Mobile robot stability control

Abstract

This invention relates to the field of mobile robot technology, and particularly to a method and system for rapid assessment and active control of tipping risk in mobile robotic arms. The method first assesses the tipping risk of the mobile robotic arm in its current state. If no tipping risk exists in the current state, the future center of gravity position of the entire system is predicted. Based on this future center of gravity position, the future support force at each contact point is estimated, and a further tipping risk assessment is performed based on this future support force, thus providing an early warning of tipping risk. When a tipping risk exists in the future state, the position of the counterweight is adjusted to reduce the risk through active control. This method enables timely monitoring of the stability of the mobile robotic arm under different working conditions, preventing tipping accidents and improving the safety and reliability of the mobile robotic arm.

Description

Technical Field

[0001] This invention relates to the field of mobile robot technology, and in particular to a method and system for rapid assessment and active control of tipping risk of mobile robotic arms. Background Technology

[0002] Mobile robotic arms integrate the advantages of a mobile chassis and a robotic arm, expanding the operating space of the robotic arm to a greater extent. During the movement of a mobile robotic arm, any overturning moment may cause the mobile robotic arm to tilt relative to the ground. When the overturning moment increases to a certain extent, it will not only pose a risk of tipping over on the ground, but also cause damage to the mobile chassis and the robotic arm.

[0003] In the most commonly used technologies, the torque value of a mobile robotic arm along the overturning axis is affected by multiple components. Therefore, when calculating the overturning moment, all possible torques applied to the overturning axis must be calculated to obtain the corresponding torque magnitude on each overturning axis. The entire calculation process involves a large number of coordinate calculations and vector operations, which is cumbersome, requires high data processing and computing capabilities, has poor real-time performance, and is not conducive to quickly assessing the overturning risk of the mobile robotic arm under different working conditions. In addition, existing technologies lack the ability to predict and actively control dynamic center of gravity changes in real time, and cannot meet the safety requirements in complex working environments. Summary of the Invention

[0004] The main objective of this invention is to provide a method and system for rapid assessment and active control of the tipping risk of a mobile robotic arm. This system aims to quickly assess the tipping risk of the mobile robotic arm under different working conditions and has the ability to predict and actively control dynamic center of gravity changes in real time, thereby meeting the safety requirements in complex working environments.

[0005] To achieve the above objectives, the first aspect of this invention proposes a method for rapid assessment and active control of tipping risk of a mobile robotic arm, comprising the following steps:

[0006] The contact points between the mobile chassis and the ground form a polygonal convex hull, and each side length of the polygonal convex hull is defined as the overturning axis.

[0007] Perform the current state overturning assessment steps:

[0008] The current supporting force of each contact point on the mobile chassis is collected by the weighing sensor, and the current attitude data of the mobile chassis is obtained by the inertial measurement unit.

[0009] The current net overturning moment is calculated based on the current support force and current attitude data at each contact point.

[0010] Based on the current net overturning moment and the current support force at each support point, determine whether there is an overturning risk. If so, issue an alarm signal; otherwise, perform a future overturning assessment.

[0011] The steps for performing a future state overturning assessment include:

[0012] Based on the motion parameters of the robotic arm, the current posture data of the mobile chassis, and the position of the counterweights, the overall trajectory of the mobile robotic arm is predicted. The location of the future center of gravity after time;

[0013] Estimate the future support force corresponding to each contact point based on the future center of gravity position of the mobile robotic arm as a whole;

[0014] The future net overturning moment is calculated based on the future support force of each contact point and the current attitude data of the mobile chassis.

[0015] Determine whether there is a risk of overturning based on the future net overturning moment and the future support force of each support point. If so, adjust the position of the counterweight on the moving chassis coordinates and return to execute the current state overturning assessment step; if not, return to execute the current state overturning assessment step.

[0016] In the aforementioned rapid assessment and active control method for the tipping risk of a mobile robotic arm, the base of the robotic arm is mounted on a mobile chassis, and the end effector is connected to the base via multiple links; the overall tipping risk of the mobile robotic arm is predicted. The location of the future center of gravity after time includes the following steps:

[0017] Collect the current joint angle, current angular velocity, and current angular acceleration of each joint of the robotic arm;

[0018] Each joint calculates its current joint angle, current angular velocity, and current angular acceleration. Joint angle after time;

[0019] Each joint The joint angles after a certain time are input into the forward kinematics model of the robotic arm. Combined with the mass parameters of the end effector and each link itself, the coordinates of the end effector and each link in the base coordinate system are calculated. The position of the center of gravity after time;

[0020] Position the end effector and each link itself in the base coordinate system. The center of gravity position after a certain time is transferred to the coordinate system of the mobile chassis, and combined with the center of gravity position and mass of the mobile chassis in its current pose, as well as the position and mass of the counterweights; a weighted average is then used to predict the overall position of the mobile robotic arm based on the mass. The location of the future center of gravity after time.

[0021] The above-mentioned rapid assessment and active control method for the tipping risk of a mobile robotic arm includes the following steps for estimating the future support force corresponding to each contact point based on the future center of gravity position of the mobile robotic arm as a whole:

[0022] Obtain the coordinates of each contact point in the mobile chassis coordinate system;

[0023] Under the condition that the future support force at each contact point satisfies static equilibrium, the force balance equation in the Z direction, the torque balance equation around the Y axis, and the torque balance equation around the X axis are constructed based on the coordinates of each contact point, the future support force at each contact point, and the position of the future center of gravity of the entire mobile robotic arm.

[0024] The linear matrix A×N=B is formed by the force balance equation in the Z direction, the torque balance equation around the Y axis, and the torque balance equation around the X axis.

[0025] By solving the matrix equation: N=A + The minimum norm solution of ×B yields the future support force of each support point, where A + This represents the pseudo-inverse of matrix A.

[0026] In the aforementioned method for rapid assessment and active control of tipping risk of mobile robotic arms, adjusting the position of the counterweight on the mobile chassis coordinates includes the following steps:

[0027] Establish the objective function and constraints to calculate the optimal position, where the objective is to minimize the overturning moment of the mobile robotic arm after the counterweight is adjusted, and the feasible working area of ​​the counterweight is the constraint.

[0028] The objective function is optimized to obtain the optimal counterweight position.

[0029] The drive actuator moves the counterweight to the optimal counterweight position.

[0030] In the aforementioned method for rapid assessment and active control of tipping risk of a mobile robotic arm, the polygonal convex hull is square, and the formula for calculating the net tipping moment includes:

[0031] ;

[0032] ;

[0033] in, This represents the net overturning moment value in the left and right directions. This indicates the distance between the overturning axis on the left and the overturning axis on the right. This indicates the supporting force at the contact point on the right rear. This indicates the supporting force at the contact point on the right front. This indicates the supporting force at the contact point on the left front. This indicates the supporting force at the contact point on the left rear. This represents the projection factor. If the moving chassis is on a horizontal plane, then... =1, if the mobile chassis is on a slope, then , Let X be the component of gravity along the X-axis in the coordinate system of the moving chassis. This represents the Y-axis component of gravity in the coordinate system of the moving chassis.

[0034] This represents the net overturning moment value in the forward and backward directions. This indicates the distance between the front overturning axis and the rear overturning axis; This represents the projection factor. If the moving chassis is on a horizontal plane, then... =1, if the mobile chassis is on a slope, then .

[0035] The above-mentioned rapid assessment and active control method for the tipping risk of mobile robotic arms includes the following steps in determining whether a tipping risk exists:

[0036] Determine if there is a risk of overturning based on the supporting force at each contact point:

[0037] If the minimum support force is less than the preset value, there is a risk of overturning.

[0038] When the minimum supporting force is zero, the structure has already overturned and there is a risk of overturning.

[0039] If the minimum support force is greater than the preset value, the risk of overturning is determined based on the net overturning moment:

[0040] when =0 and =0, then there is no risk of capsizing; otherwise, there is a risk of capsizing.

[0041] The above-mentioned rapid assessment and active control method for the tipping risk of mobile robotic arms includes the following steps before calculating the current net tipping moment:

[0042] Determine whether the roll angle and pitch angle in the current attitude data exceed the set threshold. If so, issue an alarm signal and apply emergency braking; otherwise, calculate the current net overturning moment.

[0043] A second aspect of this invention proposes a rapid assessment and active control system for the tipping risk of a mobile robotic arm, applied to the aforementioned rapid assessment and active control method for the tipping risk of a mobile robotic arm. The system includes:

[0044] The definition module is used to form a polygonal convex hull with the contact points between the mobile chassis and the ground, and defines each side length of the polygonal convex hull as the overturning axis.

[0045] The first execution module is used to perform the current state overturning assessment step, and the first execution module includes:

[0046] The first acquisition unit is used to collect the current support force of each contact point on the mobile chassis through the weighing sensor, and to acquire the current attitude data of the mobile chassis through the inertial measurement unit.

[0047] The first calculation unit is used to calculate the current net overturning moment based on the current support force and current attitude data of each contact point.

[0048] The first judgment unit is used to determine whether there is a risk of overturning based on the current net overturning moment and the current support force of each support point. If so, an alarm signal is issued; if not, the second execution module is triggered to perform the future state overturning assessment step.

[0049] The second execution module is used to perform the future overturning assessment step, and the second execution module includes:

[0050] The prediction unit is used to predict the overall motion of the mobile robotic arm based on the motion parameters of the robotic arm, the current posture data of the mobile chassis, and the position of the counterweight. The location of the future center of gravity after time;

[0051] The estimation unit is used to estimate the future support force corresponding to each contact point based on the future center of gravity position of the mobile robotic arm as a whole.

[0052] The second calculation unit is used to calculate the future net overturning moment based on the future support force of each contact point and the current attitude data of the mobile chassis.

[0053] The second judgment unit is used to determine whether there is a risk of overturning based on the future net overturning moment and the future support force of each support point. If so, the position of the counterweight block on the moving chassis coordinates is adjusted, and the system returns to the first execution module to perform the current state overturning assessment step; if not, the system returns to the first execution module to perform the current state overturning assessment step.

[0054] A third aspect of the present invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method described in any of the first aspects of the present invention.

[0055] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described in any of the first aspects of the present invention.

[0056] The technical solution provided by this invention may include the following beneficial effects:

[0057] This application first assesses the tipping risk of the mobile robotic arm in its current state. If no tipping risk exists in the current state, the future center of gravity position of the entire mobile robotic arm system is predicted. Based on the future center of gravity position, the future support force at each contact point is estimated, and a tipping risk assessment is performed again based on this future support force, thus providing early warning of tipping risk. When a tipping risk exists in the future state, the position of the counterweight is changed to adjust the weight, achieving active control and reducing the tipping risk. This allows for timely monitoring of the stability state of the mobile robotic arm under different working conditions, preventing tipping accidents, improving the safety and reliability of the mobile robotic arm, and ensuring its stable operation in complex environments. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0059] Figure 1 The flowchart shows the method for rapid assessment and active control of tipping risk of a mobile robotic arm according to the present invention.

[0060] Figure 2 The present invention predicts the overall mobile robotic arm A flowchart showing the future location of the center of gravity after a certain time.

[0061] Figure 3 This is a flowchart illustrating how the future support force at each contact point is estimated based on the position of the overall center of gravity of the mobile robotic arm, according to the present invention.

[0062] Figure 4 This is a framework diagram of the mobile robotic arm's rapid overturning risk assessment and active control system of the present invention;

[0063] Figure 5 This is a structural framework diagram of the electronic device of the present invention;

[0064] Figure 6 This is a schematic diagram of the structure of a mobile robotic arm in a specific embodiment of the present invention;

[0065] Figure 7 for Figure 6 A schematic diagram of the four overturning axes in the embodiment. Detailed Implementation

[0066] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0067] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0068] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0069] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the word "and / or" throughout the text means including three parallel solutions; taking "A and / or B" as an example, it includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0070] The present invention discloses a method for rapid assessment and active control of tipping risk of a mobile robotic arm, applicable to a mobile robotic arm comprising a mobile chassis and a robotic arm mounted on the mobile chassis. The mobile chassis has a counterweight, and the method can adjust the weight by changing the position of the counterweight to prevent tipping of the mobile robotic arm. It is worth noting that the rapid tipping risk assessment in this application considers the risk of tipping caused by the current state and future movement of the robotic arm under static conditions of the mobile chassis.

[0071] This application first assesses the tipping risk of the mobile robotic arm in its current state. If no tipping risk exists in the current state, the future center of gravity position of the entire mobile robotic arm system is predicted. Based on the future center of gravity position, the future support force at each contact point is estimated, and a tipping risk assessment is performed again based on this future support force, thus providing early warning of tipping risk. When a tipping risk exists in the future state, the position of the counterweight is changed to adjust the weight, achieving active control and reducing the tipping risk. This allows for timely monitoring of the stability state of the mobile robotic arm under different working conditions, preventing tipping accidents, improving the safety and reliability of the mobile robotic arm, and ensuring its stable operation in complex environments.

[0072] Example 1

[0073] For the purpose of illustrating this technical solution, this application uses... Figure 6 Taking the mobile robotic arm shown as an example, we will demonstrate a method for rapid assessment and active control of the tipping risk of a mobile robotic arm. Figure 6 The mobile robotic arm includes a mobile chassis 610 and a robotic arm 620. The mobile chassis 610 is a wheeled mobile chassis; therefore, the midpoint of the straight line connecting the curved surface of the wheel of the mobile chassis 610 to the ground is the contact point as referred to in this application. A weighing sensor 630 is installed at the contact point. The mobile chassis 610 has four wheels, such as... Figure 7 As shown, four contact points are distributed on a circle with radius R. It is worth noting that the rapid overturning risk assessment in this application considers the risk of overturning caused by the current state of the robotic arm 620 and its future state after movement, under the static condition of the mobile chassis 610. Therefore, since the mobile chassis 610 does not need to move, the influence of the weighing sensor 630 on the movement of the mobile chassis 610 does not need to be considered. The robotic arm 620 is a multi-axis robotic arm, consisting of a base 621, an end effector 622, multiple joints 623, and multiple links 624. The base 621 is located at the center of the mobile chassis 610. Furthermore, the mobile chassis 610 is equipped with an actuator for adjusting the position of the counterweight. Specifically, in Figure 6 In one embodiment, the actuator includes a turntable 611 rotatable relative to the movable chassis. The turntable 611 is fitted around the outer periphery of the base, and a movable platform 612 capable of radial translation is provided on the turntable 611. A counterweight 613 is disposed on the movable platform 612. Therefore, the counterweight 613 can be adjusted in position within a ring-shaped region.

[0074] It is worth noting that in the current state overturning assessment step, since the support force data at the contact points can be measured in real time, the net overturning moment can be calculated based on the measured support force data. Therefore, it is not necessary to consider the end effector 622, link 624, and counterweight 613 of the robotic arm 620. However, in the future state overturning assessment step, the support force at the contact points cannot be measured. Therefore, it is necessary to consider the end effector 622, link 624, and counterweight 613 of the robotic arm 620 to predict the future center of gravity of the entire moving robotic arm. Then, based on the future center of gravity, the future support force of each contact point is predicted, and the net overturning moment of the future state is calculated based on the future support force.

[0075] Combination Figure 1 As shown, the method for rapid assessment and active control of tipping risk of mobile robotic arms proposed in this application includes the following steps:

[0076] Step S1: Construct a polygonal convex hull using the contact points between the mobile chassis and the ground, and define each side of the polygonal convex hull as the overturning axis. The overturning axis refers to the axis around which the mobile chassis overturns.

[0077] Optionally, step S1 includes the following steps:

[0078] Step S11: Number each contact point in clockwise or counterclockwise order, and connect them sequentially according to the numbers to form a polygonal convex hull; thus, with Figure 6 Taking the mobile robotic arm shown as an example, when executing step S1, the four contact points are numbered 1, 2, 3, and 4 in a counter-clockwise direction. Point "1" represents the right rear contact point, point "2" represents the right front contact point, point "3" represents the left front contact point, and point "4" represents the left rear contact point. Connecting the points in numerical order yields the following... Figure 7 The polygonal convex hull shown is square.

[0079] Step S12: Define the overturning axis for each side length of the polygonal convex hull according to the contact point number. A i，k ; i Indicates the number of the contact point that serves as the starting point. k This indicates the number of the contact point that serves as the endpoint. That is, there is an overturning axis. A 1，2 , A 2，3 , A 3，4 , A 4，1 Each overturning axis has a length of L. In the coordinate system of the moving chassis, the X-axis is parallel to the overturning axis. A 1，2 , A 3，4Parallel to each other, the Y-axis is parallel to the overturning axis. A 2，3 , A 4，1 Parallel.

[0080] Step S2: Perform the current state overturning assessment steps:

[0081] Step S21: Collect the current support force of each contact point on the mobile chassis using the weighing sensor, and obtain the current attitude data of the mobile chassis using the inertial measurement unit; Figure 6 Taking the mobile robotic arm shown as an example, when executing step S21, the current support force at the four contact points is obtained, denoted as... N 1. N 2. N 3 and N 4, N 1 indicates the current support force of the support point numbered "1"; N 2 indicates the current support force of the support point numbered "2"; N 3 indicates the current support force of the support point numbered "3"; N 4 indicates the current support force at support point number "4". Current attitude data includes quaternions, roll angle, and pitch angle.

[0082] Step S22: Calculate the current net overturning moment based on the current support force and current posture data at each contact point. The overturning assessment of the current state is directly calculated by collecting the current support force at the contact point, eliminating the need to calculate the moment value affecting the overturning axis from various parts, making it simple and convenient. It is worth noting that using sensors to collect the current support force at the contact point as the data source provides excellent real-time performance, enabling rapid detection of unexpected anomalies and timely monitoring of the stability of the mobile robotic arm under different working conditions. This prevents overturning accidents, improves the safety and reliability of the mobile robotic arm, and ensures its stable operation in complex environments. For example, when the wheels of the mobile chassis suddenly press into a soft pit, the support force at that point will instantly decrease. However, the center of gravity of the mobile robotic arm may not have changed significantly at this time. If the current support force at the contact point is estimated by calculating the current center of gravity, it will fail to reflect the change in support force, resulting in a certain lag. Furthermore, by combining the current attitude data of the mobile chassis when calculating the net overturning moment, it is possible to simulate slope and irregular ground environments, thereby improving the versatility of the method in this application.

[0083] by Figure 6 When the mobile robotic arm performs step S22, the formula for calculating the net overturning moment includes:

[0084] ;

[0085] ;

[0086] in, This represents the net overturning moment value in the left and right directions. This indicates the distance between the overturning axis on the left and the overturning axis on the right. Figure 6 In the embodiments, L; This indicates the supporting force at the contact point on the right rear. This indicates the supporting force at the contact point on the right front. This indicates the supporting force at the contact point on the left front. This indicates the supporting force at the contact point on the left rear. This represents the projection factor. If the moving chassis is on a horizontal plane, then... =1, if the mobile chassis is on a slope, then , Let X be the component of gravity along the X-axis in the coordinate system of the moving chassis. This represents the Y-axis component of gravity in the coordinate system of the moving chassis.

[0087] This represents the net overturning moment value in the forward and backward directions. This indicates the distance between the front overturning axis and the rear overturning axis. Figure 6 In the embodiments, L; This represents the projection factor. If the moving chassis is on a horizontal plane, then... =1, if the mobile chassis is on a slope, then .

[0088] Specifically, in this embodiment, when calculating the current net overturning moment, the current support force at each contact point is substituted into the formula to calculate the current net overturning moment, that is... N 1. N 2. N 3 and N 4. Substitute , , and Similarly, when calculating the future net overturning moment, the future support forces at each contact point can be substituted into the formula to calculate the future net overturning moment.

[0089] It is worth noting that, in practice, the mobile chassis travels on non-horizontal surfaces, such as slopes. Therefore, the direction of the overturning moment does not coincide with the overturning axis, requiring projection calculation of the effective moment component in the axial direction. To this end, a rotation matrix is ​​constructed by obtaining quaternions from the inertial measurement unit, and the gravity vector in the mobile chassis coordinate system is calculated:

[0090] ;

[0091] in, This represents the gravity vector in the chassis coordinate system. Represents the rotation matrix. Represents gravitational acceleration. This represents the component of gravity along the Z-axis in the coordinate system of the moving chassis.

[0092] Extracting and normalizing the components in the XY plane yields:

[0093] ;

[0094] in, This represents the gravitational component on a horizontal plane.

[0095] Left and right axes: Used to assess the direction vector of the moment of rollover (causing rotation about the Y-axis). Therefore, if the mobile chassis is on a horizontal plane, then the projection factor is... =1; if the moving chassis is on a non-horizontal surface;

[0096] Then projection factor ;

[0097] Front and rear axis: Used to assess the direction vector of the moment caused by front and rear rollover (causing rotation about the X-axis). Therefore, if the mobile chassis is on a horizontal plane, then the projection factor is... =1: If the mobile chassis is on a non-horizontal surface;

[0098] Then projection factor .

[0099] Step S23: Determine whether there is a risk of overturning based on the current net overturning moment and the current support force of each support point. If so, issue an alarm signal; if not, perform the future state overturning assessment step. The future state is the state of the robotic arm after a short period of movement when the mobile chassis does not move, such as the state after 1-2 seconds of movement in the future, that is, the center of gravity of the mobile chassis remains unchanged, while the center of gravity of the robotic arm changes.

[0100] Specifically, determining whether there is a risk of capsizing includes the following steps:

[0101] Step S231: Determine if there is a risk of overturning based on the support force at each contact point. Specifically, compare the minimum support force with a preset value. If the minimum support force is less than the preset value, there is a risk of overturning; the preset value is a value close to zero, such as 0.1, 0.5, or 1. When the minimum support force is zero, meaning the corresponding contact point has lifted off the ground, overturning has occurred, and there is a risk of overturning.

[0102] If the minimum support force is greater than the preset value, then step S232 is executed;

[0103] Step S232 is to determine whether there is a risk of overturning based on the net overturning moment:

[0104] when =0 and =0, then there is no risk of capsizing; otherwise, there is a risk of capsizing.

[0105] Specifically, when If the value is greater than 0, there is a risk of capsizing to the left, meaning there is a risk of capsizing around the capsizing axis. A 3，4 The risk of capsizing; when If the value is less than 0, there is a risk of capsizing to the right, meaning there is a risk of capsizing around the capsizing axis. A 1，2 The risk of capsizing; when If the value is greater than 0, there is a risk of forward overturning, meaning there is a risk of overturning around the overturning axis. A 2，3 The risk of capsizing; when If the value is less than 0, there is a risk of overturning backward, i.e., there is a risk of overturning around the overturning axis. A 4，1 The risk of capsizing.

[0106] Step S3: The step of performing the future state overturning assessment includes:

[0107] Step S31: Based on the motion parameters of the robotic arm, the current posture data of the mobile chassis, and the position of the counterweight, predict the overall movement of the mobile robotic arm. The future position of the center of gravity after a certain time. The motion parameters include the current joint angle, current angular velocity, and current angular acceleration of each joint of the robotic arm, collected by sensors. The counterweight position refers to the coordinates of the counterweight in the coordinate system of the moving chassis.

[0108] As an optional implementation, in the robotic arm, the base is mounted on a mobile chassis, and the end effector is connected to the base via multiple links; step S31 includes the following steps:

[0109] Step S311: Collect the current joint angle, current angular velocity, and current angular acceleration of each joint of the robotic arm using sensors;

[0110] Step S312: Each joint calculates its current joint angle, current angular velocity, and current angular acceleration. The joint angle after time; the calculation formula is:

[0111] ;

[0112] in, Indicates that the j-th joint is in Joint angles after time, This represents the current joint angle of the j-th joint. This represents the current angular velocity of the j-th joint. Indicates the time of change. This represents the current angular acceleration of the j-th joint;

[0113] Step S313: Place each joint in The joint angles after a certain time are input into the forward kinematics model of the robotic arm. Combined with the mass parameters of the end effector and each link itself, the coordinates of the end effector and each link in the base coordinate system are calculated. The position of the center of gravity after time;

[0114] Step S314: Position the end effector and each link itself in the base coordinate system. After a certain time, the center of gravity position is transferred to the coordinate system of the mobile chassis. Combined with the current center of gravity position and mass of the mobile chassis, and the position and mass of the counterweights, a weighted average is used to predict the overall position of the mobile robotic arm. The future position of the center of gravity after a certain time. The coordinate transformation method is to multiply the position of the center of gravity of the end effector and each link in the base coordinate system by the transformation matrix from the base coordinate system to the moving chassis coordinate system.

[0115] Specifically, the calculation formula is as follows:

[0116] ;

[0117] This indicates the future center of gravity of the mobile robotic arm relative to the coordinates of the mobile chassis. Indicates the mass of the mobile chassis; This indicates the center of gravity position of the mobile chassis; n represents the number of components in the robotic arm, namely the sum of the number of end effectors and multiple links. This represents the mass of the u-th component in the robotic arm; This represents the future center of gravity coordinates of the u-th component of the robotic arm in the coordinate system of the moving chassis. Indicates the mass of the counterweight; This indicates the position of the counterweight in the coordinate system of the moving chassis, and is initially initialized based on the actual position. This represents the overall mass of the mobile robotic arm. Among them, ; This represents the X-coordinate of the u-th component in the moving chassis coordinate system. This represents the Y-coordinate of the u-th component in the moving chassis coordinate system. This represents the Z-axis coordinate of the u-th component in the moving chassis coordinate system.

[0118] Step S32: Estimate the future support force corresponding to each contact point based on the future center of gravity position of the mobile robotic arm as a whole;

[0119] Step S321: Obtain the coordinates of each contact point in the moving chassis coordinate system. Figure 6 Taking the mobile robotic arm shown as an example, if step S321 is executed, the coordinates of the contact point numbered "1" are ( x 1 ，y 1) The coordinates of the contact point numbered "2" are ( x 2 ，y 2) The coordinates of the contact point numbered "3" are ( x 3 ，y 3) The coordinates of the contact point numbered "4" are ( x 4 ，y 4);

[0120] Step S322: Under the condition that the future support force at each contact point satisfies the static equilibrium condition, construct the force balance equation in the Z direction, the torque balance equation around the Y axis, and the torque balance equation around the X axis based on the coordinates of each contact point, the future support force at each contact point, and the position of the future center of gravity of the entire mobile robotic arm.

[0121] Specifically, the force balance equation in the Z direction is:

[0122] ;

[0123] in, The future supporting strength of the support point numbered "1"; The future supporting strength of the support point numbered "2"; The future supporting strength of the support point numbered "3"; The future support strength of the support point numbered "4"; It represents the acceleration due to gravity.

[0124] The torque balance equation about the Y-axis is:

[0125] ;

[0126] in, This represents the coordinate of the future center of gravity of the mobile robotic arm in the X direction within the coordinate system of the mobile chassis.

[0127] The torque balance equation about the X-axis is:

[0128] ;

[0129] in, This represents the coordinate of the future center of gravity of the mobile robotic arm in the Y direction within the coordinate system of the mobile chassis.

[0130] Step S323: Based on the force balance equations in the Z direction, the moment balance equations about the Y axis, and the moment balance equations about the X axis, construct a linear matrix A×N=B; the linear matrix A×N=B is:

[0131] ;

[0132] Step S324: Solve the matrix equation: N=A + The minimum norm solution of ×B yields the future support force of each support point, where A + This represents the pseudoinverse of matrix A. The resulting solution... It refers to the smoothest and most uniform distribution of future supporting forces, provided that all mechanical equilibrium conditions are met.

[0133] Step S33: Calculate the future net overturning moment based on the future support force of each contact point and the current attitude data of the mobile chassis;

[0134] The future support force of each contact point is then substituted into the following formula:

[0135] ;

[0136] .

[0137] It is worth noting that the rapid overturning risk assessment of this invention considers the risk of overturning occurring only after the robotic arm moves, under static conditions on the mobile chassis. Therefore, and The value is still calculated from the current attitude data of the mobile chassis.

[0138] Step S34: Determine whether there is a risk of overturning based on the future net overturning moment and the future support force of each support point. If so, adjust the position of the counterweight block on the moving chassis coordinates and return to execute the current state overturning assessment step; if not, return to execute the current state overturning assessment step.

[0139] The specific steps for adjusting the position of the counterweight in the coordinate system of the moving chassis are as follows:

[0140] An objective function and constraints are established to calculate the optimal position. The objective is to minimize the overturning moment of the mobile robotic arm after the counterweight adjustment, and the feasible working area of ​​the counterweight is used as the constraint. The magnitude of the overturning moment of the mobile robotic arm is calculated from the net overturning moment values ​​in the left-right and forward-backward directions. By adjusting the position of the counterweight through an optimization algorithm, the net overturning moment values ​​in the left-right and forward-backward directions are reduced to zero or close to zero, thus minimizing the overturning moment of the mobile robotic arm after the counterweight adjustment and reducing the risk of overturning.

[0141] Specifically, with Figure 6 Taking the mobile robotic arm shown as an example, the objective function is:

[0142] ;

[0143] in, This represents the overturning moment of the mobile robotic arm after the counterweight is adjusted. x represents the coordinate of the center of gravity of the counterweight in the X direction of the mobile chassis coordinate system; y represents the coordinate of the center of gravity of the counterweight in the Y direction of the mobile chassis coordinate system. and Indicates that the robotic arm remains The predicted state after time is static, the moving chassis is static, and the counterweight has moved to a static position. When the position is determined, the net overturning moment values ​​in the left-right direction and the net overturning moment values ​​in the front-back direction are re-predicted.

[0144] The constraints are:

[0145] ;

[0146] in, This indicates the minimum effective radius of the counterweight. This indicates the maximum effective radius of the counterweight.

[0147] The optimal counterweight position is obtained by solving the objective function optimization problem. Specifically, the optimal counterweight position can be obtained by calling the fmincon function in MATLAB.

[0148] The drive actuator moves the counterweight to the optimal counterweight position. This can be achieved by controlling the rotation of the turntable and the movement of the movable platform, thus moving the counterweight to the optimal position.

[0149] Example 2

[0150] Based on the above embodiment 1, before calculating the current net overturning moment, the following steps are also included:

[0151] The system determines whether the roll and pitch angles in the current attitude data exceed set thresholds. If so, an alarm signal is issued and emergency braking is initiated; otherwise, the current net overturning moment is calculated. Specifically, in some optional embodiments, the set threshold is 30°. If |γ| > 30° or |γ| > 30°, the mobile robot is determined to be in a critical state, and emergency braking is immediately triggered and a warning is issued. γ represents the roll angle, and γ represents the pitch angle.

[0152] like Figure 4 As shown, the second aspect of the present invention proposes a rapid assessment and active control system 400 for the tipping risk of a mobile robotic arm, which is applied to the above-mentioned rapid assessment and active control method for the tipping risk of a mobile robotic arm. The system includes a definition module 410, a first execution module 420, and a second execution module 430.

[0153] The definition module 410 is used to form a polygonal convex hull with the contact points between the mobile chassis and the ground, and to define each side length of the polygonal convex hull as the overturning axis.

[0154] The first execution module 420 is used to perform the current state overturning assessment step, and the first execution module 420 includes:

[0155] The first acquisition unit 421 is used to acquire the current support force of each contact point on the mobile chassis through the weighing sensor, and to acquire the current attitude data of the mobile chassis through the inertial measurement unit.

[0156] The first calculation unit 422 is used to calculate the current net overturning moment based on the current support force and current attitude data of each contact point;

[0157] The first judgment unit 423 is used to determine whether there is a risk of overturning based on the current net overturning moment and the current support force of each support point. If so, an alarm signal is issued; if not, the second execution module 430 is triggered to execute the future state overturning assessment step.

[0158] The second execution module 430 is used to perform the future overturning assessment step, and the second execution module 430 includes:

[0159] Prediction unit 431 is used to predict the overall movement of the mobile robotic arm based on the motion parameters of the robotic arm, the current posture data of the mobile chassis, and the position of the counterweight. The location of the future center of gravity after time;

[0160] The estimation unit 432 is used to estimate the future support force corresponding to each contact point based on the future center of gravity position of the mobile robotic arm as a whole.

[0161] The second calculation unit 433 is used to calculate the future net overturning moment based on the future support force of each contact point and the current attitude data of the mobile chassis.

[0162] The second judgment unit 434 is used to determine whether there is a risk of overturning based on the future net overturning moment and the future support force of each support point. If so, the position of the counterweight block on the moving chassis coordinates is adjusted, and the system returns to the first execution module 420 to perform the current state overturning assessment step; if not, the system returns to the first execution module 420 to perform the current state overturning assessment step.

[0163] like Figure 5 As shown, another aspect of the present invention discloses an electronic device 500, including a processor 501 and a memory 502. The processor 501 and the memory 502 are connected, for example, via a bus 503. Further, the electronic device 500 may also include a transceiver 504. It should be noted that in practical applications, the transceiver 504 is not limited to one, and the structure of the electronic device 500 does not constitute a limitation on the embodiments of this application. The processor 501 is used in the embodiments of this application to implement a method for rapid assessment and active control of the tipping risk of a mobile robotic arm. The processor 501 can be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor 501 can also be a combination that implements computing functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc. The bus 503 may include a path for transmitting information between the above components. The bus 503 may be a PCI bus or an EISA bus, etc. The 503 bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 5 The bus is represented by a single thick line, but this does not imply that there is only one bus or one type of bus. The memory 502 can be a ROM or other type of static storage device capable of storing static information and instructions, RAM or other type of dynamic storage device capable of storing information and instructions, or it can be an EEPROM, CD-ROM or other optical disc storage, optical disk storage (including compressed optical disks, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto. The memory 502 is used to store the application program code that executes the scheme of this application, and its execution is controlled by the processor 501. The processor 501 is used to execute the application program code stored in the memory 502 to implement the steps of the mobile robotic arm tipping risk rapid assessment and active control method provided by this invention.

[0164] On the other hand, embodiments of the present invention provide a storage medium storing a computer program that is executed by a processor as described above in the method for rapid assessment and active control of the tipping risk of a mobile robotic arm.

[0165] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for rapid assessment and active control of tipping risk of a mobile robotic arm, characterized by: Includes the following steps: The contact points between the mobile chassis and the ground form a polygonal convex hull, and each side length of the polygonal convex hull is defined as the overturning axis. Perform the current state overturning assessment steps: The current supporting force of each contact point on the mobile chassis is collected by the weighing sensor, and the current attitude data of the mobile chassis is obtained by the inertial measurement unit. The current net overturning moment is calculated based on the current support force and current attitude data at each contact point. Determine whether there is a risk of overturning based on the current net overturning moment and the current support force at each support point; if so, issue an alarm signal. If not, then proceed with the future state overturning assessment step; The steps for performing a future state overturning assessment include: Based on the motion parameters of the robotic arm, the current posture data of the mobile chassis, and the position of the counterweights, the overall trajectory of the mobile robotic arm is predicted. The location of the future center of gravity after time; Estimate the future support force corresponding to each contact point based on the future center of gravity position of the mobile robotic arm as a whole; The future net overturning moment is calculated based on the future support force of each contact point and the current attitude data of the mobile chassis. Based on the future net overturning moment and the future support force of each support point, determine whether there is a risk of overturning. If so, adjust the position of the counterweight in the coordinate system of the moving chassis and return to execute the current state overturning assessment step; if not, return to execute the current state overturning assessment step.

2. The method for rapid assessment and active control of tipping risk of a mobile robotic arm according to claim 1, characterized in that, In the robotic arm, the base is mounted on a mobile chassis, and the end effector is connected to the base via multiple links; predicting the overall mobile robotic arm... The location of the future center of gravity after a certain time includes the following steps: Collect the current joint angle, current angular velocity, and current angular acceleration of each joint of the robotic arm; Each joint calculates its current joint angle, current angular velocity, and current angular acceleration. Joint angle after time; Each joint The joint angles after a certain time are input into the forward kinematics model of the robotic arm. Combined with the mass parameters of the end effector and each link itself, the kinematics of the end effector and each link in the base coordinate system are calculated. The position of the center of gravity after time; The end effector and each link itself in the base coordinate system The center of gravity position after a certain time is transferred to the coordinate system of the mobile chassis, and combined with the center of gravity position and mass of the mobile chassis in its current pose, as well as the position and mass of the counterweights; a weighted average is then used to predict the overall position of the mobile robotic arm based on the mass. The location of the future center of gravity after time.

3. The method for rapid assessment and active control of tipping risk of a mobile robotic arm according to claim 1, characterized in that, Estimating the future support force at each contact point based on the future center of gravity of the mobile robotic arm includes the following steps: Obtain the coordinates of each contact point in the mobile chassis coordinate system; Under the condition that the future support force at each contact point satisfies static equilibrium, the force balance equation in the Z direction, the torque balance equation around the Y axis, and the torque balance equation around the X axis are constructed based on the coordinates of each contact point, the future support force at each contact point, and the position of the future center of gravity of the entire mobile robotic arm. The force balance equations in the Z direction are: ； in, The future support strength of support point number 1; The future support strength of support point number 2; The future support strength of support point number 3; The future support strength of support point number 4; Represents gravitational acceleration; Indicates the overall mass of the mobile robotic arm; The torque balance equation about the Y-axis is: ； in, This represents the X-axis coordinate of support point number 1 in the moving chassis coordinate system. The coordinates of support point numbered 2 in the X direction in the moving chassis coordinate system. The coordinates of support point number 3 in the X direction in the moving chassis coordinate system. The coordinates of support point number 4 in the X direction in the moving chassis coordinate system. This represents the coordinate of the future center of gravity of the mobile robotic arm in the X direction within the coordinate system of the mobile chassis. The torque balance equation about the X-axis is: ； in, This represents the Y-coordinate of support point numbered 1 in the moving chassis coordinate system. This represents the Y-coordinate of support point number 2 in the moving chassis coordinate system. This represents the Y-coordinate of support point number 3 in the moving chassis coordinate system. This indicates the Y-coordinate of support point number 4 in the mobile chassis coordinate system. This represents the coordinate of the future center of gravity of the mobile robotic arm in the Y direction within the coordinate system of the mobile chassis. Based on the force balance equations in the Z direction, the moment balance equations about the Y axis, and the moment balance equations about the X axis, a linear matrix A×N=B is formed. The linear matrix A×N=B is: ； By solving the matrix equation: N=A + The minimum norm solution of ×B yields the future support force of each support point, where A + This represents the pseudo-inverse of matrix A.

4. The method for rapid assessment and active control of tipping risk of a mobile robotic arm according to claim 1, characterized in that, Adjusting the position of the counterweight in the coordinate system of the moving chassis includes the following steps: Establish the objective function and constraints to calculate the optimal position, where the objective is to minimize the overturning moment of the mobile robotic arm after the counterweight is adjusted, and the feasible working area of ​​the counterweight is the constraint. The objective function is optimized to obtain the optimal counterweight position. The drive actuator moves the counterweight to the optimal counterweight position.

5. The method for rapid assessment and active control of tipping risk of a mobile robotic arm according to claim 1, characterized in that, The polygonal convex hull is square, and the formula for calculating the net overturning moment includes: ； ； in, This represents the net overturning moment value in the left and right directions. This indicates the distance between the overturning axis on the left and the overturning axis on the right. This indicates the supporting force at the contact point on the right rear. This indicates the supporting force at the contact point on the right front. This indicates the supporting force at the contact point on the left front. This indicates the supporting force at the contact point on the left rear. This represents the projection factor. If the moving chassis is on a horizontal plane, then... =1, if the mobile chassis is on a slope, then , Let X be the component of gravity along the X-axis in the coordinate system of the moving chassis. This represents the Y-axis component of gravity in the coordinate system of the moving chassis. This represents the net overturning moment value in the forward and backward directions. This indicates the distance between the front overturning axis and the rear overturning axis; This represents the projection factor. If the moving chassis is on a horizontal plane, then... =1, if the mobile chassis is on a slope, then .

6. The method for rapid assessment and active control of tipping risk of a mobile robotic arm according to claim 5, characterized in that, Determining whether there is a risk of capsizing includes the following steps: Determine if there is a risk of overturning based on the supporting force at each contact point: If the minimum support force is less than the preset value, there is a risk of overturning. When the minimum supporting force is zero, the structure has already overturned and there is a risk of overturning. If the minimum support force is greater than the preset value, the risk of overturning is determined based on the net overturning moment: when =0 and =0, then there is no risk of capsizing; otherwise, there is a risk of capsizing.

7. The method for rapid assessment and active control of tipping risk of a mobile robotic arm according to claim 1, characterized in that, Before calculating the current net overturning moment, the following steps are also included: Determine whether the roll angle and pitch angle in the current attitude data exceed the set threshold. If so, issue an alarm signal and apply emergency braking; otherwise, calculate the current net overturning moment.

8. A rapid assessment and active control system for the tipping risk of a mobile robotic arm, characterized in that: The system, applied in the rapid assessment and active control method for tipping risk of a mobile robotic arm as described in any one of claims 1-7, comprises a definition module, a first execution module, and a second execution module: The definition module is used to form a polygonal convex hull with the contact points between the mobile chassis and the ground, and defines each side length of the polygonal convex hull as the overturning axis. The first execution module is used to perform the current state overturning assessment step, and the first execution module includes: The first acquisition unit is used to collect the current support force of each contact point on the mobile chassis through the weighing sensor, and to acquire the current attitude data of the mobile chassis through the inertial measurement unit. The first calculation unit is used to calculate the current net overturning moment based on the current support force and current attitude data of each contact point. The first judgment unit is used to determine whether there is a risk of overturning based on the current net overturning moment and the current support force of each support point. If so, an alarm signal is issued; if not, the second execution module is triggered to perform the future state overturning assessment step. The second execution module is used to perform the future overturning assessment step, and the second execution module includes: The prediction unit is used to predict the overall motion of the mobile robotic arm based on the motion parameters of the robotic arm, the current posture data of the mobile chassis, and the position of the counterweight. The location of the future center of gravity after time; The estimation unit is used to estimate the future support force corresponding to each contact point based on the future center of gravity position of the mobile robotic arm as a whole. The second calculation unit is used to calculate the future net overturning moment based on the future support force of each contact point and the current attitude data of the mobile chassis. The second judgment unit is used to determine whether there is a risk of overturning based on the future net overturning moment and the future support force of each support point. If so, the position of the counterweight block in the coordinate system of the moving chassis is adjusted, and the system returns to the first execution module to perform the current state overturning assessment step; if not, the system returns to the first execution module to perform the current state overturning assessment step.

9. An electronic device, characterized in that: It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method described in any one of claims 1-7.

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