Self-adaptive control method of roller skates and roller skates thereof

Abstract

The application relates to a self-adaptive control method of a roller skate and the roller skate, and relates to the field of sports products.The method comprises the following steps: acquiring a first pressure value, a second pressure value and a real-time wheel speed value of a foot in real time; comparing the first pressure value with the second pressure value to determine a motion intention; verifying the adjustment action authority according to the wheel speed value; and controlling an electric cylinder to drive a support frame to execute wheel track adjustment and simultaneously drive a lifting plate to execute height adjustment according to the intention and the verification result. The motion intention comprises a first intention that the wheel track is elongated and the lifting plate is lifted, and a second intention that the wheel track is shortened and the lifting plate is lowered. The application also provides a roller skate for realizing the above method, and three groups of electric cylinders are used to respectively realize wheel track adjustment, lifting plate height adjustment and lateral displacement in a curve. The application can self-adaptively adjust the wheel track and the wheel frame height according to the stress state of the foot, and significantly improves the stability, flexibility and safety in a curve of sliding.

Description

Technical Field

[0001] This invention relates to the field of sports products, and in particular to an adaptive control method for roller skates and roller skates thereof. Background Technology

[0002] Roller skates, as a sporting product that combines fitness and transportation, are widely used in leisure and entertainment, professional speed skating, and figure skating performances. Based on the wheel arrangement, roller skates are mainly divided into inline skates and quad skates. Inline skates, due to their low drag and high speed, have become the mainstream product in the market. Existing inline skates typically consist of a skate body and a wheel frame fixed to the underside of the skate body. The wheel frame has multiple wheels arranged longitudinally. However, traditional inline skates have the following technical drawbacks in practical use:

[0003] First, the wheelbase between the front and rear wheels of existing inline skates is fixed. While a longer wheelbase provides better stability at high speeds, it results in insufficient agility and a large turning radius during low-speed turns or freestyle maneuvers. Conversely, a shorter wheelbase offers more maneuverability but makes the skater prone to drifting or even tipping over at high speeds. Users cannot adjust the wheelbase in real-time according to their skating conditions, making it difficult for the product to meet the needs of different scenarios.

[0004] Secondly, the ground clearance of existing roller skates' wheel frames relative to the soles is fixed. When skating at high speeds on smooth surfaces, a lower center of gravity is desirable to improve stability; however, on rough surfaces or when navigating obstacles, a higher ground clearance is desirable to prevent the wheel frames from scraping the ground. Fixed-height wheel frames cannot meet these diverse needs.

[0005] Third, since the four wheels of inline skates are on the same longitudinal straight line, they lack the speed difference mechanism between the left and right wheels like inline skates when turning. They rely entirely on the user's tilt angle and body center of gravity control. When turning, the friction between the outer wheel and the ground is insufficient, making it very easy to slip sideways or even fall. This requires a high level of skill from the user and also limits the safety of inline skates in complex road conditions.

[0006] Fourth, existing roller skates are all purely mechanical fixed structures, and the wheel track and frame height cannot be actively adjusted according to the force applied to the user's feet. The user's movement intentions (such as acceleration, deceleration, turning, etc.) rely entirely on body posture adjustments, and cannot be assisted by the active deformation of the roller skates themselves. This results in low intelligence and poor human-machine coordination. Summary of the Invention

[0007] To address the aforementioned problems, this application adopts the following technical solution: An adaptive control method for roller skates includes the following steps: S1: Real-time acquisition of the first and second pressure values ​​of the foot inside the roller skate, as well as the real-time wheel speed value output by any one of the roller skates; S2: Compare the first pressure value with the second pressure value, and determine the user's movement intention based on the comparison result. The movement intention includes a first intention to trigger the wheel track to extend and the lifting plate to move upward, and a second intention to trigger the wheel track to shorten and the lifting plate to move downward. S3: Verify the adjustment action corresponding to the motion intention based on the real-time wheel speed value. When the real-time wheel speed value reaches a preset first threshold, restrict the execution permission of the wheel track shortening action. S4: Based on the stated motion intention and verification results, control the first and second electric cylinders to drive the front and rear support frames to perform wheel track adjustment, and simultaneously control the third electric cylinder to drive the lifting plate to perform height adjustment through the drive block and drive groove.

[0008] Preferably, in S3, when the real-time wheel speed value is greater than or equal to the preset first threshold, the following operations are performed: Lock the drive direction of the first and second electric cylinders used to perform the wheelbase shortening action, so that the front support frame and the rear support frame are only allowed to perform wheelbase extension actions that move away from each other and are prohibited from performing wheelbase shortening actions that move closer to each other; at the same time, limit the drive speed of the third electric cylinder to control the descent rate of the lifting plate.

[0009] Preferably, in S4, when the first intention is determined, the first electric cylinder and the second electric cylinder respectively drive the front support frame to move forward and the rear support frame to move backward, thereby increasing the wheel distance between the two sets of pulleys; at the same time, the third electric cylinder drives the drive block to slide along the first direction, and the drive rod slides along the corresponding section of the drive groove and drives the lifting plate to move upward, so that the foot is close to the ground, thereby lowering the center of gravity of the slide; When the second intention is determined, the first electric cylinder and the second electric cylinder respectively drive the front support frame to move backward and the rear support frame to move forward, thereby shortening the wheel distance between the two sets of pulleys; at the same time, the third electric cylinder drives the drive block to slide along the second direction, causing the drive rod to slide along the corresponding section of the drive groove and drive the lifting plate to move downward, so that the foot is away from the ground, thereby increasing the ground clearance.

[0010] Preferably, the control method also includes curve assist adjustment, the specific steps of which are as follows: The wheel speed difference between the first and last pulleys is obtained. When the wheel speed difference exceeds a preset second threshold, it is determined that the current situation is in a turning trajectory, and the turning direction is identified. Based on the identification results, the control component drives the front support frame and the rear support frame to generate a relative lateral misalignment in the horizontal plane, wherein: When a left turn is detected, the front support frame is controlled to move laterally to the left, while the rear support frame is controlled to move laterally to the right, forming an alternating wheel track distribution of front left and rear right; When a right turn is detected, the front support frame is controlled to move laterally to the right, while the rear support frame is controlled to move laterally to the left, forming an alternating wheel track distribution of front right and rear left.

[0011] Preferably, the lateral misalignment of the front support frame and the rear support frame is proportional to the absolute value of the wheel speed difference.

[0012] Preferably, after S4 is completed and the comparison result between the first pressure value and the second pressure value falls back to the preset static dead zone range, the system further includes an automatic return-to-center reset step: When the real-time wheel speed value is less than a preset third threshold, and the comparison result of the first pressure value and the second pressure value remains within the static dead zone for a preset duration, the first electric cylinder and the second electric cylinder are controlled to drive the front support frame and the rear support frame to retract to the preset center wheel distance. At the same time, the third electric cylinder is controlled to drive the drive block to slide to the preset center position, so that the lifting plate is restored to the preset center height. The control component is then controlled to drive the front support frame and the rear support frame to synchronously return to the longitudinal center line position of the lifting plate.

[0013] Preferably, the present invention also provides a roller skate for implementing the above method, the roller skate including a shoe body and a sole plate, the sole plate having a first pressure unit and a second pressure unit arranged in a distributed manner on its upper part, the bottom surface of the sole plate having a longitudinally extending strip-shaped cavity, the strip-shaped cavity also having a controller and a rectangular hollow block, the rectangular hollow block being fitted with a lifting plate, the front and rear ends of the lifting plate having T-shaped grooves respectively, each T-shaped groove having a front support frame and a rear support frame slidably mounted in it via a control component, the front support frame and the rear support frame each having a set of pulleys mounted on them, the rectangular hollow block also having a drive block slidably mounted inside it, the... The drive block has a drive groove, and a drive rod is horizontally arranged in the drive groove and fixedly connected to both sides of the lifting plate. A first electric cylinder and a second electric cylinder are also mirrored below the lifting plate. The telescopic ends of the first electric cylinder and the second electric cylinder are fixedly connected to the corresponding front support frame and rear support frame, respectively. A third electric cylinder is also provided in the rectangular hollow block. The telescopic end of the third electric cylinder is also fixedly connected to the drive block. A wheel speed acquisition unit is also installed at the axle center of any pulley. The controller is also connected to the first pressure unit, the second pressure unit, the control component, the first electric cylinder, the second electric cylinder, the third electric cylinder, and the wheel speed acquisition unit.

[0014] Preferably, the control component includes a T-shaped plate and a transverse plate. The upper part of the T-shaped plate is slidably fitted into corresponding T-shaped slots. A control motor is also provided inside the T-shaped plate. A rotating wheel is fixedly installed at the output end of the control motor. The output shaft of the control motor and the rotating wheel are eccentrically arranged. Multiple T-shaped limiting guide blocks are also fixedly provided on each side of the T-shaped plate. The transverse plate is located below the T-shaped plate and is slidably connected to the multiple T-shaped limiting guide blocks. A drive ring is also fixed on the side of the transverse plate opposite to the bottom of the T-shaped plate. The rotating wheel is horizontally located inside the drive ring and contacts the inner wall of the drive ring. The control motor is also signal-connected to the controller.

[0015] Preferably, the upper part of the lifting plate is also provided with multiple shock-absorbing springs, and the upper part of each shock-absorbing spring is fixedly connected to the strip cavity. Straight slots are opened on both sides of the rectangular hollow block. The straight slots are arranged in a vertical direction, and the two ends of the drive rod pass through the straight slots respectively.

[0016] Preferably, the drive groove is zigzag-shaped, including two horizontal through-sections and an inclined through-section. The inclined through-section is located between the two horizontal through-sections and is interconnected. The rectangular hollow block is also provided with two horizontal guide rails. The drive block is located between the two horizontal guide rails. When the drive block reciprocates under the control command of the third electric cylinder, the drive groove forces the drive rod to move up and down along the straight groove opening in the vertical direction, so that the lifting plate can be raised and lowered.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Achieving adaptive wheelbase adjustment: This invention acquires real-time forefoot and heel pressure values ​​inside the shoe. Based on the pressure comparison results, it automatically identifies the user's acceleration or agile steering intentions and drives the first and second electric cylinders to push the front and rear support frames to slide longitudinally along the T-slot, thereby increasing or decreasing the wheelbase between the two sets of pulleys accordingly. This achieves intelligent stepless adjustment of the wheelbase, perfectly balancing the seemingly contradictory needs of high-speed gliding stability and low-speed steering agility.

[0018] 2. This invention uses a third electric cylinder to drive a drive block to slide reciprocally along a horizontal guide rail. The horizontal reciprocating motion is converted into the vertical lifting motion of the lifting plate by utilizing the interlocking of a zigzag drive groove on the drive block and the drive rod. When acceleration is detected, the lifting plate moves upward, bringing the feet closer to the ground to lower the center of gravity and improve gliding stability. When agility is detected, the lifting plate moves downward, moving the feet away from the ground to increase ground clearance, facilitating obstacle clearance or sharp turns. Synchronous linkage control allows wheelbase and height adjustments to be performed in tandem, optimizing the gliding posture.

[0019] 3. This invention uses wheel speed acquisition units set at the axle centers of the first and last pulleys to acquire the wheel speed difference between the front and rear pulleys in real time. When the wheel speed difference exceeds a preset threshold, it is determined that the skater is in a turning state. The eccentric rotating wheel in the control component drives the front and rear support frames to generate a relative lateral misalignment in the horizontal plane—a left-front-left-rear-right staggered pattern during left turns and a right-front-right-rear-left staggered pattern during right turns. This actively forms a staggered wheel track distribution that matches the curve's arc, effectively increasing the ground friction of the outer wheel during cornering and significantly improving the cornering tracking and safety of inline skates.

[0020] 4. When the real-time wheel speed reaches a preset first threshold, this invention automatically locks the drive direction of the first and second electric cylinders used for wheelbase shortening, allowing the front and rear support frames to only perform wheelbase extension while prohibiting wheelbase shortening. Simultaneously, it limits the drive speed of the third electric cylinder to control the descent rate of the lifting plate. This mechanism effectively prevents unexpected wheelbase shortening or sudden changes in center of gravity triggered by minor foot vibrations during high-speed gliding, avoiding the risk of tipping over or falling forward, and significantly improving the safety of high-speed gliding. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the control method of the present invention; Figure 2 This is a three-dimensional structural diagram of the roller skate of the present invention; Figure 3 This is a three-dimensional structural diagram of the shoe sole. Figure 4 A three-dimensional structural diagram of the shoe sole from another angle; Figure 5 This is a top view of the shoe sole structure. Figure 6 for Figure 5 A three-dimensional structural diagram showing the cross-section along line AA. Figure 7 for Figure 6 Enlarged structural diagram of section B; Figure 8 for Figure 6 Enlarged structural diagram of section C; Figure 9 This is a schematic diagram of the shoe sole structure viewed from below. In the diagram: 1. Shoe body; 2. Sole plate; 3. First pressure unit; 4. Second pressure unit; 5. Strip cavity; 6. Controller; 7. Rectangular hollow block; 8. Lifting plate; 9. T-slot; 10. Control component; 11. Front support frame; 12. Rear support frame; 13. Pulley; 14. Drive block; 15. Drive slot; 16. Drive rod; 17. First electric cylinder; 18. Second electric cylinder; 19. Third electric cylinder; 20. Wheel speed acquisition unit; 100. T-slot plate; 101. Transverse plate; 102. Control motor; 103. Rotating wheel; 104. T-shaped limit guide block; 105. Drive ring; 21. Shock-absorbing spring; 22. Straight slot; 150. Horizontal through part; 151. Inclined through part; and 23. Horizontal guide rail. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] Example 1: Before understanding this solution, it is necessary to clarify that the wheel spacing referred to in this application refers to the distance between the centers of the axes of the second and third pulleys 13 arranged in a straight line in the horizontal longitudinal direction, that is, the longitudinal distance between the two sets of pulleys. The following is combined with... Figures 1 to 9 The specific embodiments of the present invention will be described in detail below.

[0025] See Figure 1 An adaptive control method for roller skates includes the following steps: S1: Real-time acquisition of the first and second pressure values ​​of the foot inside the roller skate, as well as the real-time wheel speed value output by any one of the roller skates 13; S2: Compare the first pressure value with the second pressure value, and determine the user's movement intention based on the comparison result. The movement intention includes a first intention to trigger the wheel track to extend and the lifting plate 8 to move upward, and a second intention to trigger the wheel track to shorten and the lifting plate 8 to descend. S3: Verify the adjustment action corresponding to the motion intention based on the real-time wheel speed value. When the real-time wheel speed value reaches a preset first threshold, restrict the execution permission of the wheel track shortening action. S4: Based on the stated motion intention and verification results, control the first electric cylinder 17 and the second electric cylinder 18 to drive the front support frame 11 and the rear support frame 12 to perform wheel track adjustment, and simultaneously control the third electric cylinder 19 to drive the lifting plate 8 to perform height adjustment through the drive block 14 and the drive groove 15.

[0026] Specifically: The first pressure unit 3 is disposed on the upper surface of the sole plate 2 corresponding to the metatarsal area of ​​the forefoot. It is used to detect the pressure on the forefoot area in real time and convert the pressure value into an electrical signal, which is transmitted to the controller 6. This pressure value is the first pressure value described in this application. The second pressure unit 4 is disposed on the upper surface of the sole plate 2 corresponding to the heel area of ​​the foot. It is used to detect the pressure on the heel area in real time and convert the pressure value into an electrical signal, which is transmitted to the controller 6. This pressure value is the second pressure value described in this application. The first pressure unit 3 and the second pressure unit 4 are preferably thin-film pressure sensors or flexible oil bladder pressure sensors, embedded inside the insole on the upper surface of the sole plate 2, which ensures detection accuracy without affecting wearing comfort.

[0027] During use, the wheel speed acquisition unit 20, installed at the axis of any pulley 13, detects the rotational speed of the pulley 13 in real time and transmits the wheel speed signal to the controller 6. The wheel speed acquisition unit 20 is preferably a Hall sensor, which rotates synchronously with the pulley 13 and generates a pulse signal each time it passes through a magnetic pole. The controller 6 calculates the real-time wheel speed value of the current sliding movement based on the number of pulses per unit time.

[0028] In S2, controller 6 calculates the difference between the first pressure value and the second pressure value, which is the difference between the forefoot pressure and the heel pressure. This difference reflects the longitudinal shift direction and degree of the user's center of gravity. When the body leans forward, the center of gravity shifts forward, the force on the forefoot increases, the first pressure value is greater than the second pressure value, and the difference increases positively. When the body leans backward, the center of gravity shifts backward, the force on the heel increases, the second pressure value is greater than the first pressure value, and the difference increases negatively. Controller 6 compares this difference with a preset static dead zone threshold range. The static dead zone threshold range is set to prevent frequent misadjustments caused by minor road bumps or slight foot wobbling. Its specific value can be adaptively set according to the user's weight; for example, a user weighing 50kg corresponds to a smaller dead zone range, and a user weighing 100kg corresponds to a larger dead zone range.

[0029] When the difference is within the static dead zone threshold range, i.e., the difference between forefoot pressure and heel pressure is not significant, the controller 6 determines that the user is currently in a static standing or constant speed cruising state. At this time, no adjustment action is triggered, and the first electric cylinder 17, the second electric cylinder 18, and the third electric cylinder 19 all remain unchanged. The height of the lifting plate 8 and the wheelbase of the front and rear support frames remain unchanged to maintain the stability of the gliding state. When the difference positively exceeds the upper limit of the static dead zone threshold range, i.e., the forefoot pressure is significantly greater than the heel pressure, the controller 6 determines that the user has the intention to lean forward to accelerate or push off the ground uphill, i.e., the first intention described in this application. At this time, the roller skates need to increase the wheelbase to improve the stability of high-speed gliding, and at the same time, the lifting plate 8 needs to be moved upward to reduce the height of the feet off the ground, so as to lower the center of gravity and further improve stability. When the negative difference exceeds the lower limit of the static dead zone threshold range, i.e., the heel pressure is significantly greater than the forefoot pressure, the controller 6 determines that the user intends to lean back to slow down, control speed downhill, or make agile movements, i.e., the second intention described in this application. At this time, the roller skates need to shorten the wheel track to reduce the turning radius and improve agility, while the lifting plate 8 needs to be lowered to increase the height of the feet off the ground, raising the center of gravity to facilitate large turning movements or passing obstacles.

[0030] In some preferred embodiments, in S3, when the real-time wheel speed value is greater than or equal to the preset first threshold, the following operations are performed: Lock the drive direction of the first electric cylinder 17 and the second electric cylinder 18 for performing the wheel track shortening action, so that the front support frame 11 and the rear support frame 12 are only allowed to perform wheel track lengthening actions that move away from each other and are prohibited from performing wheel track shortening actions that move closer to each other; at the same time, limit the drive speed of the third electric cylinder 19 to control the descent rate of the lifting plate 8.

[0031] Specifically, after the controller 6 initially determines the motion intention based on the pressure comparison results, it does not immediately execute the corresponding adjustment action. Instead, it first performs a safety verification of the adjustment action corresponding to the motion intention based on the real-time wheel speed value. The controller 6 compares the real-time wheel speed value with a preset first threshold, which is a speed threshold, such as 20km / h or 25km / h, representing the dividing line between high-speed skating and medium-low speed skating. The specific value of this threshold can be set according to the type of roller skates and the usage scenario. Racing roller skates can be set with a higher threshold, while recreational roller skates can be set with a lower threshold.

[0032] When the real-time wheel speed is less than the preset first threshold, the roller skates are in a low-to-medium speed gliding state. The controller 6 determines that the safety risk of the current adjustment action is low and allows all types of adjustment actions to be performed, including wheel track extension, wheel track shortening, and the raising and lowering of the lifting plate 8.

[0033] When the real-time wheel speed reaches or exceeds a preset first threshold, the roller skates are in a high-speed gliding state. Controller 6 determines that certain adjustment actions pose a safety risk, especially the actions of shortening the wheel track and rapidly lowering the lifting plate 8, which may cause a sudden change in the center of gravity or wheel track, leading to the user tipping over or falling forward. Therefore, controller 6 performs the following safety protection operations: Firstly, the drive direction of the first electric cylinder 17 and the second electric cylinder 18 used to perform the wheelbase shortening action is locked. That is, the controller 6 no longer sends retraction commands to the first electric cylinder 17 and the second electric cylinder 18, but only allows extension commands. In this way, the front support frame 11 and the rear support frame 12 are only allowed to perform wheelbase extension actions that move away from each other, while prohibiting wheelbase shortening actions that move closer to each other. This mechanism ensures that the wheelbase will not shorten unexpectedly during high-speed coasting, maintaining the stability brought by the long wheelbase.

[0034] Secondly, the driving speed of the third electric cylinder 19 is limited. The controller 6 limits the maximum speed at which the extension or retraction end of the third electric cylinder 19 extends or retracts in order to control the lifting rate of the lifting plate 8, especially the descent rate. This mechanism prevents the risk of a sudden increase in the height of the feet off the ground and a sharp change in the center of gravity caused by the rapid descent of the lifting plate 8 at high speed.

[0035] With the above dual safety protection measures, roller skates are only allowed to perform adjustment actions that are beneficial to stability (lengthening the wheel track) when gliding at high speeds, and are prohibited from performing adjustment actions that may compromise stability (shortening the wheel track and rapidly lowering the skate), effectively ensuring the safety of the user.

[0036] In some preferred embodiments, in S4, when the first intention is determined, the first electric cylinder 17 and the second electric cylinder 18 respectively drive the front support frame 11 to move forward and the rear support frame 12 to move backward, thereby increasing the wheelbase between the two sets of pulleys; at the same time, the third electric cylinder 19 drives the drive block 14 to slide along the first direction, so that the drive rod 16 slides along the corresponding section of the drive groove 15 and drives the lifting plate 8 to move upward, so that the foot is close to the ground, thereby lowering the center of gravity of the slide; When the second intention is determined, the first electric cylinder 17 and the second electric cylinder 18 respectively drive the front support frame 11 to move backward and the rear support frame 12 to move forward, so that the wheel distance between the two sets of pulleys is shortened; at the same time, the third electric cylinder 19 drives the drive block 14 to slide along the second direction, so that the drive rod 16 slides along the corresponding section of the drive groove 15 and drives the lifting plate 8 to move downward, so that the foot is away from the ground, thereby increasing the ground clearance.

[0037] Specifically, in scenario one, if the initial intention is determined to be forward acceleration, the controller 6 sends an extension command to the first electric cylinder 17 and the second electric cylinder 18. For example... Figures 2 to 6As shown, the cylinder body of the first electric cylinder 17 is fixedly installed at the front end below the lifting plate 8, and its telescopic end is fixedly connected to the front support frame 11. When the first electric cylinder 17 receives an extension command, its telescopic end extends forward, pushing the front support frame 11 to slide forward along the T-slot 9 at the front end. At the same time, the cylinder body of the second electric cylinder 18 is fixedly installed at the rear end below the lifting plate 8, and its telescopic end is fixedly connected to the rear support frame 12. When the second electric cylinder 18 receives an extension command, its telescopic end extends backward, pushing the rear support frame 12 to slide backward along the T-slot 9 at the rear end.

[0038] As the front support frame 11 moves forward and the rear support frame 12 moves backward, the longitudinal distance between them increases, which means the wheelbase between the two sets of pulleys 13 increases. The increased wheelbase makes the support span of the front and rear pulley sets longer, significantly improving the longitudinal stability of the gliding, making it very suitable for high-speed straight-line gliding or uphill push-off scenarios.

[0039] Synchronously, the controller 6 sends a drive command in the first direction to the third electric cylinder 19. The cylinder body of the third electric cylinder 19 is fixedly installed inside the rear end of the rectangular hollow block 7, and its telescopic end is fixedly connected to the drive block 14. When the third electric cylinder 19 receives the drive command in the first direction, its telescopic end extends, pushing the drive block 14 to slide forward along the two horizontal guide rails 23 (i.e., in the first direction). When the drive block 14 slides forward, the drive rod 16 enters the inclined through-section 151 from the horizontal through-section 150 at the rear end of the drive groove 15. Since the inclined through-section 151 gradually rises from back to front, the drive rod 16 slides upward along the straight groove 22 under the constraint of the inclined through-section 151, thereby driving the lifting plate 8 to move upward relative to the rectangular hollow block 7. The upward movement of the lifting plate 8 brings the foot closer to the ground, lowers the center of gravity during gliding, and further improves the stability of high-speed gliding.

[0040] Scenario 2: If the second intention is determined (flexible backward movement), controller 6 sends a retraction command to the first electric cylinder 17 and the second electric cylinder 18. The telescopic end of the first electric cylinder 17 retracts, pulling the front support frame 11 to slide backward along the front T-slot 9. The telescopic end of the second electric cylinder 18 retracts, pulling the rear support frame 12 to slide forward along the rear T-slot 9. With the front support frame 11 moving backward and the rear support frame 12 moving forward, the longitudinal distance between them decreases, meaning the wheelbase between the two sets of pulleys 13 is shortened. The shortened wheelbase reduces the turning radius, significantly improving gliding flexibility, making it ideal for low-speed turns, freestyle maneuvers, or navigating complex urban road conditions.

[0041] Synchronously, the controller 6 sends a second-direction drive command to the third electric cylinder 19. The telescopic end of the third electric cylinder 19 retracts, pulling the drive block 14 backward along the two horizontal guide rails 23 (i.e., the second direction). As the drive block 14 slides backward, the drive rod 16 enters the inclined through-section 151 from the horizontal through-section 150 at the front end of the drive groove 15. Since the inclined through-section 151 gradually decreases from front to back, the drive rod 16 slides downward along the straight groove 22 under the constraint of the inclined through-section 151, thereby driving the lifting plate 8 to move downward relative to the rectangular hollow block 7. The downward movement of the lifting plate 8 makes the foot away from the ground, increasing the ground clearance and facilitating large turning maneuvers or obstacle passage.

[0042] During wheelbase and height adjustment, the real-time rate of the adjustment action is positively correlated with the deviation between the first and second pressure values. That is, the greater the force with which the user leans forward or backward, the greater the pressure deviation, the faster the drive speed of the first electric cylinder 17, the second electric cylinder 18, and the third electric cylinder 19, and the more rapid the changes in wheelbase and height. This achieves rapid-response stepless speed adjustment, allowing the roller skates to instantly follow the user's intentions.

[0043] In some preferred embodiments, the control method further includes curve assist adjustment, the specific steps of which are as follows: The wheel speed difference between the first pulley 13 and the last pulley 13 is obtained. When the wheel speed difference exceeds a preset second threshold, it is determined that the current situation is in a turning trajectory and the turning direction is identified. Based on the identification results, the control component 10 drives the front support frame 11 and the rear support frame 12 to generate a relative lateral misalignment in the horizontal plane, wherein: When a left turn is detected, the front support frame 11 is controlled to move laterally to the left, while the rear support frame 12 is controlled to move laterally to the right, forming an alternating wheel track distribution of front left and rear right; When a right turn is detected, the front support frame 11 is controlled to move laterally to the right, while the rear support frame 12 is controlled to move laterally to the left, forming an alternating wheel track distribution of front right and rear left.

[0044] Specifically, controller 6 acquires the rotational speeds of the first pulley 13 and the last pulley 13 in real time and calculates the difference between them, i.e., the speed difference between the front and rear wheels. When inline skates turn, because the front and rear wheels are arranged along the same longitudinal straight line, the radii of the arcs traversed by the front and rear wheels during the turn are different, resulting in a difference in their rotational speeds. Therefore, by detecting the speed difference between the front and rear wheels, it is possible to accurately determine whether the inline skates are in a turning state, as well as the direction and speed of the turn.

[0045] The controller 6 compares the absolute value of the speed difference between the front and rear wheels with a preset second threshold. When the absolute value of the speed difference is less than or equal to the preset second threshold, it determines that the roller skates are in a straight line or slightly curved state, and does not trigger the cornering assist adjustment.

[0046] When the absolute value of the wheel speed difference exceeds a preset second threshold, the roller skates are determined to be in a significant turning trajectory. The controller 6 further identifies the turning direction based on the relationship between the rotational speeds of the first pulley 13 and the last pulley 13: when the rotational speed of the first pulley 13 is less than that of the last pulley 13, it is determined to be a left turn; when the rotational speed of the first pulley 13 is greater than that of the last pulley 13, it is determined to be a right turn.

[0047] After identifying the turning direction, the controller 6 drives the front support frame 11 and the rear support frame 12 to generate relative lateral misalignment in the horizontal plane through the control component 10.

[0048] In some preferred embodiments, the lateral misalignment of the front support frame 11 and the rear support frame 12 is proportional to the absolute value of the wheel speed difference. When the controller 6 drives the control motor 102 to rotate, the eccentrically positioned rotating wheel 103 rotates within the drive ring 105. Because the rotating wheel 103 contacts the inner wall of the drive ring 105, the eccentric rotation of the rotating wheel 103 causes the drive ring 105 to swing laterally left and right, thereby causing the transverse plate 101 to move laterally relative to the T-shaped plate 100. Since the bottom of the transverse plate 101 is fixedly connected to the corresponding front support frame 11 or rear support frame 12, the lateral displacement of the transverse plate 101 causes the front support frame 11 or rear support frame 12 to move laterally.

[0049] In some preferred embodiments, after S4 is completed and the comparison result between the first pressure value and the second pressure value falls back to the preset static dead zone range, an automatic return-to-center reset step is also included: When the real-time wheel speed value is less than a preset third threshold, and the comparison result of the first pressure value and the second pressure value remains within the static dead zone for a preset duration, the first electric cylinder 17 and the second electric cylinder 18 are controlled to drive the front support frame 11 and the rear support frame 12 to retract to the preset center wheel track. At the same time, the third electric cylinder 19 is controlled to drive the drive block 14 to slide to the preset center position, so that the lifting plate 8 returns to the preset center height. The control component 10 is then controlled to drive the front support frame 11 and the rear support frame 12 to synchronously return to the longitudinal center line position of the lifting plate.

[0050] Specifically, after the user completes actions such as acceleration and turning, the comparison result between the first pressure value and the second pressure value will gradually fall back to the preset static dead zone range, indicating that the user has returned to a static standing or constant speed cruising state. At this time, the controller 6 does not immediately perform a reset operation, but continues to monitor the real-time wheel speed value and the duration of the pressure steady state. When the controller 6 detects that the real-time wheel speed value is less than the preset third threshold (i.e., the roller skates have dropped to an extremely low speed, such as below 3 km / h, close to a stop), and the comparison result between the first pressure value and the second pressure value remains within the static dead zone range for a preset duration (such as 2 to 3 seconds), it determines that the user has stopped skating or is preparing to start again. At this time, an automatic return-to-center reset operation is performed, such as the controller 6 sending a retraction command to the first electric cylinder 17 and the second electric cylinder 18, driving the front support frame 11 and the rear support frame 12 to retract to the preset center wheel track. The preset center wheel track is a pre-set standard wheel track value, which is neither too long nor too short, and is suitable as the initial state for starting skating. Simultaneously, controller 6 sends a drive command to the third electric cylinder 19, causing the drive block 14 to slide to the preset center position. The drive rod 16 is located at the intersection of the corresponding horizontal through-hole 150 and inclined through-hole 151 of the drive groove 15, and the lifting plate 8 returns to the preset center height, which is the standard value of the foot height off the ground. Controller 6 also drives the front support frame 11 and the rear support frame 12 to synchronously return to the longitudinal center line position of the lifting plate 8 through the control component 10, so that the front and rear sets of pulleys 13 return to a collinear distribution.

[0051] After resetting, the roller skates return to their standard initial gliding posture, providing a stable and reliable foundation for the user's next push-off. The above stages are not completed in one go, but rather cyclically executed according to a preset control cycle. Within each control cycle, controller 6 starts from the data acquisition stage and sequentially executes steps such as intent determination, wheel speed verification, linkage adjustment, cornering assistance judgment, and reset condition judgment. Through this continuous, high-frequency cyclical control, the roller skates can adaptively adjust wheel track and height in real time to follow changes in the user's movement intent, achieving an intelligent and coordinated gliding experience where the skates and rider are one.

[0052] Example 2: See Figures 2-9The present invention also provides a roller skate for implementing the above method. The roller skate includes a shoe body 1 and a sole plate 2. A first pressure unit 3 and a second pressure unit 4 are arranged on the upper part of the sole plate 2. A longitudinally extending strip-shaped cavity 5 is formed on the bottom surface of the sole plate 2. The strip-shaped cavity 5 is the base for installation. Inside the strip-shaped cavity 5, there is also a controller 6 and a rectangular hollow block 7. A lifting plate 8 is also fitted outside the rectangular hollow block 7. The lifting of the lifting plate 8 is controlled by a drive block 14. T-shaped grooves 9 are respectively formed at the front and rear ends of the lifting plate 8. A front support frame 11 and a rear support frame 12 are slidably fitted in each T-shaped groove 9 through a control component 10. A set of pulleys 13 are respectively installed on the front support frame 11 and the rear support frame 12. The drive block 14 is also slidably arranged inside the rectangular hollow block 7. The drive block 14 has a drive groove 15 extending horizontally, and a drive rod 16 is horizontally arranged in the drive groove 15. The drive rod 16 is also fixedly connected to both sides of the lifting plate 8. A first electric cylinder 17 and a second electric cylinder 18 are also mirrored below the lifting plate 8. The telescopic ends of the first electric cylinder 17 and the second electric cylinder 18 are fixedly connected to the corresponding front support frame 11 and rear support frame 12, respectively. A third electric cylinder 19 is also provided in the rectangular hollow block 7. The telescopic end of the third electric cylinder 19 is also fixedly connected to the drive block 14. A wheel speed acquisition unit 20 is also installed at the axle position of any pulley 13. The controller 6 is also connected to the first pressure unit 3, the second pressure unit 4, the control component 10, the first electric cylinder 17, the second electric cylinder 18, the third electric cylinder 19 and the wheel speed acquisition unit 20.

[0053] Wheelbase adjustment is driven by a first electric cylinder 17 and a second electric cylinder 18. The cylinder body of the first electric cylinder 17 is fixedly installed at the front end below the lifting plate 8, and its telescopic end extends forward longitudinally and is fixedly connected to the front support frame 11. The cylinder body of the second electric cylinder 18 is fixedly installed at the rear end below the lifting plate 8, and its telescopic end extends backward longitudinally and is fixedly connected to the rear support frame 12. The two electric cylinders are arranged in a mirror-symmetrical manner and can extend or retract synchronously under the control of the controller 6.

[0054] When the front support frame 11 and the rear support frame 12 need to move away from each other to increase the wheelbase, the controller 6 sends an extension command to the first electric cylinder 17, causing its telescopic end to extend forward, pushing the front support frame 11 forward along the front T-slot 9; simultaneously, it sends an extension command to the second electric cylinder 18, causing its telescopic end to extend backward, pushing the rear support frame 12 backward along the rear T-slot 9. The synchronous, opposite movements increase the axle distance between the two sets of pulleys 13, thus increasing the wheelbase. When the front support frame 11 and the rear support frame 12 need to move closer together to shorten the wheelbase, the controller 6 sends a retraction command to the first electric cylinder 17, causing its telescopic end to retract, pulling the front support frame 11 backward along the T-slot 9; simultaneously, it sends a retraction command to the second electric cylinder 18, causing its telescopic end to retract, pulling the rear support frame 12 forward along the T-slot 9. The synchronous, opposite movements shorten the wheelbase.

[0055] The T-shaped groove 9 has a T-shaped cross section, which slides in conjunction with the T-shaped cross section on the upper part of the T-shaped plate 100. This provides guidance for longitudinal sliding and restricts the freedom of the support frame in the vertical and lateral directions, ensuring that the front support frame 11 and the rear support frame 12 can only slide in a straight longitudinal direction, thus guaranteeing the accuracy and stability of the wheel track adjustment.

[0056] Lifting platform height adjustment 8: When the third electric cylinder 19 drives the drive block 14 to slide backward along the horizontal guide rail 23 (i.e., slide in the second direction), the relative position of the drive rod 16 in the drive groove 15 changes, and the drive rod 16 enters the inclined through-section 151 from the horizontal through-section 150 at the front end of the drive groove 15. As the inclined through-section 151 gradually decreases from front to back, the drive rod 16 slides downward along the straight groove 22 under the constraint of the inclined through-section 151, thereby driving the lifting plate 8, which is fixedly connected to both ends of the drive rod 16, to move downward relative to the rectangular hollow block 7. The downward movement of the lifting plate 8 increases the clearance between the foot and the ground.

[0057] Conversely, when the third electric cylinder 19 drives the drive block 14 to slide forward along the horizontal guide rail 23 (i.e., slide in the first direction), the drive rod 16 enters the inclined through-section 151 from the horizontal through-section 150 at the rear end of the drive groove 15. As the inclined through-section 151 gradually rises from back to front, the drive rod 16 slides upward along the straight groove 22 under the constraint of the inclined through-section 151, thereby driving the lifting plate 8 to move upward. The upward movement of the lifting plate 8 brings the feet closer to the ground, lowering the center of gravity.

[0058] The horizontal through-holes 150 at both ends of the drive slot 15 have an important locking function. When the drive rod 16 is located within the horizontal through-hole 150, no matter how the drive block 14 moves slightly in the horizontal direction, the drive rod 16 will not be displaced in the vertical direction, that is, the height of the lifting plate 8 remains constant. This horizontal through-hole 150 is equivalent to a mechanical locking section, which allows the lifting plate 8 to maintain a stable height after being adjusted to the correct position, without the need to continuously consume electrical energy to maintain the position.

[0059] In some preferred embodiments, the control component 10 includes a T-shaped plate 100 and a transverse plate 101. The upper part of the T-shaped plate 100 is slidably fitted into the corresponding T-shaped grooves 9. A control motor 102 is also provided inside the T-shaped plate 100. A rotating wheel 103 is fixedly installed at the output end of the control motor 102. The output shaft of the control motor 102 is eccentrically set with the rotating wheel 103. A plurality of T-shaped limiting guide blocks 104 are fixedly provided on each side of the T-shaped plate 100. The transverse plate 101 is located below the T-shaped plate 100 and is slidably connected to the plurality of T-shaped limiting guide blocks 104. A drive ring 105 is fixedly provided on the side of the transverse plate 101 opposite to the bottom of the T-shaped plate 100. The bottom of the transverse plate 101 is fixedly connected to the corresponding front support frame 11 or rear support frame 12. The rotating wheel 103 is also horizontally located inside the drive ring 105 and contacts the inner wall of the drive ring 105. The control motor 102 is also signal-connected to the controller 6.

[0060] When the controller 6 sends a rotation command to the control motor 102, the output shaft of the control motor 102 drives the eccentrically mounted rotating wheel 103 to rotate. Since the rotating wheel 103 is in contact with the inner wall of the drive ring 105, its eccentric portion exerts a periodic pushing force on the inner wall of the drive ring 105 during rotation. The lateral component of this pushing force causes the drive ring 105 to swing laterally left and right. Because the drive ring 105 is fixed to the transverse plate 101, the transverse plate 101 also undergoes lateral displacement. The lateral displacement of the transverse plate 101 causes the front support frame 11 or the rear support frame 12 to translate laterally.

[0061] The T-shaped limit guide block 104 restricts the sliding direction of the transverse plate 101 to be purely lateral, ensuring the straightness and accuracy of the lateral displacement and avoiding jamming or motion interference caused by skewness.

[0062] When the control motor 102 stops after rotating a certain angle, the contact between the eccentric part of the rotating wheel 103 and the inner wall of the drive ring 105 locks the transverse plate 101 in its current lateral position. Even under vibration and impact during sliding, because the rotating wheel 103 and the drive ring 105 are in surface contact and the control motor 102 has a self-locking torque, the position of the transverse plate 101 will not change unexpectedly, thus achieving reliable locking of lateral misalignment.

[0063] In some preferred embodiments, the upper part of the lifting plate 8 is further provided with multiple shock-absorbing springs 21, and the upper part of each shock-absorbing spring 21 is fixedly connected to the strip cavity 5. Straight slots 22 are opened on both sides of the rectangular hollow block 7, and the straight slots 22 are vertically oriented, with both ends of the drive rod 16 passing through the straight slots 22 respectively. The installation of the shock-absorbing springs 21 does not affect the active lifting and lowering movement of the lifting plate 8 driven by the third electric cylinder 19. When the third electric cylinder 19 drives the lifting plate 8 to rise, the lifting plate 8 overcomes the elastic force of the shock-absorbing springs 21 and moves upward, further compressing the shock-absorbing springs 21 and storing elastic potential energy. When the third electric cylinder 19 drives the lifting plate 8 to descend, the shock-absorbing springs 21 release elastic potential energy, assisting the lifting plate 8 to descend smoothly. Therefore, the shock-absorbing springs 21 not only play a passive damping role but also assist the movement of the lifting plate 8, making the lifting process smoother and gentler.

[0064] In some preferred embodiments, the drive groove 15 is zigzag-shaped, including two horizontal through-sections 150 and an inclined through-section 151. The inclined through-section 151 is located between the two horizontal through-sections 150 and is interconnected. The rectangular hollow block 7 is also provided with two horizontal guide rails 23. The drive block 14 is located between the two horizontal guide rails 23. When the drive block 14 reciprocates under the control command of the third electric cylinder 19, the drive groove 15 forces the drive rod 16 to move up and down in the vertical direction along the straight groove opening 22, so that the lifting plate 8 can be raised and lowered.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An adaptive control method for roller skates, characterized in that, Includes the following steps: S1: Real-time acquisition of the first and second pressure values ​​of the foot inside the roller skate, as well as the real-time wheel speed value output by any one of the roller skates; S2: Compare the first pressure value with the second pressure value, and determine the user's movement intention based on the comparison result. The movement intention includes a first intention to trigger the wheel track to extend and the lifting plate to move upward, and a second intention to trigger the wheel track to shorten and the lifting plate to move downward. S3: Verify the adjustment action corresponding to the motion intention based on the real-time wheel speed value. When the real-time wheel speed value reaches a preset first threshold, restrict the execution permission of the wheel track shortening action. S4: Based on the stated motion intention and verification results, control the first and second electric cylinders to drive the front and rear support frames to perform wheel track adjustment, and simultaneously control the third electric cylinder to drive the lifting plate to perform height adjustment through the drive block and drive groove.

2. The roller skate adaptive control method according to claim 1, characterized in that, In S3, when the real-time wheel speed value exceeds the preset first threshold, the following operations are performed: Lock the drive direction of the first and second electric cylinders used to perform the wheelbase shortening action, so that the front support frame and the rear support frame are only allowed to perform wheelbase extension actions that move away from each other and are prohibited from performing wheelbase shortening actions that move closer to each other; at the same time, limit the drive speed of the third electric cylinder to control the descent rate of the lifting plate.

3. The roller skate adaptive control method according to claim 1, characterized in that, In S4, when the first intention is determined, the first electric cylinder and the second electric cylinder respectively drive the front support frame to move forward and the rear support frame to move backward, thereby increasing the wheel distance between the two sets of pulleys; at the same time, the third electric cylinder drives the drive block to slide along the first direction, causing the drive rod to slide along the corresponding section of the drive groove and drive the lifting plate to move upward, so that the foot is close to the ground, thereby lowering the center of gravity of the slide; When the second intention is determined, the first electric cylinder and the second electric cylinder respectively drive the front support frame to move backward and the rear support frame to move forward, thereby shortening the wheel distance between the two sets of pulleys; at the same time, the third electric cylinder drives the drive block to slide along the second direction, causing the drive rod to slide along the corresponding section of the drive groove and drive the lifting plate to move downward, so that the foot is away from the ground, thereby increasing the ground clearance.

4. The roller skate adaptive control method according to claim 1, characterized in that, It also includes cornering assist adjustment, the specific steps of which are as follows: The wheel speed difference between the first and last pulleys is obtained. When the wheel speed difference exceeds a preset second threshold, it is determined that the current situation is in a turning trajectory, and the turning direction is identified. Based on the identification results, the control component drives the front support frame and the rear support frame to generate a relative lateral misalignment in the horizontal plane, wherein: When a left turn is detected, the front support frame is controlled to move laterally to the left, while the rear support frame is controlled to move laterally to the right, forming an alternating wheel track distribution of front left and rear right; When a right turn is detected, the front support frame is controlled to move laterally to the right, while the rear support frame is controlled to move laterally to the left, forming an alternating wheel track distribution of front right and rear left.

5. The roller skate adaptive control method according to claim 4, characterized in that, The lateral misalignment of the front support frame and the rear support frame is directly proportional to the absolute value of the wheel speed difference.

6. The roller skate adaptive control method according to claim 1, characterized in that, After S4 is completed and the comparison result between the first pressure value and the second pressure value falls back to the preset static dead zone range, the automatic return to center reset is also included. The specific steps are as follows: When the real-time wheel speed value is less than a preset third threshold, and the comparison result of the first pressure value and the second pressure value remains within the static dead zone for a preset duration, the first electric cylinder and the second electric cylinder are controlled to drive the front support frame and the rear support frame to retract to the preset center wheel distance. At the same time, the third electric cylinder is controlled to drive the drive block to slide to the preset center position, so that the lifting plate is restored to the preset center height. The control component is then controlled to drive the front support frame and the rear support frame to synchronously return to the longitudinal center line position of the lifting plate.

7. A roller skate for implementing the roller skate adaptive control method according to any one of claims 1-6, characterized in that, The roller skate includes a shoe body and a sole plate. The upper part of the sole plate is provided with a first pressure unit and a second pressure unit. A longitudinally extending strip-shaped cavity is formed on the bottom surface of the sole plate. A controller and a rectangular hollow block are also housed inside the strip-shaped cavity. A lifting plate is fitted onto the outside of the rectangular hollow block. T-slots are formed at the front and rear ends of the lifting plate. A front support frame and a rear support frame are slidably mounted in each T-slot via a control component. A set of pulleys is installed on each of the front and rear support frames. A drive block is slidably disposed inside the rectangular hollow block. The drive block has a drive groove extending through it. A drive rod is horizontally arranged in the drive groove and fixedly connected to both sides of the lifting plate. A first electric cylinder and a second electric cylinder are also mirror-arranged below the lifting plate. The telescopic ends of the first electric cylinder and the second electric cylinder are fixedly connected to the corresponding front support frame and rear support frame, respectively. A third electric cylinder is also provided in the rectangular hollow block. The telescopic end of the third electric cylinder is also fixedly connected to the drive block. A wheel speed acquisition unit is also installed at the axle center of any pulley. The controller is also connected to the first pressure unit, the second pressure unit, the control component, the first electric cylinder, the second electric cylinder, the third electric cylinder, and the wheel speed acquisition unit.

8. The roller skates according to claim 7, characterized in that, The control assembly includes a T-shaped plate and a transverse plate. The upper part of the T-shaped plate is slidably fitted into corresponding T-shaped slots. A control motor is also installed inside the T-shaped plate. A rotating wheel is fixedly installed at the output end of the control motor. The output shaft of the control motor and the rotating wheel are eccentrically arranged. Multiple T-shaped limit guide blocks are also fixedly installed on each side of the T-shaped plate. The transverse plate is located below the T-shaped plate and is slidably connected to the multiple T-shaped limit guide blocks. A drive ring is also fixed on the side of the transverse plate opposite to the bottom of the T-shaped plate. The rotating wheel is horizontally located inside the drive ring and contacts the inner wall of the drive ring. The control motor is also signal-connected to the controller.

9. The roller skates according to claim 7, characterized in that, The upper part of the lifting plate is also provided with multiple shock-absorbing springs, and the upper part of each shock-absorbing spring is fixedly connected to the strip cavity. Straight slots are opened on both sides of the rectangular hollow block. The straight slots are set in the vertical direction, and the two ends of the drive rod pass through the straight slots respectively.

10. The roller skates according to claim 7, characterized in that, The drive groove is zigzag-shaped, including two horizontal through-sections and an inclined through-section. The inclined through-section is located between the two horizontal through-sections and is interconnected. The rectangular hollow block is also provided with two horizontal guide rails. The drive block is located between the two horizontal guide rails. When the drive block reciprocates under the control command of the third electric cylinder, the drive groove forces the drive rod to move up and down along the straight groove opening in the vertical direction, so that the lifting plate can be raised and lowered.

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