An unmanned aerial vehicle temporary landing pad assembly and method of installation thereof

Abstract

The present application relates to a kind of unmanned aerial vehicle temporary parking apron assembly, comprising: parking platform and unmanned aerial vehicle guiding device.Parking platform is provided with multiple guide areas and a collection area, guide area is arranged around collection area, and the side of guide area close to collection area is lower than the side away from collection area.Guide groove is opened in guide area, one end of guide groove is towards collection area, the other end is towards the outside of parking platform, and first guide surface and second guide surface are arranged on the two sides of guide groove in guide area.Unmanned aerial vehicle guiding device includes several rolling foot sleeves, and rolling foot sleeve is detachably connected with unmanned aerial vehicle.The present application also discloses a kind of installation method of unmanned aerial vehicle temporary parking apron.The present application is matched with one-to-one correspondence of guide groove and rolling foot sleeve, and position is returned to center and heading angle is passively oriented using the gravity of unmanned aerial vehicle itself, so as to solve the problem that existing parking apron lacks heading angle orientation correction ability.

Description

Technical Field

[0001] This invention relates to the field of drone landing pad technology, and in particular to a drone temporary landing pad component and its installation method. Background Technology

[0002] Lightweight drones (empty weight 0.25kg–4kg, maximum takeoff weight not exceeding 7kg) have been widely used in low-altitude operations such as urban road inspection, city security, traffic flow surveys, and emergency fire patrols. To ensure the safe takeoff, landing, and temporary loitering of drones during mission breaks, a technical solution integrating temporary helipads into existing streetlight poles has emerged in recent years. These pole-mounted helipads fully utilize existing pole space on both sides of the road without additionally occupying pedestrian walkways or green areas. Simultaneously, the high-altitude location of the takeoff and landing platform, away from pedestrians and non-motorized vehicle traffic, effectively reduces the risk of propeller injuries and collisions. Furthermore, the open high-altitude environment helps reduce interference from trees and buildings on drone positioning and signal transmission, thereby improving operational safety during takeoff and landing.

[0003] However, existing pole-mounted helipads still have the following significant technical shortcomings: (a) Gimbal obstruction problem. Most existing platforms adopt an overall enclosed panel structure. After the UAV lands, the panel completely obscures the gimbal camera under the fuselage, making it impossible for the UAV to continue to perform road patrol tasks during its stay, and making it difficult to meet the continuous operation requirement of "stopping but not patrolling".

[0004] (ii) Insufficient landing positioning accuracy. Currently, the landing process mainly relies on manual control by the pilot. Affected by GPS signal drift and high-altitude wind disturbances, it is difficult for the UAV to land accurately in the center area of ​​the platform every time, which poses a risk of slipping or overturning, and seriously restricts the reliability of automated take-off and landing.

[0005] (iii) Poor environmental adaptability of the alignment mechanism. Some platforms use traditional mechanical-electrically driven alignment devices to move the UAV to the platform's predetermined position. However, such devices are exposed to harsh outdoor environments such as alternating high and low temperatures, rain, and dust for extended periods. The motors and transmission components are prone to corrosion, jamming, or even failure, resulting in high maintenance costs and making it difficult to meet the low-maintenance requirements of urban infrastructure.

[0006] (iv) Lack of heading angle orientation capability. Existing pole-mounted platforms only focus on the rough parking position of the UAV in the horizontal plane, without solving the problem of correcting the heading angle (rotation direction around the vertical axis) of the fuselage after landing. Due to the randomness of the UAV's orientation during landing, even if the platform does not completely block the gimbal, the shooting direction of the gimbal camera often deviates from the target patrol road area, making it impossible to effectively utilize the dwell time to perform directional patrol tasks. Although traditional electric turntables can adjust the gimbal orientation, they also face the inherent drawback of poor reliability in outdoor environments. In addition, Chinese invention patent CN115503955A proposes a UAV system that uses the UAV's gravity to make it slide as a whole to the bottom of the trough to complete geometric centering. However, this solution relies on the cooperation of the UAV's dedicated arc-shaped guide structure and the large-area complementary guide surface of the parking trough, mainly to achieve center positioning. It does not address how to adapt the existing conventional UAV landing gear structure with low-profile modifications, how to constrain multiple support feet to correct the parking heading, or how to ensure that the gimbal's line of sight automatically corresponds to the platform's preset observation direction after correction.

[0007] (v) Damage to light poles caused by installation methods. Existing solutions generally involve drilling multiple fixing holes in the outer wall of the light pole for installation. Drilling not only easily damages the pre-embedded cables inside the pole and destroys the anti-corrosion layer on the surface of the pole, leading to rust and cracking, but also generates metal shavings and dust pollution during construction. High-altitude drilling is inefficient. More importantly, the holes left in the pole after disassembly are difficult to repair, significantly increasing the operation and maintenance costs of municipal facilities and posing structural safety hazards.

[0008] In summary, existing pole-mounted helipads have significant shortcomings in terms of continuous observation capability, landing positioning accuracy, reliability of the yaw mechanism, autonomous heading angle orientation, and non-destructive installation on light poles. There is an urgent need to propose a new pole-mounted UAV parking solution that takes into account safety, reliability, environmental adaptability, and low modification adaptability. Summary of the Invention

[0009] The purpose of this invention is to provide a temporary landing pad component for unmanned aerial vehicles (UAVs) and its installation method, in order to solve the problem that existing landing pads lack the ability to correct the heading angle of the UAV after landing.

[0010] To achieve the above objectives, this invention discloses a temporary drone landing pad assembly, comprising: a landing platform and a drone guiding device. The landing platform has multiple guiding areas and a converging area, the converging area being located within the landing platform. The guiding areas surround the converging area, with the side of the guiding area closer to the converging area lower than the side farther from the converging area. A guiding groove is formed within each guiding area, one end of which faces the converging area and the other end facing the outside of the landing platform. A first guiding surface and a second guiding surface are respectively provided on both sides of the guiding area along the guiding groove, with the side of the first and second guiding surfaces farther from the guiding groove higher than the side closer to the guiding groove. The drone guiding device includes several rolling feet, which are detachably connected to the drone. Each rolling foot can slide into its corresponding guiding groove under the weight of the drone and be limited by the guiding groove.

[0011] Preferably, a through-slot extending through the thickness of the parking platform is provided on one side of the parking platform.

[0012] Preferably, the viewing slot is V-shaped or U-shaped.

[0013] Preferably, the rolling foot cover includes a connecting part and a rolling part, the rolling part is installed below the connecting part, and the connecting part is detachably connected to the drone.

[0014] Preferably, the connecting part is an elastic silicone sleeve, the rolling part is a universal ball pulley or universal wheel, and the elastic silicone sleeve is fitted onto the drone support foot.

[0015] Preferably, the collection area is located at the lowest point of the parking platform, and a drain hole is provided in the collection area.

[0016] Preferably, four guide areas are provided, and a ring of fencing is provided around the outside of the parking platform.

[0017] The present invention also discloses an installation method for a temporary drone landing pad, wherein the temporary drone landing pad component is installed on horizontal poles on both sides of a road, the horizontal poles including any one or more of the following: horizontal light arms of light poles, horizontal light arms of traffic lights, and support crossbars of road signs.

[0018] Preferably, the temporary drone landing pad assembly further includes an installation component, which includes a clamp and a chute. Two chutes are provided, symmetrically distributed at the bottom of the landing platform. The clamp is used to hold the horizontal member, and both ends of the clamp are detachably connected to the chute by bolts. The head of the bolt is disposed within the chute, and the shank of the bolt passes through the chute and is locked by a nut.

[0019] Preferably, a vibration damping pad and / or an insulating pad are provided between the clamp and the horizontal member.

[0020] The present invention has the following beneficial effects: 1. This invention, through the one-to-one correspondence between four guide grooves and four rolling foot sleeves, enables the UAV to simultaneously achieve position centering and passive heading angle orientation using its own gravity, thus solving the technical problem of the lack of heading angle orientation correction capability in existing helipads.

[0021] 2. The distribution direction of the guide slots and the line-of-sight slots on the landing platform have a preset spatial correspondence. After the UAV is aligned, the gimbal optical axis automatically aligns with the line-of-sight slots, and the line of sight is unobstructed, reaching the road below, realizing the continuous operation capability of "inspecting immediately upon landing".

[0022] 3. The rolling foot covers use a combination of elastic silicone sleeves and universal ball bearings, which can be detachably fitted onto the original support feet of the drone without changing the main structure of the drone. Different sizes of foot covers can be used to adapt to various models.

[0023] 4. The entire correction process is a purely physical passive correction. The guide area is tilted, and the ball bearings slide independently along the guide surface under the drive of gravity. It does not rely on GPS signals or manual control, effectively eliminating the risk of drift and wind disturbance causing deviation.

[0024] 5. The parking platform is equipped with drainage holes, and the guide area also serves as a collection surface. Rainwater flows through the guide slope and is discharged through the drainage holes to prevent water accumulation on the platform.

[0025] 6. The installation components are fixed to the external pole body by clamping and locking, which does not require drilling and does not damage the pole body; the sliding groove adjustment margin allows the same platform to adapt to light poles of different diameters, and there are no residual holes after disassembly; the installation position of the clamp and the bolt spacing in the sliding groove are adjustable, which makes it easy to align the viewing groove with the target road direction.

[0026] 7. Four guide slots are set according to the distribution positions of the four landing gear support feet of the UAV. Each rolling foot sleeve slides into its corresponding guide slot under gravity. The four guide slots together limit the UAV's planar position and rotational degree of freedom around the vertical axis, so that the UAV can only stop in the predetermined heading. The entire process requires no electric drive components, achieving passive orientation correction with zero power consumption and zero maintenance. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure provided in a specific embodiment of the present invention; Figure 2 This is a right-side view of the overall structure provided in a specific embodiment of the present invention; Figure 3 This is a rear view diagram of the overall structure provided in a specific embodiment of the present invention; Figure 4 This is a schematic front view of the overall structure provided in a specific embodiment of the present invention; Figure 5 This is a cross-sectional schematic diagram of the shutdown platform provided in a specific embodiment of the present invention; Figure 6 This is a partially enlarged schematic diagram of point A provided in a specific embodiment of the present invention; Figure 7 This is a top view of the overall structure provided in a specific embodiment of the present invention; Figure 8 This is a top view of the parking platform provided in a specific embodiment of the present invention; Figure 9 This is a top view of the parking platform with the dividing line hidden, provided in a specific embodiment of the present invention; Figure 10 This is an exploded view of the installation components provided in a specific embodiment of the present invention; Figure 11 This is a schematic diagram of the structure of the rolling foot sleeve provided in a specific embodiment of the present invention; Figure 12 This is a schematic diagram of the structure of the drainage hole provided in a specific embodiment of the present invention; Figure 13 This is a schematic diagram of the actual installation of the drone temporary landing pad component provided in a specific embodiment of the present invention.

[0028] Explanation of symbols for main components: 1. Parking platform; 11. Visibility channel; 12. Guide area; 121. Guide channel; 13. Collection area; 131. Drain hole; 14. Enclosure; 2. UAV; 21. Connecting part; 22. Rolling part; 3. External rod; 41. Clamp; 42. Slide groove; 43. Bolt; 44. Nut; 45. Washer. Detailed Implementation

[0029] 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.

[0030] like Figures 1-13This invention provides a temporary landing pad assembly for unmanned aerial vehicles (UAVs), including a landing platform 1, a UAV guiding device, and installation components. The landing platform 1 is a load-bearing structural plate, and its shape can be rectangular, circular, or polygonal, depending on actual needs. The landing platform 1 is provided with multiple guiding areas 12 and a converging area 13. The converging area 13 is located inside the landing platform 1, and can be located in the central area of ​​the landing platform 1. The guiding areas 12 are arranged around the converging area 13, and the side of the guiding area 12 closer to the converging area 13 is lower than the side farther from the converging area 13; that is, the guiding areas 12 gradually slope downwards from the outer edge of the landing platform 1 towards the converging area 13. With this arrangement, when the UAV 2 lands on the landing platform 1, it can slide along the guiding areas 12 towards the converging area 13 under its own gravity.

[0031] Preferably, four guide areas 12 are provided, which are evenly distributed along the circumference of the landing platform 1 and correspond to the four landing gear support legs of the UAV 2, respectively. Of course, the number of guide areas 12 can also be adjusted according to the number of landing gear support legs of the UAV 2, such as three or six.

[0032] Each guide region 12 has a straight guide groove 121, with one end facing the collection area 13 and the other end facing the outside of the landing platform 1. The four guide grooves 121 are arranged one-to-one with the distribution of the four landing gear support feet of the UAV 2, and each guide groove 121 corresponds to a rolling foot sleeve 3 on one of the landing gear support feet of the UAV 2. A first guide surface and a second guide surface are respectively provided on both sides of the guide region 12 located at the guide groove 121. The side of the first and second guide surfaces away from the guide groove 121 is higher than the side closer to the guide groove 121. That is, the first and second guide surfaces gradually bulge upwards from the guide groove 121 to both sides. Therefore, when the guide region 12 is divided in a direction perpendicular to the guide groove 121, the resulting guide region 12 has a V-shaped or U-shaped cross-section to facilitate smooth sliding of the rolling elements on the landing gear support feet of the UAV 2.

[0033] The collection area 13 is located at the lowest point of the parking platform 1, and a drainage hole 131 penetrating the thickness of the parking platform 1 is provided within the collection area 13. In this embodiment, the collection area 13 is the area where the drainage hole 131 is located, that is, the drainage hole 131 covers the entire collection area 13. The inclined surface of the guide area 12 also serves as the confluence surface, allowing rainwater to naturally flow along the inclined surface of the guide area 12 to the collection area 13, and then be discharged through the drainage hole, thus preventing water accumulation on the surface of the parking platform 1.

[0034] like Figures 7-9As shown, a through-slot 11 penetrating the thickness of the parking platform 1 is also provided on one side. The through-slot 11 extends from the front edge of the parking platform 1 towards the converging area 13, forming a completely through-slot structure, which constitutes an unobstructed optical channel for the gimbal camera of the UAV 2. The spatial position of the through-slot 11 has a preset correspondence with the distribution direction of the four guide areas 12: when the four support feet of the UAV 2 enter the guide slots 121 of the four guide areas 12 respectively, the flight direction of the UAV 2 is uniquely determined. At this time, the optical axis direction of the airborne gimbal camera is exactly aligned with the through-slot 11, and the gimbal's line of sight goes directly to the road below without obstruction through the through-slot 11.

[0035] The viewing slot 11 is V-shaped or U-shaped. In this embodiment, when the viewing slot 11 adopts a V-shaped structure, the two inclined surfaces of the V-shaped structure provide lateral guidance during the process of the landing gear sliding into the adjacent guide slot 121, preventing the landing gear from accidentally entering the viewing slot 11. The edges and corners of the viewing slot 11 are all rounded (rounded corner radius not less than 2mm) to prevent impact damage when the landing gear contacts the slot.

[0036] The drone guiding device includes several rolling foot sleeves 3, which are detachably connected to the drone 2 and can move along the guide groove 121. Specifically, as shown... Figure 11 The rolling foot cover 3 includes a connecting part 21 and a rolling part 22. The rolling part 22 is installed below the connecting part 21, and the connecting part 21 is detachably connected to the drone 2.

[0037] Preferably, the connecting part 21 is an elastic silicone sleeve, and the rolling part 22 is a universal ball bearing pulley or a universal wheel. The elastic silicone sleeve is fitted onto the original landing gear support feet of the UAV 2, and is fixedly connected to the original support feet by the clamping force of the elastic material. The rolling part 22 uses steel universal ball bearings, which can roll in multiple directions with low friction in the guide area. By replacing the elastic silicone sleeves with different inner diameter specifications, the same landing platform 1 can be adapted to various models of light UAVs (empty weight 0.25kg to 4kg, maximum takeoff weight ≤7kg).

[0038] In this embodiment, the rolling part 22 uses omnidirectional ball bearings, and the width of the guide groove 121 is smaller than the diameter of the ball bearings. Of course, when using omnidirectional ball bearings or omnidirectional wheels, the entire rolling part 22 or the wheel body of the omnidirectional wheel can be placed within the guide groove 121, as long as the movement performance of the rolling part 22 is guaranteed. That is to say, the width of the guide groove 121 can be flexibly set according to actual needs.

[0039] A perimeter fence 14 is installed around the outside of the parking platform 1. The perimeter fence 14 is used to prevent the drone 2 from accidentally sliding off the parking platform 1 during takeoff and landing, thereby improving operational safety.

[0040] The present invention also discloses an installation method for a temporary drone landing pad, wherein the above-mentioned temporary drone landing pad components are installed on horizontal poles on both sides of the road. The horizontal poles include any one or more of the following: the horizontal arm of a light pole, the horizontal arm of a traffic signal light, and the support crossbar of a road sign.

[0041] During installation, firstly, select suitable rolling foot covers 3 according to the model of UAV 2, and then put the rolling foot covers 3 onto each landing gear support foot of UAV 2. Then, move the landing platform 1 to the predetermined installation position of the horizontal pole 3 and fix it in place. This installation method makes full use of the existing horizontal pole resources on both sides of the road, without the need for additional pole erection or occupying ground space, resulting in high construction efficiency and flexible deployment.

[0042] like Figure 6 and Figure 10 The drone temporary landing pad assembly also includes an installation component, which consists of a clamp 41 and a slide rail 42. Two slide rails 42 are provided, symmetrically distributed at the bottom of the landing platform 1, with each slide rail 42 having an effective adjustment stroke of no less than 30mm. The clamp 41 is used to hold the horizontal member 3. Both ends of the clamp 41 are detachably connected to the slide rail 42 via bolts 43, with the head of the bolt 43 positioned within the slide rail 42. The shank of the bolt 43 passes through the slide rail 42 and is then locked by a nut 44. During installation, the clamp 41 is wrapped around the outside of the horizontal member 3, the bolt 43 is inserted into the slide rail 42 and slid along the rail to adjust the distance between the two bolts, thus adapting to horizontal members of different diameters. Finally, it is locked in place by the nut 44. The entire process requires no drilling of any fixing holes in the member, does not damage the member structure or surface anti-corrosion layer, and leaves no residual holes after disassembly. Meanwhile, by adjusting the installation position of the clamp 41 on the horizontal bar 3 and the spacing of the bolts 43 in the slide 42, the horizontal orientation of the parking platform 1 can be flexibly adjusted so that the viewing slot 11 is aligned with the target road direction.

[0043] A vibration-damping pad and / or an insulating pad are also provided between the clamp 41 and the horizontal member 3. The vibration-damping pad is used to absorb vibrations caused by the take-off and landing of the UAV 2 and wind force, preventing bolt loosening, and protecting the surface coating of the horizontal member 3 from damage; the insulating pad is used to meet electrical safety requirements, preventing equipment damage or safety accidents caused by the pole becoming electrified. In addition, the vibration-damping pad and the insulating pad can increase the friction between the clamp 41 and the horizontal member 3, improving the locking reliability. Furthermore, both the vibration-damping pad and the insulating pad can protect the surface of the outer member 3, preventing damage to the protective layer on the surface of the outer member 13 during the clamping process of the clamp 41.

[0044] When the helipad needs to be moved to a new deployment location, loosening nut 44 will release the clamp 41 from the horizontal member 3, and the entire helipad 1 can be completely removed from the original member. After being moved to the new horizontal member, it can be reinstalled according to the above steps.

[0045] The working principle of this invention will be explained below.

[0046] Landing and Correction Process: After the UAV 2 reaches the area above the parking platform 1 (horizontal positioning accuracy within ±0.5m) via GPS or visual positioning system, it descends slowly. The four landing gear support legs equipped with rolling foot sleeves 3 contact the parking platform 1 within the predetermined landing area with certain positional and angular deviations. The universal ball bearings on each support leg contact their respective guide areas 12. Driven by the inclined plane force generated by the UAV 2's own gravity (including load), each universal ball bearing independently rolls and slides along the first or second guide surface of its respective guide area 12, moving towards its corresponding guide groove 121. The universal ball bearing design of the rolling foot sleeves 3 eliminates sliding direction constraints, allowing each ball bearing to roll independently in different directions without interference. Finally, the four support legs enter the four guide grooves 121, simultaneously defining the UAV 2's planar position (center) and rotation angle around the vertical axis (heading angle). The entire process is purely physical passive correction, without relying on any electronic control components, sensors, or external commands.

[0047] Dwelling and Patrol Process: After landing, the four support feet are located in the four guide slots 121 respectively. The planar position and heading angle of the UAV 2 are jointly defined, and the degrees of freedom of horizontal translation and rotation around the vertical axis are constrained. Because the distribution direction of the four guide slots 121 has a preset spatial correspondence with the line-of-sight slot 11, the optical axis direction of the gimbal camera is automatically aligned with the line-of-sight slot 11. The gimbal's line of sight passes through the line-of-sight slot 11 without obstruction and directly reaches the road below, realizing uninterrupted directional patrol operations during landing and dwell.

[0048] Drainage process: Water accumulated on the surface of the parking platform 1 flows naturally from the inclined surface of the guide area 12 to the collection area 13, and then is discharged through the drain hole 131, keeping the bearing surface of the parking platform 1 dry. The guide groove 121 can also serve as an auxiliary drainage channel.

[0049] Disassembly and relocation process: When the deployment position needs to be adjusted, simply loosen nut 44 to release the clamp 41 from the outer pole 3 without damaging the protective layer of the outer pole 3. The entire parking platform 1 can be completely removed from the original outer pole 3 and relocated to the new deployment position. During reinstallation, the position of bolt 43 can be adjusted along the slide 42, and the horizontal orientation of the parking platform 1 can be adjusted so that the viewing slot 11 is aligned with the new target inspection area.

[0050] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A temporary landing pad assembly for unmanned aerial vehicles (UAVs), characterized in that, include: Parking platform and drone guidance device; The parking platform is provided with multiple guide areas and one convergence area. The convergence area is located inside the parking platform, and the guide areas are arranged around the convergence area. The side of the guide area closer to the convergence area is lower than the side farther away from the convergence area. A guide groove is provided in the guide area. One end of the guide groove faces the collection area and the other end faces the outside of the parking platform. A first guide surface and a second guide surface are respectively provided on both sides of the guide groove in the guide area. The side of the first guide surface and the second guide surface away from the guide groove is higher than the side close to the guide groove. The drone guiding device includes several rolling foot sleeves, which are detachably connected to the drone. Each rolling foot sleeve can slide into its corresponding guide groove under the weight of the drone and be limited by the guide groove.

2. The UAV temporary landing pad component according to claim 1, characterized in that: A through-slot extending through the thickness of the parking platform is provided on one side of the parking platform.

3. The UAV temporary landing pad component according to claim 2, characterized in that: The viewing slot is V-shaped or U-shaped.

4. The UAV temporary landing pad component according to claim 1, characterized in that: The rolling foot cover includes a connecting part and a rolling part, the rolling part being installed below the connecting part, and the connecting part being detachably connected to the drone.

5. A temporary landing pad assembly for unmanned aerial vehicles according to claim 4, characterized in that: The connecting part is an elastic silicone sleeve, the rolling part is a universal ball pulley or universal wheel, and the elastic silicone sleeve is fitted onto the drone support foot.

6. The UAV temporary landing pad assembly according to claim 1, characterized in that: The collection area is located at the lowest point of the parking platform, and a drain hole is provided in the collection area.

7. A temporary landing pad assembly for unmanned aerial vehicles according to claim 1, characterized in that: There are four guide areas, and a fence surrounds the outside of the parking platform.

8. A method for installing a temporary landing pad for unmanned aerial vehicles (UAVs), characterized in that: The UAV temporary landing pad assembly according to any one of claims 1 to 7 is installed on horizontal poles on both sides of the road, wherein the horizontal poles include any one or more of the following: horizontal light arms of light poles, horizontal light arms of traffic lights, and support crossbars of road signs.

9. The method for installing a temporary unmanned aerial vehicle (UAV) landing pad according to claim 8, characterized in that: The temporary drone landing pad assembly also includes an installation assembly, which includes a clamp and a chute. Two chutes are provided, symmetrically distributed at the bottom of the landing platform. The clamp is used to hold the horizontal rod. Both ends of the clamp are detachably connected to the chute by bolts, and the head of the bolt is located in the chute. The shank of the bolt passes through the chute and is locked by a nut.

10. The method for installing a temporary unmanned aerial vehicle (UAV) landing pad according to claim 9, characterized in that: A vibration damping pad and / or an insulating pad are also provided between the clamp and the horizontal member.

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