 21 is based on the flowchart in Figure 16, with the determination process in step S214 added.

[0086] In the process shown in Figure 21, if the difference in magnetic intensity between the front and rear exceeds the threshold Th (S103:YES), relaxation control is executed and the flag value is set to 1 (S104→S105). Subsequently, if the difference in magnetic intensity between the front and rear falls within the threshold Th (S103:NO), the threshold determination in step S214 is executed via step S114. This threshold determination concerns the temporal rate of change of magnetic intensity measured by the front magnetic sensor array 4F and the temporal rate of change of magnetic intensity measured by the rear magnetic sensor array 4R. If either rate of change exceeds a preset threshold (S214:YES), relaxation control continues through the processing from step S104 onward, even if the difference in magnetic intensity between the front and rear is below the threshold Th (S103:NO).

[0087] For example, in the bottom graph of magnetic intensity difference in Figure 9, if the magnetic intensity difference instantaneously falls below the threshold Th at times t12 to t13, then both the temporal rate of change of magnetic intensity measured by the front magnetic sensor array 4F and the temporal rate of change of magnetic intensity measured by the rear magnetic sensor array 4R exceed the threshold. In this case, the process from step S104 onwards is executed according to the sequence S103:NO → S114:YES → S214:YES, and the relaxation control during the floating period is continued.

[0088] (Example 2) This example is based on the control method of the vehicle system 1 in Example 1, but modified to a control method that corresponds to the type of undulation of the route. This will be explained using Figures 8 to 15 and 17 to 20, which were referenced in Example 1.

[0089] In the control method of Example 1, the lift state of the front or rear of the vehicle 2 is detected and mitigation control is performed without identifying the type of undulation of the path, such as ridges or steps. In this control method, mitigation control is applied not only to the lift period when the difference in magnetic intensity between the front magnetic sensor array 4F and the rear magnetic sensor array 4R exceeds a threshold Th, but also to the period after the end of the lift period until the vehicle travels a threshold distance (referred to as the separation period).

[0090] The application period for mitigation control after the lift-up period has ended is set considering the case of descending the step 506 (see Figure 14). This is because when descending the step 506, an impact may occur not only when the front of the vehicle 2 lands on the lower step, but also when the rear of the vehicle 2 lands on the road surface 500 of the lower step. On the other hand, when crossing the ridge 501 (Figure 8) or driving onto the step 505 (Figure 12), there is only one timing when an impact may occur.

[0091] In this example, the application period of mitigation control is shortened by determining the type of undulation along the route. By shortening the application period of mitigation control, which reduces the speed of vehicle 2, the time required for vehicle 2 to travel can be reduced. In this example, the type of undulation along the route is determined by the pattern of change in the magnetic intensity difference between the front magnetic sensor array 4F and the rear magnetic sensor array 4R.

[0092] In this example, thresholding is employed for the rate of change of the magnetic intensity difference when the magnetic intensity difference between the front magnetic sensor array 4F and the rear magnetic sensor array 4R exceeds a threshold Th. This thresholding determines whether the magnetic intensity difference increased gradually from zero to exceed the threshold Th, or increased rapidly from zero to exceed the threshold Th. As shown in Figures 17 and 19, if the magnetic intensity difference between the front magnetic sensor array 4F and the rear magnetic sensor array 4R increases gradually from zero, it can be determined that the terrain is either crossing a ridge 501 (Figure 8) or riding over a step 505 (Figure 12). On the other hand, as shown in Figure 20, if the magnetic intensity difference increases rapidly, it can be determined that the terrain is descending a step 506 (Figure 14).

[0093] As described above, when crossing ridge 501 or riding onto step 505, the only time an impact can occur is once during the lifting period when the front or rear side is lifted. Therefore, in this example, if it is determined that the type of undulation is either crossing ridge 501 or riding onto step 505, the mitigation control is applied only during the lifting period described above, and the period after the end of the lifting period is excluded from the application of the mitigation control.

[0094] On the other hand, when descending a step 506, as described above, impacts can occur not only during the lifting period when the front or rear side is lifted, but also during the period after the lifting period has ended. Therefore, in this example, when the type of undulation for descending a step is determined, the mitigation control is applied to the lifting period as well as the detachment period after the lifting period has ended, similar to Example 1.

[0095] Alternatively, instead of using the difference in magnetic intensity between the front magnetic sensor array 4F and the rear magnetic sensor array 4R to determine the type of undulation, the type of undulation may be determined using the magnetic intensity measured by the front magnetic sensor array 4F. When the magnetic intensity measured by the front magnetic sensor array 4F gradually decreases from a reference intensity R to a minimum (see Figures 9 and 13), it can be determined that the undulation is either crossing a ridge 501 or riding onto a step 505. When the magnetic intensity measured by the front magnetic sensor array 4F rapidly decreases from a reference intensity R to a minimum (see Figure 15), it can be determined that the undulation is descending a step 506.

[0096] Furthermore, when crossing ridge 501 and when driving onto step 505, impacts can occur only once during the lift-up period, as shown in Figures 17 and 19. Therefore, it is also possible to detect the landing of the front of vehicle 2 and cancel the mitigation control. Similarly, when descending step 506, impacts can occur once during the lift-up period and once during the period after the lift-up period ends, as shown in Figure 20. It is also possible to detect the landing of the front of vehicle 2 during the lift-up period and cancel the mitigation control, while resuming the mitigation control upon the end of the lift-up period. Moreover, during the departure period after the end of the lift-up period, it is also possible to detect the landing of the rear of vehicle 2 and cancel the mitigation control again. The landing of vehicle 2 from the lifted state can be detected by threshold processing related to the acceleration in the pitching direction of the vehicle.

[0097] The other components and effects are the same as in Example 1.

[0098] Although specific examples of the present invention have been described in detail as shown in the examples above, these examples only disclose an example of the technology covered by the claims. Needless to say, the claims should not be interpreted restrictively based on the configuration or numerical values ​​of the specific examples. The claims encompass technologies obtained by various modifications, changes, or combinations of the above examples using prior art or the knowledge of those skilled in the art. [Explanation of Symbols]

[0099] 1. Vehicle System 2 vehicles (tracked vehicles, crawler vehicles) 2B vehicle 21L·R Crawler 20 Control circuits 30 Detection Circuit 4. Magnetic sensor array (magnetic measurement circuit) 4L Front magnetic sensor array 4R Rear magnetic sensor array 43 Detection Processing Unit 5 routes 500 road surface 51 Magnetic tape (magnetic components)

Claims

1. A vehicle system in which a tracked vehicle travels along a path laid out with magnetic components that exert a magnetic effect on its surroundings, One or more magnetic measuring circuits attached to the tracked vehicle to measure the magnetic intensity acting from the aforementioned magnetic components, A detection circuit for detecting when either the front or rear side of the tracked vehicle lifts off the road surface, The system comprises a control circuit for controlling the movement of the tracked vehicle, The detection circuit detects the levitation state by processing the magnetic intensity measured by at least one of the one or more magnetic measurement circuits. A vehicle system configured such that, upon detection of the lifted state by the detection circuit, the control circuit performs mitigation control to mitigate the impact that may occur when the original lifted state is resolved as a result of transitioning to a new lifted state in which either the front or rear side leaves the road surface, or when the original lifted state is resolved as a result of transitioning to a state in which both the front and rear sides are in contact with the road surface.

2. The vehicle system according to claim 1, wherein the mitigation control includes at least control to reduce speed.

3. A vehicle system according to claim 1, wherein the magnetic component is a continuous strip of magnetic tape laid along a path.

4. In any one of claims 1 to 3, the tracked vehicle has at least two magnetic measurement circuits arranged at two locations spaced apart in the front-rear direction, The detection circuit is configured to detect the levitation state when the difference between two magnetic intensities measured at the same time by the two magnetic measurement circuits, which are located at two locations separated in the longitudinal direction of the tracked vehicle, exceeds a preset threshold.

5. A vehicle system according to any one of claims 1 to 3, wherein the detection circuit is configured to detect the levitation state when the magnetic intensity measured by any one of the one or two or more magnetic measurement circuits falls below a preset threshold.

6. A control method for a tracked vehicle that travels along a path laid with magnetic components that exert a magnetic effect on its surroundings, The aforementioned tracked vehicle is equipped with one or more magnetic measuring circuits to detect the magnetic components and measure the magnetic intensity acting from the magnetic components. By processing the magnetic intensity measured by at least one of the one or two or more magnetic measurement circuits, a lifting state in which either the front or rear side of the tracked vehicle is lifted away from the road surface is detected. A control method that, upon detection of the lifted state, performs mitigation control to mitigate the impact that may occur when the original lifted state is resolved due to a transition to a new lifted state in which either the front or rear side leaves the road surface, or when the original lifted state is resolved due to a transition to a state in which both the front and rear sides come into contact with the road surface.

7. The control method according to claim 6, wherein the relaxation control includes at least a control that reduces the speed.

8. A control method according to claim 6, wherein the magnetic component is a continuous strip of magnetic tape laid along a path.

9. In any one of claims 6 to 8, the tracked vehicle has at least two magnetic measurement circuits arranged at two locations spaced apart in the front-rear direction, A control method for detecting the levitation state when the difference between two magnetic intensities measured at the same time by two magnetic measurement circuits located at two points separated in the longitudinal direction of the tracked vehicle exceeds a preset threshold.

10. A control method according to any one of claims 6 to 8, wherein the levitation state is detected when the magnetic intensity measured by any one of the one or two or more magnetic measurement circuits falls below a preset threshold.

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