Chassis control methods for aerial work platforms and aerial work platforms

Abstract

This invention belongs to the technical field of aerial work platforms, and discloses a chassis control method for an aerial work platform and the platform itself. The chassis control method includes, upon receiving an instruction to extend or retract the outriggers, controlling the extension / retraction cylinders to rotate the outriggers relative to the main body; simultaneously calculating the rotation angle of the outriggers; and controlling the steering cylinders to rotate the wheels in the opposite direction to the outrigger rotation, with the wheel rotation angle equal to the outrigger rotation angle. This chassis control method ensures that after the outriggers are extended or retracted, the wheels always align with the direction of travel, preventing the need to adjust the wheels during movement. This facilitates the wheels conforming to the turning angle relationship, effectively avoiding excessive load on the power source during movement due to misalignment of the wheels, which could lead to slowdown or stalling. It also effectively prevents abnormal tire wear.

Description

Technical Field

[0001] This invention relates to the field of aerial work platform technology, and in particular to a chassis control method for an aerial work platform and an aerial work platform. Background Technology

[0002] To ensure the stability of the entire vehicle during high-altitude operations, aerial work platforms typically have a very wide chassis. However, an excessively wide chassis can cause inconvenience during transportation. Therefore, the chassis is designed with a retractable structure, and the wheels can be extended or retracted to ensure stability and passability.

[0003] In existing technology, the wheels are deployed or retracted by the outriggers rotating relative to the chassis body. However, when the outriggers rotate, the wheels tilt relative to the vehicle's direction of travel. If the wheel direction is not adjusted, the tilted wheels will generate significant friction with the ground when the aerial work platform moves, causing excessive tire wear and increasing the load on the power source, potentially leading to engine slowdown or stalling. Adjusting the direction during travel will also create significant friction, resulting in excessive tire wear, engine slowdown, and stalling. Furthermore, adjusting the wheel direction during travel may cause the travel direction to be inconsistent with the operator's operating direction, leading to operational inconvenience. Summary of the Invention

[0004] The purpose of this invention is to provide a chassis control method for an aerial work platform and an aerial work platform that can automatically adjust the wheel direction to the travel direction of the aerial work platform when the outriggers are extended or retracted, so as to prevent excessive tire wear and excessive load caused by the wheels not conforming to the turning angle relationship when traveling after the outriggers have been extended or retracted.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] The chassis control methods for aerial work platforms include:

[0007] Upon receiving an instruction to extend or retract the outriggers, the system controls the expansion and retraction cylinders to rotate the outriggers relative to the main body. Simultaneously, the system calculates the rotation angle of the outriggers and controls the steering cylinders to rotate the wheels in the opposite direction to the rotation of the outriggers, with the rotation angle of the wheels equal to the rotation angle of the outriggers.

[0008] As an alternative, the support leg is a right-angle rod, which includes a first rod and a second rod that are perpendicularly connected to each other. The first rod is hinged to the main body, and the second rod is hinged to the wheel. By calculating α1, the wheel is controlled to rotate so that α1 = α2. When α1 = α2, the rotation angle of the wheel is the same as the rotation angle of the support leg.

[0009] Where α1 is the angle between the line connecting the two first rods in each group to the hinge point of the main body and the first rod, and α2 is the angle between the second rod and the center line of the wheel.

[0010] As an alternative, α1 = ARCcos(((L2-L1) / 2) / L3);

[0011] Wherein, L1 is the length of the expansion cylinder, L2 is the distance between the hinge points of the two first rods in each group and the main body, and L3 is the distance between the hinge point of the first rod and the main body and the hinge point of the first rod and the expansion cylinder.

[0012] As an optional solution, the two expansion and contraction cylinders are designated as a front expansion and contraction cylinder and a rear expansion and contraction cylinder, respectively. When controlling the operation of the front and rear expansion and contraction cylinders, both cylinders initially expand and contract at their maximum expansion and contraction speed, and the real-time lengths of the front and rear cylinders are monitored in real time. If the absolute value of the difference between the real-time lengths of the front and rear cylinders is within a first set value, then the front and rear cylinders maintain their maximum expansion and contraction speed. If the difference between the real-time lengths of the front and rear cylinders is less than the real-time length of the rear cylinder, then the front and rear cylinders continue to expand and contract at their maximum speed. If the difference between the real-time lengths of the front and rear expansion cylinders is greater than the second set value, the expansion speed of the front expansion cylinder is reduced, while the rear expansion cylinder maintains its maximum expansion speed. If the difference between the real-time lengths of the front and rear expansion cylinders is greater than the second set value, the expansion speed of the rear expansion cylinder is reduced, while the front expansion cylinder maintains its maximum expansion speed. If the absolute value of the difference between the real-time lengths of the front and rear expansion cylinders is between the first and second set values, the current expansion speeds of the front and rear expansion cylinders remain unchanged. The second set value is greater than the first set value.

[0013] As an alternative, the expansion and contraction speed of the expansion and contraction cylinder is achieved by controlling the current.

[0014] As an optional solution, if the absolute value of the difference between the real-time lengths of the front and rear expansion cylinders is within the first set value, the control current of both the front and rear expansion cylinders is set to its maximum value; if the difference between the real-time length of the front and rear expansion cylinders is greater than the second set value, the control current of the front expansion cylinder decreases at a preset rate, while the rear expansion cylinder maintains its maximum control current; if the difference between the real-time length of the rear and front expansion cylinders is greater than the second set value, the control current of the rear expansion cylinder decreases at a preset rate, while the front expansion cylinder maintains its maximum control current; if the absolute value of the difference between the real-time lengths of the front and rear expansion cylinders is between the first and second set values, the current control currents of both the front and rear expansion cylinders remain unchanged.

[0015] As an optional solution, the wheel rotation control process is as follows:

[0016] The angle α2 between the centerline of the wheel and the second rod is detected in real time. If the absolute value of the difference between α2 and α1 is less than or equal to a third set value, the wheel stops rotating; if the absolute value of the difference between α2 and α1 is greater than the third set value, the wheel is controlled to continue rotating.

[0017] As an alternative, the rotation of the wheel is controlled by a switching valve, with T as the time period of the switching valve, the switching valve is energized t milliseconds each time, and the maximum number of times the switching valve is energized within one time period is nmax = T / t;

[0018] When the absolute value of the difference between α2 and α1 is greater than the third set value, then n = k * |α1 - α2|, and when n > nmax, then n = nmax;

[0019] When the absolute value of the difference between α2 and α1 is less than the third set value, then n = 0.

[0020] As an alternative, the rotation of the wheel is controlled by a switching valve, with T as the time period of the switching valve, and the valve is energized n times in each time period. The maximum energizing time tmax = T / n in one time period of the switching valve.

[0021] When the absolute value of the difference between α2 and α1 is greater than the third set value, then t = k * |α1 - α2|, and when t > tmax, t = tmax;

[0022] When the absolute value of the difference between α2 and α1 is less than the third set value, then t = 0.

[0023] Aerial work platform, including the chassis control method for aerial work platform as described in any of the above embodiments.

[0024] The beneficial effects of this invention are:

[0025] This invention provides a chassis control method for an aerial work platform. When the outriggers are extended or retracted, the method controls the wheels to rotate in the opposite direction of the outrigger rotation by detecting the rotation angle of the outriggers relative to the main body. The rotation angle of the wheels is the same as that of the outriggers, ensuring that the wheels remain aligned with the travel direction after the outriggers are extended or retracted. This facilitates the movement and steering of the aerial work platform and prevents the need for wheel adjustments during movement. This chassis control method ensures that the wheels are always aligned with the travel direction after the outriggers are extended or retracted, and that the wheels conform to the turning angle relationship. This effectively avoids excessive load on the power source during movement, which could lead to slowdown or stalling due to wheels not conforming to the turning angle relationship. It also effectively prevents abnormal tire wear and improves tire lifespan. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the outriggers of the chassis of the aerial work platform involved in the embodiment of the present invention when retracted;

[0027] Figure 2 This is a schematic diagram of the outriggers of the chassis of the aerial work platform involved in the embodiment of the present invention when they are deployed;

[0028] Figure 3 This is a simplified diagram showing the relationship between L1, L2, L3, and α1 involved in the embodiments of the present invention.

[0029] In the picture:

[0030] 10. Main body; 20. Wheels; 30. Outriggers; 31. First rod; 32. Second rod; 40. Expansion / contraction cylinder; 41. Front expansion / contraction cylinder; 42. Rear expansion / contraction cylinder; 50. Steering cylinder. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] This invention provides an aerial work platform, which includes a chassis that supports the entire vehicle and ensures its stability. Figures 1-2 As shown, the chassis includes a main body 10 and four wheels 20. The four wheels 20 are respectively hinged to the four corners of the main body 10 via four support legs 30. The four wheels 20 are arranged in pairs, and the two groups of wheels 20 are symmetrically arranged. An expansion and contraction cylinder 40 is hinged between the two support legs 30 in each group. The two expansion and contraction cylinders 40 can drive the two groups of support legs 30 to expand to ensure the stability of the whole vehicle, or to retract to ensure passability. A steering cylinder 50 is provided between each support leg 30 and its corresponding wheel 20. The steering cylinder 50 can drive the wheel 20 to rotate relative to the support leg 30.

[0036] The aerial work platform uses a retractable hydraulic cylinder 40 to extend and retract the four outriggers 30. The wheels 20 are mounted on the outriggers 30, which allows the four wheels 20 to extend outward or retract inward, thus balancing the stability and maneuverability of the aerial work platform.

[0037] To ensure that the centerline of the four wheels 20 is in the same direction of travel after they are extended outward or retracted inward, this embodiment of the invention also provides a chassis control method for an aerial work platform, including the following steps: After receiving an instruction to extend or retract the outriggers 30, the expansion cylinder 40 is controlled to rotate relative to the main body 10, and the rotation angle of the outriggers 30 is calculated. Then, the steering cylinder 50 is activated to make the wheels 20 rotate in the opposite direction to the rotation of the outriggers 30, and the rotation angle of the wheels 20 is the same as the rotation angle of the outriggers 30. For example, taking the left front wheel 20 as an example, after the expansion cylinder 40 drives the left front outrigger 30 to extend outward and rotate counterclockwise, the left front wheel 20 rotates clockwise, and the rotation angle is the same as the rotation angle of the left front outrigger 30.

[0038] The chassis control method of this aerial work platform ensures that the wheels 20 are always aligned with the direction of travel after the outriggers 30 are extended or retracted, preventing the need to adjust the wheels 20 during travel. This facilitates the travel and steering of the aerial work platform. The wheels 20 conform to the turning angle relationship, effectively avoiding excessive load on the power source during travel due to wheels not conforming to the turning angle relationship, which could lead to slowdown or stalling. It also prevents abnormal tire wear on the wheels 20, thus improving tire lifespan.

[0039] Continue to refer to Figure 1 and Figure 2 The outrigger 30 is a right-angle rod, which includes a first rod 31 and a second rod 32 that are perpendicularly connected to each other. The first rod 31 is hinged to the main body 10, and the second rod 32 is hinged to the wheel 20. The angle between the line connecting the two first rods 31 in each group to the hinge point of the main body 10 and the first rod 31 is set as α1. The angle between the second rod 32 and the center line of the wheel 20 is set as α2. Through trigonometric relationships, it can be concluded that when α1 and α2 are equal, the center line of the wheel 20 is in the same direction of travel. Therefore, when the outrigger 30 stops rotating, α1 is calculated, and then the wheel 20 is controlled to rotate at the same angle value as the outrigger 30, so that α1 and α2 are equal. The logic control is simple.

[0040] Furthermore, combined Figure 3 α1 = ARCcos(((L2-L1) / 2) / L3); where L1 is the length of the expanding / contracting cylinder 40, which can be detected by a length sensor; L2 is the distance between the hinge points of the two first rods 31 in each group and the main body 10; and L3 is the distance between the hinge points of the first rod 31 and the main body 10 and the hinge points of the first rod 31 and the expanding / contracting cylinder 40. L2 and L3 are constant values ​​and can be measured by a ruler. α1 is calculated using the above formula, and the calculation process is simple.

[0041] To ensure that the length error between the two expanding cylinders 40 is within the allowable range after they stop, so that the width between the two wheels 20 in each group is basically the same when the two expanding cylinders 40 stop at any position, thus ensuring that the turning angle of the wheel 20 matches the steering angle and further reducing tire wear, for ease of explanation, the two expanding cylinders 40 are defined as the front expanding cylinder 41 and the rear expanding cylinder 42, respectively.

[0042] In the initial state, both the front expansion cylinder 41 and the rear expansion cylinder 42 are controlled to expand and contract at their maximum expansion and contraction speeds. The real-time lengths of the front and rear expansion cylinders 41 and 42 are monitored. If the absolute value of the difference between their real-time lengths is within a first set value, then the front and rear expansion cylinders 41 and 42 maintain their maximum expansion and contraction speeds. Since the absolute value of the difference between their real-time lengths is within the first set value, it indicates that the lengths of the front and rear expansion cylinders 41 and 42 are within the allowable range. Therefore, the front and rear expansion cylinders 41 and 42 operate at their maximum speed to ensure work efficiency.

[0043] If the real-time length of the front expansion cylinder 41 minus the real-time length of the rear expansion cylinder 42 is greater than the second set value, then the expansion speed of the front expansion cylinder 41 is reduced, while the rear expansion cylinder 42 maintains the maximum expansion speed, so that the real-time length error between the front expansion cylinder 41 and the rear expansion cylinder 42 is within the allowable range; if the real-time length of the rear expansion cylinder 42 minus the real-time length of the front expansion cylinder 41 is greater than the second set value, then the expansion speed of the rear expansion cylinder 42 is reduced, while the front expansion cylinder 41 maintains the maximum expansion speed, so that the real-time length error between the front expansion cylinder 41 and the rear expansion cylinder 42 is within the allowable range.

[0044] If the absolute value of the difference between the real-time lengths of the front expansion cylinder 41 and the rear expansion cylinder 42 is between the first set value and the second set value, then the current expansion and contraction speeds of the front expansion cylinder 41 and the rear expansion cylinder 42 remain unchanged. For example, if both the front expansion cylinder 41 and the rear expansion cylinder 42 operate at maximum speed, then if the absolute value of the difference between the real-time lengths of the front expansion cylinder 41 and the rear expansion cylinder 42 is between a first set value and a second set value, then the front expansion cylinder 41 and the rear expansion cylinder 42 continue to operate at maximum speed. If the difference between the real-time length of the front expansion cylinder 41 and the real-time length of the rear expansion cylinder 42 is greater than the second set value, then the expansion speed of the front expansion cylinder 41 is reduced, while the rear expansion cylinder 42 maintains its maximum expansion speed. If the absolute value of the difference between the real-time lengths of the front expansion cylinder 41 and the rear expansion cylinder 42 is between the first set value and the second set value, then the front expansion cylinder 41 maintains its reduced expansion speed, while the rear expansion cylinder 42 maintains its maximum expansion speed. The second set value is greater than the first set value.

[0045] In this embodiment, the first setting value is 10mm and the second setting value is 20mm.

[0046] Optionally, the expansion and contraction speed of the expansion cylinder 40 is achieved by controlling the current, which is controlled by a switching valve, making the control simple.

[0047] The current control process is as follows:

[0048] If the absolute value of the difference between the real-time lengths of the front expansion cylinder 41 and the rear expansion cylinder 42 is within 10mm, the control current of both the front expansion cylinder 41 and the rear expansion cylinder 42 is set to their maximum values. If the difference between the real-time length of the front expansion cylinder 41 and the real-time length of the rear expansion cylinder 42 is greater than 20mm, the control current of the front expansion cylinder 41 decreases at a preset rate, i.e., the preset value is reduced for each program execution cycle, while the rear expansion cylinder 42 maintains its maximum control current. If the difference between the real-time length of the rear expansion cylinder 42 and the real-time length of the front expansion cylinder 41 is greater than 20mm, the control current of the rear expansion cylinder 42 decreases at a preset rate, i.e., the preset value is reduced for each program execution cycle, while the front expansion cylinder 41 maintains its maximum control current. If the absolute value of the difference between the real-time lengths of the front expansion cylinder 41 and the rear expansion cylinder 42 is between 10mm and 20mm, the current control currents of both the front expansion cylinder 41 and the rear expansion cylinder 42 remain unchanged. Optionally, the default value can be selected as 10mA. Of course, other values ​​can also be selected, and there are no restrictions here.

[0049] The rotation control of wheel 20 is as follows: the current angle α2 between the center line of wheel 20 and the second rod 32 is detected in real time by the angle sensor, and α1 is the target angle. If the absolute value of the difference between α2 and α1 is less than or equal to the third set value, it means that wheel 20 has rotated to an angle value that is basically the same as that of outrigger 30; if the absolute value of the difference between α2 and α1 is greater than or equal to the third set value, it means that the center line of wheel 20 is not in the direction of travel and needs to continue to rotate.

[0050] For example, the third setting is 0.5°. Taking the left front wheel 20 as an example, when the expansion cylinder 40 controls the left front outrigger 30 to expand counterclockwise, it controls the left front wheel 20 to rotate clockwise. When the absolute value of the difference between α2 and α1 is less than or equal to 0.5°, the left front wheel 20 stops rotating. When α1-α2>0.5°, it means that the left front wheel 20 is lagging behind, and the left front wheel 20 continues to rotate clockwise. When α2-α1>0.5°, it means that the left front wheel 20 is overshooting, and the left front wheel 20 rotates counterclockwise.

[0051] Wheel steering can be controlled using either a proportional valve or an on / off valve. When using a proportional valve, the steering ratio can be directly controlled proportionally. The control principle is that the larger the deviation, the greater the current and voltage supplied to the proportional valve. For example, a 50% deviation requires 50% of the rated current, and a 60% deviation requires 60% of the rated current. When overshoot occurs, the proportional valve is de-energized, or another proportional valve is used for reverse adjustment. When using an on / off valve, current technology typically only has two states: energized and de-energized. When the deviation is too large, the on / off valve remains energized until the deviation is within an acceptable range, then de-energizes. When the deviation is adjusted to the point of overshoot, the on / off valve is de-energized, or another on / off valve is used for reverse adjustment. The proportional valve's current can range from the dead zone to the rated current, while the on / off valve either supplies the rated current or is de-energized.

[0052] In this embodiment, a switching valve is used for control. Optionally, if T is the time period of the switching valve, and the switching valve is energized t milliseconds each time, and T and t are set as fixed values, then the maximum number of energizations within one time period of the switching valve is nmax = T / t. When the absolute value of the difference between α2 and α1 is greater than the third set value, it means that the wheel 20 needs to rotate, then n = k * |α1-α2|, where k is a constant. When n > nmax is calculated, then n = nmax. When the absolute value of the difference between α2 and α1 is less than the third set value, it means that the error is acceptable, and the wheel 20 is not adjusted, then n = 0.

[0053] With time period T, the power is applied for t milliseconds each time, and the power is applied n times in each time period. T and t are fixed, and the size of n is controlled according to the size of α1-α2.

[0054] Optionally, the rotation of the wheel 20 is controlled by a switching valve, with T as the time period of the switching valve. The valve is energized n times within each time period. T and n are set as fixed values. The maximum energizing time tmax = T / n within one time period of the switching valve is: When the absolute value of the difference between α2 and α1 is greater than a third set value, it indicates that the wheel 20 needs to rotate, then t = k * |α1 - α2|, where k is a constant. When t > tmax, t = tmax. When the absolute value of the difference between α2 and α1 is less than the third set value, it indicates that the error of the wheel 20 is within the allowable range, and the wheel 20 does not need to rotate, then t = 0.

[0055] With time period T, the circuit is energized n times in each time period, and each energization lasts for t milliseconds. T and n are fixed, and the value of t is controlled according to the value of α1-α2.

[0056] Through the control logic of the above-mentioned switching valve, precise adjustment can be achieved, effectively preventing overshoot.

[0057] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A chassis control method for an aerial work platform, characterized in that, include: Upon receiving an instruction to extend or retract the outrigger (30), the expansion cylinder (40) is controlled to rotate the outrigger (30) relative to the main body (10). At the same time, the rotation angle of the outrigger (30) is calculated, and the steering cylinder (50) is controlled to rotate the wheel (20) in the opposite direction to the rotation of the outrigger (30), and the rotation angle of the wheel (20) is equal to the rotation angle of the outrigger (30). The support leg (30) is a right-angle rod. The support leg (30) includes a first rod (31) and a second rod (32) that are perpendicularly connected to each other. The first rod (31) is hinged to the main body (10), and the second rod (32) is hinged to the wheel (20). By calculating α1, the wheel (20) is controlled to rotate so that α1 = α2. When α1 = α2, the angle of rotation of the wheel (20) is the same as the angle of rotation of the support leg (30). Where α1 is the angle between the line connecting the two first rods (31) in each group to the hinge point of the main body (10) and the first rod (31), and α2 is the angle between the second rod (32) and the center line of the wheel (20); The two expansion and contraction cylinders (40) are a front expansion and contraction cylinder (41) and a rear expansion and contraction cylinder (42), respectively. When controlling the front expansion and contraction cylinder (41) and the rear expansion and contraction cylinder (42) to move, both the front expansion and contraction cylinder (41) and the rear expansion and contraction cylinder (42) initially expand and contract at the maximum expansion and contraction speed, and the real-time length of the front expansion and contraction cylinder (41) and the rear expansion and contraction cylinder (42) is detected in real time. If the absolute value of the difference between the real-time length of the front expansion and contraction cylinder (41) and the rear expansion and contraction cylinder (42) is within a first set value, then the front expansion and contraction cylinder (41) and the rear expansion and contraction cylinder (42) maintain the maximum expansion and contraction speed; if the real-time length of the front expansion and contraction cylinder (41) minus the real-time length of the rear expansion and contraction cylinder (42) is less than the real-time length of the rear expansion and contraction cylinder (42), then the front expansion and contraction cylinder (41) and the rear expansion and contraction cylinder (42) maintain the maximum expansion and contraction speed. If the real-time length of the front expansion cylinder (41) is greater than the second set value, then the expansion speed of the front expansion cylinder (41) is reduced, and the rear expansion cylinder (42) maintains the maximum expansion speed; if the real-time length of the rear expansion cylinder (42) minus the real-time length of the front expansion cylinder (41) is greater than the second set value, then the expansion speed of the rear expansion cylinder (42) is reduced, and the front expansion cylinder (41) maintains the maximum expansion speed; if the absolute value of the difference between the real-time lengths of the front expansion cylinder (41) and the rear expansion cylinder (42) is between the first set value and the second set value, then the current expansion speeds of the front expansion cylinder (41) and the rear expansion cylinder (42) remain unchanged; the second set value is greater than the first set value.

2. The chassis control method for an aerial work platform according to claim 1, characterized in that, α1=ARCcos(((L2-L1) / 2) / L3); Wherein, L1 is the length of the expansion cylinder (40), L2 is the distance between the hinge points of the two first rods (31) in each group and the main body (10), and L3 is the distance between the hinge point of the first rod (31) and the main body (10) and the hinge point of the first rod (31) and the expansion cylinder (40).

3. The chassis control method for an aerial work platform according to claim 1, characterized in that, The expansion and contraction speed of the expansion and contraction cylinder (40) is achieved by controlling the current.

4. The chassis control method for an aerial work platform according to claim 3, characterized in that, If the absolute value of the difference between the real-time lengths of the front expansion cylinder (41) and the rear expansion cylinder (42) is within the first set value, the control current of both the front expansion cylinder (41) and the rear expansion cylinder (42) is set to the maximum value; if the difference between the real-time length of the front expansion cylinder (41) and the real-time length of the rear expansion cylinder (42) is greater than the second set value, the control current of the front expansion cylinder (41) decreases at a preset rate, while the rear expansion cylinder (42) maintains the maximum control current; if the difference between the real-time lengths of the front expansion cylinder (41) and ... within the first set value, the control current of the front expansion cylinder (41) decreases at a preset rate, while the control current of the rear expansion cylinder (42) remains at the maximum value. If the real-time length of the rear expansion cylinder (42) minus the real-time length of the front expansion cylinder (41) is greater than the second set value, then the control current of the rear expansion cylinder (42) decreases at a preset rate, while the front expansion cylinder (41) maintains the maximum control current; if the absolute value of the difference between the real-time lengths of the front expansion cylinder (41) and the rear expansion cylinder (42) is between the first set value and the second set value, then the current control currents of the front expansion cylinder (41) and the rear expansion cylinder (42) remain unchanged.

5. The chassis control method for an aerial work platform according to claim 1, characterized in that, The rotation control process of the wheel (20) is as follows: The angle α2 between the centerline of the wheel (20) and the second rod (32) is detected in real time. If the absolute value of the difference between α2 and α1 is less than or equal to the third set value, the wheel (20) stops rotating; if the absolute value of the difference between α2 and α1 is greater than the third set value, the wheel (20) is controlled to continue rotating.

6. The chassis control method for an aerial work platform according to claim 5, characterized in that, The wheel (20) is rotated by a switching valve. The switching valve is energized n times in each time period, and the switching valve is energized t milliseconds each time. The maximum number of times the switching valve is energized in one time period is nmax = T / t. When the absolute value of the difference between α2 and α1 is greater than the third set value, then n = k * |α1 - α2|, and when n > nmax, then n = nmax, where k is a constant. When the absolute value of the difference between α2 and α1 is less than the third set value, then n = 0.

7. The chassis control method for an aerial work platform according to claim 5, characterized in that, The wheel (20) is rotated by a switching valve. T is the time period of the switching valve. The valve is energized n times in each time period. The maximum energization time tmax = T / n in one time period of the switching valve. When the absolute value of the difference between α2 and α1 is greater than the third set value, then t = k * |α1 - α2|, and when t > tmax, t = tmax; When the absolute value of the difference between α2 and α1 is less than the third set value, then t = 0.

8. An aerial work platform, characterized in that, Including the chassis control method of the aerial work platform as described in any one of claims 1-7.

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