Modular robotic truss climbing gait planning method

Abstract

The application provides a modular robot truss climbing gait planning method, aiming at solving the problem of efficient and stable movement of a modular robot in a complex truss structure environment. The application analyzes and designs a structure of a modular unit to model the modular robot, studies a truss structure to design a method for processing a truss map, studies a semicircular motion and a linear motion trajectory to design a motion trajectory of an end of the modular robot, solves angle values of each joint of the modular robot by using an analytical method, and designs four gaits, i.e., an opposite side spanning gait, an adjacent side horizontal climbing gait, a rotating around a rod piece gait, and a inchworm along a rod piece gait, and a selection strategy for the stable climbing gait planning of the modular robot in the truss structure. The application is suitable for the non-fixed structure of the modular robot and different truss structures, can quickly obtain accurate joint angle values, improves the stability of the modular robot truss climbing, and is suitable for scenes such as spaceflight and building maintenance.

Description

Technical Field

[0001] This invention relates to a modular robot gantry crawling gait planning method, belonging to the field of robotics. Background Technology

[0002] In recent years, truss structures have been widely used in fields such as construction, aerospace, bridges, and towers. However, due to the special nature of truss structures, robots can only move by grasping members, and their movement direction is limited. Traditional robots usually have fixed structures, resulting in insufficient flexibility and adaptability when moving on trusses, and there are areas that are difficult to reach. This requires robots to have higher flexibility and stability to adapt to the truss environment.

[0003] Modular robots are flexible and adaptable, making them particularly advantageous for truss crawling tasks. However, current gait designs are mostly designed for traditional, fixed-structure robots, which are difficult to adapt to the non-fixed structures of modular robots. Furthermore, the crawling gait design in truss structures must ensure the robot's motion stability during truss movement. Therefore, research on gait planning methods for modular robot truss crawling has significant theoretical research value. Summary of the Invention

[0004] In view of this, the present invention provides a modular robot truss crawling gait planning method, which designs four gait modes to enable the robot to adapt to various truss structure scenarios and improve motion efficiency and stability.

[0005] The modular robot gantry crawling gait planning method of the present invention includes:

[0006] 1. A modular robot gantry crawling gait planning method, characterized in that the method includes:

[0007] The design of the modular robot structure includes: the modular robot is composed of N modular units connected together. Each modular unit includes 2 shells, 3 motor-reducer assemblies, 2 male interfaces and 2 female interfaces. The 3 motor-reducer assemblies are distributed on the body center of the modular unit and the two shells. Each modular unit has 3 joints inside. Each joint of the modular unit can rotate around the central axis of the male interface and the central axis of the modular unit.

[0008] Based on the truss structure and the motion patterns of modular robots on the truss, a truss map is constructed;

[0009] Based on the motion requirements of the modular robot, the motion is decomposed into motion in the same plane and three-dimensional plane transformation motion. Motion in the same plane includes three types of motion: motion along the direction of the rod, traversing the opposite side of the truss, and climbing the adjacent side of the truss. Three-dimensional plane transformation motion includes rotational motion around the rod.

[0010] Based on gait requirements, construct mathematical expressions for motion trajectories and design modular robot end effector motion trajectories;

[0011] Establish a kinematic model of the modular robot and use the inverse kinematics analytical method to solve for the joint angle values ​​of the modular robot;

[0012] Based on the decomposed modular robot motion types, four gaits are designed: side-crossing gait, adjacent-side lateral climbing gait, rotation around the pole gait, and inchworm gait along the pole gait, and a gait selection strategy is established.

[0013] 2. The method according to claim 1, characterized in that, the step of constructing a truss map based on the truss structure and the motion patterns of the modular robot on the truss includes:

[0014] Taking 2 as the length of a rod, q i =[x i ,y i ,z i ] T Let x represent the coordinates of the i-th node on the truss structure. i y i z i All numbers are even, construct a set of node coordinates Q = {q1, q2, ..., q...} m}, where m represents the total number of nodes on the truss; identify and select node q. i Calculate its relationship with existing neighboring nodes q i_1 =[x i +2,y i ,z i ] T q i_2 =[x i ,y i +2,z i ] T q i_3 =[x i ,y i ,z i +2] T Find the geometric midpoint, record the coordinates of the midpoint and number it s. j s j+1 s j+2 The set of reachable points S = {s1, s2, ..., s} in the truss map constitutes the set of reachable points. n}

[0015] 3. The method according to claim 1, characterized in that, the step of constructing a mathematical expression for the motion trajectory based on gait requirements and designing the modular robot end effector motion trajectory includes:

[0016] The formula for the trajectory of a semicircular motion is established as follows:

[0017]

[0018] Where, x s x is the starting horizontal position of the modular robot. f z represents the final horizontal position of the modular robot. s T represents the initial height position of the modular robot. s For the step period of the semi-circular motion of the modular robot, Let x be the radius of the semicircular motion of the modular robot. t Let z be a horizontal position function with respect to time t. t Let σ be the height function with respect to time t, and σ be the radian function with respect to time t.

[0019] For linear motion where only the altitude changes, the trajectory formula is as follows:

[0020]

[0021] Among them, z s z represents the initial height position of the modular robot. f T represents the final height position of the modular robot. s For the step period of linear motion of a modular robot, z represents the speed of linear motion of the modular robot. t It is a height function with respect to time t.

[0022] 4. The method according to claim 1, characterized in that, the step of establishing the kinematic model of the modular robot and solving the joint angle values ​​of the modular robot using the inverse kinematics analytical method includes: modeling a single-chain robot; for a multi-branch robot, decoupling it into multiple single-chain robots for processing; modeling using the DH method; and solving the joint i transformation matrix. The formula is as follows:

[0023]

[0024] Where, θ i d is the joint angle. i For link offset, a i Let α be the length of the connecting rod. i The link twist angle;

[0025] Inverse kinematics analysis is used to solve for the angles of the three rotational joints of each modular robot unit. Let the final position and orientation of the modular robot's end effector be... k is the total number of joints. Given the total transformation matrix, multiply both sides of the equation step by step by the transformation matrix on the left. The formula is as follows:

[0026]

[0027] Establish a new equation based on the elements of the matrices on both sides of the equation, and solve for the angle value θ of the joint. i .

[0028] 5. The method according to claim 1, characterized in that the design of the four gait types—opposite-side crossing gait, adjacent-side lateral climbing gait, rotational gait around the pole, and inchworm gait along the pole—includes:

[0029] ① Define the basic parameters of the modular robot's gait;

[0030] ② In the side-crossing gait mode, the modular robot crosses the opposite pole. The two branches switch between the fixed branch and the moving branch. In one motion cycle, the robot moves a distance equal to the length of one pole.

[0031] ③ In the adjacent side climbing gait, the modular robot climbs to adjacent rods, switching between a fixed branch and a moving branch. Within one movement cycle, the robot travels a distance of [missing information]. Length of each member;

[0032] ④ The modular robot performs three-dimensional plane transformation in the gait of rotating around the rod. The two branches switch between the fixed branch and the moving branch. Within one motion cycle, the position of the robot body on the rod does not move.

[0033] ⑤ In the inchworm gait along the rod, the modular robot moves towards the rod, and the two branches switch between the fixed branch and the moving branch. In one motion cycle, the robot moves a distance equal to the length of one rod.

[0034] 6. The method according to claim 1, wherein the gait selection strategy comprises:

[0035] ① Since the modular robot crawls on the truss surface, each reachable point in the set S must have a coordinate representing the truss plane. By comparing the previous movement point with the current movement point, when the coordinate value of the next movement point representing the truss plane changes, the movement needs to transform the truss plane and use a gait around the rod.

[0036] ② When one of the coordinate values ​​of the current motion point or the next motion point changes, the motion is a movement of the truss plane along the direction of the members, using the inchworm gait along the members;

[0037] ③ When two coordinate values ​​change at the current point of motion and the next point of motion, and the odd coordinates change, the motion is a rapid oblique movement in the truss plane, using the adjacent side lateral climbing gait;

[0038] ④ When two coordinate values ​​change at the current point of motion and the next point of motion, and the odd coordinates do not change, the motion is a rapid crossing between truss plane members, using the opposite side crossing gait. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments 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 these drawings without any creative effort.

[0040] Figure 1 This is a flowchart illustrating the steps of a modular robot gantry crawling gait planning method provided in an embodiment of the present invention.

[0041] Figure 2 This is a physical structural diagram of a modular robot provided in an embodiment of the present invention.

[0042] Figure 3 This is a schematic diagram of a modular robot's side-crossing gait provided in an embodiment of the present invention.

[0043] Figure 4 This is a schematic diagram of the gait of a modular robot for lateral climbing near an edge, provided in an embodiment of the present invention.

[0044] Figure 5 This is a schematic diagram of the gait of a modular robot rotating around a rod, provided in an embodiment of the present invention.

[0045] Figure 6 This is a schematic diagram of the gait of a modular robot along a rod provided in an embodiment of the present invention. Detailed Implementation

[0046] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0047] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0048] This invention provides a modular robot gantry crawling gait planning method.

[0049] Please refer to Figure 1 This is a flowchart illustrating the steps of a modular robot gantry crawling gait planning method provided in an embodiment of the present invention. The method includes the following steps:

[0050] Step 101: Design the structure of the modular robot.

[0051] Please refer to the modular robot structure diagram. Figure 2 As shown, the modular robot is composed of N modular units connected together. Each modular unit includes 2 shells, 3 motor-reducer assemblies, 2 male interfaces and 2 female interfaces. The 3 motor-reducer assemblies are distributed on the body center of the modular unit and the two shells. Each modular unit has 3 joints inside. Each joint of the modular unit can rotate around the central axis of the male interface and the central axis of the modular unit.

[0052] Based on the motion requirements of modular robots, motion is decomposed into motion in the same plane and three-dimensional plane transformation motion. Motion in the same plane includes three types of motion: motion along the direction of the rod, traversing the opposite side of the truss, and climbing the adjacent side of the truss. Three-dimensional plane transformation motion includes rotational motion around the rod.

[0053] Step 102: Construct a truss map based on the truss structure and the motion patterns of the modular robot on the truss.

[0054] Specifically, taking 2 as the length of a rod, q i =[x i ,y i ,z i ] T Let x represent the coordinates of the i-th node on the truss structure. i y i z i All numbers are even, construct a set of node coordinates Q = {q1, q2, ..., q...} m}, where m represents the total number of nodes on the truss; identify and select node q. i Calculate its relationship with existing neighboring nodes q i_1 =[x i +2,y i ,z i ] T q i_2 =[x i ,y i +2,z i ] T q i_3 =[x i ,y i ,z i +2] T Find the geometric midpoint, record the coordinates of the midpoint and number it s. j s j+1 s j+2 The set of reachable points S = {s1, s2, ..., s} in the truss map constitutes the set of reachable points. nEach reachable point in the set S has an odd-numbered coordinate value. These reachable points are used in the modular robot gait planning process and to establish subsequent gait selection strategies, ensuring stable and efficient path planning and motion control of the robot within the truss structure.

[0055] Step 103: Construct a mathematical expression for the motion trajectory based on the gait requirements, and design the motion trajectory of the modular robot end effector.

[0056] Specifically, the study determined the motion trajectory to be a cycloid, and designed the modular robot's end effector trajectory to be a semicircle connected by a straight line:

[0057] The formula for the trajectory of a semicircular motion is established as follows:

[0058]

[0059] Where, x s x is the starting horizontal position of the modular robot. f z represents the final horizontal position of the modular robot. s T represents the initial height position of the modular robot. s For the step period of the semi-circular motion of the modular robot, Let x be the radius of the semicircular motion of the modular robot. t Let z be a horizontal position function with respect to time t. t Let σ be the height function with respect to time t, and σ be the radian function with respect to time t.

[0060] For linear motion where only the altitude changes, the trajectory formula is as follows:

[0061]

[0062] Among them, z s z represents the initial height position of the modular robot. f T represents the final height position of the modular robot. s For the step period of linear motion of a modular robot, z represents the speed of linear motion of the modular robot. t It is a height function with respect to time t.

[0063] Step 104: Establish the kinematic model of the modular robot and use the inverse kinematics analytical method to solve for the joint angle values ​​of the modular robot.

[0064] Specifically, modeling is performed for single-chain robots. For multi-branch robots, they are decoupled into multiple single-chain robots and modeled using the DH method to solve for the transformation matrix of joint i. The formula is as follows:

[0065]

[0066] Where, θ i d is the joint angle. i For link offset, a i Let α be the length of the connecting rod. i The link twist angle;

[0067] Inverse kinematics analysis is used to solve for the angles of the three rotational joints of each modular robot unit. Let the final position and orientation of the modular robot's end effector be... k is the total number of joints. Given the total transformation matrix, multiply both sides of the equation step by step by the transformation matrix on the left. The formula is as follows:

[0068]

[0069] Establish a new equation based on the elements of the matrices on both sides of the equation, and solve for the angle value θ of the joint. i .

[0070] Step 105: Based on the decomposed modular robot motion types, design four gait types: opposite-side crossing gait, adjacent-side lateral climbing gait, rotation around a pole gait, and inchworm gait along a pole gait, and establish a gait selection strategy. The opposite-side crossing gait, adjacent-side lateral climbing gait, rotation around a pole gait, and inchworm gait along a pole include:

[0071] ① Define the basic parameters of the modular robot's gait;

[0072] ② Please refer to Figure 3 In the side-crossing gait mode, the modular robot crosses the opposite pole. The two branches switch between the fixed branch and the moving branch. In one motion cycle, the robot moves a distance equal to the length of one pole.

[0073] ③ Please refer to Figure 4 In the adjacent side-climbing gait, the modular robot laterally climbs adjacent poles, switching between fixed and moving branches. Within one movement cycle, the robot travels a distance of [distance missing]. Length of each member;

[0074] ④ Please refer to Figure 5 The modular robot performs three-dimensional plane transformations in a gait around the rod, with the two branches switching between a fixed branch and a moving branch. Within one motion cycle, the robot's position on the rod does not change.

[0075] ⑤ Please refer to Figure 6The modular robot moves towards the link in the inchworm gait along the link, with the two branches switching between a fixed branch and a moving branch. Within one motion cycle, the robot moves a distance equal to the length of one link.

[0076] The gait selection strategy includes:

[0077] ① Since the modular robot crawls on the truss surface, each reachable point in the set S must have a coordinate representing the truss plane. By comparing the previous movement point with the current movement point, when the coordinate value of the next movement point representing the truss plane changes, the movement needs to transform the truss plane and use a gait around the rod.

[0078] ② When one of the coordinate values ​​of the current motion point or the next motion point changes, the motion is a movement of the truss plane along the direction of the members, using the inchworm gait along the members;

[0079] ③ When two coordinate values ​​change at the current point of motion and the next point of motion, and the odd coordinates change, the motion is a rapid oblique movement in the truss plane, using the adjacent side lateral climbing gait;

[0080] ④ When two coordinate values ​​change at the current movement point and the next movement point, and the odd-numbered coordinates remain unchanged, the movement is a rapid crossing between truss planar members, using an opposite-side crossing gait. The technical solution of this embodiment of the invention has the following beneficial effects:

[0081] The technical solution of this invention proposes a modular robot truss crawling gait planning method. Based on the structure of a modular unit, the method analyzes and designs the modular robot, models it, studies the truss structure, designs a method to process the truss map, studies the trajectory of semi-circular motion, and designs the motion trajectory of the modular robot's end effector. It uses analytical methods to solve for the angle values ​​of each joint of the modular robot. Four gaits are designed: opposite-side crossing gait, adjacent-side lateral climbing gait, rotation around a member gait, and inchworm gait along a member gait, along with selection strategies for smooth crawling gait planning of the modular robot's truss structure. This invention is adaptable to the non-fixed structure and different truss structures of modular robots, can quickly obtain accurate joint angle values, improves the stability of modular robot truss crawling, and is suitable for scenarios such as aerospace and building maintenance.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0083] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A modular robot gantry crawling gait planning method, characterized in that, The method includes: The design of the modular robot structure includes: the modular robot is composed of N modular units connected together. Each modular unit includes 2 shells, 3 motor-reducer assemblies, 2 male interfaces and 2 female interfaces. The 3 motor-reducer assemblies are distributed on the body center of the modular unit and the two shells. Each modular unit has 3 joints inside. Each joint of the modular unit can rotate around the central axis of the male interface and the central axis of the modular unit. Based on the truss structure and the motion patterns of modular robots on the truss, a truss map is constructed, including: using 2 as the length of a single member. Let represent the coordinates of the i-th node on the truss structure, where All numbers are even; construct a set of node coordinates. , Indicates that there are a total of Nodes; identify and select nodes Calculate its relationship with existing neighboring nodes. , , Find the geometric midpoint, record the coordinates of the midpoint and number it. , , This constitutes the set of reachable points in the truss map. ; Based on the motion requirements of the modular robot, the motion is decomposed into motion in the same plane and three-dimensional plane transformation motion. Motion in the same plane includes three types of motion: motion along the direction of the rod, traversing the opposite side of the truss, and climbing the adjacent side of the truss. Three-dimensional plane transformation motion includes rotational motion around the rod. Based on gait requirements, construct mathematical expressions for motion trajectories and design modular robot end effector motion trajectories; Establish a kinematic model of the modular robot and use the inverse kinematics analytical method to solve for the joint angle values ​​of the modular robot; Based on the decomposed modular robot motion types, four gait types are designed: opposite-side crossing gait, adjacent-side lateral climbing gait, around-the-rod rotation gait, and inchworm gait along-the-rod. A gait selection strategy is also established, including: ① Since the modular robot crawls on the truss surface, each reachable point in the set S must have a coordinate representing the truss plane. By comparing the previous movement point with the current movement point, when the coordinate value of the next movement point representing the truss plane changes, the movement needs to transform the truss plane and use a gait around the rod. ② When one of the coordinate values ​​of the current motion point or the next motion point changes, the motion is a movement of the truss plane along the direction of the members, using the inchworm gait along the members; ③ When two coordinate values ​​change at the current point of motion and the next point of motion, and the odd coordinates change, the motion is a rapid oblique movement in the truss plane, using the adjacent side lateral climbing gait; ④ When two coordinate values ​​change at the current point of motion and the next point of motion, and the odd coordinates do not change, the motion is a rapid crossing between truss plane members, using the opposite side crossing gait.

2. The method according to claim 1, characterized in that, The process of constructing a mathematical expression for the motion trajectory based on gait requirements and designing the modular robot end effector trajectory includes: The formula for the trajectory of a semicircular motion is established as follows: in, This is the starting horizontal position for the modular robot. The horizontal position of the modular robot's endpoint. This is the starting height position of the modular robot. For the step period of the semi-circular motion of the modular robot, The radius of the semi-circular motion of the modular robot. Let be a function of horizontal position with respect to time t. Let height be a function of time t. It is a radian function with respect to time t; For linear motion where only the altitude changes, the trajectory formula is as follows: in, This is the starting height position of the modular robot. The endpoint height position of the modular robot. For the step period of linear motion of a modular robot, The speed of linear motion of the modular robot. It is a height function with respect to time t.

3. The method according to claim 1, characterized in that, The process of establishing a kinematic model for the modular robot and solving for the joint angle values ​​using inverse kinematics analytical methods includes: For single-chain robots, modeling is performed. For multi-branch robots, they are decoupled into multiple single-chain robots and modeled using the DH method to solve for the transformation matrix of joint i. The formula is as follows: in, Joint angle, For link offset, For the length of the connecting rod, The link twist angle; Inverse kinematics analysis is used to solve for the angles of the three rotational joints of each modular robot unit. Let the final position and orientation of the modular robot's end effector be... k is the total number of joints. Given the total transformation matrix, multiply both sides of the equation step by step by the transformation matrix on the left. The formula is as follows: Establish a new equation based on the elements of the matrices on both sides of the equation, and solve for the angle values ​​of the joint. .

4. The method according to claim 1, characterized in that, The design includes four gait types: side-crossing gait, adjacent-side lateral climbing gait, rotational gait around the pole, and inchworm gait along the pole. ① Define the basic parameters of the modular robot's gait; ② In the side-crossing gait mode, the modular robot crosses the opposite pole. The two branches switch between the fixed branch and the moving branch. In one motion cycle, the robot moves a distance equal to the length of one pole. ③ In the adjacent side climbing gait, the modular robot climbs to adjacent rods, switching between a fixed branch and a moving branch. Within one movement cycle, the robot travels a distance of [missing information]. Length of each member; ④ The modular robot performs three-dimensional plane transformation in the gait of rotating around the rod. The two branches switch between the fixed branch and the moving branch. Within one motion cycle, the position of the robot body on the rod does not move. ⑤ In the inchworm gait along the rod, the modular robot moves towards the rod, and the two branches switch between the fixed branch and the moving branch. In one motion cycle, the robot moves a distance equal to the length of one rod.

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