Automatic protection device and method for asphalt core wall rolling construction

Abstract

The present invention provides an automated protective device and method for asphalt core wall rolling construction, comprising a plurality of scaffolds arranged in sequence, each scaffold being provided with a walking device at the bottom for walking along the transition material on both sides of the asphalt core wall; a horizontally arranged covering film shaft is provided on the scaffold located at one end, the covering film shaft being connected to a driving device for realizing automatic winding, the covering film being wound on the covering film shaft, and the covering film actively covering the surface of the asphalt core wall; a scaffold located in the middle being provided with a bottom film pressing roller for pressing the covering film onto the surface of the asphalt core wall; during the construction process, the scaffold moves with the roller and the device. By providing a structure of multiple scaffolds, covering films, and windproof films, the surface of the asphalt concrete can be automatically covered after paving, thereby avoiding excessive temperature loss on the surface of the asphalt concrete. It can also reduce the impact of sand and dust on asphalt concrete paving, significantly reduce the steps of subsequent manual processing, improve safety, and reduce labor intensity.

Description

Technical Field

[0001] The present invention relates to the field of core wall dam construction, and in particular to an automated protective device and method for asphalt core wall rolling construction. Background Art

[0002] The asphalt concrete core wall of a hydropower station is vertical, with a thickness ranging from 0.5m to 1.5m. The design features a gradual gradient: the core wall top elevation is 2478.0m, with a top thickness of 0.5m; the core wall bottom elevation is 2377.8m, with a bottom thickness of 1.5m. A 3m-high footing is provided at the core wall bottom, gradually decreasing the thickness from 1.5m to 3m. The core wall's enlarged foundation is located on the reinforced concrete foundation gallery at the dam foundation. The paving temperature is 135°C and needs to be lowered to 70-90°C before rolling. Asphalt is a hydrophobic material, and rainwater significantly affects the quality of the mixture. Protecting against rainwater can effectively improve the compaction quality of the asphalt concrete core wall. Construction dust significantly impacts the compaction quality of the asphalt concrete core wall. Excessive dust requires heating the surface layer, manually removing the entire surface, and then re-paving and compacting, which is labor-intensive and costly. On-site, wind also significantly impacts the quality of asphalt concrete compaction. Besides generating significant dust, strong winds can also lead to rapid cooling of the mixture during on-site control. Excessive temperature loss can lead to poor compaction and poor asphalt concrete quality. Currently, no effective solution has been found in existing technologies. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an automated protective device and method for asphalt core wall rolling construction, which can improve and reduce the impact of dust on the construction quality of asphalt concrete core wall, especially can better control the surface temperature loss of asphalt concrete, accurately control and grasp the timing of rolling construction, improve the rolling construction quality of asphalt concrete, and reduce permeability.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: an automated protective device for asphalt core wall rolling construction, comprising a plurality of scaffolds arranged in sequence, each scaffold having a walking device at the bottom thereof for walking along the transition material on both sides of the asphalt core wall;

[0005] A horizontally arranged covering film shaft is provided on the scaffolding at one end. The covering film shaft is connected to a driving device for realizing automatic winding. The covering film is wound on the covering film shaft and actively covers the surface of the asphalt core wall.

[0006] The scaffolding in the middle is provided with a bottom film pressing roller, which is used to press the covering film onto the surface of the asphalt core wall;

[0007] During construction, the scaffolding moves with the rollers and equipment.

[0008] In a preferred solution, vertical windproof film shafts are provided on both sides of the scaffolding at one end, the windproof film is wound on the windproof film shafts, and the windproof film is connected to a driving device for realizing automatic winding.

[0009] In the preferred solution, the covering film shaft is located inside the scaffolding, and both ends of the covering film shaft are connected to the transfer case, which has two output shafts, one of which is connected to the covering film shaft, and the other is connected to the windproof film shaft through a universal coupling;

[0010] One of the transfer cases is connected to the film winding motor.

[0011] In the preferred solution, the structure of the traveling device is as follows: a sled seat is provided at the bottom of the shed, the edges of the sled seat are raised upward, and a rake wheel is provided, which is connected to the traveling motor, the edge of the rake wheel passes through the bottom of the sled seat, and the edge of the rake wheel is lower than the bottom of the sled seat.

[0012] In a preferred solution, a temperature sensor is further provided in the scaffolding, the temperature sensor is used to detect the surface temperature of the asphalt concrete, and the temperature sensor is electrically connected to the main control device;

[0013] The main control device is also electrically connected to the travel motor and the film rolling motor of the travel device.

[0014] In the preferred solution, a bottom film pressing roller is provided near the bottom of the middle scaffolding to press the covering film onto the surface of the asphalt concrete. Vertical side film pressing rollers are also provided on both sides of the scaffolding to provide support for the windproof film.

[0015] In a preferred solution, a distance measuring sensor is provided at the front end of the scaffolding at one end, and distance measuring sensors are provided at both ends of the scaffolding located in the middle.

[0016] In a preferred embodiment, the covering film is a composite film, and an aerogel layer is provided on the aluminum-plastic film.

[0017] A construction method using the above-mentioned automated protective device for asphalt core wall rolling construction comprises the following steps:

[0018] S1. Read the construction plan;

[0019] S2. According to the construction plan, set active scaffolding and fixed scaffolding in each scaffolding;

[0020] S3. Set the working mode of the active scaffolding to automatic following;

[0021] S4. Arrange each scaffold on the asphalt core wall after paving, and use a temperature sensor in each scaffold to monitor the current temperature parameters in the scaffold;

[0022] S5. When the temperature parameter reaches the expected value, a signal is sent;

[0023] S6: The roller starts rolling, the active scaffold follows the roller, and the film winding motor works in a constant torque mode to wind up the covering film;

[0024] Active and fixed scaffolds are arranged on the compacted asphalt core wall. The active scaffold moves along with the roller. The film-rolling motor works in a constant torque mode to cover the compacted asphalt core wall with the covering film. The windproof film is located on both sides of the covering film.

[0025] The above steps are used to realize the thermal insulation and windproof construction after the asphalt core wall is rolled.

[0026] The preferred solution further includes the following steps: In step S6,

[0027] The automatic following control steps of the active scaffolding are as follows: the active scaffolding reads the current working mode. If the working mode is following, the distance parameter between the current active scaffolding and the roller in front is read; the difference between the distance parameter and the preset distance parameter is calculated; the relative position between the current active scaffolding and the roller is read, the rotation direction of the travel motor is calculated, and the travel distance of the active scaffolding is calculated based on the difference, which is converted into the rotation angle parameter of the travel motor. The main control device sends a pulse control signal to the travel motor. If a new distance parameter is received, the subsequent pulse control signal replaces the previous pulse control signal, and the previous pulse control signal is no longer executed.

[0028] The automatic following control steps of the middle scaffolding are as follows: the middle scaffolding reads the current working mode. When the working mode is following, the distance measuring sensor collects the distance parameters between the middle scaffolding and the front and rear, calculates the rotation direction of the walking motor based on the larger value of the distance parameter, calculates the walking distance based on the difference between the larger value and the average value of the distance parameter, and sends a pulse signal to the walking motor; if a new distance parameter is received, the later pulse signal replaces the earlier pulse signal, and the earlier pulse signal is no longer executed.

[0029] The present invention provides an automated protective device and method for asphalt core wall rolling construction. Through the structure of multiple scaffoldings, covering films and windproof films, it can automatically cover the surface of asphalt concrete after paving to avoid excessive temperature loss on the surface of asphalt concrete. It can also reduce the impact of sand and dust on asphalt concrete paving, greatly reduce the steps of subsequent manual processing, improve safety, and reduce labor intensity. The set automatic following function can greatly reduce labor intensity, reduce or eliminate the chance of manual approach to the paver and roller, improve construction safety, ensure that the temperature gradient difference of asphalt concrete is within a preset range, and improve the construction quality of asphalt concrete. The set temperature sensor can accurately grasp the timing of asphalt concrete rolling construction and further improve the construction quality of asphalt concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and examples:

[0031] Figure 1 It is a structural schematic diagram of the active scaffolding of the present invention.

[0032] Figure 2 It is a side view of multiple shelves of the present invention.

[0033] Figure 3 It is a side view of multiple scaffolds of the present invention during the rolling construction process.

[0034] Figure 4 This is a top view of multiple scaffolds of the present invention during the rolling construction process.

[0035] Figure 5 It is a schematic structural diagram of the covering film shaft, windproof film shaft and walking device of the present invention.

[0036] Figure 6 It is a structural schematic diagram of the intermediate shelf of the present invention.

[0037] Figure 7 It is a flow chart of the construction method of the present invention.

[0038] Figure 8 This is a control flow chart of the active scaffolding automatic following of the present invention.

[0039] Figure 9 This is a control flow chart for the automatic following of the intermediate shelf of the present invention.

[0040] In the figure: active scaffolding 1, frame 101, covering film shaft 102, film winding motor 103, transfer case 104, universal joint 105, windproof film shaft 106, bottom film pressing roller 107, side film pressing roller 108, first transfer gear 109, second transfer gear 110, intermediate scaffolding 2, fixed scaffolding 3, roller 4, covering film 5, windproof film 6, rake wheel 7, travel motor 8, sled seat 9, temperature sensor 10, distance sensor 11, transition material 12, asphalt core wall 13, main control device 14. DETAILED DESCRIPTION

[0041] Example 1:

[0042] like Figures 1 to 6 In the present invention, an automated protective device for asphalt core wall rolling construction includes a plurality of scaffolds arranged in sequence. In this example, Figure 3 、 4In the example, each group of scaffolding is divided into active scaffolding 1, intermediate scaffolding 2 and fixed scaffolding 3. The active scaffolding 1 is close to the roller or paver, and the fixed scaffolding 3 is far away from the roller or paver. A plurality of intermediate scaffolding 2 are provided between the active scaffolding 1 and the fixed scaffolding 3. Usually, a group of scaffolding is provided at each end of each roller or paver. In this example, the roller is taken as an example. It should be noted that as the asphalt core wall is constructed, the length of the asphalt core wall will become longer and longer, so the scaffolding on each side may also include multiple groups of scaffolding structures including active scaffolding 1, intermediate scaffolding 2 and fixed scaffolding 3. During the construction process, the entire group of scaffolding needs to be moved from one end of the roller or paver to the other.

[0043] Each scaffold is provided with a walking device at the bottom thereof for walking along the transition material 12 on both sides of the asphalt core wall 13;

[0044] A horizontally arranged covering film shaft 102 is mounted on the scaffolding at one end. This shaft is connected to a drive mechanism for automatic rewinding. The covering film 5 is wound around the shaft 102 and actively covers the surface of the asphalt core wall 13. Preferably, the covering film 5 is a composite film, with an aerogel layer applied over the aluminum-plastic film. This structure ensures excellent dustproofing, tensile strength, windproofing, and thermal insulation while maintaining a thin and lightweight structure.

[0045] The middle scaffolding, i.e. the middle scaffolding 2, is provided with a bottom film pressing roller 107, which is used to press the covering film 5 onto the surface of the asphalt core wall 13;

[0046] During the construction process, the scaffolding moves along with the roller 4 and the device.

[0047] The preferred solution is Figure 1 In the embodiment, vertical windproof film shafts 106 are provided on both sides of the scaffolding at one end. Windproof film 6 is wound around windproof film shafts 106 and connected to a drive device for automatic rewinding. The windproof film 6 further reduces the impact of dust on the covering film 5, providing wind and sand protection and assisting in thermal insulation.

[0048] The preferred solution is Figure 1 、 5 In the figure, the covering film shaft 102 is located inside the scaffolding, and both ends of the covering film shaft 102 are connected to the distributor 104. The distributor 104 has two output shafts, one of which is connected to the covering film shaft 102, and the other is connected to the windproof film shaft 106 through a universal coupling 105.

[0049] The input shaft of one of the transfer cases 104 is connected to the film winding motor 103. In a preferred embodiment, the transfer case 104 is two mutually meshing gears with the same parameters, and has one input shaft and two output shafts.

[0050] The preferred solution is Figure 1 、 5 In the embodiment, the traveling device is structured as follows: a sled seat 9 is provided at the bottom of the scaffolding, with the edges of the sled seat 9 tilted upward. A rake wheel 7 is also provided, which is connected to a traveling motor 8. The edge of the rake wheel 7 passes through the bottom of the sled seat 9 and is lower than the bottom of the sled seat 9. The rake wheel 7 is a wheel with multiple protrusions on the edge. In this example, a wheel with a paddle-like structure is used. This is because the particle size of the transition material is usually large, ranging from 5mm to 80mm, and ordinary wheels are difficult to drive the machine. After multiple tests, the inventors found that the combination of the sled seat 9 and the rake wheel 7 is more effective.

[0051] The preferred solution is Figure 1 、 5 6, a temperature sensor 10 is further provided in the scaffolding. Preferably, the temperature sensor 10 is an infrared temperature sensor. The temperature sensor 10 is used to detect the surface temperature of the asphalt concrete. The temperature sensor 10 is electrically connected to the main control device 14; the main control device 14 is preferably a main control device based on the STM32F series main control chip, and a wifi chip is also provided to form a local area network in a relay manner for communication.

[0052] The main control device 14 is also electrically connected to the travel motor 8 and film-winding motor 103 of the travel mechanism. The main control chip sends pulse signals to control the rotation angle and direction of the travel motor 8 and film-winding motor 103. The travel motor 8 and film-winding motor 103 are preferably variable-frequency motors, with the control of the rotation angle and direction being achieved by the variable-frequency controllers built into the travel motor 8 and film-winding motor 103.

[0053] The preferred solution is Figure 6 In the figure, a bottom film pressing roller 107 is provided near the bottom of the middle scaffolding to press the covering film 5 onto the surface of the asphalt concrete. Vertical side film pressing rollers 108 are provided on both sides of the scaffolding to provide support for the windproof film 6. Preferably, the side film pressing rollers 108 are provided on the inner side of the frame 101 and supported by bearings. The windproof film 6 passes between the side film pressing rollers 108 and the frame 101.

[0054] The preferred solution is Figure 3 、 4In the embodiment, a distance measuring sensor 11 is provided at the front end of the scaffolding at one end, and a distance measuring sensor 11 is provided at both ends of the scaffolding in the middle. Preferably, the distance measuring sensor 11 adopts a laser radar or ultrasonic radar sensor. Since the present invention does not require high distance accuracy, it is preferred to use an automotive ultrasonic radar sensor as the distance measuring sensor 11. The distance measuring sensor 11 is electrically connected to the main control device 14. The data collected by the distance measuring sensor 11 is fitted into a number of 0 to 10 levels in the main control device 14, and each level corresponds to a distance of approximately 15 cm. Data exceeding level 10 are all regarded as level 10. This greatly reduces the calculation accuracy.

[0055] The windproof film 6 is a plastic plain film or a plastic woven film.

[0056] Example 2:

[0057] like Figure 7 A construction method using the above-mentioned automated protective device for asphalt core wall rolling construction comprises the following steps:

[0058] S1. Read the construction plan; the construction plan includes parameters such as the asphalt concrete paving temperature, preset cooling time, rolling construction temperature, following distance and harrow wheel 7 diameter.

[0059] S2. According to the construction plan, each scaffold is configured with an active scaffold 1 and a fixed scaffold 3. The running gear of the fixed scaffold 3 remains stationary, but during film collection operations, the fixed scaffold 3 moves toward the active scaffold 1. This operation is primarily used when there are multiple scaffolds at each end of the rig and the scaffolds need to be swapped from one end to the other. During this swap, a loader is used on-site to lift and move the scaffolding groups, typically consisting of one active scaffold 1, one fixed scaffold 3, and two or three intermediate scaffolds 2. During the swap, the running gear must not come into contact with the asphalt concrete surface.

[0060] S3, setting the working mode of active scaffolding 1 to automatic following;

[0061] S4. Arrange each scaffold on the asphalt core wall 13 after paving. The temperature sensor 10 in each scaffold measures the current temperature parameter in the scaffold.

[0062] S5. When the temperature parameter reaches the expected value, for example, it drops to a temperature suitable for starting rolling, such as 90°C, a signal is sent; the temperature sensor 10 and the main control device 14 also monitor and analyze an important parameter, namely the cooling gradient, which is the functional relationship between the time for the temperature to drop and the absolute value of the temperature change. If the cooling gradient exceeds expectations, for example, in low temperature or windy weather, the surface of the asphalt concrete cools down too quickly, while the internal temperature is still relatively high, it will affect the rolling quality, so additional insulation and warming measures need to be taken. This solution can further ensure the rolling quality of asphalt concrete. The insulation measure is to add thickened canvas as a covering film 5. The warming measure is to wait until the internal temperature drops to a temperature suitable for rolling, the temperature is measured by an inserted temperature sensor, and then the surface is heated to the rolling temperature by electric heating or natural gas before rolling construction is carried out.

[0063] S6: The roller starts rolling construction, the active scaffold 1 follows the roller, and the film winding motor 103 works in a constant torque mode to wind up the covering film 5;

[0064] An active scaffolding 1 and a fixed scaffolding 3 are arranged on the compacted asphalt core wall 13. The active scaffolding 1 moves along with the roller. The film-rolling motor 103 operates in a constant torque mode, and as the covering film 5 is covered on the compacted asphalt core wall 13, the windproof film 6 is located on both sides of the covering film 5.

[0065] The torque of the film winding motor 103 is set to automatically tighten the covering film 5 and windproof film 6. As the walking device moves, the torque of the film winding motor 103 automatically lowers or rewinds the covering film 5 and windproof film 6. Preferably, the torque f1 = f0 + k * d1 - d0, where f0 is the initial torque and k is a correction factor, primarily due to the effect of increased diameter on torque changes. This correction factor is obtained through calibration. d1 is the increased diameter of the covering film 5 or windproof film 6 after winding, and d0 is the initial diameter of the covering film 5 or windproof film 6.

[0066] like Figure 8 As shown in , the automatic following control steps of the active scaffolding 1 are as follows: the active scaffolding 1 reads the current working mode. When the working mode is following, the distance parameter between the current active scaffolding 1 and the roller 4 in front is read; the difference is calculated with the preset distance parameter; the relative position between the current active scaffolding 1 and the roller 4 is read, the rotation direction of the travel motor 8 is calculated, and the travel distance of the active scaffolding 1 is calculated based on the difference, and converted into the rotation angle parameter of the travel motor 8. The main control device 14 sends a pulse control signal to the travel motor 8. If a new distance parameter is received, the subsequent pulse control signal replaces the previous pulse control signal, and the previous pulse control signal is no longer executed.

[0067] like Figure 9As shown in , the automatic following control steps of the middle scaffold 2 are as follows: the middle scaffold 2 reads the current working mode. When the working mode is following, the distance measuring sensor 11 collects the distance parameters between the middle scaffold 2 and the front and rear, calculates the rotation direction of the walking motor 8 based on the larger value of the distance parameter, calculates the walking distance based on the difference between the larger value and the average value of the distance parameter, and sends a pulse signal to the walking motor 8; if a new distance parameter is received, the subsequent pulse signal replaces the previous pulse signal, and the previous pulse signal is no longer executed.

[0068] The above steps are used to realize the thermal insulation and windproof construction after the asphalt core wall is rolled.

[0069] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The embodiments and features in the embodiments of this application may be arbitrarily combined with each other unless they conflict. The scope of protection of the present invention shall be the technical solutions described in the claims, including equivalent alternatives to the technical features of the technical solutions described in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A construction method for an automated protective device for asphalt core wall rolling construction, characterized by: It comprises a plurality of scaffolds arranged in sequence, each scaffold having a walking device at the bottom thereof for walking along the transition material (12) on both sides of the asphalt core wall (13); A horizontally arranged covering film shaft (102) is provided on a scaffolding at one end. The covering film shaft (102) is connected to a driving device for realizing automatic winding. The covering film (5) is wound on the covering film shaft (102). The covering film (5) actively covers the surface of the asphalt core wall (13). The scaffolding located in the middle is provided with a bottom film pressing roller (107), and the bottom film pressing roller (107) is used to press the covering film (5) onto the surface of the asphalt core wall (13); A vertical windproof film shaft (106) is provided on both sides of the scaffolding at one end, the windproof film (6) is wound on the windproof film shaft (106), and the windproof film (6) is connected to a driving device for realizing automatic winding; During the construction process, the scaffolding moves with the roller (4) and the device; The construction method includes the following steps: S1. Read the construction plan; S2. According to the construction plan, set active scaffolding (1) and fixed scaffolding (3) in each scaffolding; S3, setting the working mode of the active scaffolding (1) to automatic following; S4, arranging each scaffold on the asphalt core wall (13) after paving, and the temperature sensor (10) in each scaffold collects the current temperature parameters in the scaffold; S5. When the temperature parameter reaches the expected value, a signal is sent; S6, the roller starts rolling construction, the active scaffold (1) follows the roller, and the film winding motor (103) works in a constant torque mode to wind up the covering film (5); An active scaffold (1) and a fixed scaffold (3) are arranged on the compacted asphalt core wall (13), the active scaffold (1) follows the roller, and the film rolling motor (103) operates in a fixed torque mode to cover the covering film (5) on the compacted asphalt core wall (13), and the windproof film (6) is located on both sides of the covering film (5); The above steps are used to realize the thermal insulation and windproof construction after the asphalt core wall is rolled.

2. The construction method of an automated protective device for asphalt core wall rolling construction according to claim 1 is characterized by: The covering film shaft (102) is located inside the scaffolding, and both ends of the covering film shaft (102) are connected to a distributor (104). The distributor (104) is provided with two output shafts, one of which is connected to the covering film shaft (102), and the other is connected to the windproof film shaft (106) via a universal joint (105). One of the transfer cases (104) is connected to the film rolling motor (103).

3. The construction method of an automated protective device for asphalt core wall rolling construction according to claim 1 is characterized by: The structure of the traveling device is as follows: a sled seat (9) is provided at the bottom of the scaffolding, the edges of the sled seat (9) are tilted upward, and a rake wheel (7) is provided. The rake wheel (7) is connected to the traveling motor (8), and the edge of the rake wheel (7) passes through the bottom of the sled seat (9), and the edge of the rake wheel (7) is lower than the bottom of the sled seat (9).

4. The construction method of an automated protective device for asphalt core wall rolling construction according to claim 2 is characterized by: A temperature sensor (10) is also provided in the scaffolding. The temperature sensor (10) is used to detect the surface temperature of the asphalt concrete. The temperature sensor (10) is electrically connected to the main control device (14). The main control device (14) is also electrically connected to the travel motor (8) and the film rolling motor (103) of the travel device.

5. The construction method of an automated protective device for asphalt core wall rolling construction according to claim 4 is characterized by: A bottom film pressing roller (107) is provided near the bottom of the middle scaffolding for pressing the covering film (5) onto the surface of the asphalt concrete. Vertical side film pressing rollers (108) are provided on both sides of the scaffolding for providing support for the windproof film (6).

6. The construction method of an automated protective device for rolling construction of asphalt core wall according to claim 5 is characterized by: A distance measuring sensor (11) is provided at the front end of the scaffolding located at one end, and distance measuring sensors (11) are provided at both ends of the scaffolding located in the middle.

7. The construction method of an automated protective device for asphalt core wall rolling construction according to claim 1 is characterized by: The covering film (5) is a composite film, and an aerogel layer is provided on the aluminum-plastic film.

8. The construction method of an automated protective device for rolling construction of asphalt core wall according to claim 1 is characterized by further The following steps are involved: In step S6, The automatic following control steps of the active scaffold (1) are as follows: the active scaffold (1) reads the current working mode, and when the working mode is following, the distance parameter between the current active scaffold (1) and the roller (4) in front is read; and the difference between the distance parameter and the preset distance parameter is calculated; The relative position between the active scaffold (1) and the roller (4) is read, the rotation direction of the travel motor (8) is calculated, the travel distance of the active scaffold (1) is calculated based on the difference, and the difference is converted into the rotation angle parameter of the travel motor (8). The main control device (14) sends a pulse control signal to the travel motor (8). If a new distance parameter is received, the subsequent pulse control signal replaces the previous pulse control signal, and the previous pulse control signal is no longer executed; The automatic following control steps of the middle scaffold (2) are as follows: the middle scaffold (2) reads the current working mode. When the working mode is following, the distance sensor (11) collects the distance parameters between the middle scaffold (2) and the front and rear, calculates the rotation direction of the walking motor (8) based on the larger value of the distance parameter, calculates the walking distance based on the difference between the larger value and the average value of the distance parameter, and sends a pulse signal to the walking motor (8); if a new distance parameter is received, the later pulse signal replaces the earlier pulse signal, and the earlier pulse signal is no longer executed.

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