Posture stability control method and system for pipeline robot

Abstract

The invention provides a pipeline robot attitude stability control method and system, and relates to the technical field of attitude control, and the method comprises the steps: obtaining the speed data and curve curvature data of a robot in a pipeline curve, and the roll angle of each wheel, and carrying out the analysis to determine the equivalent centrifugal force of each wheel of the pipeline robot; setting a limit roll angle, determining a safety margin, determining to execute a deceleration strategy or a compensation strategy according to the safety margin, determining a centrifugal force unbalance degree based on the equivalent centrifugal force, and further determining a centrifugal compensation torque; acquiring a comprehensive roll angle and a jitter compensation torque, and applying a reverse compensation torque to each wheel in a mode of applying a torque to the wheel in a reverse compensation torque manner; and verifying the effect of executing the compensation strategy, and executing the deceleration strategy if the result is not qualified.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of posture control, in particular to a pipeline robot posture stability control method and system. BACKGROUND

[0002] With the increasing complexity and scale of urban underground pipe network system, pipeline robots play an irreplaceable role in the inspection, cleaning and maintenance of pipelines for water supply, drainage, oil and gas transportation, etc. These robots can replace manual work to enter narrow, humid, toxic or dangerous environments with poor accessibility, perform high-definition video shooting, leakage detection, pipe wall damage identification and other tasks, greatly improving the safety and intelligent level of municipal management and energy transportation. However, the inside of the pipeline is not an ideal straight path, and there are generally complex structures such as bends, tees and reducers. When the robot travels in the curved section, it will be subjected to the coupling effect of centrifugal force, gravity, pipe wall contact force and driving force, and is prone to posture instability, which is manifested as body tilting, lateral shaking or even overall overturning. Such instability not only leads to blurred images and distorted sensor data, but also may cause the robot to be stuck, fall or be damaged, directly threatening the continuity of the task and the safety of the equipment.

[0003] The existing technology mainly focuses on two types of methods: speed regulation and torque compensation. However, both methods have obvious limitations. The speed regulation method reduces the centrifugal force effect by reducing the travel speed, which is simple and reliable, but severely sacrifices the inspection efficiency and economic efficiency of the operation, making it difficult to meet the real-time requirements of large-scale, long-period pipeline detection. The torque compensation method generates an anti-overturning torque by applying a braking force or driving force to some wheels, but in the actual variable pipeline environment, due to the strong nonlinearity of the robot's dynamic response and the complexity of system jitter factors, the compensation strategy with fixed parameters often appears rigid, which may lead to control lag due to insufficient compensation or system oscillation due to excessive compensation, and cannot adapt to changes in different motion states throughout the journey.

[0004] The above information disclosed in the background section is only used to enhance the understanding of the background of the present disclosure, and therefore it can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] The purpose of the present application is to provide a pipeline robot posture stability control method and system to solve the problems raised in the background.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A pipeline robot posture stability control method, the specific steps comprising: Step 1: Obtain the speed data of the robot in the pipeline bend, the bend curvature data and the roll angle of each wheel, and analyze and determine the equivalent centrifugal force at each wheel of the pipeline robot; Step 2: set a limit roll angle, determine a safety margin based on the limit roll angle and the roll angle, determine a control strategy according to the safety margin, the control strategy is a deceleration strategy or a compensation strategy, if the compensation strategy is adopted, step 3 is performed, if the deceleration strategy is adopted, step 5 is performed; Step 3: determine the centrifugal force imbalance degree based on the equivalent centrifugal force at all wheels, and further determine the centrifugal compensation torque; determine the comprehensive roll angle of the pipeline robot based on the roll angle of the wheel, obtain the pipeline robot jitter acceleration, determine the jitter compensation torque based on the jitter acceleration, determine the reverse compensation torque of each wheel based on the positional relationship between the wheel and the center of the curve, the centrifugal force imbalance degree, the centrifugal compensation torque, the comprehensive roll angle, the jitter acceleration and the jitter compensation torque, and apply the reverse compensation torque to each wheel by applying torque to the wheel; Step 4: measure the jitter acceleration of the pipeline robot after executing the compensation strategy, and compare it with the jitter acceleration before executing the compensation strategy, determine whether the compensation strategy is qualified according to the comparison result, if not, go to step 5; Step 5: set a deceleration step and a centrifugal iteration termination condition, decelerate the current speed by the deceleration step, if the centrifugal iteration termination condition is met, reduce the speed of the pipeline robot to the speed at the iteration termination; if the centrifugal iteration termination condition is not met within a preset number of iterations, halve the speed of the pipeline robot.

[0007] Further, the direction pointing to the center of the curve is called the inner side of the curve, and the direction opposite to the inner side of the curve is called the outer side of the curve; if the roll angle deviates to the outer side of the curve, the roll angle is set to a positive value, if the roll angle deviates to the inner side of the curve, the roll angle is set to a negative value, the comprehensive roll angle is the sum of all roll angles, if the comprehensive roll angle is positive, the comprehensive roll angle deviates to the outer side of the curve, if the comprehensive roll angle is negative, the comprehensive roll angle deviates to the inner side of the curve; The formula for calculating the equivalent centrifugal force is: ; Wherein, is the equivalent centrifugal force received by the pipeline robot, is the mass of the pipeline robot, is the speed of the pipeline robot, is the curvature radius of the curve at the position of the pipeline robot; is the roll angle of the i-th wheel of the pipeline robot, the roll angle of the wheel is the angle between the wheel and the vertical upward direction, i is the index of the wheel.

[0008] Further, absolute values of the roll angles of the wheels are compared to determine a maximum absolute value of the roll angles, a difference between the limit roll angle and the maximum absolute value of the roll angles is calculated, the difference is a safety margin, a safety margin threshold is preset, if the safety margin is less than the safety margin threshold, a deceleration strategy is used for control, and if the safety margin is not less than the safety margin threshold, a compensation strategy is used for control.

[0009] Further, the wheels are divided into inner wheels and outer wheels based on positions of the wheels in the pipeline, a wheel on a side of the pipeline robot close to a center of a pipeline curve is defined as an inner wheel, and a wheel on a side of the pipeline robot far from the center of the pipeline curve is defined as an outer wheel. The logic for calculating the centrifugal force imbalance degree is that equivalent centrifugal forces of all the wheels are analyzed to obtain the centrifugal force imbalance degree. The formula for calculating the centrifugal force imbalance degree is: ; Wherein, is the centrifugal force imbalance degree of the pipeline robot, is a weight of the i-th wheel of the pipeline robot, is a total number of the wheels, and the specific weight setting is based on that if the wheel is an outer wheel, the weight is set as 1, and if the wheel is an inner wheel, the weight is set as -1. The jitter acceleration is a maximum jitter acceleration in a latest control period. The formula for calculating the jitter compensation torque is: ; is the jitter compensation torque of the pipeline robot, is a component of the jitter acceleration of the pipeline robot in a motion direction of the pipeline robot, is a wheel radius; The centrifugal compensation torque is a first centrifugal compensation torque or a second centrifugal compensation torque, and the second centrifugal compensation torque is greater than the first centrifugal compensation torque, a centrifugal force imbalance degree threshold is preset, if the centrifugal force imbalance degree is less than the centrifugal force imbalance degree, the first centrifugal compensation torque is used as the centrifugal compensation torque, and if the centrifugal force imbalance degree is not less than the centrifugal force imbalance degree threshold, the second centrifugal compensation torque is used as the centrifugal compensation torque. Further, if the comprehensive roll angle deviates to an outer side of the curve, a reverse compensation torque of a sum of the centrifugal compensation torque and the jitter compensation torque is applied to the inner wheels, and a reverse compensation torque of the jitter compensation torque is applied to the outer wheels. If the comprehensive roll angle deviates to an inner side of the curve, reverse compensation torques of the jitter compensation torques are applied to the inner wheels and the outer wheels.

[0010] Further, the jitter acceleration of the pipeline robot after executing the compensation strategy is obtained, if the jitter acceleration of the pipeline robot is less than the jitter acceleration before executing the compensation strategy, it is judged that the compensation strategy is qualified, otherwise, the compensation strategy is unqualified.

[0011] Further, the deceleration strategy is specifically: setting a deceleration step, decelerating the current speed according to the deceleration step, and calculating the equivalent centrifugal force and the centrifugal force imbalance degree, iterating, if the centrifugal iteration termination condition is met, the speed of the pipeline robot is reduced to the speed at the iteration termination; if the centrifugal iteration termination condition is not met within the preset iteration times, the speed of the pipeline robot is halved. The centrifugal iteration termination condition is that the centrifugal force is less than a preset centrifugal force threshold, and the centrifugal force imbalance degree is less than a centrifugal force imbalance degree threshold.

[0012] The application further provides a pipeline robot posture stability control system, which is used for the pipeline robot posture stability control method, and specifically comprises: The centrifugal analysis module is used for obtaining the speed data, the curve data of the curve and the roll angle of each wheel of the robot in the pipeline curve, and analyzing and determining the equivalent centrifugal force at each wheel of the pipeline robot. The strategy selection module is used for setting a limit roll angle, determining a safety margin based on the limit roll angle and the roll angle, determining a control strategy according to the safety margin, the control strategy being a deceleration strategy or a compensation strategy, if the compensation strategy is adopted, step 3 is performed, and if the deceleration strategy is adopted, step 5 is performed. The strategy compensation module is used for determining the centrifugal force imbalance degree based on the equivalent centrifugal force at all wheels, and further determining the centrifugal compensation torque; determining the comprehensive roll angle of the pipeline robot based on the roll angle of the wheel, obtaining the jitter acceleration of the pipeline robot, determining the jitter compensation torque based on the jitter acceleration, determining the reverse compensation torque of each wheel based on the positional relationship between the wheel and the center of the curve, the centrifugal force imbalance degree, the centrifugal compensation torque, the comprehensive roll angle, the jitter acceleration and the jitter compensation torque, and applying the reverse compensation torque to each wheel by applying a torque to the wheel. The compensation evaluation module is used for measuring the jitter acceleration of the pipeline robot after executing the compensation strategy, and comparing the jitter acceleration before and after executing the compensation strategy, judging whether the compensation strategy is qualified according to the comparison result, and if not, entering step 5. The strategy deceleration module is used for setting a deceleration step and a centrifugal iteration termination condition, decelerating the current speed according to the deceleration step, if the centrifugal iteration termination condition is met, the speed of the pipeline robot is reduced to the speed at the iteration termination; if the centrifugal iteration termination condition is not met within the preset iteration times, the speed of the pipeline robot is halved.

[0013] Compared with the prior art, the present application has the following advantages: The present application builds a dual-mode controller by introducing the key criterion of "safety margin". When the attitude risk is low (sufficient safety margin), the system preferentially adopts the torque compensation mode, actively offsets the unbalanced torque through precise motor torque distribution, thereby maintaining stability without speed reduction, and guarantees the inspection efficiency. When the attitude risk is high (insufficient safety margin), the system intelligently switches to the speed reduction mode, eliminating the risk through the most reliable way of quickly reducing the speed.

[0014] The compensation strategy of the present application is not single and fixed. It quantifies the instability degree through "centrifugal force imbalance degree" and accordingly calls different compensation torques in different levels (first, second), achieving the fine control of "small deviation fine tuning, large deviation strong intervention". At the same time, the "shaking compensation torque" is introduced, which brings the influence of robot's own vibration into the compensation system, making the control model more close to the actual complex working conditions.

[0015] The present application does not end after performing compensation in an "open loop" manner, but adds a key "post-compensation evaluation" link. The control effect is verified by comparing the shaking acceleration before and after compensation, and if the compensation is unqualified, the speed reduction strategy is switched. This closed-loop design enables the system to have the ability of "self-verification and error correction", preventing the system from sticking to the wrong decision when the compensation strategy is not effective, thereby falling into an out-of-control state, greatly enhancing the reliability and safety of the system. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The present application is a whole method flowchart.

[0017] Figure 2 The present application is a whole system structure schematic diagram. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with specific embodiments.

[0019] It should be noted that the technical terms or scientific terms used in the present application should be understood as the general meaning understood by those skilled in the art unless otherwise defined. The terms "first", "second" and the like used in the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and the like mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and the like are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect. The terms "up", "down", "left", "right" and the like are only used to represent relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] Embodiment: Please refer to Figure 1 The present application provides a technical solution: A pipeline robot posture stability control method, the specific steps comprising: Step 1: Obtain the speed data of the robot in the pipeline curve, the curve curvature data and the roll angle of each wheel, and analyze and determine the equivalent centrifugal force at each wheel of the pipeline robot; Further, the direction pointing to the center of the curve is called the inner side of the curve, and the direction opposite to the inner side of the curve is called the outer side of the curve; if the roll angle deviates to the outer side of the curve, the roll angle is set to positive, if the roll angle deviates to the inner side of the curve, the roll angle is set to negative, the comprehensive roll angle is the sum of all roll angles, if the comprehensive roll angle is positive, the comprehensive roll angle deviates to the outer side of the curve, if the comprehensive roll angle is negative, the comprehensive roll angle deviates to the inner side of the curve; The formula for calculating the equivalent centrifugal force is: ; Wherein, is the equivalent centrifugal force received by the pipeline robot, is the mass of the pipeline robot, is the speed of the pipeline robot, is the curve radius of the position where the pipeline robot is located; is the roll angle of the i-th wheel of the pipeline robot, the roll angle of the wheel is the angle between the wheel and the vertical upward direction, and i is the index of the wheel.

[0021] For the centrifugal force suffered by the pipeline robot when passing through the bend, due to the complexity of the environment in the pipeline and the fact that the pipeline is circular, the pipeline robot is likely to not travel horizontally forward, at this time the wheels are not vertical upward, the angle between the pipeline robot and the vertical upward direction, that is, the roll angle of the wheel; the centrifugal force is orthogonally decomposed, among which the equivalent centrifugal force component in the wheel plane will be offset by the weight of the pipeline robot and will not affect the posture of the pipeline robot, and the equivalent centrifugal force component perpendicular to the wheel plane will directly affect the posture balance of the pipeline robot when passing through the bend, and the analysis of the equivalent centrifugal force can further obtain the influence of the equivalent centrifugal force on different wheels, providing an important theoretical basis for later compensation control.

[0022] Step 2: set the limit roll angle, determine the safety margin based on the limit roll angle and the roll angle, determine the control strategy according to the safety margin, the control strategy is a deceleration strategy or a compensation strategy, if the compensation strategy is adopted, step 3 is performed, if the deceleration strategy is adopted, step 5 is performed; The limit roll angle can be determined by inviting experts in the field to analyze and demonstrate based on the actual size and shape of the pipeline and the pipeline robot, and then giving the maximum roll angle of the wheel without affecting the normal driving of the pipeline robot as the limit roll angle. Based on the structural parameters and operating environment of the pipeline robot, the posture stability boundary of the pipeline robot at different speeds and bend curvatures is determined through dynamic simulation, the angle of multiple pipeline robot rollover is simulated, and the average value of 90% is taken to determine the limit roll angle. The limit roll angle is set to 20%-30% as the safety margin threshold, which not only reserves sufficient response margin for the control system, but also avoids frequent triggering of the deceleration strategy due to the threshold being too conservative. This is prior art and will not be described here.

[0023] Further, the logic for obtaining the safety margin is: comparing the absolute values of the roll angles of each wheel to determine the maximum roll angle absolute value, calculating the difference between the limit roll angle and the maximum roll angle absolute value, which is the safety margin. A safety margin threshold is preset, if the safety margin is less than the safety margin threshold, it means that the pipeline robot is already in an unstable state, so the control method should be immediate and stable, to avoid accidents such as pipeline robot rollover that directly lead to termination of pipeline robot operation, that is, directly using the deceleration strategy for control, if the safety margin is not less than the safety margin threshold, it means that the posture of the pipeline robot is relatively far from the limit, and there is a relatively large control margin, so a fine-tuning method can be used to slowly compensate for the posture stability of the pipeline robot, that is, using the compensation strategy for control. The present application divides the pipeline robot into relatively unstable and relatively stable postures through the safety margin, and adopts different control strategies for different situations. It can adopt appropriate control strategies according to the actual motion of the pipeline robot to realize posture stability control that meets the actual situation of the pipeline robot.

[0024] Step 3: determine the centrifugal force imbalance degree based on the equivalent centrifugal forces at all wheels, and then determine the centrifugal compensation torque; determine the comprehensive roll angle of the pipeline robot based on the roll angles of the wheels, obtain the pipeline robot jitter acceleration, determine the jitter compensation torque based on the jitter acceleration, determine the reverse compensation torque of each wheel based on the positional relationship between the wheels and the center of the curve, the centrifugal force imbalance degree, the centrifugal compensation torque, the comprehensive roll angle, the jitter acceleration and the jitter compensation torque, and apply the reverse compensation torque to each wheel by applying torque to the wheels; Further, the wheels are divided into inner wheels and outer wheels based on their positions in the pipeline, the wheels on the side of the pipeline robot close to the center of the curve of the pipeline are referred to as inner wheels, and the wheels on the side of the pipeline robot away from the center of the curve of the pipeline are referred to as outer wheels; The logic for calculating the centrifugal force imbalance degree is to analyze the equivalent centrifugal forces of all wheels to obtain the centrifugal force imbalance degree; The formula for calculating the centrifugal force imbalance degree is: ; Wherein, is the centrifugal force imbalance degree of the pipeline robot, is the weight of the i-th wheel of the pipeline robot, is the total number of wheels, and the specific weight setting is based on: if the wheel is an outer wheel, the weight is set to 1, and if the wheel is an inner wheel, the weight is set to -1; After the pipeline robot supported by the wheels is subjected to the effect of the centrifugal force, the inner wheels and the outer wheels will produce different effects, wherein, since the centrifugal force points to the outer wheels, the pipeline robot has a tendency to turn outward, so the centrifugal effect on the outer wheels is to tighten the outer wheels, while the centrifugal effect on the inner wheels is to relax the wheels, the effects are completely opposite, therefore, this is the inevitable result of the pipeline robot subjected to the centrifugal force. However, for the entire system, the real cause of the unstable posture of the pipeline robot is the comprehensive imbalance after the centrifugal force effects of the inner and outer wheels are offset. The centrifugal force imbalance degree reflects the comprehensive imbalance after the centrifugal force effects of the inner and outer wheels are offset, and reflects the net overturning trend caused by the centrifugal force. The larger the value is, the more serious the comprehensive imbalance after the centrifugal force effects of the outer wheels are offset, and the greater the overturning trend, which requires a large compensation, and vice versa, which requires a small compensation; The jitter acceleration is the maximum jitter acceleration in the last control cycle; since the pipeline robot has a high jitter frequency, a representative maximum jitter acceleration is needed to represent the comprehensive jitter situation, if the maximum can make the pipeline robot stable, other moments will make the pipeline robot more stable, therefore, the jitter acceleration is the maximum jitter acceleration in the last control cycle; wherein, one control cycle is 30-70 seconds.

[0025] The pipeline robot itself generates jitter when running, which also causes the posture of the pipeline robot to be unstable, and the influence is relatively small compared with the influence caused by the centrifugal force, but still cannot be ignored; The formula for calculating the jitter compensation torque is: The jitter compensation torque of the pipeline robot, is the component of the jitter acceleration of the pipeline robot in the direction of the movement of the pipeline robot, is the wheel radius; is the force generated by the jitter in the direction of the movement of the pipeline robot, according to the formula of the torque, is the torque of the wheel of the pipeline robot in the direction of the movement of the pipeline robot, since the directions of all the wheels are approximately directed to the direction of the movement of the pipeline, the torque of the wheel of the pipeline robot in the direction of the movement of the pipeline robot is calculated by The jitter compensation torque of each wheel is analyzed. The jitter compensation torque considers the influence of the jitter of the pipeline robot on the posture of the pipeline robot, and can make the posture analysis of the pipeline robot more accurate.

[0026] The centrifugal compensation torque is a first centrifugal compensation torque or a second centrifugal compensation torque, and the second centrifugal compensation torque is greater than the first centrifugal compensation torque. A preset centrifugal force imbalance threshold is provided. If the centrifugal force imbalance is less than the centrifugal force imbalance threshold, it indicates that the influence of the centrifugal force on the posture of the pipeline robot is relatively small, and a smaller centrifugal compensation torque, i.e., the first centrifugal compensation torque, can be used. The first centrifugal compensation torque is used as the centrifugal compensation torque. If the centrifugal force imbalance is not less than the centrifugal force imbalance threshold, it indicates that the influence of the centrifugal force on the posture of the pipeline robot is relatively large, and a larger centrifugal compensation torque, i.e., the second centrifugal compensation torque, needs to be used. The second centrifugal compensation torque is used as the centrifugal compensation torque. In this embodiment, the posture instability caused by the centrifugal force received by the pipeline robot is analyzed through the centrifugal force imbalance threshold, different centrifugal compensation torques are used for compensation according to different situations, and more accurate adaptive control is realized.

[0027] The first centrifugal compensation torque and the second centrifugal compensation torque are preset centrifugal compensation torques, which can be determined by experts in the field according to the actual structure and control system of the pipeline robot. First, the critical compensation torque at which the pipeline robot will lose stability at a typical curve speed is measured through experiment or simulation. Since the compensation torque is the superposition of various torques, at this time, the centrifugal force is the most important factor, and therefore 50% of the critical compensation torque is set as the first centrifugal compensation torque, which is used to cope with slight centrifugal force imbalance. 85% of the critical centrifugal force torque value is set as the second centrifugal compensation torque.

[0028] ​Further, the reverse of the reverse compensation torque is in the opposite direction of the motion.

[0029] If the integrated roll angle is inclined to the outside of the curve, a reverse compensation torque of the sum of the centrifugal compensation torque and the shaking compensation torque is applied to the inner wheel, and a reverse compensation torque of the shaking compensation torque is applied to the outer wheel. Since the shaking compensation torque is in the direction of the motion, the inner wheel and the outer wheel both have shaking in the direction of the motion, and thus the shaking compensation torque needs to be applied to both wheels. If the integrated roll angle is inclined to the outside of the curve, it indicates that the posture of the pipe robot in the pipe is that the inner wheel is high and the outer wheel is low, and the centrifugal force has a tendency to overturn the pipe robot. Therefore, a reverse compensation torque of the centrifugal compensation torque is needed to be applied to the inner wheel to form a speed difference and offset the tendency to overturn the pipe robot, and thus a reverse compensation torque of the sum of the centrifugal compensation torque and the shaking compensation torque is needed to be applied to the inner wheel.

[0030] If the integrated roll angle is inclined to the inside of the curve, a reverse compensation torque of the shaking compensation torque is applied to the inner wheel and the outer wheel.

[0031] Since the shaking compensation torque is in the direction of the motion, the inner wheel and the outer wheel both have shaking in the direction of the motion, and thus the shaking compensation torque needs to be applied to both wheels. If the integrated roll angle is inclined to the inside of the curve, it indicates that the posture of the pipe robot in the pipe is that the outer wheel is high and the inner wheel is low, and the overturning tendency of the centrifugal force is directly offset by the support force of the pipe on the pipe robot. Therefore, the centrifugal compensation torque is not needed to be compensated, and only the shaking compensation torque in the direction of the motion needs to be compensated.

[0032] In the embodiment, the actual posture of the pipe robot when passing the curve of the pipe is considered, and whether the centrifugal torque compensation needs to be performed is determined according to the actual posture, to complete the self-adaptive stability control in the pipe.

[0033] Step 4: The shaking acceleration of the pipe robot after the compensation strategy is performed is measured and compared with the shaking acceleration before the compensation strategy is performed, and whether the compensation strategy is qualified is determined according to the comparison result, and if not, step 5 is entered. Generally, the compensation strategy is qualified after the compensation strategy is performed, but since the centrifugal compensation torque is a preset constant value, in the case of extremely large or extremely small centrifugal force, the effect of the compensation strategy may be small, or even have a reverse effect. The compensation strategy can be performed only when there is enough control margin (the safety margin is not less than the safety margin threshold value), otherwise, if in an extreme case, the pipe robot cannot maintain stability, and accidents may occur directly. Since the effect of the compensation strategy may be small or even have a reverse effect, the stability of the pipe robot after compensation needs to be verified to ensure the posture stability of the pipe robot.

[0034] Further, the shaking acceleration of the pipeline robot after the compensation strategy is executed is obtained, if the shaking acceleration of the pipeline robot is less than the shaking acceleration before the compensation strategy is executed, it is judged that the compensation strategy is qualified, otherwise, the compensation strategy is unqualified.

[0035] Step 5: setting a deceleration step and a centrifugal iteration termination condition, iteratively decelerating the current speed according to the deceleration step, if the centrifugal iteration termination condition is met, the speed of the pipeline robot is reduced to the speed at the iteration termination; if the centrifugal iteration termination condition is not met within a preset iteration number, the speed of the pipeline robot is halved.

[0036] Further, the deceleration strategy specifically comprises: setting a deceleration step, iteratively decelerating the current speed according to the deceleration step, and calculating the equivalent centrifugal force and the centrifugal force imbalance degree, if the centrifugal iteration termination condition is met, the speed of the pipeline robot is reduced to the speed at the iteration termination; if the centrifugal iteration termination condition is not met within a preset iteration number, the speed of the pipeline robot is halved. The centrifugal iteration termination condition is that the equivalent centrifugal force is less than a preset centrifugal force threshold, and the centrifugal force imbalance degree is less than a centrifugal force imbalance degree threshold.

[0037] The application further provides a pipeline robot posture stability control system, which is used for the pipeline robot posture stability control method and specifically comprises: A centrifugal analysis module is configured to obtain speed data, curve data and the roll angle of each wheel of the robot in the pipeline curve, and analyze and determine the equivalent centrifugal force at each wheel of the pipeline robot. A strategy selection module is configured to set a limit roll angle, determine a safety margin based on the limit roll angle and the roll angle, determine a control strategy according to the safety margin, the control strategy is a deceleration strategy or a compensation strategy, if the compensation strategy is adopted, step 3 is performed, if the deceleration strategy is adopted, step 5 is performed. A strategy compensation module is configured to determine the centrifugal force imbalance degree based on the equivalent centrifugal force at all wheels, and further determine the centrifugal compensation torque, determine the comprehensive roll angle of the pipeline robot based on the roll angle of the wheel, obtain the shaking acceleration of the pipeline robot, determine the shaking compensation torque based on the shaking acceleration, determine the reverse compensation torque of each wheel based on the positional relationship between the wheel and the curve center, the centrifugal force imbalance degree, the centrifugal compensation torque, the comprehensive roll angle, the shaking acceleration and the shaking compensation torque, and apply the reverse compensation torque to each wheel by applying a torque to the wheel. A compensation evaluation module is configured to measure the shaking acceleration of the pipeline robot after the compensation strategy is executed, and compare it with the shaking acceleration before the compensation strategy is executed, judge whether the compensation strategy is qualified according to the comparison result, if not, step 5 is entered. The strategy deceleration module is configured to set a deceleration step and a centrifugal iteration termination condition, to perform deceleration iteration on the current speed according to the deceleration step, to reduce the speed of the pipeline robot to the speed at the iteration termination if the centrifugal iteration termination condition is met, and to halve the speed of the pipeline robot if the centrifugal iteration termination condition is not met within a preset iteration number.

[0038] The above formulas are dimensionless values calculated, the formulas are obtained by collecting a large amount of data to simulate a formula of the most recent real situation, and preset parameters in the formulas are set by a person skilled in the art according to actual conditions.

[0039] The above embodiments can be realized wholly or partially by software, hardware, firmware or any other combination. When realized by software, the above embodiments can be realized wholly or partially in the form of a computer program product. Those skilled in the art can realize that the units and algorithm steps of the examples described in connection with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized by hardware or software methods depends on the specific application and design constraints of the technical solutions.

[0040] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, which can be located in one place or distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0041] The above is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can not easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for stabilizing the attitude of a pipeline robot, characterized in that, The specific steps include: Step 1: Obtain the robot's speed data, curve curvature data, and roll angle of each wheel in the pipe bend, and analyze them to determine the equivalent centrifugal force at each wheel of the pipe robot; Step 2: Set the limit roll angle and determine the safety margin based on the limit roll angle and the roll angle. Determine the control strategy based on the safety margin. The control strategy is either a deceleration strategy or a compensation strategy. If a compensation strategy is adopted, proceed to step 3. If a deceleration strategy is adopted, proceed to step 5. Step 3: Determine the centrifugal force imbalance based on the equivalent centrifugal force at all wheels, and then determine the centrifugal compensation torque; determine the comprehensive roll angle of the pipeline robot based on the roll angle of the wheels, obtain the vibration acceleration of the pipeline robot, determine the vibration compensation torque based on the vibration acceleration, and determine the reverse compensation torque of each wheel based on the positional relationship between the wheel and the center of the curve, the centrifugal force imbalance, the centrifugal compensation torque, the comprehensive roll angle, the vibration acceleration, and the vibration compensation torque. Apply the reverse compensation torque to each wheel by applying torque to the wheel. Step 4: Measure the jitter acceleration of the pipeline robot after implementing the compensation strategy and compare it with the jitter acceleration before implementing the compensation strategy. Determine whether the compensation strategy is qualified based on the comparison result. If it is not qualified, proceed to step 5. Step 5: Set the deceleration step size and centrifugal iteration termination condition. Perform deceleration iteration on the current speed according to the deceleration step size. If the centrifugal iteration termination condition is met, reduce the speed of the pipeline robot to the speed at the end of the iteration. If the centrifugal iteration termination condition is not met within the preset number of iterations, reduce the speed of the pipeline robot by half.

2. The method for attitude stabilization control of a pipeline robot according to claim 1, characterized in that: The direction pointing towards the center of the curve is called the inside of the curve, and the direction opposite to the inside of the curve is called the outside of the curve. If the roll angle is biased towards the outside of the curve, the roll angle is set to a positive value. If the roll angle is biased towards the inside of the curve, the roll angle is set to a negative value. The total roll angle is the sum of all roll angles. If the total roll angle is positive, the total roll angle is biased towards the outside of the curve. If the total roll angle is negative, the total roll angle is biased towards the inside of the curve. The formula for calculating the equivalent centrifugal force is: ； in, The equivalent centrifugal force experienced by the pipeline robot, For the quality of pipeline robots, For the speed of the pipeline robot, The radius of curvature of the bend where the pipeline robot is located; Let be the rolling angle of the i-th wheel of the pipeline robot, where the rolling angle of the wheel is the angle between the wheel and the vertically upward direction, and i is the index of the wheel.

3. The posture stabilization control method for a pipeline robot according to claim 1, characterized in that... The logic for obtaining the safety margin is as follows: compare the absolute values ​​of the roll angles of each wheel to determine the absolute value of the maximum roll angle, calculate the difference between the absolute value of the limit roll angle and the absolute value of the maximum roll angle, and this difference is the safety margin. A safety margin threshold is preset. If the safety margin is less than the safety margin threshold, a deceleration strategy is used for control. If the safety margin is not less than the safety margin threshold, a compensation strategy is used for control.

4. The posture stabilization control method for a pipeline robot according to claim 2, characterized in that: Based on the position of the wheels in the pipe, the wheels are divided into inner wheels and outer wheels. The wheels on the side of the pipe robot closer to the center of the pipe bend are called inner wheels, and the wheels on the side of the pipe robot farther away from the center of the pipe bend are called outer wheels. The logic for calculating the centrifugal force imbalance is as follows: analyze the equivalent centrifugal force of all wheels to obtain the centrifugal force imbalance. The formula for calculating the centrifugal force imbalance is: ； in, For the centrifugal force imbalance of the pipeline robot, Let be the weight of the i-th wheel of the pipeline robot. The total number of wheels is determined by the following weighting: if the wheel is the outermost wheel, the weight is set to 1; if the wheel is the innermost wheel, the weight is set to -1. The jitter acceleration is the maximum jitter acceleration in the most recent control cycle; The formula for calculating the jitter compensation torque is: ； For the vibration compensation torque of the pipeline robot, Let be the component of the pipe robot's jitter acceleration in the direction of the pipe robot's motion. The radius of the wheel; The centrifugal compensation torque is either a first centrifugal compensation torque or a second centrifugal compensation torque, and the second centrifugal compensation torque is greater than the first centrifugal compensation torque. A preset centrifugal force imbalance threshold is set. If the centrifugal force imbalance is less than the centrifugal force imbalance threshold, the first centrifugal compensation torque is used as the centrifugal compensation torque. If the centrifugal force imbalance is not less than the centrifugal force imbalance threshold, the second centrifugal compensation torque is used as the centrifugal compensation torque.

5. The posture stabilization control method for a pipeline robot according to claim 4, characterized in that: If the overall roll angle is biased towards the outside of the curve, then apply a reverse compensation torque equal to the sum of the centrifugal compensation torque and the vibration compensation torque to the inner wheel, and apply a reverse compensation torque equal to the magnitude of the vibration compensation torque to the outer wheel. If the overall roll angle is biased towards the inside of the curve, then a reverse compensation torque equal to the magnitude of the vibration compensation torque is applied to the inner and outer wheels.

6. The posture stabilization control method for a pipeline robot according to claim 5, characterized in that: Obtain the jitter acceleration of the pipeline robot after executing the compensation strategy. If the jitter acceleration of the pipeline robot is less than the jitter acceleration before executing the compensation strategy, the compensation strategy is considered qualified; otherwise, the compensation strategy is considered unqualified.

7. The posture stabilization control method for a pipeline robot according to claim 1, characterized in that: The deceleration strategy is as follows: set a deceleration step size, decelerate the current speed according to the deceleration step size, calculate the equivalent centrifugal force and centrifugal force imbalance, perform iteration, and if the centrifugal iteration termination condition is met, reduce the speed of the pipeline robot to the speed at the end of the iteration. If the centrifugal iteration termination condition is not met within the preset number of iterations, the speed of the pipeline robot will be halved. The centrifugal iteration terminates when the equivalent centrifugal force is less than a preset centrifugal force threshold and the centrifugal force imbalance is less than the centrifugal force imbalance threshold.

8. A posture stabilization control system for a pipeline robot, characterized in that: The system is used to implement the posture stabilization control method for the pipeline robot according to any one of claims 1-7, specifically including: The centrifugal analysis module is used to acquire the robot's speed data, curvature data, and roll angle of each wheel in the pipe bend, and to analyze and determine the equivalent centrifugal force at each wheel of the pipe robot. The strategy selection module is used to set the limit roll angle, determine the safety margin based on the limit roll angle and the roll angle, and determine the control strategy according to the safety margin. The control strategy is a deceleration strategy or a compensation strategy. If the compensation strategy is adopted, step 3 is performed; if the deceleration strategy is adopted, step 5 is performed. The strategy compensation module is used to determine the centrifugal force imbalance based on the equivalent centrifugal force at all wheels, and then determine the centrifugal compensation torque; determine the comprehensive roll angle of the pipeline robot based on the roll angle of the wheels, obtain the vibration acceleration of the pipeline robot, determine the vibration compensation torque based on the vibration acceleration, and determine the reverse compensation torque of each wheel based on the positional relationship between the wheel and the center of the curve, the centrifugal force imbalance, the centrifugal compensation torque, the comprehensive roll angle, the vibration acceleration, and the vibration compensation torque, and apply the reverse compensation torque to each wheel by applying torque to the wheel; The compensation evaluation module is used to measure the jitter acceleration of the pipeline robot after the compensation strategy is implemented and compare it with the jitter acceleration before the compensation strategy is implemented. Based on the comparison result, it is determined whether the compensation strategy is qualified. If it is not qualified, proceed to step 5. The strategy deceleration module is used to set the deceleration step size and centrifugal iteration termination condition. It decelerates the current speed according to the deceleration step size. If the centrifugal iteration termination condition is met, the speed of the pipeline robot is reduced to the speed at the end of the iteration. If the centrifugal iteration termination condition is not met within the preset number of iterations, the speed of the pipeline robot is halved.

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