A clamping mechanism for pole climbing robot and a control method thereof

Abstract

This application provides a gripping mechanism and its control method for a pole-climbing robot. The gripping mechanism includes multiple pairs of gripping units arranged symmetrically in a vertical arrangement, a drive unit, and a connecting and fixing assembly. The gripping units are drively connected to the drive unit, and the connecting and fixing assembly is used to achieve a detachable connection between the gripping units and the main frame of the pole-climbing robot. Each pair of gripping units includes two symmetrically arranged gripping arms. The axis of the gripping arms forms an acute angle with the normal to the surface of the object being climbed, and when the two gripping arms are closed, they form a ring-shaped structure that covers the cross-section of the object being climbed. This application can improve the load capacity of the gripping mechanism.

Description

Technical Field

[0001] This application relates to the field of pole climbing robot technology, specifically to a clamping mechanism and control method for a pole climbing robot. Background Technology

[0002] With the rapid development of industries such as power, communications, and petrochemicals, the demand for maintenance and inspection of pole-type infrastructure is increasing. Furthermore, the harvesting of fruits from tall trees such as coconut, durian, and jackfruit trees in forestry still relies on manual climbing, trained animals, or simple long-handled sickles, which are costly and inefficient, necessitating the development of efficient pole-climbing mechanisms.

[0003] Pole-climbing robots have broad application prospects in vertical surface operations such as industrial maintenance, building inspection, and disaster relief. The core challenge lies in designing a gripping unit that can reliably adhere to various surfaces (such as concrete, brick walls, and metal plates) and effectively support the robot's own weight. Traditional climbing gripping units mostly employ suction cups, magnetic attachments, or parallel gripper structures, which have significant drawbacks: suction cups are greatly affected by surface flatness and cleanliness; magnetic attachments are only suitable for ferromagnetic materials; and parallel grippers have limited gripping ability on low-friction surfaces, and stress concentration can easily lead to structural failure, especially when bearing the robot's own weight and dynamic loads during operation.

[0004] Currently, the conventional clamping type is the most widely used structure among existing pole climbing mechanisms. The working principle of this clamping type is as follows: it generally consists of two clamping units, upper and lower, connected by a telescopic mechanism. When the upper clamping unit is fixed, the telescopic mechanism raises the lower clamping unit. Then, after the lower clamping unit is fixed, the telescopic mechanism pushes the upper clamping unit upwards. Climbing is achieved by alternately fixing the upper and lower clamping units. However, this method concentrates all the stabilizing force on the clamping units and uses a horizontal lifting force, resulting in a low load capacity and high destructive potential. Further analysis reveals the following problems with existing climbing clamping units:

[0005] Insufficient gripping force and sensitivity to surface friction coefficient: Traditional grippers mainly rely on friction generated by normal force to counteract gravity. For surfaces with low friction coefficients (such as smooth metals or wet rod-shaped objects), a very large normal force is required to ensure sufficient gripping force. This not only places high demands on the drive system but also limits the robot's overall load capacity. When the surface friction coefficient is too low, gripping often fails.

[0006] Stress concentration and limited structural strength: The driving force of the gripper is usually concentrated at the root or shaft where it connects to the actuator (motor, cylinder). When subjected to the robot's gravity and operational impacts, these areas are prone to stress concentration, becoming weak points in the structure, which may lead to fatigue fracture or permanent deformation, affecting the reliability and lifespan of the pole-climbing robot.

[0007] Poor adaptability and difficulty in dealing with complex surfaces: When the gripper with a fixed geometry faces an uneven surface or a small gap, it is difficult to ensure continuous and uniform contact and pressure, resulting in unstable grip. Summary of the Invention

[0008] The purpose of this application is to provide a gripping mechanism for a pole-climbing robot, which can improve the load capacity of the gripping pole-climbing mechanism.

[0009] In a first aspect, this application provides a gripping mechanism for a pole-climbing robot, comprising multiple pairs of gripping units, a drive unit, and a connecting and fixing assembly arranged symmetrically in an upper and lower configuration; the gripping units are connected to the drive unit in a transmission manner, and the connecting and fixing assembly is used to realize a detachable connection between the gripping units and the main frame of the pole-climbing robot; each pair of gripping units includes two gripping arms arranged symmetrically, the axis of the gripping arms forms an acute angle with the normal to the surface of the object being climbed, and when the two gripping arms are closed, they form a ring-shaped structure that can cover the cross-section of the object being climbed.

[0010] In one possible implementation, the gripping arm adopts a three-section structure, including a root section, a middle section, and an end contact section connected in sequence by a rotary hinge, with each section being adjusted relative to the curved contour of the object being climbed.

[0011] In one possible implementation, the root section is widened and thickened and has built-in reinforcing ribs, and the inner side of the end contact section is provided with a contact layer, which is a flexible gasket, a rubber bushing, or a textured hard alloy.

[0012] In one possible implementation, the design method for the angle is as follows: calculate the theoretical optimal angle θ_optimal=arctan(1 / μ), where μ is the friction coefficient between the object being climbed and the contact layer of the clamping arm. Considering engineering constraints, fine-tune the calculated theoretical optimal angle to obtain the final design angle.

[0013] In one possible implementation, the drive unit includes a high torque density motor and a reducer, which drive the clamping arms to move relative to each other through a transmission system. The transmission system preferably adopts a gear-linkage composite transmission system, which includes a meshing driving gear and a driven gear, as well as a linkage connecting the driven gear and the clamping arm, which can convert the rotational motion of the gears into the opening and closing motion of the clamping arms. Depending on the constraints of the drive space and the torque transmission efficiency requirements, a cam mechanism transmission system or other equivalent transmission methods can also be selected to achieve synchronous opening and closing of the clamping arms. The drive unit is located close to the rotation center of the clamping arms to ensure the shortest force transmission path and the least loss.

[0014] In one possible implementation, the main frame is made of a lightweight, high-strength material, such as a composite material or aluminum alloy. The connecting and fixing components include standard interface structures in the form of flanges or bolt holes to achieve uniform force transmission and avoid stress concentration at the connection points. The root region of the clamping arm is widened, forming a closed, embracing structure that covers the cross-section of the object being climbed when closed.

[0015] In one possible implementation, the clamping mechanism further includes a sensing component for collecting various physical parameters during the clamping process, providing data support for clamping control.

[0016] In one possible implementation, the sensing components include a torque sensor mounted at the root of the gripper arm, an encoder mounted at the motion execution end of the gripper arm, an IMU fixed at the geometric center or center of gravity of the robot's main frame, and a pressure sensor array mounted on the inner arc surface of the gripper arm. The torque sensor is used to collect clamping force data, the encoder is used to collect gripper arm position data, the IMU is used to collect robot attitude (pitch angle) and axial acceleration data, and the pressure sensor is used to collect pressure distribution data at different points in the contact area between the inner arc surface contact layer of the gripper arm and the surface of the object being climbed.

[0017] In one possible implementation, the slewing hinge includes a first slewing hinge and a second slewing hinge; the first slewing hinge connects the root section and the middle section, allowing the middle section to deflect ±10° relative to the root section in a plane perpendicular to the clamping arm axis; the second slewing hinge connects the middle section and the end contact section, allowing the end contact section to pitch ±8° relative to the middle section in a plane parallel to the clamping arm axis; the slewing hinge incorporates a torsion spring or damping element to achieve reset or oscillation suppression functions.

[0018] Secondly, this application provides a control method for a gripping mechanism for a pole-climbing robot, applied to the aforementioned gripping mechanism for a pole-climbing robot, comprising the following steps:

[0019] A control method for a gripping mechanism for a pole-climbing robot, applied to the gripping mechanism for a pole-climbing robot described in Embodiment 1, includes the following steps:

[0020] Step 1: Collect real-time data through sensing components and perform preprocessing;

[0021] Step 2: Based on the preprocessed data, determine whether there is a risk of slippage and assess the confidence level of the risk;

[0022] Step 3: Update the friction coefficient estimate online based on the preprocessed data and the dynamic equilibrium equation;

[0023] Step 4: Dynamically adjust the safety factor according to the operating mode, calculate the minimum clamping force to satisfy stable clamping using the static equilibrium equation, and use it as the target clamping force. Then, dynamically adjust the target clamping force in combination with slippage risk, risk confidence level, and contact conditions. The operating modes include slippage recovery mode, climbing mode, and stationary mode.

[0024] Step 5: The deviation between the target clamping force and the actual clamping force is converted into a force control value through a PID closed-loop control algorithm, and then converted into a motor torque command according to the type of drive mechanism and output.

[0025] In step 1, the preprocessing includes filtering noise, etc.

[0026] In one possible implementation, the preprocessing includes performing a moving average filter on the clamping force data, calculating the relative motion speed of the clamping arm based on the clamping arm position data, correcting the axial acceleration data acquired by the IMU, and calculating the pressure distribution uniformity index of the contact area between the inner arc surface contact layer of the clamping arm and the surface of the object being climbed.

[0027] In one possible implementation, in step 2, a multi-dimensional detector is used to collaboratively determine whether there is a risk of slippage and to assess the confidence level of the risk. The multi-dimensional detector includes a relative displacement detector of the clamping arm, an acceleration anomaly detector, a clamping force fluctuation detector, and a pressure distribution anomaly detector. Each detector is assigned a preset weight, and when the weighted total confidence level exceeds a preset threshold, it is determined that there is a risk of slippage.

[0028] In one possible implementation, in step 3, the friction coefficient estimate is subjected to physical rationality constraints and low-pass filtering.

[0029] By updating the friction coefficient estimate online, it is possible to adapt to changes in the working conditions of the rod surface.

[0030] In one possible implementation, the relative displacement detector of the clamping arm, the acceleration anomaly detector, the clamping force fluctuation detector, and the pressure distribution anomaly detector are weighted at 40%, 30%, 20%, and 10%, respectively. When the weighted total confidence exceeds 0.3, it is determined that there is a risk of slippage.

[0031] In one possible implementation, in step 4, the safety factor is dynamically adjusted according to the operating mode: 1.5~2.0 for slippage recovery mode, 1.3 for climbing mode, and 1.2 for stationary mode, with an adaptive margin added; in step 5, the PID controller includes preset proportional gain, integral gain, and derivative gain, and the gain coefficient is adapted to the load characteristics and transmission efficiency of the clamping mechanism; in step 5, both the force control value and the motor torque are provided with limiting thresholds.

[0032] This application has the following beneficial effects:

[0033] Significantly enhanced load capacity: The direct upward force generated by the angled clamp effectively distributes the weight, allowing the clamping unit to bear greater weight with less driving force, or to increase the load under the same driving force. This also reduces damage and material strength.

[0034] Enhanced adaptability to low-friction surfaces: Reduced dependence on the coefficient of friction enables stable climbing on a wider range of surfaces, including smooth or slippery surfaces that are difficult for traditional grippers to handle.

[0035] Improved structural reliability: The encircling stress dispersion design significantly reduces stress concentration, the three-section structure enhances surface adaptability and robustness, extends the service life of the clamping unit, and improves stability under dynamic loads.

[0036] Reduced energy consumption: The reduced driving force can effectively reduce overall energy consumption. Attached Figure Description

[0037] Figure 1 This is a left view of the clamping mechanism in one embodiment of this application;

[0038] Figure 2 This is a perspective view of the clamping mechanism in one embodiment of this application;

[0039] Figure 3 This is a flowchart illustrating the optimized design of the clamping arm's angle in one embodiment of this application.

[0040] Figure 4 This is a flowchart illustrating the alternating climbing action of the upper and lower clamping units in one embodiment of this application;

[0041] Figure 5 This is a schematic diagram of the circumferential structure of the clamping mechanism in one embodiment of this application;

[0042] Figure 6 This is a schematic diagram of a three-section clamping arm structure of a clamping mechanism in one embodiment of this application. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present application, the technical solution of the present application will be further described in detail below with reference to the embodiments and accompanying drawings.

[0044] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0045] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0046] Furthermore, some of the aforementioned terms, besides indicating location or positional relationships, may also have other meanings. For example, the term "above" may, in certain circumstances, indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0047] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linked," and "socketing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0048] This solution proposes a gripping mechanism (gripping unit structure, grasping mechanism) for pole climbing robots, which aims to improve the adhesion stability and load-bearing capacity of pole climbing robots on complex surfaces through unique mechanical principles and structural design.

[0049] This gripping mechanism can be directly applied to pole-climbing robots (gripping-type pole-climbing mechanisms) as their core gripping unit structure; at the same time, it is also suitable for all climbing mechanisms that use pole-shaped objects as climbing objects, and can be used as a dedicated gripping unit for such mechanisms. Typical application scenarios include, but are not limited to, forestry manned fruit-picking platforms, high-voltage tower maintenance mechanisms, etc.

[0050] Specific embodiments according to this application will now be described with reference to the accompanying drawings.

[0051] Example 1:

[0052] like Figure 1 and Figure 2 As shown, this application provides a gripping mechanism for a pole-climbing robot, including multiple pairs of gripping units, a drive unit, and a connecting and fixing assembly arranged symmetrically in an upper and lower position; the gripping units are connected to the drive unit in a transmission manner, and the connecting and fixing assembly is used to realize the detachable connection between the gripping units and the main frame of the pole-climbing robot; each pair of gripping units includes two gripping arms arranged symmetrically, the axis of the gripping arms forms an acute angle with the normal of the surface of the object being climbed, and when the two gripping arms are closed, they form a ring-shaped structure that can cover the cross-section of the object being climbed.

[0053] This application can solve the problems of low load capacity, high destructiveness, and high material strength requirements for climbing mechanisms in traditional structures.

[0054] Clamping units: comprising multiple pairs (at least two pairs) arranged vertically. Figure 1 and Figure 2 The image shows two pairs of clamping units. Each pair of clamping arms is symmetrically arranged. The ends of the clamping arms are designed with a wraparound contact structure. The drive unit drives the clamping arms to move around a specific center, so that the longitudinal central axis of the clamping arm forms an acute angle (θ) with the normal direction of the surface of the object being climbed (the pole), thus achieving a slanted clamping effect. At the same time, the inner side of the clamping arm is machined with a concave arc surface adapted to the curvature of the pole. When the clamping arm is closed, all the arc surfaces together form a wraparound contact structure surrounding the pole, achieving a wraparound effect. The contact layer on the inner side of the clamping arm can be made of flexible pads, rubber bushings, or other materials to improve contact adaptability and friction.

[0055] The angle θ is the core parameter for the clamping mechanism to achieve stable climbing. It can be optimized by combining the characteristics of the target climbing surface and the expected load to ensure that the clamping stability and load-bearing capacity meet the standards.

[0056] In some embodiments, the main frame of the pole-climbing robot can be made of lightweight, high-strength composite materials or aluminum alloy to ensure overall rigidity.

[0057] In some embodiments, such as Figure 3 As shown, optimized design can be achieved through three steps: establishing a mechanical model, solving for the theoretical optimal angle, and fine-tuning based on actual working conditions. The specific process is as follows:

[0058] Step 1: Establish the static model and core equilibrium equations;

[0059] First, perform a force analysis on a single (one-sided) clamping arm to identify key mechanical parameters and equilibrium relationships:

[0060] 1) Core parameter definition:

[0061] F_clamp: The total clamping force applied to the rod by the drive unit through the clamping arm, with the direction along the axis of the clamping arm;

[0062] θ: Inclined angle (the angle between the axis of the clamping arm and the normal to the surface of the rod);

[0063] F_normal: The component of F_clamp in the direction normal to the rod, used to generate friction. The calculation formula is F_normal = F_clamp × cosθ;

[0064] F_parallel: The component of F_clamp in the tangential direction (upward) of the rod, which directly cancels out gravity. The calculation formula is F_parallel = F_clamp × sinθ.

[0065] F_friction: The maximum static friction force provided by the surface of the rod, calculated by the formula F_friction=μ×F_normal, where μ is the coefficient of friction between the rod and the contact layer of the clamping arm;

[0066] G: Total weight of the robot (including load);

[0067] S: Safety factor, usually taken as 1.5~2.0, used to cope with uncertainties such as dynamic loads and impacts.

[0068] 2) Establishing a static model – system equilibrium equations:

[0069] The mechanism contains n gripping arms (n≥4). To balance gravity and achieve stable climbing, the following condition must be met: n×(F_parallel+F_friction)≥S×G;

[0070] Substituting the calculation formulas for F_normal, F_parallel, and F_friction, we finally obtain the core equilibrium equation: n×F_clamp×(sinθ+μ×cosθ)≥S×G.

[0071] Step 2: Define the optimization objective and solve for the theoretically optimal angle;

[0072] The optimization objective is to minimize the total clamping force n×F_clamp while satisfying the balance condition, thereby reducing the size of the drive unit and reducing energy consumption.

[0073] 1) Simplify the equilibrium equations:

[0074] Let K(θ) = sinθ + μ×cosθ, the core equilibrium equation can be simplified to: n×F_clamp×K(θ) ≥ S×G;

[0075] The derivation shows that the required total clamping force n×F_clamp≥(S×G) / K(θ).

[0076] 2) Solving for the theoretically optimal angle:

[0077] To minimize the total clamping force, K(θ) needs to be maximized. By differentiating K(θ) with respect to θ and setting the derivative to zero (dK(θ) / dθ=cosθ-μ×sinθ=0), we finally obtain: tanθ_optimal=1 / μ, that is, θ_optimal=arctan(1 / μ), where θ_optimal represents the theoretical optimal angle.

[0078] This indicates that the theoretically optimal angle of inclination is determined solely by the coefficient of friction μ of the contact layer between the rod and the clamping arm.

[0079] Step 3: Based on actual working conditions, fine-tune the theoretically optimal angle to determine the final design angle;

[0080] The theoretically optimal angle needs to be fine-tuned to consider engineering constraints and ensure design feasibility. Specific steps include:

[0081] 1) Determine the coefficient of friction μ:

[0082] Experimental measurement: For material pairings in practical applications (such as rubber-cement, alloy-steel), the friction coefficient is tested under different working conditions such as dry, wet, and dusty conditions. The minimum value μ_min is taken as the design basis (to ensure reliability under the worst working conditions).

[0083] Reference values: Rubber-dry cement μ≈0.6~0.8; Rubber-wet cement μ≈0.3~0.4; Hard alloy-steel μ≈0.2~0.3.

[0084] 2) Calculate the theoretically optimal angle based on the friction coefficient μ:

[0085] For example, if the object to be climbed is a slippery cement pole (μ_min=0.35), then the theoretical optimal angle θ_optimal=arctan(1 / 0.35)≈70.7°.

[0086] 3) Fine-tune the calculated theoretical optimal angle considering engineering constraints:

[0087] Constraint 1: Structural interference constraint: If θ is too large (e.g., >75°), it may cause the root of the gripper arm to collide with the robot body or the gripper arm on the other side. θ needs to be reduced appropriately.

[0088] Constraint 2: Surface protection constraint: According to F_normal=F_clamp×cosθ, the smaller θ is, the larger the normal force F_normal is. For fragile surfaces (such as painted utility poles, trees, etc.), θ needs to be increased to reduce the normal force and avoid pressure damage.

[0089] Constraint 3: Drive efficiency constraint: The force transmission efficiency of the drive mechanism (such as the linkage) is different at different angles. The angle with the optimal efficiency should be selected by combining the kinematic analysis.

[0090] 4) Final design angle determined:

[0091] The final design angle θ_final should be selected near the theoretically optimal angle, and the recommended range is θ_final = θ_optimal ± 10°.

[0092] In some embodiments, the drive unit may employ a small, high-torque-density motor (such as a brushless DC motor or a stepper motor) in conjunction with a reducer, which drives the two clamping arms to move relative to each other through a transmission system to achieve opening and closing. The drive unit should be located as close as possible to the rotation center of the clamping arms to reduce torque load.

[0093] The transmission system can preferably adopt a gear-linkage composite transmission system, which includes a driving gear and a driven gear that mesh with each other, as well as a link connecting the driven gear and the clamping arm, which can convert the rotational motion of the gear into the opening and closing motion of the clamping arm; depending on the driving space constraints and torque transmission efficiency requirements, a cam mechanism transmission system or other equivalent transmission methods can also be selected to achieve synchronous opening and closing of the clamping arm.

[0094] In some embodiments, the connection and fixing components may employ standard interfaces (such as flanges or bolt holes). The clamping unit can be connected to the main frame of the pole-climbing robot via a standard interface (such as a flange or bolt holes). The connection design considers the force transmission path to avoid unnecessary stress concentration at the connection point.

[0095] Figure 4 This is a flowchart illustrating the alternating climbing action of the upper and lower clamping units in one embodiment of this application; the workflow is as follows:

[0096] Adsorption phase: The clamping unit is in the open state when it is in the air or when it moves from one attachment point to the next target position.

[0097] Clamping Phase: When the clamping unit reaches the target position and contacts the surface of the object to be climbed, the drive unit is activated, causing the clamping arm to tighten inward. Due to the presence of the inclined plane, the clamping arm not only applies normal pressure to the surface of the object to be climbed, but also generates an upward component force F_parallel.

[0098] Stable phase: As the clamping force increases, the upward component force F_parallel and the frictional force F_friction are sufficient to balance the robot's gravity G and possible dynamic loads. The encircling structure ensures uniform force distribution and structural stability.

[0099] Release and movement phase: After confirming that the next gripping unit has been stably attached, the drive unit of the current gripping unit moves in the opposite direction, causing the gripping arm to release the surface of the object being climbed, and the robot body moves accordingly.

[0100] This application combines the inclined clamping structure with the principle of stress dispersion:

[0101] (1) Force analysis of oblique clamp type:

[0102] like Figure 1 As shown, the clamping unit is no longer parallel to the surface of the object being climbed, but forms a certain angle (oblique angle) with the surface of the object being climbed. When the driving unit causes the clamping unit to close and clamp the surface of the object being climbed, the clamping unit generates an oblique force F on the surface of the object being climbed.

[0103] The force F can be decomposed into two components: a normal force F_normal perpendicular to the surface of the object being climbed, which generates friction F_friction = μ × F_normal (μ is the coefficient of friction of the surface of the object being climbed); and an upward component F_parallel parallel to the surface of the object being climbed.

[0104] The key is that this F_parallel component directly counteracts part of the robot's downward gravity G, forming a direct load balance. Therefore, the total normal force F_normal required to maintain the stability of the gripper unit on the surface of the object being climbed can be less than that required by a traditional gripper that relies entirely on friction to balance gravity. That is: F_parallel + F_friction ≥ G.

[0105] This mechanism differs from conventional gripping units, which primarily rely on the normal force to increase friction (f = μN, where μ is the coefficient of friction) to counteract gravity indirectly. The latter has lower energy conversion efficiency and limited gripping effectiveness on objects with low coefficients of friction (low μ value), thus limiting the system's load capacity. For robots of the same weight, the angled gripping design can achieve stable attachment with a smaller driving force (and therefore a smaller normal force F_normal), or, for the same driving force, can support a heavier robot. This significantly improves energy conversion efficiency and enhances gripping ability on low-friction surfaces.

[0106] (2) Encircling stress dispersion:

[0107] like Figure 5As shown, this application decomposes a single rigid wedge into multiple distributed elastic contact units. These units work together to expand the contact area of ​​the clamping unit based on the mechanical principle of the wedge clamp, forming a continuous, highly fitted contact band, approaching a wraparound structure. This means that the contact between the clamping unit and the wall line (or surface) is no longer a point or a narrow line, but a wider arc or ring.

[0108] like Figure 5 As shown, in order to achieve "encircling high-fit contact" between the clamping unit and the rod, a combination structure of arc-shaped contact layer + flexible support is adopted on the inner side of the clamping arm.

[0109] Among them, the arc-shaped contact layer: the inner side of the clamping arm is designed (processed or installed) as a concave arc surface that matches the curvature of the target rod. Its radius of curvature R_arm is slightly larger than the rod radius R_pole (e.g., R_arm=1.05×R_pole), replacing the traditional planar inclined surface and providing a geometric basis for large-area contact.

[0110] Among them, the flexible support structure is a flexible transition layer (flexible gasket, rubber bushing, etc.) added between the arc-shaped contact layer and the rigid body of the clamping arm to compensate for manufacturing tolerances and rod irregularities.

[0111] This structure achieves the expansion from line contact to contact zone through the synergistic effect of elastic deformation and oblique clamping force:

[0112] Initial contact stage: In the initial stage of clamping arm closure, due to manufacturing tolerances and rod irregularities, the arc-shaped contact layer and the rod may first form line contact.

[0113] Contact expansion stage: As the clamping force F_clamp increases, the flexible transition layer undergoes elastic deformation. This deformation allows the rigid arc-shaped contact layer to adaptively conform to the rod surface, and the contact state quickly expands from a line to a narrow, continuous contact band (replacing the traditional single-point / narrow-line contact).

[0114] The combined effect of the force components: Since the clamping arm is in an inclined position, the force exerted on the rod by each point on the contact strip can be decomposed into a normal force F_normal (enhancing friction) and an upward component force F_parallel. The combined upward component forces of all points form a considerable direct lifting force, which, together with the friction force corresponding to the normal force, ensures stable clamping.

[0115] In the angled clamping mode, when the clamping unit is closed, the surface of the object being climbed provides a reverse supporting force to the clamping unit. This supporting force, combined with the clamping force of the clamping unit itself and the frictional force between the clamping unit and the surface of the object being climbed, works together.

[0116] Unlike traditional grippers where stress is concentrated at the connection root, the wraparound structure distributes stress over a wider contact area and the upper structure of the gripping unit. The supporting force is no longer borne solely by the vulnerable area of ​​the connecting actuator, but rather by the more robust wraparound portion and the overall structure of the gripping unit.

[0117] This design significantly reduces stress concentration in the clamping unit structure, allowing the use of lower-strength, more cost-effective materials. This improves the overall impact and fatigue resistance of the clamping unit, thereby reducing the requirements for yield strength and fatigue performance of the constituent materials and minimizing the risk of structural failure due to stress concentration. Even with enlarged dimensions, the maximum stress σ_max of conventional clamping units remains highly concentrated in the handle root region connected to the drive motor. The angled clamp configuration, through structural optimization, disperses stress to a larger area, such as the upper flange of the angled clamp, creating a stress distribution state with the combined action of multiple forces (clamping force, object reaction force, friction, and its own weight), effectively alleviating the stress concentration problem.

[0118] (3) Three-segment adaptive bonding design:

[0119] In some embodiments, such as Figure 6 As shown, the gripping arm adopts a three-section structure. The three-section gripping arm consists of three segments with different functions (root segment, middle segment, and end contact segment) connected by two movable joints (rotary hinges). The specific structure is as follows:

[0120] 1) Segment design:

[0121] Root section: Directly connected to the drive unit (such as connecting rod or cam), it is the input section for active motion and the main load-bearing structure. The structure adopts a widened and thickened design with built-in reinforcing ribs, ensuring maximum strength and stable force transmission and its own rigidity.

[0122] The middle section, which is the longest and serves as the force transmission and adaptive section, is the main body of the clamping arm. It is responsible for transmitting the motion and force of the root section to the end and also undertakes the main deflection adjustment task.

[0123] End contact section: It directly contacts the surface of the rod and has a relatively compact structure. The inner side is equipped with an arc-shaped contact layer and a flexible support structure, which ultimately achieves a wrap-around fit and force transmission.

[0124] 2) Joint connection relationship:

[0125] In some embodiments, the slewing hinge includes a first slewing hinge and a second slewing hinge. The first slewing hinge connects the root section and the intermediate section. It allows the intermediate section to deflect relative to the root section in a plane perpendicular to the axis of the gripping arm (yaw direction). Exemplarily, the range of motion is ±10°. This functionality can be achieved using a pin hinge with a torsion spring (providing a restoring torque to ensure the gripping arm returns to a neutral position when no load is applied) or a damping element (suppressing oscillations that may occur during adaptation).

[0126] The second slewing hinge connects the intermediate section to the end contact section. It allows the end contact section to pitch relative to the intermediate section in a plane parallel to the clamping arm axis. For example, the range of motion is ±8°. A combination of a pin hinge and a spring element can also be used.

[0127] This "two-degree-of-freedom" hinge design makes the clamping arm an adaptive mechanism with a certain degree of compliance, rather than a completely rigid body.

[0128] In some embodiments, the three-section clamping arm can achieve a stable connection and power transmission between the drive unit and the clamping arm through a gear-linkage composite transmission system, i.e., a combination structure of gear meshing + linkage transmission + revolute connection:

[0129] Power input: The driving gear is directly connected to the drive motor as the power source; the driven gear meshes with the driving gear to complete motion transmission and direction conversion. The driving gear can be located inside the base.

[0130] Linkage transmission: Two symmetrical linkages connect the driven gear and the clamping arm (gripper fingers) respectively, forming a four-bar linkage that converts the rotational motion of the gear into the opening and closing motion of the clamping arm.

[0131] Rotary joint protection: The base and the drive gear achieve fixed-axis rotation through a rotating joint supported by bearings; the gear and the connecting rod are connected by a rotating joint through a pin to transmit rotational motion; the connecting rod and the clamping arm are connected by a rotating joint through a hinge to realize the opening and closing motion of the fingers, ensuring smooth motion transmission.

[0132] In this embodiment, the transmission system of the clamping mechanism is designed with gear-linkage composite transmission as its core. Its advantages are high transmission accuracy, balanced force, and adaptability to the synchronous control requirements of multiple clamping units. When there are special constraints in the application scenario (such as narrow installation space, or the need to simplify the transmission link to improve reliability), it can be replaced with an equivalent solution such as cam mechanism transmission.

[0133] Adaptation conditions and design considerations for cam mechanism transmissions:

[0134] Suitable scenarios: Single pair of gripping units, small to medium load (e.g., robot weight of 15-20kq), and scenarios with high requirements for simplified transmission links (e.g., power inspection robots, small fruit picking robots).

[0135] Core design: The cam profile needs to be optimized according to the movement trajectory of the clamping arm to ensure smooth speed and uniform clamping force during the opening and closing of the clamping arm; wear-resistant bushings need to be installed at the contact point between the cam and the clamping arm to improve service life;

[0136] Force transmission verification: After replacement, the transmission efficiency needs to be verified through static simulation (such as FEA) to ensure that the clamping arm can meet the design clamping force requirements after the motor output torque is transmitted through the cam mechanism.

[0137] In some embodiments, the three-segment gripper arm's multi-dimensional adaptive adjustment mechanism includes:

[0138] Synchronous opening and closing adjustment: By precisely designing the gear ratio and optimizing the linkage length, the left and right clamping arms are ensured to open and close synchronously and their movement trajectories are approximately straight; a completely symmetrical layout is adopted to eliminate movement deviation.

[0139] Grasping range adjustment: The base is equipped with an adjustable limit block to control the maximum opening and closing angle of the gripping arm; the gear meshing clearance is adjusted by shims to improve transmission accuracy; the motion stroke is flexibly adjusted by changing the connection position of the connecting rod and the gear.

[0140] Force control adjustment: The gripping force is adjusted by controlling the output torque of the motor; the torque is amplified by the gear reduction ratio to ensure sufficient clamping force; the inner contact layer (anti-slip layer) of the gripping arm is optimized to improve the friction coefficient and enhance gripping stability.

[0141] The three-section structure adapts to the clamping requirements of the rod under different working conditions through the coordinated action of the sections and hinges. The following are two typical working conditions for illustrative purposes:

[0142] Working condition 1: Clamping the ideal straight rod

[0143] The drive unit operates, pushing the root section inward. Power is transmitted unimpeded through the first and second rotary hinges to the middle and end contact sections, keeping the three sections in a straight line and the hinges in a neutral position; the arc-shaped contact layer of the end contact section is evenly attached to the surface of the rod, forming a stable embracing structure.

[0144] Working condition 2: Clamping a bent or protruding rod

[0145] When the end contact segment first contacts the protrusion or the outer side of the bend of the rod, it will be subjected to an uneven reaction force. The second slewing hinge (in the pitch direction) moves first, and the end segment rotates in pitch around the axis of the second slewing hinge, so that the arc-shaped contact layer is in contact with the protruding surface as much as possible, avoiding the phenomenon of "lifting" or "knocking".

[0146] If the end adjustment still cannot achieve a complete fit, the first slewing hinge (deflection) then moves, causing the middle section to deflect around the axis of the first slewing hinge, so that the entire middle and end sections adapt to the macroscopic bending of the rod.

[0147] During the adaptive process, the torsion springs within the hinge accumulate energy. Once the positions of each segment stabilize, these spring forces are converted into additional contact pressure, creating a stable "mechanical locking" effect that maintains the fit.

[0148] Ultimately, through fine-tuning with two hinges, the three segments form a multi-segmented polygonal envelope that closely conforms to the irregular profile of the rod. This maximizes the contact area, evens out stress distribution, and significantly improves grip reliability.

[0149] The three-segment structure offers several advantages: First, it provides the gripping unit with superior adaptability to curved surfaces. Compared to traditional integral gripping units, which struggle to perfectly conform to complex or irregular surfaces, the three-segment design allows each segment to maintain connection while possessing a degree of relative adjustment capability. This enables it to better conform to the curved contours of the object being climbed (such as poles, pipes, etc.). This "segmented fit" mechanism ensures a tighter and more uniform contact between the gripping unit and the object's surface, effectively increasing the effective force-bearing area and preventing excessive local stress concentration. Second, this design significantly improves the stability and gripping reliability of the mechanism under different working conditions. When the climbing mechanism encounters slight surface undulations or deformations, the three-segment structure can adapt to the changes through fine-tuning of each segment, maintaining overall gripping stability and reducing the risk of slippage or instability due to poor fit. Simultaneously, wider contact means that the distribution basis N (normal force) of friction (f=μN) is more effectively utilized across the entire contact area, rather than relying solely on a few points. This plays a positive role in maintaining gripping force, especially during dynamic climbing. Furthermore, segmented design can also improve structural flexibility and fault tolerance. If one segment suffers minor wear or deformation due to an accident, the other segments can still maintain basic functionality, preventing the entire clamping unit from failing and improving the system's robustness. In addition, from a manufacturing and maintenance perspective, segmented design may also facilitate the individual replacement of worn parts.

[0150] Application examples:

[0151] Based on the proposed solution, a gripping mechanism for a pole-climbing robot is implemented. This pole-climbing robot is an autonomous pole-climbing robot used for power line inspection. It needs to stably climb on circular concrete poles with a diameter of approximately 150-200 mm and maintain its posture while performing operations on the pole. The main challenge lies in overcoming the robot's own weight of approximately 15 kg and adapting to adverse conditions such as slipperiness and dust on the pole surface.

[0152] In this application example, the core structural engineering implementation of the gripping mechanism for the pole-climbing robot is as follows:

[0153] Drive Unit: A planetary geared brushless motor with a rated torque of 15 Nm and a speed of 50 rpm was selected. Based on the optional scheme of the transmission system in this application, a precision-designed cam mechanism is used to directly drive two symmetrical clamping arms (suitable for the single pair of clamping units, 15 kg load, and simplified transmission chain requirements of this example). The profile of the cam mechanism is optimized according to the opening and closing trajectory of the clamping arms, and wear-resistant bushings are fitted at the contact points. Its transmission efficiency has been verified by FEA to be equivalent to that of a gear-connecting rod composite transmission system, and the transmission chain is simplified, improving reliability in inspection scenarios.

[0154] Angled clamping arm design: The two clamping arms are made of high-strength aluminum alloy, with a total length of 180mm. The angle of the clamping arms is set at 30°. The contact surfaces are inlaid with engineering plastics (such as UHMW-PE) to provide a good coefficient of friction and a certain degree of cushioning. The clamping arms are connected to the base and drive cam by two high-strength alloy steel pins.

[0155] Enveloping Expansion: The base of the clamping arms is designed to be relatively wide. When the clamping arms are fully closed, the base areas of the two clamping arms form a near-enveloping closed structure, effectively covering the pole cross-section. This design not only increases the contact area, but more importantly, the huge reaction force generated during clamping, as well as the stress generated by the motor drive torque, no longer acts concentrated at the connecting pin as in traditional designs, but is instead distributed and transmitted throughout the entire enveloping area.

[0156] Control and Sensing: A torque sensor is installed at the root of each gripper arm to monitor the clamping force in real time. In addition, encoders, IMUs, and pressure sensors can be used to collect gripper arm encoder position data (for determining relative motion), robot IMU attitude and acceleration data (for assessing motion state), and pressure distribution matrix (for assessing contact fit). The robot's main control unit precisely controls the motor's output torque based on sensor data and preset algorithms, thereby achieving adaptive clamping: automatically increasing the clamping force when starting to climb or detecting a risk of slippage; maintaining a stable clamping force during uniform climbing or when stationary to reduce energy consumption and wear.

[0157] Example 2:

[0158] This application provides a control method for a gripping mechanism of a pole-climbing robot, applied to the gripping mechanism of the pole-climbing robot described in Embodiment 1, including the following steps:

[0159] Step 1: Collect real-time data through sensing components and perform preprocessing;

[0160] Step 2: Based on the preprocessed data, determine whether there is a risk of slippage and assess the confidence level of the risk;

[0161] Step 3: Update the friction coefficient estimate online based on the preprocessed data and the dynamic equilibrium equation;

[0162] Step 4: Dynamically adjust the safety factor according to the operating mode, calculate the minimum clamping force to satisfy stable clamping using the static equilibrium equation, and use it as the target clamping force. Then, dynamically adjust the target clamping force in combination with slippage risk, risk confidence level, and contact conditions. The operating modes include slippage recovery mode, climbing mode, and stationary mode.

[0163] Step 5: The deviation between the target clamping force and the actual clamping force is converted into a force control value through a PID closed-loop control algorithm, and then converted into a motor torque command according to the type of drive mechanism and output.

[0164] The robot's main control unit executes clamping control in a continuous loop, completing the entire chain of "data acquisition - risk assessment parameter update - target calculation - torque output" in each cycle. Torque commands are output to the motors to control the motion of the clamping mechanism. After step 5, relevant data is recorded to optimize subsequent control strategies.

[0165] In some embodiments, step 1 may include:

[0166] The raw clamping force data collected by the torque sensor is processed by moving average filtering (retaining the average of the most recent sampling points) to eliminate high-frequency noise and obtain accurate current actual clamping force.

[0167] The motion speed of the clamping arm relative to the rod is calculated by the encoder position difference (the difference between the current position and the previous position of the encoder) and the time interval.

[0168] Based on the robot pitch angle (pitch_angle) calculated by the IMU, the original axial acceleration (a_z) collected by the IMU is obtained. The influence of gravity component on the axial acceleration is removed, that is, a_z-9.8×cos(pitch_angle) is calculated to obtain the axial acceleration reflecting the actual motion state of the mechanism; where 9.8 is the constant of gravitational acceleration, with the unit being 9.8m / s².

[0169] If a pressure sensor is configured, the pressure distribution uniformity index (0-1 range, 1 being completely uniform) can be calculated to help evaluate the contact and fit between the clamping arm and the rod.

[0170] In some embodiments, step 2, slip risk detection may include:

[0171] The system uses four detectors to collaboratively determine the risk of slippage. Each detector corresponds to a slippage feature, and the final evaluation is based on the weights of each detector.

[0172] In some embodiments, the judgment logic of each detector is as follows:

[0173] The clamping arm relative displacement detector is used to detect the relative displacement of the clamping arm. During normal and stable clamping, there should be no relative movement between the clamping arm and the rod. If the detected movement speed of the clamping arm exceeds the preset speed threshold (e.g., 0.03 m / s), a slippage risk alarm is triggered. The greater the speed exceeds the threshold, the higher the confidence level (maximum 1).

[0174] An acceleration anomaly detector is used to detect acceleration anomalies. The robot's motion planning pre-determines a theoretical axial acceleration. If the deviation between the actual axial acceleration and the theoretical axial acceleration exceeds a preset deviation threshold (e.g., 0.5 m / s²), and the actual axial acceleration is less than the theoretical axial acceleration (indicating ineffective power transmission and slippage), a slippage risk alarm is triggered. The larger the deviation, the higher the confidence level.

[0175] The clamping force fluctuation detector is used to detect clamping force fluctuations. During stable clamping, the clamping force should remain stable. If the ratio of the standard deviation to the mean of the most recent preset number (20) clamping force sampling points (fluctuation coefficient) exceeds the preset fluctuation coefficient threshold (e.g., 0.15), it indicates that the clamping state is unstable, and a slippage risk alarm is triggered. The larger the fluctuation coefficient, the higher the confidence level.

[0176] The pressure distribution anomaly detector is used to detect abnormal pressure distribution. If the pressure distribution uniformity index is lower than the preset uniformity threshold (e.g., 0.6), it indicates poor contact adhesion, triggering a slippage risk alarm. The lower the uniformity, the higher the risk confidence level.

[0177] Comprehensive risk assessment:

[0178] In some embodiments, weights are assigned to the four detectors. For example, the confidence weights of the relative displacement detector of the clamping arm, the acceleration anomaly detector, the clamping force fluctuation detector, and the pressure distribution anomaly detector are 40%, 30%, 20%, and 10%, respectively. The weighted total confidence of all detectors that trigger the slippage risk alarm is calculated. When at least one detector triggers the slippage risk alarm and the total confidence exceeds 0.3, it is finally determined that there is a slippage risk.

[0179] In some embodiments, the online estimation of the friction coefficient is achieved by combining the inverse solution of the dynamic equation with a low-pass filtering strategy, thereby realizing real-time and accurate estimation of the friction coefficient between the rod and the clamping arm. The specific process is as follows:

[0180] Initial parameter configuration: During initialization, a preset initial estimate of the friction coefficient is established, and a historical friction coefficient record list is created to store the estimated values. The learning rate of the low-pass filter is set to control the weight of the influence of new measurements on the final estimate. For example, the preset initial estimate of the friction coefficient can be 0.4, and the learning rate of the low-pass filter can be set to 0.05.

[0181] Estimated value update trigger condition: If the absolute value of the robot's actual acceleration along the axis of the rod is greater than the preset acceleration threshold (0.2m / s²), the friction coefficient estimated value update will be initiated.

[0182] Setting this estimate update trigger condition can prevent invalid calculations and estimate deviations caused by sensor noise when the robot is stationary.

[0183] Estimated value update: If the update conditions are met, extract the following parameters: the current actual clamping force F_clamp of the gripper arm, the actual axial acceleration of the robot after correcting for gravity interference a_actual, the angle θ of the gripper arm (in radians), the total weight of the robot G and the total mass m, and the number of gripper arms n; based on the dynamic equilibrium equation n×(F_clamp×sinθ+μ×F_clamp×cosθ)-G=m×a_actual, rearrange the formula; calculate the numerator: m×a_actual+Gn×F_clamp×sinθ; calculate the denominator: n×F_clamp×cosθ; if the absolute value of the denominator is greater than 1e-6 (to avoid division by zero error), then obtain the original measured value μ of the friction coefficient by "numerator / denominator".

[0184] Physical rationality constraint: To ensure that the estimated value conforms to the physical laws of actual working conditions, the original measured value of the calculated friction coefficient is limited to a reasonable range of 0.1 to 1.0: if the measured value is less than 0.1, it is forcibly corrected to 0.1; if the measured value is greater than 1.0, it is forcibly corrected to 1.0; if the measured value is within the range of 0.1 to 1.0, the original value remains unchanged.

[0185] Low-pass filtering updates the final estimate: A low-pass filtering strategy is used to fuse historical estimates and current measurements to obtain the final friction coefficient estimate. The formula is: Final estimate = (1 - learning rate) × historical estimate + learning rate × current measurement. For example, the learning rate is 0.05, meaning the historical estimate accounts for 95% of the weight, and the current measurement accounts for 5%, ensuring smooth changes in the estimate and avoiding sudden changes caused by fluctuations in a single measurement.

[0186] Historical data management: After each update, the latest friction coefficient estimate is stored in the historical record list; when the list length exceeds the preset threshold (e.g., 100 records), the oldest record is automatically deleted, thus preserving sufficient historical reference data while avoiding data redundancy.

[0187] Estimated value output: A dedicated interface needs to be provided to retrieve the latest estimated value of the friction coefficient at any time, providing core parameter support for subsequent calculation of the target clamping force.

[0188] In some embodiments, the calculation of the target clamping force (the clamping force that just provides stable support) is based on static equilibrium, and dynamically adjusted in conjunction with slippage state, operating mode, and contact conditions. The calculation process may include:

[0189] Step 4.1 Extract the core parameters required for calculation: total robot weight G, clamping arm angle θ, number of clamping arms n, and the current rod-clamping arm friction coefficient μ obtained through online estimation.

[0190] Step 4.2: Dynamically adjust the safety factor according to the operating mode:

[0191] The safety factor determines the safety margin of the clamping force, and is set differently according to the robot's operating state:

[0192] Slippage recovery mode: If slippage is detected, a higher safety factor is used. For example, let the safety factor = 1.5 + 0.5 × slippage confidence level (final range 1.5~2.0). The higher the confidence level, the larger the safety factor and the higher the clamping force margin.

[0193] Climbing mode: If the robot is in a climbing state, a medium safety factor (e.g., 1.3) is used.

[0194] Static mode: Employs a base safety factor (e.g., 1.2) plus adaptive margin adjustment.

[0195] The adaptive margin base value is 1.1 (i.e., 10% margin); if there are slippage records in a short period of time (such as within the last 60 seconds), the margin is increased according to the number of slippages (up to 30% can be added).

[0196] If the robot runs stably for longer than the set time threshold (e.g., 5 minutes), the margin can be slightly reduced (a minimum of 5% can be set). The final safety factor = basic safety factor × adaptive margin.

[0197] Step 4.3: Based on the static equilibrium equation n×F_clamp×(sinθ+μ×cosθ)≥safety factor×G, derive the minimum clamping force F_min that satisfies stable clamping:

[0198] First, calculate the denominator: n×(sinθ+μ×cosθ). If the denominator ≤ 1e-6 (to avoid mathematical calculation errors), it is determined that the clamping is theoretically unstable and returns infinity.

[0199] Then, calculate the minimum clamping force under the corresponding safety factor using the formula F_min=(safety factor×G) / denominator, and use it as the basic target clamping force.

[0200] Step 4.4: Optimize the basic target clamping force based on pressure distribution:

[0201] If pressure distribution uniformity data is collected and the value is less than the uniformity threshold (e.g., 0.7), it indicates poor contact fit. The basic target clamping force is increased by 10% to improve the contact state between the clamping arm and the rod.

[0202] Step 4.5: Based on the risk of slippage, compensate for the slippage and determine the final target clamping force:

[0203] If slippage is detected, the final target clamping force = basic target clamping force × (1.0 + 0.8 × slippage confidence level), and the force value is further increased to quickly restore stability;

[0204] When no slippage is detected, the final target clamping force equals the basic target clamping force.

[0205] After the calculation is completed, record information such as the operating mode, safety factor, target clamping force, and friction coefficient for subsequent debugging and optimization.

[0206] In some embodiments, a PID controller converts the deviation between the target clamping force and the current actual clamping force into a force control value, ensuring that the actual clamping force precisely matches the target value. This process may include:

[0207] Step 5.1: First, calculate the deviation error between the target clamping force and the current actual clamping force.

[0208] Step 5.2: Calculate the proportional, integral, and derivative control components:

[0209] Proportional term (P): Directly responds to the current deviation. P = proportional gain Kp × deviation. The larger the deviation, the larger the proportional adjustment. For example, Kp = 3.0.

[0210] Integral term (I): Accumulate historical deviations to eliminate static errors. First, add "deviation × control cycle time (dt)" to the integral value, and then limit the integral value (e.g., limit it to the range of -50.0 to 50.0). Finally, I = integral gain Ki (e.g., 0.1) × the limited integral value; for example, integral gain Ki = 0.1.

[0211] Differential term (D): Based on the rate of change of deviation, adjust in advance to suppress system oscillation: First calculate the rate of change of deviation ((current error - previous cycle error) / dt), then optimize the rate of change of deviation through low-pass filtering to obtain the filtered rate of change. Finally, D = differential gain Kd = 0.8 × filtered rate of change. For example, the filter coefficient of the low-pass filter is 0.1. For example, Kd = 0.8.

[0212] Step 5.3: Use the superposition result of P+I+D as the force control value of the PID output, and limit the force control value (e.g., limit it to the range of -100.0~100.0) to avoid excessive output that could damage the mechanism.

[0213] After obtaining the force control value, the force control value output by the PID controller is converted into a torque command that the motor can execute, ensuring the safe operation of the motor.

[0214] Select the corresponding force-torque conversion rule based on the type of drive mechanism to perform force-torque conversion:

[0215] Gear-connecting rod composite transmission: Torque command = force control value × gear reduction ratio × connecting rod lever arm coefficient (preset to 0.95, adapted to transmission efficiency);

[0216] Cam mechanism transmission: Torque command = force control value × cam base circle radius × cam pressure angle cosine value (calibrated based on actual cam design parameters);

[0217] The torque command for both transmission methods must be limited to the rated torque range of the motor to ensure drive safety.

[0218] In actual control, the risk of slippage is first detected and the friction coefficient estimate is updated. Then, the target clamping force is calculated according to the above steps. The force control value is obtained through PID control, converted into motor torque, and then output, forming a complete closed loop of perception-calculation-control-output.

[0219] Implementation effect verification:

[0220] A climbing test simulating a utility pole environment was conducted on the clamping mechanism. The results show that:

[0221] Maximum load capacity: With a surface friction coefficient μ=0.3 (simulating wet conditions), the gripping mechanism successfully supported and climbed a robot model weighing 18kg, exceeding the design target in terms of load capacity.

[0222] Stability: During uniform ascent (0.5 m / s), the robot's posture remained stable with no significant swaying. Even under simulated slight bumps (±5 mm vertical vibration), it maintained its grip.

[0223] Stress testing: Finite element analysis (FEA) comparison shows that, compared with the traditional parallel gripper design, the maximum stress value of this application is reduced by about 40%, and the stress distribution is more uniform, mainly concentrated in the reinforcing ribs and circumferential area of ​​the gripper arm, away from the critical connecting pin, which significantly improves the structural life.

[0224] Surface adaptability: Reliable gripping was achieved under various pole surface conditions simulating dryness, slipperiness, and thin dust, and it was insensitive to changes in the coefficient of friction.

[0225] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A pole climbing robot gripping mechanism control method characterized by, This invention relates to a gripping mechanism for pole-climbing robots. The gripping mechanism comprises multiple pairs of gripping units arranged symmetrically in a vertical arrangement, a drive unit, a connecting and fixing assembly, and a sensing assembly. The gripping units are connected to the drive unit via a transmission mechanism. The connecting and fixing assembly enables a detachable connection between the gripping units and the main frame of the pole-climbing robot. Each pair of gripping units includes two symmetrically arranged gripping arms. The axis of each gripping arm forms an acute angle with the normal to the surface of the object being climbed, and when the two gripping arms are closed, they form a ring-shaped structure that covers the cross-section of the object being climbed. The sensing assembly includes a torque sensor installed at the root of the gripping arm for collecting clamping force data. The design method for the angle of inclination is as follows: calculate the theoretical optimal angle θ_optimal=arctan(1 / μ), where μ is the friction coefficient between the object being climbed and the contact layer of the clamping arm. Considering engineering constraints, the calculated theoretical optimal angle is finely adjusted to obtain the final design angle. The method includes the following steps: Step 1: Collect real-time data through the sensing components and perform preprocessing; Step 2: Based on the preprocessed data, determine whether there is a risk of slippage and assess the confidence level of the risk; Step 3: Update the friction coefficient estimate online based on the preprocessed data and the dynamic equilibrium equation; Step 4: Dynamically adjust the safety factor according to the operating mode; based on the estimated friction coefficient and the safety factor, calculate the minimum clamping force to satisfy stable clamping using the static equilibrium equation, and use it as the target clamping force. Combine the slippage risk, risk confidence, and contact conditions to dynamically adjust the target clamping force; wherein, the operating mode includes slippage recovery mode, climbing mode, and stationary mode; Step 5: The deviation between the target clamping force and the actual clamping force is converted into a force control value through a PID closed-loop control algorithm, and then converted into a motor torque command according to the type of drive mechanism and output.

2. The control method for the clamping mechanism of the pole-climbing robot according to claim 1, characterized in that, In step 1, the preprocessing includes performing moving average filtering on the clamping force data, calculating the relative motion speed of the clamping arm based on the clamping arm position data, correcting the axial acceleration data collected by the IMU, and calculating the pressure distribution uniformity index of the contact area between the inner arc surface contact layer of the clamping arm and the surface of the object being climbed.

3. The control method for the clamping mechanism of the pole-climbing robot according to claim 2, characterized in that, In step 2, a multi-dimensional detector is used to collaboratively determine whether there is a risk of slippage and to assess the confidence level of the risk. The multi-dimensional detector includes a relative displacement detector of the clamping arm, an acceleration anomaly detector, a clamping force fluctuation detector, and a pressure distribution anomaly detector. Each detector is assigned a preset weight, and when the weighted total confidence level exceeds a preset threshold, it is determined that there is a risk of slippage.

4. A gripping mechanism for a pole-climbing robot, characterized in that, The gripping mechanism for the pole-climbing robot includes multiple pairs of gripping units, a drive unit, a connecting and fixing assembly, and a sensing assembly arranged symmetrically in a vertical configuration. The gripping units are connected to the drive unit via a transmission mechanism, and the connecting and fixing assembly enables a detachable connection between the gripping units and the main frame of the pole-climbing robot. Each pair of gripping units includes two symmetrically arranged gripping arms. The axis of each gripping arm forms an acute angle with the normal to the surface of the object being climbed, and when the two gripping arms are closed, they form a wraparound structure that covers the cross-section of the object being climbed. Each gripping arm adopts a three-segment structure, including a root segment, a middle segment, and an end contact segment connected sequentially by a rotary hinge. The segments are adjusted relative to each other to adapt to the curved contour of the object being climbed. The sensing assembly includes a torque sensor installed at the root of the gripping arm for collecting clamping force data. The design method for the angle of inclination is as follows: calculate the theoretical optimal angle θ_optimal=arctan(1 / μ), where μ is the friction coefficient between the object being climbed and the contact layer of the clamping arm. Considering engineering constraints, the calculated theoretical optimal angle is finely adjusted to obtain the final design angle. The clamping mechanism of the pole-climbing robot is controlled by the method described in any one of claims 1 to 3.

5. The clamping mechanism for a pole-climbing robot according to claim 4, characterized in that, The slewing hinge includes a first slewing hinge and a second slewing hinge; the first slewing hinge connects the root section and the middle section, allowing the middle section to deflect ±10° relative to the root section in a plane perpendicular to the clamping arm axis; the second slewing hinge connects the middle section and the end contact section, allowing the end contact section to pitch ±8° relative to the middle section in a plane parallel to the clamping arm axis; the slewing hinge incorporates a torsion spring or damping element to achieve reset or oscillation suppression functions.

6. The clamping mechanism for a pole-climbing robot according to claim 4, characterized in that, The drive unit includes a high torque density motor and a reducer, which drives the clamping arm to move relative to each other through a transmission system; The transmission system adopts a gear-linkage composite transmission system or a cam mechanism transmission system; wherein, the gear-linkage composite transmission system includes a driving gear and a driven gear that mesh with each other, and a connecting rod connecting the driven gear and the clamping arm, which can convert the rotational motion of the gear into the opening and closing motion of the clamping arm; The drive unit is located near the rotation center of the clamping arm.

7. The clamping mechanism for a pole-climbing robot according to any one of claims 4 to 6, characterized in that, The sensing components also include an encoder installed at the motion execution end of the gripper arm, an IMU fixed at the geometric center or center of gravity of the robot's main frame, and a pressure sensor array installed on the inner arc surface of the gripper arm. The encoder is used to collect gripper arm position data, the IMU is used to collect robot posture and axial acceleration data, and the pressure sensors are used to collect pressure distribution data at different points in the contact area between the inner arc surface contact layer of the gripper arm and the surface of the object being climbed.

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