A diameter adaptive method and controller for robot climbing pipes

Abstract

This invention relates to a diameter adaptive method and controller for robot pipe climbing, belonging to the field of robot control technology. To address the problem of poor climbing performance of existing pipe climbing methods for pipes of different sizes, this invention, based on a robot with a body comprising multiple joints, uses the number of pressure sensors in contact with the pipe as a constraint. The robot is pre-fitted with a helical path, and then the helical radius is gradually reduced until the constraint is met. During the robot's pipe climbing process, the pipe diameter change is determined by the position of the pressure sensors, and the helical radius is adjusted accordingly to adapt to the pipe diameter while meeting the constraint.

Description

Technical Field

[0001] This invention belongs to the field of robot control technology, and relates to a diameter adaptive method and controller suitable for robots climbing pipes. Background Technology

[0002] Wheelless robots possess the ability to adapt to complex environments. With tactile feedback, the robot can sense pressure changes through sensors to obtain environmental information, enabling autonomous obstacle avoidance. However, in some complex environments, pressure sensors struggle to accurately obtain obstacle information.

[0003] Due to their lightweight and small size, thin-film pressure sensors are commonly used for pressure detection on mobile robots. However, for wheelless robots—multi-jointed biomimetic robots with highly redundant degrees of freedom—current thin-film pressure sensors struggle to perfectly realize surface pressure sensing. In fact, for pipes of unknown or varying diameters, robots need to accurately estimate the pipe diameter before effectively performing climbing tasks. Existing technologies generally use pressure exceeding a threshold to determine if the pipe is tightly wrapped. While this is more direct, it's not well-suited for pipes of different diameters, cannot achieve rapid response movement, and is prone to component damage. Some methods use lidar, cameras, etc., to pre-estimate the pipe diameter, providing data for robot movement. However, this approach often suffers from large estimation errors, resulting in poor climbing performance, especially for pipes with varying diameters, where climbing efficiency and effectiveness are not ideal, and it also suffers from slow development cycles. Summary of the Invention

[0004] This invention aims to address the problem that existing pipe climbing methods are ineffective for pipes of different sizes.

[0005] A diameter adaptive method for a robot climbing a pipe, the robot body comprising multiple joints, each joint having multiple pressure sensors disposed on its circumferential sidewall, the method comprising:

[0006] Using the number of pressure sensors in contact with the pipe as a constraint, the robot is pre-fitted with a spiral line, and then the spiral radius is gradually reduced until the constraint is met. During the robot's climbing of the pipe, the pipe diameter change is determined by the position of the pressure sensors, and the spiral radius is adjusted to adapt to the pipe diameter to meet the constraint.

[0007] Furthermore, the number of pressure sensors in contact with the pipeline is based on pressure data exceeding a contact pressure threshold. The pressure sensor was determined.

[0008] Furthermore, based on the pressure data exceeding the contact pressure threshold... In determining the number of pressure sensors in contact with the pipeline, the number of pressure sensors in contact with the pipeline within one gait cycle is calculated. N is the total number of sensors; δ(·) is an indicator function, which is 1 when the condition is met and 0 otherwise. One gait cycle τ is the pressure of the i-th pressure sensor; τ(spiral)contact is the contact pressure threshold.

[0009] Furthermore, when using the number of pressure sensors in contact with the pipeline as a constraint, a one-cycle constraint is adopted, i.e. N (spiral) λ represents the total number of pressure sensors that may come into contact with the pipe during the climbing process. err This is the allowable error.

[0010] Furthermore, during the process of determining the pipe diameter change by the position of the pressure sensor, the contact state between the robot and the pipe is determined based on the pressure sensor value. The contact state determination function between the robot and the pipe is as follows:

[0011]

[0012] in, Represents the period corresponding to the kth sampling period , This represents the pressure value of pressure sensor i; F(spiral)τ is the overpressure threshold.

[0013] Furthermore, based on the pressure data exceeding the contact pressure threshold... In determining the number of pressure sensors in contact with the pipeline, 1 / Number of pressure sensors in contact with the pipeline during each gait cycle N is the total number of sensors; δ(·) is an indicator function, which is 1 when the condition is met and 0 otherwise. One gait cycle The number of pressure sensors installed on the circumferential sidewall of the joint; τ is the pressure of the i-th pressure sensor; τ(spiral) contact is the contact pressure threshold.

[0014] Furthermore, when using the number of pressure sensors in contact with the pipeline as a constraint, 1 / Periodic constraints, i.e. N (spiral) λ represents the total number of pressure sensors that may come into contact with the pipe during the climbing process. err This is the allowable error.

[0015] Furthermore, during the process of determining the pipe diameter change by the position of the pressure sensor, the contact state between the robot and the pipe is determined based on the pressure sensor value. The contact state determination function between the robot and the pipe is as follows:

[0016]

[0017] in, Represents the kth 1 / corresponding to the period , This represents the pressure value of pressure sensor i; F(spiral)τ is the overpressure threshold.

[0018] Furthermore, the following adaptive adjustment law for the helix radius is used in the process of adjusting the helix radius to meet the constraints and adapt the pipe diameter:

[0019]

[0020] Where, r max and r min Let Δ be the limit of the helical radius of the robot in the horizontal pipe. r Adjust the step size for the radius; Where is the helix radius.

[0021] A diameter adaptive controller for a robot climbing a pipe, the controller storing a computer program for implementing the aforementioned diameter adaptive method for a robot climbing a pipe.

[0022] The beneficial effects of this invention compared to the prior art are:

[0023] This invention enables a robot to gradually estimate the diameter of the pipe it is currently contacting and how that diameter changes during movement. This is not only real-time and effective, but also boasts excellent climbing efficiency and performance. Furthermore, this invention offers advantages such as fast and accurate calculations, low hardware requirements, and the ability to directly calibrate thin-film pressure sensors installed in different locations without subsequent readjustment. This ensures consistency of calibration data from multiple sensors and improves calibration efficiency, significantly reducing the development cycle for surface pressure sensing in wheelless robots. Attached Figure Description

[0024] Figure 1 A simplified diagram illustrating a robot climbing a horizontal pipe.

[0025] Figure 2 Diagram showing a robot climbing an unknown 100mm diameter horizontal pipe.

[0026] Figure 3This is a graph showing the changes in the spiral radius and the number of sensors in contact with the pipe when climbing a 100mm diameter pipe. Detailed Implementation

[0027] Specific implementation method one: Combining Figure 1 This implementation method is described below.

[0028] This embodiment is a diameter adaptive method for a robot to climb a pipe, including the following steps:

[0029] Step 1: During the crawling process, the pressure sensor installed on the robot comes into contact with the pipe and receives a corresponding pressure pulse;

[0030] The robot's body consists of multiple joints, with pressure sensors mounted on each joint. Each joint has pressure sensors on its circumferential sidewalls. Each square joint has a pressure sensor on all four sides, ensuring that there are always pressure sensors to obtain pressure data during the robot's crawling process. In some embodiments, a robot with 16 joints has a total of 64 sensors.

[0031] Step 2: Determine whether the robot has effectively wound the pipe based on the pressure data:

[0032] The robot's envelope diameter is close to the actual diameter of the pipe. Each joint of the robot acts as part of the body that wraps around the pipe, and the thin-film pressure sensor on its surface comes into contact with the pipe, thus generating a pressure pulse. However, when the envelope diameter of some or all of the robot's joints is larger than the actual diameter of the pipe, part of the robot's body will not come into contact with the pipe. In this case, the thin-film pressure sensor at the corresponding location will not detect the contact pressure with the pipe. This method can be used to determine whether the robot has effectively wrapped around the pipe.

[0033] The theoretical constraint for the robot to fully wind around the pipe can be expressed as:

[0034]

[0035] In the formula, N(spiral) contact is the number of thin-film pressure sensors that come into contact with the pipeline in one gait cycle; N is the total number of sensors; δ(·) is the indication function, which is 1 when the condition is met and 0 otherwise. One gait cycle The pressure of the i-th pressure sensor is τ; τ(spiral) contact is the contact pressure threshold, which determines that the sensor is in contact with the pipe when the pressure exceeds this value; N (spiral) λ represents the total number of pressure sensors that may come into contact with the pipe during the climbing process. errTo allow for error, the detection of the number of times the sensor contacts the pipe is allowed to have some error.

[0036] It should be noted that a gait cycle is actually a joint control cycle. When the joint is controlled in a sinusoidal model, the joint control cycle is the sinusoidal model cycle. In order to achieve precise control with diameter adaptation and enable the robot to perform other climbing tasks, a gait cycle also corresponds to the cycle in which the robot completes one full roll.

[0037] Assuming the number of thin-film pressure sensors on the robot surface meets the theoretical constraints, to improve the detection efficiency of whether the robot effectively encloses the pipeline, the detection time can be reduced from one cycle to 1 / 4 cycle. The modified 1 / 4 cycle constraint is as follows:

[0038]

[0039] in, The number of thin-film pressure sensors that come into contact with the pipe within 1 / 4 of a gait cycle;

[0040] It should be noted that the robot with square joints (square cross-section) used in this embodiment has a contact time of 1 / 4 of a cycle for one face of the joint. If other joint types are used, such as hexahedrons or octahedrons, the corresponding cycle would be 1 / 6 or 1 / 8 of a cycle. Therefore, the contact time can be adjusted according to the number of faces of the joint. (This actually refers to the number of sensors on the joint) to set 1 / For cylindrical joints, the circumferential direction is divided according to the actual circumferential dimensions and practical needs. That's it. Typically, robot joints are square, meaning... It is usually set to 4.

[0041] Step 3: Reduce the control parameters of the robot's pipe winding spiral radius until the 1 / 4 cycle constraint condition of pipe winding is met to achieve full pipe winding: The robot is pre-fitted with a spiral with a large diameter so that it can be suspended on the pipe. As the robot moves in a spiral motion, the robot detects the situation of enveloping the pipe. When the robot does not fully envelop the pipe, the robot will reduce the control parameters of the spiral radius until the 1 / 4 cycle constraint condition is met to achieve full pipe winding.

[0042] Pre-fitting a large-diameter spiral to allow the robot to hang on the pipe means initially setting a large diameter for the entire robot. Before it is fully wound around the pipe, some of the robot's joints act as support surfaces, and the entire robot hangs on the pipe. Then, the overall spiral radius is gradually reduced until it is fully wound around the pipe. At this point, the radius of the spiral curve fitted by the robot represents the radius of the pipe.

[0043] Step 4: Determine the change in pipe diameter by checking the position of the pressure sensor.

[0044] When the robot fully encloses the pipe, if the wrapping is too tight, the pressure sensor on the robot's surface will receive a larger pressure pulse peak. In this case, the helix radius control parameter needs to be increased. Based on the above description, the contact state judgment function between the robot and the pipe should be set as follows:

[0045]

[0046] in, τ represents the number of sensors in contact with the pipe detected in the kth sampling period, i.e., the kth quarter period; F(spiral) is the overpressure threshold. When this value is exceeded, it is considered that the robot is wrapped too tightly around the pipe.

[0047] The contact state judgment function is 1, 0, and -1, which respectively indicate that the robot is winding the pipe too tightly, moderately, and too loosely.

[0048] It should be noted that step 3 uses a 1 / 4 period constraint condition, and step 4 is also based on the 1 / 4 period constraint condition for judgment. This can ensure the efficiency and accuracy of the robot's motion control. However, in reality, step 3 can also be achieved by fully winding the pipe using theoretical constraints, and step 4 can also be judged based on the theoretical constraints of step 3.

[0049] Step 5: Adjust the robot's climbing gait according to the determined diameter to adapt to the pipe. During this process, an adaptive adjustment law for the helical radius is established based on the contact state judgment function.

[0050]

[0051] Where, r max and r min Δ represents the limits of the robot's helical radius (maximum and minimum helical radius) in a horizontal pipe. r Adjust the step size for the radius; Where is the helix radius.

[0052] For pipes with unknown or varying diameters, robots need to accurately estimate the pipe diameter before effectively performing climbing tasks. This invention detects and processes data from thin-film pressure sensors at different locations on the robot, enabling the robot to gradually estimate the diameter of the currently contacted pipe and its changes during movement. Furthermore, this invention can directly calibrate thin-film pressure sensors installed at different locations without subsequent readjustment, ensuring consistency of calibration data from multiple sensors and improving calibration efficiency, significantly reducing the development cycle for surface pressure sensing in wheelless robots. Specific Implementation Method Two:

[0054] This embodiment discloses a diameter adaptive controller for a robot climbing a pipe. The controller stores a computer program that implements the diameter adaptive method for a robot climbing a pipe. In essence, the controller is a device that implements this method. The device may include a processor and / or a memory. It should be understood that this includes any device described in this invention that includes a processor and a memory. The device may also include other units or modules that perform display, interaction, processing, control, and other functions via signals or instructions. The memory stores at least one instruction, which is loaded and executed by the processor to implement the diameter adaptive method for a robot climbing a pipe.

[0055] Those skilled in the art will understand that at least one stored instruction constitutes a computer program product corresponding to a method or system. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0056] This application is described with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of this application, and can also be used with corresponding devices. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0057] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0058] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0059] Example

[0060] In industrial pipeline systems, robots often need to deal with complex pipe networks composed of different pipe diameters. To this end, multiple pipe scenarios with different diameters were built, and experimental tests were conducted based on the pipe diameter adaptive algorithm.

[0061] First, establish a spiral climbing motion control model:

[0062] The robot climbs the pipe using a spiral motion, and the fitted parametric equation of the spiral curve is as follows:

[0063]

[0064] Among them, R s h is the helix radius. s Given the pitch, calculate the curvature and deflection of the curve respectively;

[0065] The control function for determining the i-th joint angle is:

[0066]

[0067] Where l is the length of a single joint module;

[0068] By changing the helix radius R in the control parameters s To enable the robot to fit pipes of different diameters, the control parameter for selecting the helix radius can be calculated using the following formula:

[0069]

[0070] Among them, R control R is the control parameter for the robot's helix radius. pipe w is the actual radius of the pipe. snake ε is the width of the robot joint module; R To influence the robot's winding force around the pipe. For robots with square joint modules, w snake It is generally expressed as the diameter of the circumcircle of its tangent plane; ε R This is an empirical parameter; it is negative when the robot climbs the outer pipe and positive when climbing the inner pipe.

[0071] Select a total of N on the robot (spiral) = Data analysis was performed using 32 thin-film pressure sensors to set the pitch h in the joint angle control function. s = 180mm, initial helix radius control parameter R control = 120mm, joint motion angular frequency ω s = 0.25, meaning the robot's gait cycle is approximately 25.13s. The contact pressure threshold τ(spiral) contact in the 1 / 4 cycle constraint bar is set to 1.0N for the entangled pipe detection, with an allowable error λ. err = 0.25. In setting the adaptive adjustment law for the helix radius parameter, the adjustment step size Δ of the robot's helix radius is... r The value is 0.0025 mm / time.

[0072] The experiment tested the robot's movement while climbing a 100mm pipe. Figure 2 As shown, Figure 2 The motion states (a)-(f) are obtained as 0s, 15s, 30s, 45s, 60s, and 75s, respectively. Figure 2 The corresponding changes in the helix radius control parameters and the number of diaphragm pressure sensors in contact with the pipeline are as follows: Figure 3 As shown, during the experiment, the robot was always unaware of the pipe diameter parameters until it successfully and stably wound the pipe, at which point it was able to estimate the pipe diameter.

[0073] exist Figure 2 In Figure (a), the initial spiral radius is 120 mm, which is not enough to effectively wind around the pipe. As the robot moves, every 1 / 4 cycle, the robot checks the number of thin-film pressure sensors in contact with the pipe during that time period. Figure 3 The blue line in the diagram represents the change in the number of sensors, and the red line represents the helical radius parameter affected by them. When the number of sensors is less than 6, the robot is considered not to have completely enveloped the pipe, and its helical radius parameter will decrease. Figure 2As can be seen from the changes in (a) to (e), the robot basically achieved the envelopment of the pipe by 62s. After that, the number of sensors in contact with the pipe was no less than 6, and the robot's helical radius parameter finally stabilized at 97.5mm, realizing adaptive motion to pipes of unknown diameter.

[0074] The robot was placed on pipes with diameters of 100mm, 120mm, and 140mm respectively to perform a horizontal spiral climb on pipes of unknown diameter. Each test was conducted three times. Data analysis was performed on the nine sets of experiments, and the pipe diameter detection results are shown in Table 1. ε R Indicates the degree of entanglement, by The calculations show that the smaller the value, the greater the force with which the robot winds the pipe.

[0075] Table 1 Pipe Diameter Inspection Table

[0076]

[0077] As shown in Table 1, the robot can effectively entangle pipes of different diameters using the pipe diameter adaptive algorithm. This is due to the initial helix radius parameter R. control Set to 120mm, adjust the spiral radius step size Δ r For a given pipe diameter, the robot takes less time to adapt to the pipe. In practical applications, the step size Δ can be adjusted according to the specific environment. r and the initial helix radius parameter R control This further reduces the time required for adaptive pipelines.

[0078] The above examples of the present invention are merely illustrative of the computational model and process of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is impossible to exhaustively list all possible implementations here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for diameter self-adaptation of a robot to climb a pipe, the robot body comprising a plurality of joints, each joint having a plurality of pressure sensors disposed on a circumferential side wall thereof, the method comprising: determining a diameter of the pipe; and adjusting a diameter of the robot body to match the diameter of the pipe. The method includes: Using the number of pressure sensors in contact with the pipe as a constraint, the robot is pre-fitted with a spiral line, and then the spiral radius is gradually reduced until the constraint is met. During the robot's climbing of the pipe, the pipe diameter change is determined by the position of the pressure sensors and the spiral radius is adjusted to adapt to the pipe diameter to meet the constraint. The number of pressure sensors in contact with the pipeline is based on pressure data exceeding a contact pressure threshold. The pressure sensor determines that the pressure data exceeds the contact pressure threshold. In determining the number of pressure sensors in contact with the pipeline, the number of pressure sensors in contact with the pipeline within one gait cycle is calculated. N is the total number of sensors; δ(·) is an indicator function, which is 1 when the condition is met and 0 otherwise. One gait cycle The pressure of the i-th pressure sensor; The contact pressure threshold is used; when the number of pressure sensors in contact with the pipeline is used as a constraint, a one-cycle constraint condition is adopted, i.e. ; This represents the total number of pressure sensors that may come into contact with the pipe when climbing it. To account for any allowable error, the robot's contact state with the pipe is determined based on the pressure sensor readings during the pipe diameter change process, using the pressure sensor values. The robot-pipe contact state determination function is as follows: in, Represents the period corresponding to the kth sampling period , This indicates the pressure value of pressure sensor i; This is the overvoltage threshold.

2. The diameter adaptive method for robot climbing pipes according to claim 1, characterized in that, The following adaptive adjustment law for the helix radius is used to adjust the helix radius to meet the constraints and adapt the pipe diameter: in, and The limit of the helical radius of the robot in a horizontal pipe. Adjust the step size for the radius; Where is the helix radius.

3. A diameter adaptive method for a robot climbing a pipe, wherein the robot body includes multiple joints, and each joint has multiple pressure sensors disposed on its circumferential sidewall, characterized in that, The method includes: The number of pressure sensors in contact with the pipeline is based on pressure data exceeding the contact pressure threshold. The pressure sensors are determined, and the number of pressure sensors in contact with the pipe is used as a constraint. The robot is pre-fitted with a spiral line, and then the spiral radius is gradually reduced until the constraint is met. During the robot's climbing of the pipe, the pipe diameter change is judged by the position of the pressure sensors and the spiral radius is adjusted to meet the constraint and adapt to the pipe diameter. The number of pressure sensors in contact with the pipeline is based on pressure data exceeding a contact pressure threshold. The pressure sensor determines that the pressure data exceeds the contact pressure threshold. In determining the number of pressure sensors in contact with the pipeline, 1 / Number of pressure sensors in contact with the pipeline during each gait cycle N is the total number of sensors; δ(·) is an indicator function, which is 1 when the condition is met and 0 otherwise. One gait cycle The number of pressure sensors installed on the circumferential sidewall of the joint; The pressure of the i-th pressure sensor; The contact pressure threshold is used; when the number of pressure sensors in contact with the pipeline is used as a constraint, 1 / Periodic constraints, i.e. ; This represents the total number of pressure sensors that may come into contact with the pipe when climbing it. To account for any allowable error, the robot's contact state with the pipe is determined based on the pressure sensor readings during the pipe diameter change process, using the pressure sensor values. The robot-pipe contact state determination function is as follows: in, Represents the kth 1 / corresponding to the period , This indicates the pressure value of pressure sensor i; This is the overvoltage threshold.

4. The diameter adaptive method for robot climbing a pipe according to claim 3, characterized in that, The following adaptive adjustment law for the helix radius is used to adjust the helix radius to meet the constraints and adapt the pipe diameter: in, and The limit of the helical radius of the robot in a horizontal pipe. Adjust the step size for the radius; Where is the helix radius.

5. A diameter adaptive controller for a robot climbing a pipe, characterized in that, The controller stores a computer program for implementing the diameter adaptive method for a robot climbing a pipe as described in any one of claims 1 to 4.

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