Wheel wear calculation system

Abstract

The present invention relates to a wheel wear calculation system. A wear calculation system (100, 200, 300) for calculating the wear of a wheel (3) of a vehicle (2) includes a rotation sensor (48) configured to detect the rotation of the wheel (3), an acceleration sensor (49) configured to detect the acceleration of the vehicle (2) in the direction of travel, and a control unit (7) configured to calculate the distance traveled by the vehicle based on the vehicle's acceleration, and to calculate the wear based on the distance traveled and the rotation of the wheel (3).

Description

Technical Field

[0001] This invention relates to a wheel wear calculation system. Background Technology

[0002] Traditionally, wear on wheels or tires for maintenance purposes is calculated or estimated from various data, rather than being measured directly. See, for example, JP2015-051704A.

[0003] According to the system disclosed in P2015-051704A, wheel wear is estimated based on the vehicle's travel distance calculated from the vehicle's location information obtained from GPS satellites. According to this prior art, the number of wheel revolutions required for the vehicle to travel the estimated distance is calculated, and the wheel wear or change in wheel diameter is calculated based on this number of revolutions.

[0004] However, according to this existing technology, since the distance traveled is calculated based on the vehicle's position information obtained from GPS satellites, wear cannot be calculated when the vehicle is traveling in tunnels, indoors, or any other location where GPS signals are unavailable. Furthermore, the position information obtained from GPS satellites typically contains errors on the order of meters, and the time intervals between GPS signal receptions can be relatively long, making the accuracy potentially insufficient. Summary of the Invention

[0005] In view of this problem in the prior art, the main objective of the present invention is to provide a wheel wear calculation system that can calculate wheel wear with high accuracy even when GPS signals are unavailable.

[0006] To achieve this objective, the present invention provides a wear calculation system 100, 200, 300 for calculating the wear of wheels 3 of a vehicle 2, the wear calculation system comprising: a rotational speed sensor 48 configured to detect the rotational speed of the wheel 3; an acceleration sensor 49 configured to detect the acceleration of the vehicle 2 in the direction of travel; and a control unit 7 configured to calculate the distance traveled by the vehicle based on the acceleration of the vehicle, and to calculate the wear based on the distance traveled and the rotational speed of the wheel 3.

[0007] Therefore, wheel wear can be calculated even when GPS signals are unavailable. Furthermore, since accelerometers can provide data much more frequently than GPS satellites, wear can be calculated with relatively high accuracy.

[0008] According to a particular aspect of the invention, the wheel 3 includes a main wheel 19 and a pair of drive discs 18. The main wheel includes an annular member 31 having a laterally extending central axis Y1 and a plurality of driven rollers 32 rotatably supported by the annular member about a tangent to the annular member at corresponding positions of the driven rollers. Each drive disc includes a hub 18A and a plurality of drive rollers 18B. The hub is supported by the vehicle body on a corresponding side of the main wheel so as to be rotatable about a rotational centerline substantially coaxial with the central axis of the annular member. The plurality of drive rollers are circumferentially positioned on the hub so as to be inclined about the rotational centerline to the rotational centerline of the hub. The vehicle rotates and engages with the driven roller, wherein the rotation speed sensor 48 is configured to detect the rotation speed of the main wheel and the rotation speed of the driven roller, the acceleration sensor 49 is configured to detect the front-rear acceleration and lateral acceleration of the vehicle, and the control unit is configured to calculate the front-rear travel distance based on the front-rear acceleration, calculate a second wear based on the front-rear travel distance and the rotation speed of the main wheel, calculate a lateral travel distance based on the lateral acceleration, calculate a third wear based on the lateral travel distance and the rotation speed of the driven roller, and calculate a first wear based on the second wear and the third wear, wherein the first wear is the wear of the wheel.

[0009] Therefore, when calculating wheel wear, the vehicle's forward and backward travel distances and lateral travel distances can be considered, thus enabling the calculation of wheel wear with relatively high accuracy, even when the wheels are traveling in all directions.

[0010] Preferably, the control unit 7 calculates the sum of the second wear and the third wear as the first wear.

[0011] Therefore, wheel wear can be calculated with relatively high accuracy. Optionally, the second and third wear can be weighted by certain factors, and the first wear can be calculated as a weighted sum of the second and third wear.

[0012] Preferably, the wear calculation system further includes a measuring device 52 for measuring the distance between the central axis Y1 of the main wheel and a point on the outer periphery of the main wheel directly below the central axis. The control unit 7 is configured to calculate a fourth wear by comparing the measured distance with an initial distance between the central axis Y1 of the main wheel and the point on the outer periphery of the main wheel. When the fourth wear is greater than the first wear, the fourth wear is used instead of the first wear as the wear of the wheel.

[0013] This allows for more reliable calculation of wheel wear.

[0014] Preferably, the vehicle is provided with a drive unit 4, which is used to rotate the driven roller according to a predetermined schedule when the vehicle is traveling in the forward and backward direction.

[0015] This reduces the unevenness of wear on the driven roller.

[0016] In this configuration, the vehicle 2 may be provided with a pair of wheels 3 arranged on either side, and when the vehicle travels in the forward-backward direction, the drive unit 4 may be operated such that the driven roller of the main wheel rotates in the opposite direction according to a predetermined schedule.

[0017] Therefore, uneven wear between different driven rollers can be reduced.

[0018] Preferably, the wear calculation system further includes a display unit 45, which displays at least one of the wheel wear, the first wear, the second wear, and the third wear.

[0019] Therefore, users can easily know the wear condition of the wheels.

[0020] Preferably, the wear calculation system further includes a temperature sensor 50 for detecting the temperature of the driven roller and a vertical load sensor for detecting the vertical load of the vehicle. The control unit is configured to calculate the effective diameter of the driven roller and / or the main wheel by taking into account the elastic modulus of the driven roller at the detected temperature and the detected vertical load, and to calculate the travel distance based on the rotational speed of the driven roller and / or the rotational speed of the main wheel by taking into account the effective diameter.

[0021] By taking into account the effects of wheel softening and hardening caused by temperature changes on wheel diameter, the accuracy of wheel wear estimation can be further improved.

[0022] Preferably, the vehicle 2 is provided with a drive unit 4 for driving the wheels, and the rotation sensor is configured to count the rotation of the output of the drive unit, and obtain the rotation of the wheels by multiplying a coefficient greater than 0 and less than 1 by the count of the rotation of the output of the drive unit.

[0023] Therefore, the rotational speed of the main wheel can be detected relatively easily.

[0024] Therefore, the present invention provides a wheel wear calculation system that can calculate wheel wear with high accuracy even when GPS signals are unavailable. Attached Figure Description

[0025] Figure 1 This is a perspective view of a trolley equipped with a wear calculation system according to the first embodiment of the present invention;

[0026] Figure 2 This is a plan view of the cart according to the first embodiment;

[0027] Figure 3 It is a cross-sectional view of the omnidirectional wheel installed in the trolley of the first embodiment;

[0028] Figure 4 This is a side view of the omnidirectional wheel;

[0029] Figure 5 This is a flowchart of the wear calculation process performed by the wear calculation system of the first embodiment;

[0030] Figure 6 This is a flowchart of the wear calculation process performed by the wear calculation system according to the second embodiment of the present invention; and

[0031] Figure 7 This is a flowchart of the wear calculation process performed by the wear calculation system according to the third embodiment of the present invention. Detailed Implementation

[0032] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

[0033] Figure 1 and Figure 2 A trolley 1 to which the present invention is applied is shown. The trolley 1 includes a body 2, a pair of omnidirectional wheels 3 serving as the rear wheels of the trolley 1, a pair of front wheels 13 consisting of casters known per se, a pair of drive units 4 mounted to the body 2 for driving the respective omnidirectional wheels 3, a handle 5 (described below) mounted to the upper rear of the trolley 1 for operating the trolley 1, a load sensor 6 for detecting the load applied to the handle 5, and a control unit 7 for controlling the drive units 4 according to the load detected by the load sensor 6.

[0034] The vehicle body 2 extends slightly in the longitudinal direction and includes a rear portion 2A that defines a machine compartment therein and a front portion 2B with an upward-facing support base 11. The front portion 2B is lower than the rear portion 2A and is used to support cargo, equipment, etc. Relatively heavy equipment, such as an X-ray scanner, can be mounted on the front portion 2B and properly secured thereto. This equipment can be fastened to the support base 11 using suitable fittings not shown in the figure. The machine compartment located in the rear portion 2A can house the battery, control unit 7, and various sensors.

[0035] like Figure 1 As shown, the front wheel 13 is attached to the suspension base 14, which is in turn supported by the vehicle body 2 via spring 15 and damper 16. Each front wheel 13 consists of a fork-shaped member 13A and a wheel body 13B. The fork-shaped member 13A has a base end attached to the suspension base 14, and the wheel body 13B is rotatably supported by two arms of the fork-shaped member 13A.

[0036] like Figure 1 and Figure 2 As shown, the omnidirectional wheels 3 are located at the lower left and lower right corners of the rear part 2A of the vehicle body 2, and are laterally spaced apart from each other. Figures 1 to 3 As shown, the frame portion 17 is fixedly attached to each side of the lower rear portion of the vehicle body 2, and includes a pair of laterally facing side panels 17B extending downward in parallel with each other.

[0037] Each omnidirectional wheel 3 is provided with a pair of drive discs 18 and an annular main wheel 19, the pair of drive discs 18 being rotatably supported by a corresponding pair of side plates 17B located therebetween, and the main wheel 19 being positioned between the drive discs 18. Since the two omnidirectional wheels 3 are structurally identical, only one of them will be described in the following disclosure.

[0038] like Figure 3 As shown, the support shaft 21 extends laterally between the side plates 17B. Each drive disc 18 includes a pair of disc-shaped hubs 18A and a plurality of drive rollers 18B. The hubs 18A are rotatably supported by the side plates 17B (about the central axis Y1 of the support shaft 21), and each drive roller 18B is rotatably supported by the corresponding hub 18A about an axis inclined relative to the radial line and the main plane of the hub 18A. The drive discs 18 are thus rotatably supported on the support shaft 21. Lateral movement of the drive discs 18 relative to the support shaft 21 is restricted such that the drive discs 18 are opposite each other at a predetermined lateral distance.

[0039] A driven pulley 18C is fixedly attached to the outer side of each hub 18A in a coaxial relationship with the hub 18A. Each drive unit 4, which can be mounted to the lower part of the vehicle body 2, is provided with a pair of drive pulleys 26, which are individually actuated by a corresponding electric motor 25 included in the corresponding drive unit 4. A transmission belt 27, typically composed of a toothed belt, passes over each drive pulley 26 and the corresponding driven pulley 18C. The drive disc 18 is thus rotated by the corresponding drive unit 4. In particular, both drive discs 18 can be driven individually by the electric motor 25 included in the drive unit 4.

[0040] like Figure 3 and Figure 4 As shown, the main wheel 19 is positioned substantially coaxially with the drive disc 18 between the drive discs 18, and includes an annular member 31 and a plurality of driven rollers 32. Each driven roller 32 is supported by the annular member 31 so as to be tangentially rotated about a specific point on the periphery of the annular member 31. The driven rollers 32 are arranged at equal intervals in the circumferential direction of the annular member 31.

[0041] The main wheel 19 is laterally pressed between the drive discs 18 and supported only by the drive discs 18. More specifically, the drive roller 18B of the drive disc 18 is in rolling contact with the driven roller 32 of the main wheel 19. Figure 3 As shown, the drive roller 18B contacts the driven roller 32, causing the inner circumference of the main wheel 19 to be pushed radially outward by the drive roller 18B of the drive disc 18.

[0042] The operating mode of the omnidirectional wheel 3 will now be described. When the drive disc 18 rotates at the same speed in the normal direction, the driven roller 32 does not rotate, and the main wheel 19 is driven to rotate in the normal or forward direction. As a result, the vehicle moves forward in a straight line. Similarly, when the drive disc 18 rotates in the opposite direction at the same speed, the vehicle moves backward in a straight line.

[0043] When the drive disc 18 rotates at the same speed in opposite directions, the driven roller 32 rotates in the corresponding direction, causing the vehicle to move laterally while the main wheel 19 remains stationary. When the drive disc 18 rotates at different speeds, the vehicle travels in a tilt direction determined by the speed difference of the drive disc 18.

[0044] The control unit 7 is configured to control the drive unit 4 based on signals provided by a load sensor 6 located between the body 2 and the handle 5. The load sensor 6 detects the magnitude and direction of the operating force (load) applied to the handle 5 by the user, and determines the direction of travel and traction of the trolley 1 based on the signals from the load sensor 6 by controlling the amount of control of the electric motor 25 of the drive unit 4.

[0045] Due to the characteristics of the drive unit 4 described above, the control unit 7 can move the cart 1 forward, backward, laterally, or in any desired tilt direction according to the load applied by the user to the handle 5. When the cart 1 travels in a straight line forward or backward for most of the time, the driven rollers 32 may each remain in contact with the ground at a single point. As a result, the driven rollers 32 may wear unevenly. To overcome this problem, the cart 1 of the illustrated embodiment has a function to prevent uneven wear of the driven rollers 32. More specifically, the control unit 7 is configured to move the cart 1 laterally a short distance. This lateral movement may correspond to half a turn of the driven roller 32. By moving the cart 1 laterally according to a predetermined schedule, the uneven wear of the driven rollers 32 can be reduced or eliminated. When the two omnidirectional wheels 3 are used one after another as in the illustrated embodiment, the drive unit 4 can be controlled by the control unit 7 so that the two omnidirectional wheels 3 travel laterally in opposite directions. Therefore, the driven rollers 32 of the two omnidirectional wheels 3 rotate at a certain angle, allowing the ground contact point of the driven rollers 32 to change, without actually causing the cart 1 to move sideways. This avoids uneven wear of the driven rollers 32 without causing any unnecessary movement of the cart 1 or any discomfort to the user of the cart 1.

[0046] The trolley 1 is equipped with a wear calculation system 100 according to a first embodiment of the present invention. Since the trolley 1 primarily travels forward in a straight line during use, the wear calculation system 100 is configured to calculate or estimate the wear of the omnidirectional wheels 3 as is believed to occur when the trolley 1 travels forward in a straight line. The wear calculation system 100 is integrated into a control unit 7 that controls the overall operation of the trolley 1. Alternatively, the wear calculation system 100 may be a device separate from the control unit 7.

[0047] The control panel is located on the vehicle body 2, near the handle 5. For example... Figure 1 and Figure 2 As shown, the operation panel includes a switch 43 and a display unit 44. The switch 43 is used to notify the wear calculation system 100 that the omnidirectional wheel 3 has been replaced, and the display unit 44 is used to display information about the monitored wheel wear to the user. In the following description, it is assumed that the two omnidirectional wheels 3 wear in a similar manner, so only one of the omnidirectional wheels 3 is considered.

[0048] The wear calculation system 100 includes a rotation measurement module 48 and a travel distance calculation module 49. The rotation measurement module 48 includes a rotation sensor for detecting the rotation of the omnidirectional wheel 3 (or, in particular, the rotation of the main wheel 19). The travel distance calculation module 49 includes an acceleration sensor (not shown in the figure), such as an accelerometer and a gyroscope, for providing data for travel distance calculation.

[0049] The following will refer to Figure 5 The flowchart shown describes the wear calculation process performed by the wear calculation system 100. First, the wear calculation system 100 determines whether the omnidirectional wheel 3 has been changed to a new omnidirectional wheel based on the signal from the switch 43, and operates the switch 43 when the omnidirectional wheel 3 is replaced. When the trolley 1 is newly transported or the omnidirectional wheel 3 is newly replaced, a new wear calculation process begins (step S101).

[0050] When the trolley 1 starts to move forward by operating the handle 5, the rotation measurement module 48 detects the rotation of the main wheel 19 as the rotation count (quantity) (cumulative rotation) (step S102).

[0051] Then, the travel distance calculation module 49 detects the acceleration of the trolley 1 in the forward and backward direction using an acceleration sensor (step S103). By integrating the forward and backward acceleration twice with respect to time, the travel distance of the trolley 1 in the forward and backward direction is calculated.

[0052] The distance traveled by the trolley 1, calculated from the forward and backward acceleration, is compared with the distance traveled by multiplying the number of revolutions of the main wheel 19 accumulated by the revolutions measurement module 48 by the circumferential length of the main wheel 19 (which is calculated by multiplying the diameter of the main wheel 19 by π). By comparing the two values ​​of the travel distance calculated by these two methods, the change in the diameter of the main wheel 19 can be calculated (step S104). The wear calculated in this way is called "first wear". During the service life of the main wheel 19, the measurement process can be performed according to a prescribed schedule in terms of time or the distance traveled by the trolley. More specifically, when the number of revolutions of the main wheel 19 during the prescribed time period is n, the forward and backward travel distance of the trolley 1 during that time period is d, the radius of the main wheel 19 is r, and the wear of the main wheel 19 (first wear) is Δr, the following relationship holds:

[0053] d = 2π(r - Δr) × n

[0054] Therefore, the wear pattern shown below can be obtained:

[0055] Δr=r-d / (2πn)

[0056] Therefore, by repeating this measurement process according to a prescribed schedule, the wear history of the main wheel 19 can be obtained. Furthermore, since the calculated wear may fluctuate from one measurement value to another, least squares, moving averages, and other techniques can be used to smooth the data.

[0057] The wear calculation system 100 uses the first wear calculated in this way as the wear (wheel wear) of the omnidirectional wheels 3 caused by the trolley 1 traveling in the front-to-back direction. The calculated wheel wear can be transmitted to the display unit 44 to display the wheel wear on the screen of the display unit 44. In addition, if the wear is calculated separately for the two omnidirectional wheels 3, the display unit 44 can be configured to display the wear of the omnidirectional wheels 3 separately, so that the user can determine which of the omnidirectional wheels 3 is worn to the point where it needs to be replaced.

[0058] The advantages of the wear calculation system 100 according to the first embodiment will now be discussed. Wear on the main wheels 19 of the trolley 1 can be calculated even when traveling in areas where GPS location information is unavailable. Furthermore, since the vehicle location information obtained by using the accelerometer can be processed more frequently than when using GPS satellite signals, wear can be calculated with relatively high accuracy.

[0059] The following will refer to Figure 6The flowchart shown describes the wear calculation process performed by the wear calculation system 200 according to the second embodiment of the present invention. The wear calculation process performed by the wear calculation system 200 of the second embodiment calculates the wear (wheel wear) of the omnidirectional wheel 3 by considering not only the forward and backward travel of the omnidirectional wheel 3 but also the lateral travel of the omnidirectional wheel 3. In this wear calculation system 200, the rotation speed measurement module 48 is configured to measure not only the rotation speed of the main wheel 19 but also the rotation speed of the driven roller 32 about its rotation center line. Since the wear calculation system 200 is otherwise similar to the wear calculation system 100 of the first embodiment, components identical to those in the first embodiment will be omitted in the following description.

[0060] When the trolley 1 is newly transported or the omnidirectional wheel 3 is newly replaced, a new wear calculation process begins (step S201). As the trolley 1 moves, the rotation speed measurement module 48 of the wear calculation system 200 first detects the rotation speed of the main wheel 19. The rotation speed measurement module 48 of the wear calculation system 200 also detects the rotation speed of the driven roller 32. The rotation speeds of the main wheel 19 and the driven roller 32 are individually accumulated (step S202).

[0061] The travel distance calculation module 49 of the wear calculation system 200 detects the forward and backward acceleration and the lateral acceleration of the trolley 1 using an acceleration sensor (step S203). By integrating the forward and backward acceleration and the lateral acceleration twice with respect to time, the travel distance of the trolley 1 in the forward and backward directions and the lateral direction can be calculated respectively.

[0062] The travel distance of the trolley 1 calculated from the forward and backward acceleration is compared with the travel distance calculated by multiplying the number of revolutions of the main wheel 19 accumulated by the revolutions measurement module 48 by the circumferential length of the main wheel 19 (which is calculated by multiplying the diameter of the main wheel 19 by π). By comparing the two values ​​of travel distance obtained by these two methods, the change in the diameter of the main wheel 19 can be calculated (step S204). The wear calculated in this way is called "second wear". Similarly, the travel distance of the trolley 1 calculated from the lateral acceleration is compared with the travel distance calculated by multiplying the number of revolutions of the driven roller 32 accumulated by the revolutions measurement module 48 by the circumferential length of the driven roller 32 (which is calculated by multiplying the diameter of the driven roller 32 by π). By comparing the two values ​​of travel distance obtained by these two methods, the change in the diameter of the driven roller 32 can be calculated (step S204). The wear calculated in this way is called "third wear". Similar to the first embodiment, during the service life of the main wheel 19, the measurement process can be performed according to a prescribed schedule in terms of time or the distance traveled by the trolley 1.

[0063] The sum of the second and third wear is taken as the first wear (step S205). Therefore, the first wear provides the wear of the main wheel 19. According to a modified embodiment of the invention, to illustrate the contribution of the trolley 1's forward and lateral travel to the wear of the main wheel 19, a first predetermined factor and a second predetermined factor can be multiplied by the second and third wear, respectively, and the sum of these multiplied values ​​can be taken as the first wear (S205). In other words, the second and third wears are weighted by certain factors, and the first wear is calculated as the weighted sum of the second and third wears. According to yet another modified embodiment of the invention, the larger of the second and third wears can be taken as the first wear. Again, in this case, to illustrate the contribution of the trolley 1's forward and lateral travel to the wear of the main wheel 19, before determining which of these values ​​is larger, the first predetermined factor and the second predetermined factor can be multiplied by the second and third wear, respectively. In any case, the first wear is then transmitted to the display unit 44 as the wear of the main wheel 19 on the display unit 44.

[0064] The advantages of the wear calculation system 200 of the second embodiment will now be discussed. In addition to the forward and backward travel of the trolley 1, the wear calculation system 200 of the second embodiment also considers the lateral travel of the trolley 1 in the lateral direction. Therefore, wheel wear can be estimated with higher accuracy.

[0065] Even higher accuracy can be obtained by multiplying certain factors by the forward and backward travel distances and the lateral travel distances when calculating or estimating wheel wear.

[0066] The following will refer to Figure 7The flowchart shown describes the wear calculation process performed by the wear calculation system 300 according to a third embodiment of the present invention. In the wear calculation process performed by the wear calculation system 300 of the third embodiment, the wear (wheel wear) of the omnidirectional wheel 3 is calculated by considering the front-to-back travel and lateral travel of the omnidirectional wheel 3. Therefore, the rotation speed measurement module 48 is configured to measure not only the rotation speed of the main wheel 19, but also the rotation speed of the driven roller 32 about its rotation centerline. Furthermore, the wear calculation system 300 also includes: a temperature measurement module 52, placed on the vehicle body 2 so as to be opposite to the driven rollers 32, for measuring the temperature of the driven rollers 32 in a non-contact manner; a distance measurement module 50, placed on the vehicle body 2 so as to be laterally opposite to the main wheel 19, for measuring the distance between the central axis Y1 and a point on the outer periphery of the main wheel 19 (or drive roller 32) directly below the central axis Y1; and a vertical load sensor 54 for detecting the vertical load applied to each omnidirectional wheel 3. The signals provided by these modules are forwarded to the control unit 7. The effective diameter of the main wheel 19 or driven roller 32 varies depending on the load on the trolley 1 on the main wheel 19. Furthermore, the elastic modulus of the driven roller 32 varies depending on the ambient temperature. As a result, the diameter of the main wheel 19 or driven roller 32 varies depending on the vertical load and the elastic modulus or ambient temperature. Preferably, the vertical load and temperature on the diameter of the main wheel 19 or driven roller 32 are taken into account, and the effect of the diameter variation of the main wheel 19 or driven roller 32 caused by the deformation of the main wheel 19 (driven roller 32) is eliminated from the calculation of wear on the main wheel 19 or driven roller 32.

[0067] The wear calculation process performed by the wear calculation system 300 of the third embodiment is similar to the wear calculation process performed by the wear calculation system 200 of the second embodiment. More specifically, steps S201 to S205 are substantially the same as steps S301 to S305.

[0068] However, in the third embodiment, in step S306, the wear calculation system 300 uses a distance measurement module 50 (which may consist of a contact probe or a laser sensor) to measure the distance between the central axis Y1 and a point on the outer periphery of the main wheel 19 directly below the central axis Y1.

[0069] Subsequently, the wear calculation system 300 determines the difference between the current distance between the central axis Y1 measured by the distance measurement module 50 and a point on the outer periphery of the main wheel annular member 31, and the initial distance at the start of the corresponding wear calculation process. The wear given as the difference between the initial distance and the current distance is used as the "fourth wear" (step S307). Then, the wear calculation system 300 compares the first wear and the fourth wear (S308). If the first wear is greater than the fourth wear, the first wear is used as the wear (wheel wear) of the omnidirectional wheel 3 (step S309). If the fourth wear is greater than the first wear, the fourth wear is used as the wear (wheel wear) of the omnidirectional wheel 3 (step S310). Therefore, since the wear (wheel wear) of the omnidirectional wheel 3 is obtained by comparing the wear values ​​calculated using two different methods, the accuracy of the wear calculation is further improved.

[0070] The present invention has been described with reference to specific embodiments, but the invention is not limited to these embodiments and can be modified in various ways without departing from the scope of the invention. For example, the display unit 44 can display any combination of wheel wear, first wear, second wear, third wear, and fourth wear on its screen. Moreover, various features of different embodiments can be freely combined without departing from the scope of the invention.

Claims

1. A wear calculation system for calculating the wear of vehicle wheels, the wear calculation system comprising: A rotational speed sensor, configured to detect the rotational speed of the wheel; An acceleration sensor configured to detect the acceleration of the vehicle in the direction of travel; as well as A control unit configured to calculate the distance traveled by the vehicle based on the vehicle's acceleration, and to calculate the wear based on the distance traveled and the number of wheel rotations. The wheel includes a main wheel and a pair of drive discs. The main wheel includes an annular member having a laterally extending central axis and a plurality of driven rollers rotatably supported at corresponding positions of driven rollers by the tangent of the annular member around the annular member. Each drive disc includes a hub and a plurality of drive rollers. The hub is supported by the vehicle body on a corresponding side of the main wheel so as to rotate about a rotation centerline substantially coaxial with the central axis of the annular member. The plurality of drive rollers are circumferentially positioned on the hub so as to rotate about the rotation centerline at an angle to the rotation centerline of the hub and engage with the driven rollers. The rotational speed sensor is configured to detect the rotational speed of the main wheel and the rotational speed of the driven roller; the acceleration sensor is configured to detect the longitudinal acceleration and lateral acceleration of the vehicle; and the control unit is configured to calculate the longitudinal travel distance based on the longitudinal acceleration, calculate the second wear based on the longitudinal travel distance and the rotational speed of the main wheel, calculate the lateral travel distance based on the lateral acceleration, calculate the third wear based on the lateral travel distance and the rotational speed of the driven roller, and calculate the first wear based on the second wear and the third wear, wherein the first wear is the wear of the wheel.

2. The wear calculation system according to claim 1, wherein, The wear is calculated as a reduction in the outer diameter of the wheel, which is obtained from the difference between the distance traveled calculated based on the vehicle's acceleration and the distance traveled calculated based on the wheel's rotational speed.

3. The wear calculation system according to claim 1, wherein, The control unit calculates the sum of the second wear and the third wear as the first wear.

4. The wear calculation system according to claim 1 or 3, wherein, The wear calculation system further includes a measuring device for measuring the distance between the central axis of the main wheel and a point on the outer periphery of the main wheel directly below the central axis. The control unit is configured to calculate a fourth wear by comparing the measured distance with an initial distance between the central axis of the main wheel and the point on the outer periphery of the main wheel. When the fourth wear is greater than the first wear, the fourth wear is used instead of the first wear as the wear of the wheel.

5. The wear calculation system according to claim 1 or 3, wherein, The vehicle is equipped with a drive unit for rotating the driven roller according to a predetermined schedule as the vehicle travels in a forward-backward direction.

6. The wear calculation system according to claim 5, wherein, The vehicle is provided with a pair of wheels arranged on either side, and when the vehicle travels in the forward-backward direction, the drive unit operates such that the driven roller of the main wheel rotates in the opposite direction according to a predetermined schedule.

7. The wear calculation system according to claim 1 or 3, wherein, The wear calculation system further includes a display unit that displays at least one of the wheel wear, the first wear, the second wear, and the third wear.

8. The wear calculation system according to claim 1 or 3, wherein, The wear calculation system further includes a temperature sensor for detecting the temperature of the driven roller and a vertical load sensor for detecting the vertical load of the vehicle. The control unit is configured to calculate the effective diameter of the driven roller and / or the main wheel by taking into account the elastic modulus of the driven roller at the detected temperature and the detected vertical load, and to calculate the travel distance based on the rotational speed of the driven roller and / or the rotational speed of the main wheel by taking into account the effective diameter.

9. The wear calculation system according to any one of claims 1 to 3, wherein, The vehicle is provided with a drive unit for driving the wheels, and the rotation sensor is configured to count the rotation of the output of the drive unit, and obtain the rotation of the wheels by multiplying the count of the rotation of the output of the drive unit by a coefficient greater than 0 and less than 1.

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