3-UPU hexapod robot and its gait planning method for collaboratively carrying long and heavy objects

Abstract

The present invention belongs to the field of robot collaborative handling technology, and solves the problem that most mobile robots that use parallel mechanisms as leg mechanisms have relatively complex gaits during movement, require more drives, and have relatively poor applicability. A 3-UPU hexapod robot for collaboratively carrying long and heavy objects and a gait planning method thereof are provided. A clamping member is connected to the upper end of an upper platform through a rotating member. The outer circle of the upper platform is evenly hinged with multiple telescopic branches. The telescopic branches have a driving member for controlling their movements. The outer circle of the middle platform is evenly fixed with multiple first connecting rods. The outer circle of the lower platform is evenly fixed with multiple second connecting rods. The lower ends of the two adjacent telescopic branches are hinged to the lower end plates of a first connecting rod and a second connecting rod, respectively. The present invention uses the 3-UPU parallel mechanism composed of the middle platform and the lower platform as the body of the hexapod robot, which can produce a simple gait with less drive and achieve forward movement by alternating the two platforms.

Description

Technical Field

[0001] The present invention belongs to the technical field of robot collaborative handling, and particularly relates to a 3-UPU hexapod robot for collaboratively handling long and heavy objects and a gait planning method thereof. Background Art

[0002] Long, heavy objects such as steel pipes, electric poles, and gun barrels are often very heavy. Their transportation in production workshops primarily relies on lifting devices such as cranes, assisted by manual labor. However, in rugged and narrow areas, such as underground spaces where lifting equipment cannot enter, multiple people must lift or carry them on their shoulders. Injuries often occur during the handling process, and some heavy objects are even impossible to lift manually. Collaborative handling by multiple mobile robots offers a solution to this problem. By replacing manual labor with robots, this approach can address both the lack of manual labor and the safety concerns associated with manual handling in dangerous and complex environments, such as underground mines and forests.

[0003] When it comes to transporting long heavy objects, if a single robot is used, it is difficult to maintain the balance of the overall center of gravity of the long heavy object due to its long size and the difficulty in grasping the center of gravity. However, the coordinated movement of two mobile robots can simulate the purpose of "two people lifting a heavy object", so that the long heavy object can remain stable during the transportation process.

[0004] There have been many studies on dual-robot collaborative handling both domestically and internationally. Cao Xuepeng et al. established a mathematical model of a dual-robot collaborative handling system, designed a control module to improve the system's dynamic performance, and divided the dual robots into a primary and secondary robot. During the simulation, the secondary robot always followed the primary robot's movements, reducing the secondary robot's tracking error. Liu Jianfeng et al. proposed a dual-mobile robot collaborative positioning method based on Gauss-Hermite quadrature Kalman filtering, which improves the robot's positioning accuracy and facilitates the real-time collaborative positioning of multiple robots. Xie Dongfu et al. studied the static and dynamic stability of overturning in a multi-robot collaborative mode, and changed the stability of the robot system by switching the collaborative mode. Agheli et al. conducted extensive research on multi-legged mobile robots in dynamic conditions, analyzing the robot's stability based on the foot force stability margin to facilitate stability control.

[0005] However, most of the above-mentioned mobile robots use parallel mechanisms as leg mechanisms, have relatively complex gaits during movement and require more drives, and their applicability is relatively poor. Summary of the Invention

[0006] In order to solve at least one of the above-mentioned technical problems existing in the prior art, the present invention provides a 3-UPU hexapod robot for collaboratively carrying long and heavy objects and a gait planning method thereof.

[0007] The present invention is implemented by the following technical solution: a 3-UPU hexapod robot for collaboratively carrying long and heavy objects, including three platforms: upper, middle and lower platforms, a clamping member, and multiple legs; the clamping member is connected to the upper end of the upper platform through a rotating member, and the outer circle of the upper platform is evenly hinged with multiple telescopic branches, and the telescopic branches are provided with driving members for controlling their movements. The outer circle of the middle platform is evenly fixed with multiple first connecting rods, and the outer circle of the lower platform is evenly fixed with multiple second connecting rods. The first connecting rod and the second connecting rod are staggered, and the lower ends of the two adjacent telescopic branches are hinged to the lower end plates of a first connecting rod and a second connecting rod respectively, and the lower end plates are connected to the legs in a one-to-one correspondence.

[0008] Preferably, the number of telescopic branches is six, and the number of first connecting rods and second connecting rods are three each; the center line of the horizontal projection of the telescopic branch coincides with the center line of the horizontal projection of the first connecting rod or the second connecting rod connected thereto.

[0009] Preferably, the supporting legs are telescopic structures that can cope with rugged and complex terrains, the rotating member includes a rotating disk rotatably connected to the upper platform and a bracket connected to the rotating disk, and the clamping member is rotatably connected to the bracket.

[0010] The present invention also provides a gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects, comprising the following steps:

[0011] S1: Plan the movement modes of the 3-UPU hexapod robot during the starting and circulation phases based on its structure;

[0012] S2: Preliminary setting of the gait parameters of the 3-UPU hexapod robot during movement, and ensuring that the stability of the 3-UPU hexapod robot during movement under the gait parameters meets the requirements;

[0013] S3: Establish the motion trajectory equation of the 3-UPU hexapod robot and ensure that the extension and contraction of the telescopic branch chain is within the allowable range during movement;

[0014] S4: According to different handling environments, plan the combined gait of the two 3-UPU hexapod robots when they collaboratively carry long and heavy objects, and make both meet the gait parameter requirements in step S2.

[0015] Preferably, in step S1, at the initial position, all legs are supported on the ground, and the six telescopic branches have no extension, which is the minimum value; in the starting stage, the upper platform is lifted to a preset height, and then one of the middle platform or the lower platform is used as a support point, and the other is lifted while moving forward together with the upper platform, and then the platform of the middle platform or the lower platform that moves forward together with the upper platform is lowered while moving forward together with the upper platform until the platform of the middle platform or the lower platform that moves forward together with the upper platform lands again; in the circulation stage, the lower platform and the middle platform are used as support points respectively, and are alternately staggered to achieve movement, and the height of the upper platform remains unchanged; when the destination is reached, the circulation stage is ended, and the components on the 3-UPU hexapod robot are reset to the initial position.

[0016] Preferably, in step S2, the step lengths of the 3-UPU hexapod robot moving in different directions are set in combination with its structural dimensions and stability margin; on the horizontal projection plane, the vertices are B 1. B 2. B 3. B 4. B 5. B 6 regular hexagons, as the equivalent hexagons of the upper platform, with two identical regular triangles and , as the equivalent triangles of the lower platform and the middle platform respectively; in the initial position, the centers of the equivalent hexagon and the two equivalent triangles coincide, and the side lines of the equivalent triangles A 2 A 3 and A 5 A 6 are parallel, and a circle is drawn with the endpoint of the equilateral triangle as the center as the equivalent circle of the leg; when the 3-UPU hexapod robot moves along the direction of the line connecting the center point at the initial position and one of the vertices of the equivalent triangle, in the starting stage, it is ensured that the equivalent circles on the two side lines perpendicular to the moving direction of the two equivalent triangles do not interfere with each other, and the maximum distance that the middle platform or the lower platform moves from the initial position along the moving direction during the starting stage is ; In the cycle stage, it is ensured that the equivalent circles on the two vertices of the two equivalent triangles in the direction of travel do not interfere with each other, and the maximum distance that the middle platform or the lower platform moves from the initial position along the direction of travel in one cycle is ;according to Set the step length for the starting phase along the direction of travel, according to Set the step length of the cycle phase along the direction of travel; when the 3-UPU hexapod robot moves along the line connecting the center point at the initial position and one of the intersection points of the two equivalent triangles, in the starting phase, the maximum distance that the middle platform or the lower platform moves from the initial position along the direction of travel during the starting phase is In the cycle stage, the maximum distance that the middle platform or the lower platform moves from the initial position along the direction of travel in one cycle is ;according to Set the step length for the starting phase along the direction of travel, according to The step length of the cycle phase along the travel direction is set. Given a specific value of the step length, if the horizontal projection of the center of gravity of the 3-UPU hexapod robot during movement is inside the equivalent triangle of the middle platform or the lower platform serving as the support point, the 3-UPU hexapod robot can remain stable during movement.

[0017] Preferably, in step S3, the center point of the middle platform or the lower platform is used as the coordinate origin, the step end coordinate is solved according to the initial step coordinate and the step length of the point, and the coordinate of the highest point passed by the step is solved given the step height, and the above coordinates are substituted into the quadratic polynomial to solve the trajectory curve equation of the middle platform or the lower platform; the length of each telescopic branch chain during the movement process is solved: a global coordinate system is established at the center point of the upper platform, the posture and position of the middle platform and the lower platform are given, and the length of each telescopic branch chain at different positions is solved to determine whether it is within the range of change of its telescopic amount.

[0018] Preferably, when the transport environment is that two 3-UPU hexapod robots collaboratively transport a long heavy object along a straight line, the step length value that satisfies the conditions of steps S2 and S3 can be used.

[0019] Preferably, in a handling environment where two 3-UPU hexapod robots cooperate to carry a long heavy object along a straight line and there is a right-angle turn, the front 3-UPU hexapod robot is set as 3-UPU hexapod robot I, and the rear 3-UPU hexapod robot is set as 3-UPU hexapod robot II; the direction of the line connecting the center point at the initial position and one of the vertices of the equivalent triangle is the first direction, and the direction of the line connecting the center point at the initial position and one of the intersection points of the two equivalent triangles is the second direction; the 3-UPU hexapod robot I and the 3-UPU hexapod robot II move as a whole along the first direction toward the center intersection of the turn. , and walk along the center line of the channel according to the step length set in the first direction, when the 3-UPU hexapod robot 1 reaches the center intersection of the turning point At this point, it starts to move in the second direction and walks according to the step length set in the second direction. The first direction here is perpendicular to the second direction. The 3-UPU hexapod robot II at the rear needs to follow the 3-UPU hexapod robot I and continue to move in the first direction until it reaches the center intersection of the 3-UPU hexapod robot II turning point. Finally, the 3-UPU hexapod robot I and the 3-UPU hexapod robot II drive out of the narrow section along the second direction; in order to make the step length of a single 3-UPU hexapod robot in each direction meet the set value, and to make the distance between the two keep constant, As the coordinate origin, establish a coordinate system and analyze the turning process according to the set step length: Set The two ends of the long heavy object in preparation for turning correspond to the positions of 3-UPU hexapod robot I and 3-UPU hexapod robot II respectively. Towards During the process, the moving distance of the 3-UPU hexapod robot II for:

[0020]

[0021] Where, is the distance between the upper platforms of 3-UPU hexapod robot I and 3-UPU hexapod robot II; is the set step size for the loop phase in the second direction;

[0022] Assume that the 3-UPU hexapod robot I has a step length For one step cycle, we can find the i Step length of 3-UPU hexapod robot II for:

[0023]

[0024] If the robot is to pass through the bend as a whole, the step length of the 3-UPU hexapod robot II should be Less than or equal to the set step size of the first direction cycle stage; if during the entire turning process, If all the above conditions are met, the 3-UPU hexapod robot I can be Move for one step cycle until the end; if during the entire turning process, In the i If the step time is greater than the set step length of the first direction cycle stage, the gait is adjusted. i -1 movement cycle, 3-UPU hexapod robot II follows the movement of 3-UPU hexapod robot I, from i At the beginning of the step, the 3-UPU hexapod robot II walks according to the set step length of the circulation stage in the first direction, and the 3-UPU hexapod robot I follows it to move until the 3-UPU hexapod robot II reaches the turning point, and the step length of the 3-UPU hexapod robot I that follows it is less than or equal to the set step length of the circulation stage in the second direction.

[0025] Preferably, an analysis is performed to determine whether the long heavy object will collide with the wall during the turn: Under this gait planning method, the point where interference may occur is the inflection point of the inner wall at the turn. The interference is determined by judging whether the distance between the point and the long heavy object during the movement is greater than the radius of the long heavy object.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention uses a 3-UPU parallel mechanism consisting of a middle platform and a lower platform as the body of the hexapod robot, which can produce a simple gait with less drive, and relies on the alternating staggering of the two platforms to achieve forward movement in a 3+3 gait. It has the advantages of high rigidity, large load-bearing capacity, and easy control. Through the coordinated movement of two 3-UPU hexapod robots, it can achieve a carrying task similar to "two people lifting heavy objects". It has broad application prospects in the coordinated carrying of long and heavy objects such as steel pipes, electric poles, and gun barrels in narrow terrain. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 Schematic diagram of the overall structure of the 3-UPU hexapod robot of the present invention;

[0030] Figure 2 This is a schematic diagram of the 3-UPU hexapod robot of the present invention when performing degree of freedom analysis;

[0031] Figure 3 This is a three-dimensional schematic diagram of the 3-UPU hexapod robot of the present invention when walking;

[0032] Figure 4 Schematic diagram of the initial stage, starting stage, and cycle stage of the 3-UPU hexapod robot of the present invention;

[0033] Figure 5 is a diagram showing the center of gravity distribution of the 3-UPU hexapod robot of the present invention;

[0034] Figure 6 is a trajectory diagram of the center of gravity of the middle platform and the lower platform of the 3-UPU hexapod robot of the present invention when supported;

[0035] Figure 7 is a motion trajectory curve diagram of the middle platform and the lower platform of the 3-UPU hexapod robot of the present invention;

[0036] Figure 8 is a schematic diagram of the global coordinate system during the motion of the 3-UPU hexapod robot of the present invention;

[0037] Figure 9 is the equivalent rod length of the telescopic branch chain when the middle platform and the lower platform of the 3-UPU hexapod robot of the present invention move along the first direction;

[0038] Figure 10 is the equivalent rod length of the telescopic branch chain when the middle platform and the lower platform of the 3-UPU hexapod robot of the present invention move along the second direction;

[0039] Figure 11 This is a turning gait planning diagram of two 3-UPU hexapod robots of the present invention in a narrow turning terrain;

[0040] Figure 12 Schematic diagram of the turning gait of two 3-UPU hexapod robots of the present invention before and after adjustment in a narrow turning terrain;

[0041] Figure 13 Schematic diagram of the maximum step height for two 3-UPU hexapod robots of the present invention to collaboratively carry heavy objects.

[0042] In the figure: 1.1-upper platform; 1.2-middle platform; 1.3-lower platform; 2.1-telescopic branch chain; 2.2-first connecting rod; 2.3-second connecting rod; 3-clamping part; 4-support leg; 5-rotating part; 5.1-rotating disk; 5.2-bracket; 6-driving part; 7-lower end plate; 8-long heavy object. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention are clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other implementations derived by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0044] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention. It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0045] The present invention provides an embodiment:

[0046] like Figure 1 As shown, a 3-UPU hexapod robot for collaboratively carrying long and heavy objects includes three platforms: upper, middle and lower platforms, a clamping member 3, and multiple legs 4; the clamping member 3 is connected to the upper end of the upper platform 1.1 through a rotating member 5, and the outer circle of the upper platform 1.1 is evenly hinged with multiple telescopic branches 2.1, and the telescopic branches 2.1 are provided with a driving member 6 for controlling its movement. The outer circle of the middle platform 1.2 is evenly fixedly connected with multiple first connecting rods 2.2, and the outer circle of the lower platform 1.3 is evenly fixedly connected with multiple second connecting rods 2.3, and the first connecting rods 2.2 and the second connecting rods 2.3 are staggered. The lower ends of the two adjacent telescopic branches 2.1 are hinged to the lower end plates 7 at a first connecting rod 2.2 and a second connecting rod 2.3, respectively, and the lower end plates 7 are connected to the legs 4 in a one-to-one correspondence.

[0047] In this embodiment, there are six telescopic links 2.1, and three first and second links 2.2 and 2.3. The horizontal projection centerline of the telescopic link 2.1 coincides with the horizontal projection centerline of the first or second link 2.2, 2.3 to which it is connected. The legs 4 are telescopic structures designed to handle rough and complex terrain and feature a drive element 6 to control their movement. The rotating element 5 includes a rotating disk 5.1 rotatably connected to the upper platform 1.1 and a bracket 5.2 connected to the rotating disk 5.1. The clamping element 3 is rotatably connected to the bracket 5.2 to ensure a safe handling of long, heavy objects 8.

[0048] The present invention also provides a gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects, comprising the following steps:

[0049] S1: Plan the movement modes of the 3-UPU hexapod robot during the starting and circulation phases based on its structure;

[0050] S2: Preliminary setting of the gait parameters of the 3-UPU hexapod robot during movement, and ensuring that the stability of the 3-UPU hexapod robot during movement under the gait parameters meets the requirements;

[0051] S3: Establish the motion trajectory equation of the 3-UPU hexapod robot and ensure that the extension and contraction amount of the telescopic branch chain 2.1 is within the allowable range during the movement;

[0052] S4: According to different handling environments, plan the combined gait of the two 3-UPU hexapod robots when they collaboratively carry long and heavy objects, and make both meet the gait parameter requirements in step S2.

[0053] According to the above structure, the freedom degree of the 3-UPU hexapod robot is analyzed. Since the structures of the middle platform 1.2 and the lower platform 1.3 are similar, only one of them needs to be analyzed. Figure 2A rectangular coordinate system is established in the figure, and the degrees of freedom of the three telescopic branches 2.1 are analyzed respectively by the screw theory, where the motion screw system of the telescopic branch I is expressed as:

[0054]

[0055] Since the reciprocal product is zero, the anti-constrained spiral system of this branch chain can be obtained as: .

[0056] Since the end of the telescopic branch chain is subject to a restraining force couple, the restrained spiral system reaction telescopic branch chain is restricted by the z The rotation of the axis, from the spatial mechanism theory, we know that the linear vector and the maximum independent number of the spiral, we can find that the parallel mechanism still has different rotations. z The two constraint couples in the axial direction are not coplanar, so the overall spiral system of the mechanism is

[0057]

[0058] The organization as a whole has x, y, z Three purely translational degrees of freedom for axis movement.

[0059] like Figure 3 As shown, in step S1, at the initial position, all the legs 4 are supported on the ground, and the six telescopic branches 2.1 have no extension and are at the minimum value; in the starting stage, the upper platform 1.1 is lifted to a preset height, and then one of the middle platform 1.2 or the lower platform 1.3 is used as a support point, and the other is lifted while moving forward together with the upper platform 1.1, and subsequently the middle platform 1.2 or the lower platform 1.3 that moves forward together with the upper platform 1.1 is lowered while moving forward together with the upper platform 1.1 until the middle platform 1.2 or the lower platform 1.3 that moves forward together with the upper platform 1.1 lands again; in the circulation stage, the lower platform 1.3 and the middle platform 1.2 are used as support points respectively, and are alternately staggered to achieve movement, the height of the upper platform 1.1 remains unchanged, and the projection of the upper platform 1.1 on the horizontal plane is always in the middle of the projections of the other two platforms; when the destination is reached, the circulation stage is ended, and the components on the 3-UPU hexapod robot are reset to their initial positions.

[0060] like Figure 4 As shown, in step S2, in order to avoid interference between the rod and the platform, the step length of the 3-UPU hexapod robot moving in different directions needs to be set in combination with its structural dimensions and stability margin;

[0061] like Figure 4 As shown, on the horizontal projection plane, the vertices are B 1. B 2. B 3. B 4. B 5.B 6, as the equivalent hexagon of the upper platform 1.1, with two identical equilateral triangles and , as the equivalent triangles of the lower platform 1.3 and the middle platform 1.2 respectively; in the initial position, the centers of the equivalent hexagon and the two equivalent triangles coincide, and the side lines of the equivalent triangles A 2 A 3 and A 5 A 6 is parallel, and a circle is made with the endpoints of the equilateral triangle as the center, which serves as the equivalent circle of the support leg 4;

[0062] In this embodiment, the distance between the center point of the upper platform 1.1 and its end points is r =350mm, the distance between the center point of the middle platform 1.2 and the lower platform 1.3 and their end points is R =900mm, the radius of the equivalent circle of leg 4 , the maximum extension of the telescopic branch chain 2.1 is set to 600mm;

[0063] In the initial position, the length of the telescopic branch chain 2.1 is 800 mm; in the starting stage, the lifting height of the upper platform 1.1 is 200 mm, and the step heights of the middle platform 1.2 and the lower platform 1.3 are both set to 100 mm.

[0064] When the 3-UPU hexapod robot moves along the line connecting the center point at the initial position and one of the vertices of the equivalent triangle:

[0065] In the starting phase, ensure that the equivalent circles on the two sides of the two equivalent triangles perpendicular to the direction of travel do not interfere with each other, and obtain the maximum distance that the middle platform 1.2 or the lower platform 1.3 moves from the initial position along the direction of travel in the starting phase is , as can be seen from the figure ;

[0066] During the cycle, it is ensured that the equivalent circles on the two vertices of the two equivalent triangles in the direction of travel do not interfere with each other, and the maximum distance that the middle platform 1.2 or the lower platform 1.3 moves from the initial position along the direction of travel in one cycle is , as can be seen from the figure ;

[0067] In the first direction, in this embodiment, the step length of the middle platform 1.2 or the lower platform 1.3 in the starting stage is preliminarily set to 300 mm, and the step length of the middle platform 1.2 and the lower platform 1.3 in the circulation stage are both 600 mm.

[0068] When the 3-UPU hexapod robot moves along the line connecting the center point at the initial position and one of the intersection points of the two equivalent triangles, in the starting phase, the maximum distance that the middle platform 1.2 or the lower platform 1.3 moves from the initial position along the moving direction during the starting phase is , it can be seen that ;

[0069] During the cycle, the maximum distance that the middle platform 1.2 or the lower platform 1.3 moves from the initial position along the direction of travel within one cycle is , it can be seen that ;

[0070] In the second direction, in this embodiment, the step length of the middle platform 1.2 or the lower platform 1.3 in the starting stage is preliminarily set to 200 mm, and the step length of the middle platform 1.2 and the lower platform 1.3 in the circulation stage are both 400 mm.

[0071] The stability of the 3-UPU hexapod robot is judged according to the given step length value. If the horizontal projection of the center of gravity of the 3-UPU hexapod robot during movement is inside the equivalent triangle of the middle platform 1.2 or the lower platform 1.3 serving as the support point, the 3-UPU hexapod robot can remain stable during movement.

[0072] Specifically, in Figure 5 middle They represent the center of gravity of the lower platform 1.3 and its rods, the middle platform 1.2 and its rods, and the upper platform 1.1, respectively. G Indicates the center of gravity of the 3-UPU hexapod robot. When the 3-UPU hexapod robot is walking, it is always supported by one of the two platforms, the middle platform 1.2 and the lower platform 1.3. G When the projection on the horizontal plane is inside the support polygon area or on the edge, the 3-UPU hexapod robot can remain stable. Observe whether the position of the center of gravity is inside the support polygon during a movement cycle. The center of gravity trajectory is shown in the figure below. Figure 6 shown.

[0073] like Figure 6 As shown in the figure, the center of gravity trajectory diagram of the mechanism when it moves along the x and y axes when the middle and lower platforms are supported, respectively. , The intersection of the two is the center point of the triangle at the foot of the support platform. It is known that the radius of the middle platform 1.2 and the lower platform 1.3 are both 900mm. It can be seen that within the set step length range, when the robot walks, its center of gravity is G They are all within the supporting triangle area, so the robot can maintain stable walking during walking.

[0074] When the 3-UPU hexapod robot moves in one direction, the motion analysis of its legs can be obtained through the center point of the platform. By establishing the overall coordinate system of the 3-UPU hexapod robot during movement and calculating the platform coordinates of each key point, the motion trajectory curve of each platform can be obtained, such as Figure 7 shown.

[0075] Specifically, the trajectory curve adopts a quadratic polynomial, and the equation is: First, analyze the trajectory moving in the first direction. In a complete motion cycle, the center point of the lower platform 1.3 is used as the coordinate origin, that is, the coordinates of the beginning of the step are (0, 0), and the step length is given as 600mm. The coordinates of the end of the step are (600, 0). The center point of the step is also the highest point. The coordinates can be calculated as (300, 100) based on the given step height. Substituting the above coordinates into the equation, the trajectory curve equation of the lower platform 1.3 can be obtained as:

[0076]

[0077] Since the motion of the middle platform 1.2 lags behind the lower platform 1.3 by half a period, the motion trajectory equation of the middle platform 1.2 is:

[0078]

[0079] The movement of the middle platform 1.2 and the lower platform 1.3 needs to be driven by the telescopic branch chain 2.1 connected to them. In other words, the displacement of the middle platform 1.2 and the lower platform 1.3 can be reflected by the length of the telescopic branch chain 2.1. Therefore, it is necessary to calculate the equivalent rod length within a movement cycle and establish a rectangular coordinate system for each platform of the moving mechanism, such as Figure 8 shown.

[0080] To solve the length of each telescopic branch 2.1 of the moving mechanism, it is necessary to combine the inverse solution, that is, to establish a global coordinate system at the center of the upper platform 1.1.

[0081] When the 3-UPU hexapod robot moves in the first direction (the x-axis direction in this embodiment, the lower platform 1.3 is set to move first), As the equivalent rod length of the three telescopic branches 2.1 connected to the lower platform 1.3, As the equivalent rod length of the three telescopic branches 2.1 connected to the upper platform 1.2; establish a global coordinate system at the center point of the upper platform 1.1, set the posture and position of the middle platform 1.2 and the lower platform 1.3, and calculate the equivalent rod length of the lower platform 1.3 for:

[0082]

[0083] Equivalent rod length of the middle platform (1.2) for:

[0084]

[0085] Where, X, Y, Z Respectively, the telescopic branch chain 2.1 x 、 y 、 z Relative displacement in the axial direction;

[0086] Similarly, the motion trajectory equations of the middle platform 1.2 and the lower platform 1.3 and the equivalent rod length of the telescopic branch chain 2.1 can be obtained when the 3-UPU hexapod robot moves along the second direction (the y-axis direction in this embodiment, with the middle platform 1.2 moving first).

[0087] like Figure 9 and Figure 10 As shown in the figure, when the robot moves along the x-axis or y-axis for one motion cycle, the equivalent rod lengths of the telescopic branch chain 2.1 are different when the middle and lower platforms are in different positions, and the range of the equivalent rod lengths is within the variation range of the telescopic branch chain 2.1, which not only proves the feasibility of the mechanism's movement, but also provides a theoretical basis for the mechanism's control.

[0088] When the handling environment is two 3-UPU hexapod robots collaboratively carrying a long heavy object along a straight line, the step size value that meets the conditions of steps S2 and S3 can be used.

[0089] like Figure 11 、 12 As shown, when the handling environment is that two 3-UPU hexapod robots cooperate to carry a long heavy object along a straight line with a right-angle turn; in this embodiment, the parameters of the turning terrain are set as follows: the ground width is 4000mm, the height is greater than the maximum extension of the upper platform of the mobile mechanism, the length of the long heavy object is 5000mm, the distance between the gripping device and the end closest to the long heavy object is 500mm, and the diameter of the long heavy object is 500mm;

[0090] The dual 3-UPU hexapod robot moves along the x-axis toward the center intersection of the fork in the road. , and walk along the center line of the channel. The moving distance in this direction is 600mm per cycle. When the 3-UPU hexapod robot I reaches the center intersection of the fork in the road At , it starts to turn along the y-axis direction. The moving distance in this direction is 400mm per cycle. During the handling process, the distance between the two 3-UPU hexapod robots on the platform 1.1 should always be equal. It is the distance for clamping heavy objects. It means that ;

[0091] The 3-UPU hexapod II at the rear needs to follow the 3-UPU hexapod I and continue to move along the x-axis until it reaches the center intersection of the 3-UPU hexapod II intersection. Finally, the dual 3-UPU hexapod robot drives out of the narrow road along the y-axis;

[0092] In order to make the step length of a single 3-UPU hexapod robot in each direction meet the set value, and make the distance between the two equal, As the coordinate origin, establish a coordinate system and analyze the turning process according to the set step size:

[0093] set up The two ends of the long heavy object in preparation for turning correspond to the positions of 3-UPU hexapod robot I and 3-UPU hexapod robot II respectively. Towards During the process, the moving distance of the 3-UPU hexapod robot II for:

[0094]

[0095] Where, is the distance between the upper platforms of 3-UPU hexapod robot I and 3-UPU hexapod robot II; is the set step size for the loop phase in the second direction;

[0096] Assume that the 3-UPU hexapod robot I has a step length For one-step cycle, we can find the i Step length of 3-UPU hexapod robot II for:

[0097]

[0098] If the robot is to pass through the bend as a whole, the step length of the 3-UPU hexapod robot II should be Less than or equal to the set step size of the first direction cycle stage;

[0099] If during the entire turning process, If all the above conditions are met, the 3-UPU hexapod robot I can be Move until the end of a step cycle; according to the maximum step length along the x-axis is 600mm, establish the inequality: , we find that the steps taken by the 3-UPU hexapod robot II in the 9th motion cycle exceed the set step length;

[0100] The gait of the robot is adjusted. In the first 8 motion cycles, the 3-UPU hexapod robot II moves in conjunction with the 3-UPU hexapod robot I. Starting from the 9th step, the 3-UPU hexapod robot II moves along the x-axis according to the set step length, i.e. 600 mm. The 3-UPU hexapod robot I moves in conjunction with it. At the end of the 8th motion cycle, the 3-UPU hexapod robot II is 100 mm away from the robot. The point is 2400mm, and it takes exactly 4 motion cycles to complete the turn. It is calculated that the step lengths of the 3-UPU hexapod robot I that follows are all within the set step length range, that is, .

[0101] Analyze whether a long heavy object will collide with the wall during the turn: Under this gait planning method, the point where interference may occur is the inflection point of the inner wall at the turn The interference is determined by judging whether the distance between the point and the long heavy object during the movement is greater than the radius of the long heavy object.

[0102] In In the coordinate system with as the origin, The coordinates of the point are (-2000, 2000), and the distance that the 3-UPU hexapod robot I moves along the y-axis is , then the coordinates of the 3-UPU hexapod robot I during the movement process are for , the coordinates of the 3-UPU hexapod robot II are , from this we can deduce that the function expression of the center line of the long heavy object during the movement is:

[0103]

[0104] The distance formula between a point and a line can be calculated The distance between the point and the long heavy object for:

[0105]

[0106] Find the minimum value of this equation That is The minimum distance between the long and heavy objects, when the distance between 3-UPU Hexapod Robot I and 3-UPU Hexapod Robot II is When the point coordinates are equal, Take the minimum value, then , we can find out at this time , we can get ;

[0107] Since the diameter of the long weight is given to be 500mm, It is much larger than the radius of the weight, 250 mm, so it is known that the long weight will not interfere with the wall.

[0108] When two 3-UPU hexapods are carrying long, heavy objects across narrow, rugged terrain, such as underground spaces, uneven steps are one of the most common obstacles. Because the working principle is to "lift" the object through the collaborative handling of two 3-UPU hexapods, the object must be kept horizontal as much as possible during the handling process. If the obstacle exceeds the maximum height at which the object can maintain its horizontal position, there is a risk of the object tipping over, causing an accident. The maximum height of the steps that a 3-UPU hexapod can climb while maintaining the object's horizontal position reflects the robot's obstacle-crossing capabilities.

[0109] like Figure 13 As shown, if two 3-UPU hexapod robots are located at a height difference of When helping to carry long heavy objects on different ground surfaces, it can be seen that when the two 3-UPU hexapod robots are in the initial state, the height difference of their upper platforms 1.1 is also ;

[0110] When setting the initial position, the height difference between the upper platform 1.1 and the lower platform 1.3 is h 0. After calculation, when the rise of the upper platform 1.1 is within the range of [110,530], the 3-UPU hexapod robot can walk according to the set step length and step width. Since the maximum extension of the leg 4 is 450mm, the maximum step height difference that the 3-UPU hexapod robot can climb if the load is kept horizontal during transportation can be calculated as:

[0111]

[0112] The present invention proposes a dual 3-UPU hexapod robot for transporting long heavy objects, and conducts a degree of freedom analysis on the robot. The mechanism has three translational degrees of freedom in space, which can realize movement to various positions in space. The gait analysis of the mobile mechanism is performed, its walking plan is set, and the step length of the mechanism is solved in combination with the mechanism size and stability margin. The motion trajectory of the mobile mechanism is drawn and its equivalent rod length is solved. The purpose is to find out the relationship between the position and the rod length during the movement of the mechanism, which is convenient for further control. By analyzing the scenario of the mechanism transporting heavy objects on rugged terrain, it is calculated that the heavy objects transported by the mechanism can maintain a stable level on terrain with a misalignment difference of 0 to 870mm. By analyzing the narrow underground space model, the gait planning of the dual 3-UPU hexapod robot is performed. The results show that the mechanism can smoothly realize the turning function in a narrow space.

[0113] The foregoing description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed herein should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A 3-UPU hexapod robot for collaboratively carrying long and heavy objects, characterized by: The invention comprises three platforms, an upper platform, a middle platform and a lower platform, a clamping member (3) and a plurality of supporting legs (4); the clamping member (3) is connected to the upper end of the upper platform (1.1) through a rotating member (5); the outer circle of the upper platform (1.1) is evenly hinged with a plurality of telescopic branches (2.1); the telescopic branches (2.1) are provided with a driving member (6) for controlling their movement; the outer circle of the middle platform (1.2) is evenly fixedly connected with a plurality of first connecting rods (2.2); the outer circle of the lower platform (1.3) is evenly fixedly connected with a plurality of second connecting rods (2.3); the first connecting rods (2.2) and the second connecting rods (2.3) are staggered; the lower ends of two adjacent telescopic branches (2.1) are hinged with the lower end plates (7) at one first connecting rod (2.2) and one second connecting rod (2.3), respectively, and the lower end plates (7) are connected to the supporting legs (4) in a one-to-one correspondence.

2. The 3-UPU hexapod robot for collaboratively transporting long and heavy objects according to claim 1, characterized in that: The number of the telescopic branch chains (2.1) is six, and the number of the first connecting rods (2.2) and the second connecting rods (2.3) are three; the center line of the horizontal projection of the telescopic branch chain (2.1) coincides with the center line of the horizontal projection of the first connecting rod (2.2) or the second connecting rod (2.3) connected thereto.

3. The 3-UPU hexapod robot for collaboratively transporting long and heavy objects according to claim 2, characterized in that: The supporting legs (4) are telescopic structures capable of coping with rugged and complex terrains and have a driving member (6) for controlling their movement. The rotating member (5) includes a rotating disk (5.1) rotatably connected to the upper platform (1.1) and a bracket (5.2) connected to the rotating disk (5.1). The clamping member (3) is rotatably connected to the bracket (5.2).

4. A gait planning method for a 3-UPU hexapod robot for collaboratively transporting long heavy objects, based on the 3-UPU hexapod robot for collaboratively transporting long heavy objects according to any one of claims 1 to 3, characterized in that: The following steps are included: S1: Plan the movement modes of the 3-UPU hexapod robot during the starting and circulation phases based on its structure; S2: Preliminary setting of the gait parameters of the 3-UPU hexapod robot during movement, and ensuring that the stability of the 3-UPU hexapod robot during movement under the gait parameters meets the requirements; S3: Establish the motion trajectory equation of the 3-UPU hexapod robot and make the expansion and contraction of the telescopic branch chain (2.1) within the allowable range during movement; S4: According to different handling environments, plan the combined gait of the two 3-UPU hexapod robots when they collaboratively carry long and heavy objects, and make both meet the gait parameter requirements in step S2.

5. The gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects according to claim 4, characterized in that: In the step S1, at the initial position, all the legs (4) are supported on the ground, and the six telescopic branches (2.1) have no extension and are at the minimum value; in the starting stage, the upper platform (1.1) is lifted to a preset height, and then one of the middle platform (1.2) or the lower platform (1.3) is used as a support point, and the other is lifted while moving forward together with the upper platform (1.1), and subsequently the platform of the middle platform (1.2) or the lower platform (1.3) that moves forward together with the upper platform (1.1) is lowered while moving forward together with the upper platform (1.1) until the platform of the middle platform (1.2) or the lower platform (1.3) that moves forward together with the upper platform (1.1) lands again; in the circulation stage, the lower platform (1.3) and the middle platform (1.2) are respectively used as support points, and are alternately staggered to achieve movement, and the height of the upper platform (1.1) remains unchanged; when the destination is reached, the circulation stage ends, and the components on the 3-UPU hexapod robot are reset to the initial position.

6. The gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects according to claim 5, characterized in that: In step S2, the step length of the 3-UPU hexapod robot moving in different directions is set based on its structural dimensions and stability margin; On the horizontal projection plane, the vertices are B 1. B 2. B 3. B 4. B 5. B 6, as the equivalent hexagon of the upper platform (1.1), with two identical equilateral triangles and , as the equivalent triangles of the lower platform (1.3) and the middle platform (1.2); in the initial position, the centers of the equivalent hexagon and the two equivalent triangles coincide, and the side lines of the equivalent triangles A 2 A 3 and A 5 A 6. Draw a circle with the endpoints of the equilateral triangle as the center, which is the equivalent circle of the support leg (4); When the 3-UPU hexapod robot moves along the line connecting the center point at the initial position and one of the vertices of the equivalent triangle, in the starting phase, it is ensured that the equivalent circles on the two sides perpendicular to the moving direction of the two equivalent triangles do not interfere with each other. The maximum distance that the middle platform (1.2) or the lower platform (1.3) moves from the initial position along the moving direction during the starting phase is ; During the cycle, ensure that the equivalent circles on the two vertices of the two equivalent triangles in the direction of travel do not interfere with each other, and obtain the maximum distance that the middle platform (1.2) or the lower platform (1.3) moves from the initial position along the direction of travel in one cycle. ;according to Set the step length for the starting phase along the direction of travel, according to Set the step size for the cycle phase along the direction of travel; When the 3-UPU hexapod robot moves along the line connecting the center point at the initial position and one of the intersection points of the two equivalent triangles, the maximum distance that the middle platform (1.2) or the lower platform (1.3) moves from the initial position along the direction of travel during the starting phase is , cycle stage, the maximum distance that the middle platform (1.2) or the lower platform (1.3) moves from the initial position along the direction of travel in one cycle is ;according to Set the step length for the starting phase along the direction of travel, according to Set the step size for the cycle phase along the direction of travel; Given a specific value of the step length, if the horizontal projection of the center of gravity of the 3-UPU hexapod robot during movement is inside the equivalent triangle of the middle platform (1.2) or the lower platform (1.3) as the support point, the 3-UPU hexapod robot can remain stable during movement.

7. The gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects according to claim 6, characterized in that: In step S3, the center point of the middle platform (1.2) or the lower platform (1.3) is used as the coordinate origin, the step end coordinate is solved according to the step initial coordinate and step length of the point, and the coordinate of the highest point passed by the step is solved for a given step height, and the above coordinates are substituted into a quadratic polynomial to solve the trajectory curve equation of the middle platform (1.2) or the lower platform (1.3); The length of each telescopic branch chain (2.1) during the motion process is solved: a global coordinate system is established at the center point of the upper platform (1.1), and the posture and position of the middle platform (1.2) and the lower platform (1.3) are given. The length of each telescopic branch chain (2.1) at different positions is solved to determine whether it is within the range of its telescopic amount.

8. The gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects according to claim 7, characterized in that: In step S4, when the transport environment is that two 3-UPU hexapod robots collaboratively transport a long heavy object along a straight line, the step length value that meets the conditions of steps S2 and S3 can be used.

9. The gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects according to claim 8, characterized in that: In step S4, the handling environment is when two 3-UPU hexapod robots collaboratively carry a long heavy object along a straight line with a right-angle turn; The front 3-UPU hexapod robot is designated as 3-UPU hexapod robot I, and the rear 3-UPU hexapod robot is designated as 3-UPU hexapod robot II. The direction of the line connecting the center point at the initial position and one of the vertices of the equivalent triangle is designated as the first direction, and the direction of the line connecting the center point at the initial position and one of the intersection points of the two equivalent triangles is designated as the second direction. The 3-UPU hexapod robot I and the 3-UPU hexapod robot II move toward the central intersection of the turning point along the first direction. , and walk along the center line of the channel according to the step length set in the first direction, when the 3-UPU hexapod robot 1 reaches the center intersection of the turning point At , start moving in the second direction and walk according to the set step length in the second direction, where the first direction is perpendicular to the second direction; The 3-UPU hexapod robot II at the rear needs to follow the 3-UPU hexapod robot I and continue to move in the first direction until it reaches the center intersection of the turning point of the 3-UPU hexapod robot II. At the end, the 3-UPU hexapod robot I and the 3-UPU hexapod robot II drive out of the narrow road section along the second direction; In order to make the step length of a single 3-UPU hexapod robot in each direction meet the set value, and to keep the distance between the two constant, As the coordinate origin, establish a coordinate system and analyze the turning process according to the set step size: set up The two ends of the long heavy object in preparation for turning correspond to the positions of 3-UPU hexapod robot I and 3-UPU hexapod robot II respectively. Towards During the process, the moving distance of the 3-UPU hexapod robot II for: Where, is the distance between the upper platforms of 3-UPU hexapod robot I and 3-UPU hexapod robot II; is the set step size for the loop phase in the second direction; Assume that the 3-UPU hexapod robot I has a step length For one step cycle, we can find the i Step length of 3-UPU hexapod robot II for: If the robot is to pass through the bend as a whole, the step length of the 3-UPU hexapod robot II should be Less than or equal to the set step size of the first direction cycle stage; If during the entire turning process, If all the above conditions are met, the 3-UPU hexapod robot I can be Move for one step cycle until completion; If during the entire turning process, In the i If the step time is greater than the set step length of the first direction cycle stage, the gait is adjusted. i -1 movement cycle, 3-UPU hexapod robot II follows the movement of 3-UPU hexapod robot I, from i At the beginning of the step, the 3-UPU hexapod robot II walks according to the set step length of the circulation stage in the first direction, and the 3-UPU hexapod robot I follows it to move until the 3-UPU hexapod robot II reaches the turning point, and the step length of the 3-UPU hexapod robot I that follows it is less than or equal to the set step length of the circulation stage in the second direction.

10. The gait planning method for a 3-UPU hexapod robot for collaboratively carrying long and heavy objects according to claim 9, characterized in that: Analyze whether a long heavy object will collide with the wall during the turning process: Under this gait planning method, the turning point of the inner wall at the turning point is determined. Whether interference occurs is determined by whether the distance between the point and the long weight during movement is greater than the radius of the long weight.

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