Hexaglide type pose transformation supporting device and trajectory planning method thereof

Abstract

The invention discloses a Hexaglide type pose transformation supporting device and a trajectory planning method thereof. The Hexaglide type pose transformation supporting device comprises a static platform, a lead screw guide rail, a sliding block, a connecting rod and a movable platform supporting base. The static platform comprises two sets of symmetrically-arranged rod pieces, each set of rod pieces comprises two parallel vertical rods and two parallel horizontal rods, and the two ends of each vertical rod are fixedly connected with one ends of the two horizontal rods respectively. The plurality of lead screw guide rails are fixedly mounted on the vertical rods at the two ends of the static platform; the sliding block is arranged on a guide rail of the lead screw guide rail; the sliding block is connected with the movable platform supporting seat through a connecting rod; the static platform serves as a supporting base and is fixedly connected with the ground or a foundation. And the movable platform supporting seat is fixedly connected with the test model and drives the test model to carry out pose transformation. The Hexaglide type pose transformation supporting device provided by the invention has the advantages of being simple in structure, convenient to install and fast in system response.

Description

Technical Field

[0001] The present invention relates to the technical fields of non-destructive testing and multi-degree-of-freedom measurement, and specifically refers to a Hexaglide-type pose transformation support device and its trajectory planning method. Background Art

[0002] With the development of technology, parallel six-degree-of-freedom support platforms have become increasingly popular and have become indispensable important devices in fields such as dynamic entertainment facilities, various training simulators, and precision positioning equipment. The configurations of parallel six-degree-of-freedom support systems are mainly divided into Stewart type and Hexaglide type. In the field of scientific research, they are used in various laboratory equipment and research projects to provide experimental conditions and data support for scientific research by simulating motion states under different conditions. The parallel mechanism model support system based on Stewart solves the contradiction between high stiffness and high dynamic response of serial mechanisms, but there are many singular points in the working space. When the end of the moving platform moves near the singular point, the overall stiffness of the mechanism drops sharply. For the parallel mechanism model support based on Hexaglide, its actuators are located on the fixed platform rather than on the linkages, reducing the interference between linkages, expanding the working space of the system, improving the dynamic characteristics of the system, and reducing motion errors.

[0003] Chinese Patent with Application No. CN202310374019.1 discloses a six-degree-of-freedom wind tunnel model support system and control method based on a Hexaglide parallel mechanism. This patent derives the relational expression of the slider position with respect to the connecting rod position and the support rod position, and takes the derivative of the position to obtain the corresponding velocity drive. Finally, the kinematic simulation is carried out using SolidWorks software to verify the correctness of the above-mentioned position relational expression. This patent applies the genetic algorithm to perform multi-objective kinematic iteration optimization on the motion algorithm of the mechanism, optimizes the dimensional parameters of the structure, reduces the slider speed, and the corresponding slider driving force.

[0004] Although the above patent derives the relational expression of the slider position with respect to the connecting rod position and the support rod position, it does not consider the problem of motor step loss caused by excessive acceleration during motor startup and braking, resulting in insufficient running accuracy and lack of stability of the structure. It also does not specifically describe the mechanical structure form, installation support method, and processing method of the parts that complete this function. At the same time, the overall structure is relatively complex, with high processing difficulty and is not suitable for wide application. Summary of the Invention

[0005] To overcome the deficiencies of the above technologies, the purpose of the present invention is to provide a Hexaglide-type pose transformation support device and its trajectory planning method, which solve the problems of complex mechanical space structure and high processing difficulty existing in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A Hexaglide type pose transformation support device, characterized in that it includes a static platform, a lead screw guide rail, a slider, a connecting rod, and a moving platform support seat; the static platform includes two sets of symmetrically arranged rods, each set of rods includes two parallel vertical rods and two parallel horizontal rods, and both ends of each vertical rod are fixedly connected to one end of the two horizontal rods; a plurality of lead screw guide rails are provided and fixedly installed on the vertical rods at both ends of the static platform; the slider is arranged on the guide rail of the lead screw guide rail; the slider is connected to the moving platform support seat through a connecting rod; the static platform serves as a support base and is fixedly connected to the ground or foundation; the moving platform support seat is fixedly connected to the test model and drives the test model to perform pose transformation.

[0008] Further, one of the horizontal rods in the rod is fixedly connected to the ground or foundation through bolts, and the other horizontal rod is arranged above the ground or foundation.

[0009] Further, the lead screw guide rail is equipped with a stepping motor, and the motor shaft of the stepping motor is connected to the lead screw shaft of the lead screw guide rail through a coupling; the guide rail of the lead screw guide rail is a V-shaped guide rail, and the V-shaped guide rail cooperates with the slider to enable the slider to translate on the V-shaped guide rail.

[0010] As a preferred solution, the test model and the static platform are arranged on both sides of the moving platform support seat; a threaded through hole is provided in the middle of the moving platform support seat for fixedly connecting to the test model through bolts and supporting the test model; the moving platform support seat has at least one regular polygon plane, and a plurality of convex platforms are evenly distributed on the regular polygon plane, and the convex platforms are connected to the corresponding sliders through connecting rods; the number of convex platforms is the same as the number of sliders.

[0011] Further, the slider is fixedly connected to a connecting flange, the connecting flange is fixedly connected to a first spherical hinge pair, both ends of the connecting rod are fixedly connected to the first spherical hinge pair and a second spherical hinge pair respectively, and the second spherical hinge pair is fixedly connected to its corresponding convex platform, thereby fixedly connecting the slider to the moving platform support seat.

[0012] Furthermore, the connecting rod is provided with double-headed screw threads and is connected to the first spherical hinge pair and the second spherical hinge pair through bolts at both ends.

[0013] Furthermore, the connecting flange has two end faces, and its central axis is a smoothly transitioning arc perpendicular to both end faces; a threaded through-hole is provided on the slider; threaded through-holes are provided on both end faces of the connecting flange for bolt connection with the slider and the first ball hinge pair respectively; the connecting flange is obtained by 3D printing.

[0014] The present invention also provides a trajectory planning method for the above-mentioned Hexaglide type pose transformation support device, which is characterized in that it includes the following steps:

[0015] 1) Set a global coordinate system and a local coordinate system with the fixed position of the target test model as the origin, and obtain the target pose and target pose transformation speed of the target test model in the global coordinate system;

[0016] The initial pose of the target test model is q0 = [0, 0, 0, 0, 0, 0], and the target pose is q goal = [P x , P y , P z , α, β, γ], and the target pose transformation speed includes a linear velocity V m and an angular velocity W m ; P x , P y , P z are the moving distances of the origin of the local coordinate system of the target test model relative to the initial pose along the X-axis, Y-axis, and Z-axis directions in the global coordinate system respectively, and γ, β, and α are the Euler angles of the target test model around the Z-axis, Y-axis, and X-axis of the global coordinate system, and the rotation order is ZYX;

[0017] 2) Based on the target pose and target pose transformation speed, plan the target pose transformation trajectory curve of the target test model from the initial pose to the target pose; the target pose transformation trajectory includes a linear displacement stage and an angular displacement stage; the linear displacement stage / angular displacement stage includes a starting stage, a constant-speed operation stage, and a braking stage, and the starting stage and the braking stage are planned using a parabolic operation curve;

[0018] 3) Solve the target control pulse signal and direction signal of the stepping motor controller corresponding to the lead screw guide when the target test model undergoes transformation along the target pose transformation trajectory;

[0019] 4) Output the target pulse signal and direction signal of the controller to the stepping motor driver, and the stepping motor driver drives the stepping motor to move, thereby driving the slider to slide on the lead screw guide, and further driving the test model to perform pose transformation by the slider, connecting rod, and moving platform support seat.

[0020] Furthermore, in step 2), the linear displacement stage in the target pose transformation trajectory is as follows:

[0021] Startup phase: t = 0 to t A ;

[0022] Constant velocity operation phase: t = t A to t B ;

[0023] Braking phase: t = t B to t1;

[0024] The angular displacement phases in the target attitude transformation trajectory are as follows:

[0025] Startup phase: t = t1 to t C ;

[0026] Constant velocity operation phase: t = t C to t D ;

[0027] Braking phase: t = t D to t2;

[0028] Wherein, t A is the moment when the linear displacement transformation speed of the target test model increases from 0 to the set transformation speed, t B is the moment when the target test model starts to decelerate during the attitude transformation process at the set linear displacement transformation speed, t1 is the moment when the target test model completes the linear displacement attitude transformation, t C is the moment when the angular displacement transformation speed of the target test model increases from 0 to the set transformation speed, t D is the moment when the target test model starts to decelerate during the attitude transformation process at the set angular displacement transformation speed, t2 is the moment when the target test model completes the angular displacement attitude transformation; P x,t 、P y,t 、P z,t are respectively the moving distances of the origin of the local coordinate system at the rotation center of the target test model along the X-axis, Y-axis, and Z-axis directions in the global coordinate system at time t; γ t , β t , α t are respectively the Euler angles of the target test model around the Z-axis, Y-axis, and X-axis of the global coordinate system at time t.

[0029] Further, step 3) includes: sampling the target pose transformation trajectory curve to obtain a sampling curve; for the rotation center pose of the test model corresponding to each sampling point, obtaining the global coordinate system corresponding to the origin of the local coordinate system at the sampling point and obtaining the homogeneous transformation matrix of the hard points of the test model with respect to the local coordinates according to the relationship between the local coordinate system and the global coordinate system in the initial pose; obtaining the global coordinates of the corresponding hard points through homogeneous transformation matrix operations based on the coordinates of the hard points in the local coordinate system, and then deriving the global coordinates of the slider through geometric relationships; finally, determining the rotation angle of the stepping motor at the sampling moment according to the global coordinates of the slider, thereby determining the pulse signal and the direction signal.

[0030] The rotation angle of the stepping motor at the sampling moment is obtained by the following formula:

[0031]

[0032] In the formula, is the moving distance of the i-th slider relative to the initial position on the guide rail at the sampling moment; is the initial global coordinate of the i-th slider; D s is the lead of the lead screw; is the rotation angle of the stepping motor at the sampling moment; is the global coordinate of the i-th slider;

[0033] The pulse signal and the direction signal of each slider corresponding to the stepping motor controller at the sampling moment are determined through the rotation angle of the stepping motor at the sampling moment.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] A Hexaglide type pose transformation support device and its trajectory planning method disclosed by the present invention have the advantages of simple structure, convenient installation and fast system response.

[0036] (1) In the present invention, the hard points of the moving platform are symmetrically arranged in the same plane, and the position of the hard points of the static platform is optimized to coordinate the support device to meet the performance indicators of various working spaces, making the overall structure of the moving platform simple and convenient for integrated processing; at the same time, the bolt holes in the middle of the moving platform can be applied to different aircraft models, realizing the universal use of the support device.

[0037] (2) In the present invention, the central axis of the connecting flange uses an arc to reverse the normal direction of the connecting surface, and then uses 3D printing to meet the connection of two intersecting connecting surfaces and avoid the difficulty of machining through printing. The support device is connected by spherical hinge pairs, which has the characteristics of lighter structure, more flexible steering and more convenient installation compared with Hooke joints.

[0038] (3) The present invention adopts a parabolic running curve trajectory planning method, which has a short acceleration time, a fast system response, a smooth change process between the acceleration and deceleration stages and the constant speed stage, effectively alleviates the influence of excessive acceleration during the start or braking process of the stepping motor, and reduces the impact on the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 FIG. is a schematic structural diagram of a Hexaglide type pose transformation support device of the present invention;

[0040] Figure 2 is Figure 1 a schematic structural diagram of the movable platform support seat in;

[0041] Figure 3 is Figure 1 a schematic structural diagram of the connecting flange in;

[0042] Figure 4 is Figure 1 a target pose transformation speed curve diagram in the trajectory planning method of the Hexaglide type pose transformation support device;

[0043] Figure 5 is Figure 1 a target pose transformation trajectory curve diagram of the trajectory planning method of the Hexaglide type pose transformation support device;

[0044] Figure 6 is Figure 1 a pulse generation program flow chart in the trajectory planning method of the Hexaglide type pose transformation support device;

[0045] Figure 7 is a Z-direction target pose transformation trajectory curve diagram in the trajectory planning method of the Hexaglide type pose transformation support device in the specific implementation manner;

[0046] Figure 8 is Figure 7 a stepping motor angular displacement curve diagram corresponding to the Z-direction target pose transformation trajectory curve;

[0047] Figure 9 is Figure 7 a controller pulse signal curve diagram corresponding to the Z-direction target pose transformation trajectory curve;

[0048] In the figure: 1. Static platform; 101. First horizontal rod; 102. Second horizontal rod; 103. Vertical rod; 2. Lead screw guide rail; 201. First lead screw guide rail; 202. Second lead screw guide rail; 203. Third lead screw guide rail; 204. Fourth lead screw guide rail; 205. Fifth lead screw guide rail; 206. Sixth lead screw guide rail; 3. Slide block; 4. Connecting flange; 5. First ball hinge pair; 6. Connecting rod; 7. Second ball hinge pair; 8. Moving platform support seat; 801. First boss; 802. Second boss; 803. Third boss; 804. Fourth boss; 805. Fifth boss; 806. Sixth boss; 9. Center O1 of the boss hard point; 10. Global coordinate O_XYZ; 11. Rotation center O2 (local coordinate center). Detailed implementation mode

[0049] In order to better explain the present invention, the main content of the present invention will be further clarified below in conjunction with the accompanying drawings and specific embodiments, but the content of the present invention is not limited to the following embodiments only.

[0050] Embodiment 1

[0051] As Figure 1 shown, a Hexaglide type pose transformation support device, its mechanical structure includes a static platform 1, a lead screw guide rail 2, a slide block 3, a connecting flange 4, a first ball hinge pair 5, a connecting rod 6, a second ball hinge pair 7, and a moving platform support seat 8.

[0052] For the convenience of more clearly elaborating the pose transformation of the test model later, a global coordinate system and a local coordinate system are established below. Global coordinate system: When the moving platform support seat 8 is in the initial position, a global coordinate O_XYZ is established with the center of the boss hard point O19 being 60 mm directly behind the inner side of the static platform 1 as the global coordinate center 10. Its X direction points horizontally directly backward, the Z direction is perpendicular to the horizontal plane and points upward, and the Y direction follows the right-hand screw rule. Local coordinate system: A local coordinate system O2_xyz with the rotation center O211 as the local coordinate center is established 100 mm directly in front of the outer side of the boss hard point O19 close to the static platform 1. Its direction is the same as that of O_XYZ, and the coordinates of the local coordinate center in the global coordinate change with the pose transformation of the test model.

[0053] The static platform 1 serves as the base of the support device and is fixedly connected to the ground or foundation by bolts. The static platform 1 is composed of two groups of parallel and symmetrical rods. Each group of rods includes a first horizontal rod 101, a second horizontal rod 102 that is parallel to the first horizontal rod 101 and has exactly the same size, and two vertical rods that are parallel to each other and have exactly the same size. In each group of rods, the first horizontal rod 101 is placed on the ground or foundation and is fixedly connected to the ground or foundation by bolts. The second horizontal rod 102 is arranged directly above the first horizontal rod 101. The two vertical rods 103 are perpendicular to the ground or foundation, and the two ends of the vertical rods 103 are respectively fixedly connected to the two ends of the two horizontal rods.

[0054] The lead screw guide 2 is fixedly connected to the end of the static platform 1 by bolts and is respectively fixedly connected to the vertical rods 103 at the same end of the two groups of rods of the static platform 1 by bolts, thereby connecting the two groups of rods. There are six lead screw guides 2, and three are arranged on each vertical rod 103 at each end of the static platform 1. The six lead screw guides 2 are parallel to each other and are symmetrically arranged on the vertical rods at both ends of the static platform 1. Among them, the fifth lead screw guide 205 and the second lead screw guide 202 are symmetrically arranged on the upper part of the vertical rod 103, and the fourth lead screw guide 204 and the sixth lead screw guide 206 are symmetrically arranged with the first lead screw guide 201 and the third lead screw guide 203 on the lower part of the vertical rod 103 respectively.

[0055] The slider 3 is arranged on the guide rail of the lead screw guide 2, and the lead screw guide 2 is connected to the slider 3 through a screw pair. The guide rail is a V-shaped guide rail, and the V-shaped guide rail cooperates with the slider 3 so that the slider 3 can translate on the V-shaped guide rail. By setting limit blocks at both ends of the V-shaped lead screw guide rail, the slider will not slide off from both ends of the guide rail, thereby improving the safety of the slider during sliding. The lead screw guide 2 is equipped with a stepping motor, which is installed at one end of the lead screw guide 2. The motor shaft of the stepping motor is connected to the lead screw shaft of the lead screw guide 2 through a coupling. By driving the motor shaft to rotate by the stepping motor, the lead screw shaft is driven to move, and the lead screw shaft drives the ball screw to move, thereby driving the slider 3 to slide, converting the rotational motion of the stepping motor into the translational motion of the slider 3. The lead screw pitch is 10 mm. Among them, the specific structures of the lead screw guide and the stepping motor are prior arts and will not be elaborated here.

[0056] The slider 3 is connected to the moving platform support 8 through a connecting rod 6.

[0057] Specifically, the slider 3 is first fixedly connected to the connecting flange 4 by bolts, and then the connecting flange 4 is fixedly connected to the first ball joint 5 by bolts. The connecting rod 6 is provided with double-headed screw threads and is respectively connected to the first ball joint 5 and the second ball joint 7 by bolts at both ends. The second ball joint 7 is fixedly connected to the moving platform support 8. The connecting rod 6 plays a role in supporting the moving platform support 8, and the moving platform support 8 is used to connect the test model and drive the test model to perform various pose transformations.

[0058] Specifically, the first spherical hinge pair 5 and the second spherical hinge pair 7 are symmetrically distributed left and right with respect to the vertical plane O_XZ. Their central unit normal vector is initialized as I0 = [x0 y0 z0]. Then, the motion conditions of the support device under various working conditions with this initial value are solved, and the genetic algorithm is used to solve the optimal unit normal vector, so that the support device meets all the working space requirements and has the optimal size under this set of normal vector parameters. The unit normal vector after iterative optimization is as follows: the central normal vectors of the upper planes of the first spherical hinge pairs 5 connected to the first lead screw guide 201 to the sixth lead screw guide 206 are [-0.7 -0.4 0.592], [-0.7 -0.45 -0.555], [-0.7 -0.5 0.509], [-0.7 0.4 0.592], [-0.7 0.45 -0.555], [-0.7 0.5 0.509] in sequence; the central normal vectors of the upper planes of the second spherical hinge pairs 7 connected to the first lead screw guide 201 to the sixth lead screw guide 206 are [0.75 0.5 -0.433], [0.75 0.4 0.527], [0.85 0.5 -0.166], [0.75 -0.5 -0.433], [0.75 -0.4 0.527], [0.85 -0.5 -0.166] in sequence.

[0059] As Figure 2 shown, the moving platform support base 8 is a regular hexagonal plate-like structure. The static platform 1 and the test model are respectively arranged on both sides of the moving platform support base 8 and are connected to two regular hexagonal faces respectively. A threaded through hole is provided in the middle of the regular hexagon of the moving platform support base 8 for fixedly connecting with the test model through bolts and supporting the test model. Six bosses with different orientations are arranged inside the six inner angles on the regular hexagonal plane of the moving platform support base 8 close to the static platform 1 side, and screw holes are provided on the bosses for connecting with the second spherical hinge pair 7 through bolts. The moving platform support base 8 is grooved to reduce its own weight, and its body is 3D printed and threaded holes are machined by a machine tool.

[0060] Specifically, the six bosses on the moving platform support base 8 include the first boss 801, the second boss 802, the third boss 803, the fourth boss 804, the fifth boss 805, and the sixth boss 806, which are respectively connected to the sliders on the corresponding first lead screw guide 201, second lead screw guide 202, third lead screw guide 203, fourth lead screw guide 204, fifth lead screw guide 205, and sixth lead screw guide 206. Among them, the first boss 801 is connected to the slider of the first lead screw guide 201 through its corresponding second ball hinge pair 7, connecting rod 6, first ball hinge pair 5, and connecting flange 4, and so on for the others. The end faces of the six bosses facing the sliders have the same normal vector as the end face of their corresponding second ball hinge pair 7, that is, the central unit normal vectors corresponding to the planes of the first boss 801 to the sixth boss 806 are: [0.75 0.5 -0.433], [0.75 0.4 0.527], [0.85 0.5 -0.166], [0.75 -0.5 -0.433], [0.75 -0.4 0.527], [0.85 -0.5 -0.166].

[0061] As Figure 3 shown, the end face of the connecting flange 4 connected to the slider 3 is parallel to the connecting face on the slider 3 and is set as a rectangle, and the end face connected to the first ball hinge pair 5 is set as a circle and faces the direction of its corresponding boss. Four threaded through holes are provided on both end faces of the connecting flange 4. The two end faces of the connecting flange 4 are not parallel, and the central axis is a smoothly transitioning arc perpendicular to the two end faces. The part between the two end faces of the connecting flange 4 has a circular cross-section, and the diameter is smaller than the circular end face of the connecting flange 4. The circular end face of the connecting flange 4 is provided with a small circular cross-section with a diameter of 60 mm, and the rectangular end face is provided with a large circular cross-section with a diameter of 95 mm. A multi-section solid is created with the central axis as the guiding line and the large and small circles as the cross-sections. Finally, the connecting flange 4 is sliced and printed with pla material by 3D printing, which greatly saves the cost of manual machining and unnecessary material by-products. The connecting flange 4 connects two planes where the normal lines intersect, playing a role in adjusting the normal direction change of the support surface.

[0062] The circular end faces of the six connecting flanges 4 are respectively parallel to the end faces of the corresponding connecting bosses on the moving platform support base 8. The orientation of the boss matches the orientation of the end face of its corresponding connecting flange 4 to ensure uniform force transmission, reduce the stress of the connecting rod 6, avoid causing deformation or fracture, and ensure the motion accuracy and stability of the slider 3 and the connecting rod 6.

[0063] The connecting rod 6 is made of stainless steel and is processed with double-headed threads, and the two ends are respectively connected to the first ball hinge pair 5 and the second ball hinge pair 7 through bolts. The thread diameter is 5 mm, the pitch length is 0.8 m, and the thread length is 10 mm.

[0064] The static platform 1 is made of angle steel structure, and its surface is evenly processed with threaded holes. It is fixedly connected to the ground by screws, providing support and positioning for the moving platform support device. Six slideway motors are distributed on the static platform 1. Driven by a stepping motor, the lead screw drives the slider to make reciprocating linear motion on the slideway. The controller of the stepping motor used is LingSiChuangQi, which outputs 6-channel pulse signals. The driver used is a special TB6600 57-stepping motor driver, with an output current of 0.5 - 4.0A and a maximum output power of 160W. As the spatial position of the slider 3 changes, the moving platform will perform corresponding linear, rotational or composite motions.

[0065] Embodiment 2:

[0066] A trajectory planning method for a Hexaglide-type pose transformation support device, which is used for the Hexaglide-type pose transformation support device in Embodiment 1, includes the following steps:

[0067] 1) Set the global coordinate system and the local coordinate system with the fixed position of the target test model as the origin, and obtain the target pose and the target pose transformation speed of the target test model in the global coordinate system. In this embodiment, the global coordinate system and the local coordinate system are the same as those in Embodiment 1.

[0068] The initial pose of the test model is q0 = [0, 0, 0, 0, 0, 0], and the target pose of the test model is q goal =[P x , P y , P z , α, β, γ], where P x , P y , P z are the moving distances of the origin of the local coordinate system of the target test model relative to the initial pose along the X-axis, Y-axis, and Z-axis directions in the global coordinate system respectively, and γ, β, and α are the Euler angles of the target test model around the Z-axis, Y-axis, and X-axis of the global coordinate system respectively, and the rotation order is ZYX;

[0069] The target pose transformation speed of the test model includes the linear velocity V m and the angular velocity W m .

[0070] At this time, the initial pose of the origin of the local coordinate system at the rotation center of the target test model is q0 = [0, 0, 0, 0, 0, 0], and the coordinates of this initial pose in the global coordinate system are (-160, 0, 0, 0, 0, 0). Therefore, the position of the target pose in the global coordinate system is (-160 + P x , P y , P z , α, β, γ).

[0071] 2) Plan the target attitude transformation trajectory of the target test model from the initial attitude to the target attitude;

[0072] 3) Solve the target control pulse signal and direction signal of the controller of each slider corresponding stepping motor when the target test model transforms along the target attitude transformation trajectory;

[0073] 4) Output the target pulse signal and direction signal of the controller to the stepping motor driver. The stepping motor driver drives the stepping motor to move. The stepping motor drives the ball screw to rotate. The ball screw drives the slider to slide on the screw guide rail. Further, the slider, connecting rod and moving platform drive the test model to perform pose transformation.

[0074] In step 2), the target attitude transformation trajectory Xθ_t consists of a linear motion X_t and a rotational motion θ_t. The order of the linear motion and the rotational motion can be sequential. Then the target attitude can be written as the trajectory value q of the target attitude transformation trajectory at the last moment goal =[X_t,θ_t] t＝endtime .

[0075] The following takes the linear motion X_t in the X-axis direction as an example to illustrate the trajectory planning. The trajectory planning of the linear motions in the Y-axis and Z-axis directions and the rotational motion also adopts the same principle.

[0076] Assume that under the compound working condition, q goal =[x1,0,0,α1,0,0]. Then the Xθ_t target attitude transformation trajectory is divided into two stages. The linear displacement stage includes the attitude q0=[0,0,0,0,0,0] at t0 = 0 to the attitude q1=[x1,0,0,0,0,0] at t1. The angular displacement stage includes the attitude q1=[x1,0,0,0,0,0] at t1 to the attitude q2=[x1,0,0,α1,0,0] at t2.

[0077] As Figure 4 shown, adopt the running curve of a parabola to plan the target attitude transformation speed curve of the test model from t0 = 0 to t1 in the linear displacement stage. Starting stage (t = 0~t A ), Constant speed running stage (t = t A ~t B ), V = V m ; Braking stage (t = t B ~t1), Assume that the starting time and the braking time are both t A and are known. Then the total changed pose x1 in the three stages can be expressed as:

[0078]

[0079] Solve to get:

[0080]

[0081] As Figure 5 shown, the target attitude transformation trajectory curve X_t from t0 = 0 to t1 for the linear displacement stage is:

[0082] Starting stage (t = 0 to t A ),

[0083] Constant velocity operation stage (t = t A to t B ),

[0084] Braking stage (t = t B to t1),

[0085] Similarly, the transformation trajectories in the Y-axis and Z-axis directions refer to the transformation trajectory of the X-axis. That is:

[0086] Starting stage: t = 0 to t A ;

[0087] Constant velocity operation stage: t = t A to t B ;

[0088] Braking stage: t = t B to t1;

[0089] Similarly, the target attitude transformation trajectory curve θ_t from t1 to t2 for the angular displacement stage is:

[0090] Starting stage: t = t1 to t C ;

[0091] Constant velocity operation stage: t = t C to t D ;

[0092] Braking stage: t = t D to t2;

[0093] In the formula, t A is the moment when the linear displacement transformation speed of the target test model increases from 0 to the set transformation speed, t B is the moment when the target test model starts to decelerate during the attitude transformation process at the set linear displacement transformation speed, t1 is the moment when the target test model completes the linear displacement attitude transformation, t CThe moment when the angular displacement transformation speed of the target test model increases from 0 to the set transformation speed, t D The moment when the target test model starts to decelerate during the attitude transformation process at the set angular displacement transformation speed, t2 is the moment when the target test model completes the angular displacement attitude transformation; P x,t 、P y,t 、P z,t The moving distances of the origin of the local coordinate system of the target test model along the X-axis, Y-axis, and Z-axis directions in the global coordinate system at time t are respectively; γ t ,β t ,α t The Euler angles of the target test model around the rotation center around the Z-axis, Y-axis, and X-axis of the global coordinate system at time t are respectively, and the rotation order is ZYX.

[0094] Step 3) specifically includes:

[0095] Sample the target attitude transformation trajectory curve with a sampling period of 0.001 s to obtain a sampling curve.

[0096] For the attitude of the rotation center of the test model corresponding to each sampling point, based on the relationship between the local coordinate system and the global coordinate system in the initial attitude, obtain the global coordinate position [x, y, z, α, β, γ] corresponding to the rotation center of the target test model at the sampling point and obtain the homogeneous transformation matrix of the hard points of the test model with respect to the local coordinate. In this specific embodiment, among the global coordinate positions corresponding to the rotation center of the target test model at the sampling point, x, y, and z are the coordinates of the rotation center of the target test model, that is, the coordinates of the origin of the local coordinate in the global coordinate. At this time, x = -160 + P x,t ,y = P y,t ,z = P z,t .

[0097] The homogeneous transformation matrix of the hard points of the test model with respect to the local coordinate of the rotation center of the test model is:

[0098]

[0099] where [x, y, z, α, β, γ] is the attitude of the test model at the sampling point t n = n * 0.001 moment, and s, c are sine and cosine operations.

[0100] According to the coordinates of the six hard points in the local coordinate system, through homogeneous transformation matrix operations, obtain the global coordinates of the six hard points of the corresponding test model, and then deduce the position of the slider through geometric relationships. Among them, the positions of the six hard points are the positions on the moving platform support seat connected to the connecting rod. The specific operations are as follows:

[0101] Let the local coordinates of the six hard points of the test model relative to the rotation center coordinate system be The global coordinates of the six hard points of the test model are as follows:

[0102]

[0103] Among them, r1, r2,......, r6 respectively correspond to the coordinates of the hard point of the ball center of the second ball hinge pair 7 on the i-th convex platform of the moving platform support seat in the local coordinate system, i = 1 to 6, and R1, R2,......, R6 respectively correspond to the global coordinates of the six hard points.

[0104] Let the global coordinates of the slider be Then the distance between the slider and the corresponding hard point (which can be calculated based on the connecting rod length) is:

[0105]

[0106] Solving for the global coordinates of the slider

[0107]

[0108] In the formula, X i , Y i , Z i respectively represent the global coordinates of the hard point of the ball center of the i-th second ball hinge pair on the convex platform of the moving platform support seat, i = 1 to 6; is the global coordinate of the i-th slider, i = 1 to 6; L i is the distance between the i-th slider and the corresponding hard point.

[0109] Let the initial coordinates of the slider be Then the moving distance of the slider relative to the initial position on the guide rail at the sampling moment is:

[0110] Through the lead screw pitch D s , the rotation angle of the stepping motor at the sampling moment can be obtained as:

[0111]

[0112] Counting the rotation angles of the stepping motor corresponding to all sampling moments, the driving angular displacement curve of the stepping motor is obtained

[0113] The lead screw pitch of the stepping motor is 10 mm. The step angle is 1.8°.

[0114] As Figure 6 shown, let the driving angular displacement curve of the stepping motor have the last sampling moment t N = N * 0.001 s, and the determination method of the pulse signal and the direction signal is as follows:

[0115] a) At the initial moment \(n = 0\), \(t\) n \(=n\times0.001 = 0\times0.001 = 0\), the pulse - driven rotation angle \(\varPsi = 0^{\circ}\), and the absolute value of the difference between the driven angular displacement and the pulse - driven rotation angle is less than \(1.8^{\circ}\). No pulse signal is generated at this moment.

[0116] b) When \(t\) n \(=n\times0.001\), the absolute value of the difference between the driven angular displacement and the pulse - driven rotation angle is greater than or equal to \(1.8^{\circ}\). At this moment, a pulse signal and a direction signal are generated, and the pulse - driven rotation angle \(\varPsi\) is updated. If the difference between the driven angular displacement and the pulse - driven rotation angle is greater than \(1.8^{\circ}\), the updated pulse - driven rotation angle \(\varPsi=\varPsi + 1.8^{\circ}\); if the difference between the driven angular displacement and the pulse - driven rotation angle is less than \(-1.8^{\circ}\), the updated pulse - driven rotation angle \(\varPsi=\varPsi-1.8^{\circ}\).

[0117] c) Determine whether \(n\) is less than \(N\): If so, let \(n=n + 1\) and repeat step b); if not, the program ends.

[0118] In step 4), the controller outputs the above - mentioned pulse signal to the stepper - motor driver to drive the stepper motor, transmission screw, connecting rod, moving platform and test model, so that the test model is transformed to the target pose according to the planned trajectory.

[0119] The present invention will be further described below with reference to the accompanying drawings by way of example.

[0120] The target attitude of the target test model is obtained as \(q\) goal \(=[0,0,75,0,0,0]\), and the target attitude transformation speed is \(10\mathrm{mm / s}\).

[0121] The start - up time and braking time \(t\) A \(=0.375\mathrm{s}\), then the uniform - motion time \(t\) B is:

[0122]

[0123] The target - attitude transformation trajectory curve \(X_t\) from \(t_0 = 0\) to \(t_1\) for the linear - displacement stage is:

[0124] Startup stage (\(t = 0\sim0.375\mathrm{s}\)),

[0125]

[0126] Uniform - motion stage (\(t = 0.375\sim7.375\mathrm{s}\)),

[0127]

[0128] Braking stage (\(t = 7.375\sim7.75\mathrm{s}\)),

[0129]

[0130] The trajectory planning of the moving platform is as Figure 7 shown.

[0131] Sampling the target attitude transformation trajectory curve X_t, the pose at the nth moment t n = 0.001 * n and the corresponding homogeneous transformation matrix T can be obtained. Here, it is assumed that t n = 0.375 s, then P z,t = 2.5 mm. Since the Z-axis coordinates of the local coordinate and the global coordinate are the same in the initial state, the global coordinate of the rotation center at this time is: [-160, 0, 2.5, 0, 0, 0].

[0132] The homogeneous transformation matrix is:

[0133]

[0134] The local coordinates of the six hard points relative to the rotation center coordinate system are:

[0135]

[0136] Among them, r1, r2,......, r6 respectively correspond to the coordinates of the spherical center hard point of the second spherical hinge pair 7 on the i-th convex platform of the moving platform support seat in the local coordinate system, i = 1 to 6.

[0137] Then the global coordinates of the six hard points of the test model are:

[0138]

[0139] Moreover, the lengths of the six connecting rods, that is, the distances between the six sliders and the corresponding hard points are:

[0140] [L1 L2 L3 L4 L5 L6] = [625.194 488.057 574.898 625.194 488.057 574.898],

[0141] Then the global coordinates of the sliders (which is the position of the slider on the guide rail) are:

[0142]

[0143] The moving distance of the slider relative to the initial coordinate is :

[0144]

[0145] Then the rotation angle of the stepper motor at the sampling moment is:

[0146]

[0147] The stepping motor rotation angles corresponding to all sampling moments are statistically analyzed to obtain the driving angular displacement curve of the stepping motor. As Figure 8 shown. Figure 8 In it, motors 1, 2, 3, 4, 5, and 6 are the corresponding stepping motors on the first lead screw guide 201, the second lead screw guide 202, the third lead screw guide 203, the fourth lead screw guide 204, the fifth lead screw guide 205, and the sixth lead screw guide 206 respectively.

[0148] According to the driving angular displacement curve of the stepping motor the control pulse signals of each stepping motor can be obtained. As Figure 9 shown, it is the control pulse signal of motor 1. It can be seen from Figure 9 that the control pulse signal of motor 1 is relatively sparse in the start-up stage and the braking stage. In the constant-speed operation stage, the pulse signal is the densest and remains unchanged, which is consistent with the speed change of the planned test model's transformation pose. The acceleration and deceleration stage and the constant-speed operation stage are smooth, preventing excessive acceleration and reducing the impact on the motor.

[0149] Finally, the control pulse signals of each motor are input into the stepping motor driver to drive the stepping motor to rotate, and drive the lead screw, slider, connecting rod, moving platform and test model to move, so as to control the test model to reach the target pose according to the planned trajectory.

[0150] In the present invention, a special connecting flange is designed between the slider and the connecting rod, and this complex connecting structure is 3D printed. The slider, flange and connecting rod are sequentially connected by bolts, reducing the complexity of machining and assembly in the prior art. At the same time, bolt holes are provided in the middle of the moving platform, and different test models can be connected to the moving platform by bolts, improving the generalization degree of the support device.

[0151] The present invention adopts the method of parabola speed drive for pose transformation trajectory planning aiming at the target pose and the target pose transformation speed. The pose transformation trajectory is smooth in the acceleration and deceleration stage and the constant-speed operation stage, preventing excessive acceleration and reducing the impact on the motor. The angular displacement curve of the stepping motor and the control pulse signal curve of the stepping motor driver both have a start-up stage and a braking stage, effectively alleviating the influence of excessive acceleration during the start-up or braking process of the stepping motor.

[0152] Other parts not described belong to the prior art.

Claims

1. A Hexaglide type posture change support device, characterized in that: The invention comprises a static platform (1), a lead screw guide rail (2), a slider (3), a connecting rod (6), and a dynamic platform support seat (8); the static platform (1) comprises two groups of symmetrically arranged rods, each group of rods comprises two mutually parallel vertical rods and two mutually parallel horizontal rods, and the two ends of each vertical rod are respectively fixedly connected to one end of the two horizontal rods; the lead screw guide rail (2) is provided with a plurality of guides, which are fixedly mounted on the vertical rods at the two ends of the static platform (1); the slider (3) is arranged on the guide rail of the lead screw guide rail (2); the slider (3) is connected to the dynamic platform support seat (8) through a connecting rod (6); the static platform (1) serves as a support base and is fixedly connected to the ground or a foundation; the dynamic platform support seat (8) is fixedly connected to a test model to drive the test model to change its posture.

2. The Hexaglide type posture change support device according to claim 1, characterized in that: One horizontal rod among the rods is fixedly connected to the ground or foundation by bolts, and the other horizontal rod is arranged above the ground or foundation.

3. The Hexaglide type posture change support device according to claim 1, characterized in that: The lead screw guide rail (2) is equipped with a stepper motor, and the motor shaft of the stepper motor is connected to the lead screw shaft of the lead screw guide rail (2) via a coupling; the guide rail of the lead screw guide rail (2) is a V-shaped guide rail, and the V-shaped guide rail cooperates with the slider (3) so that the slider (3) can translate on the V-shaped guide rail.

4. The Hexaglide type posture change support device according to claim 1, characterized in that: The test model and the static platform (1) are arranged on both sides of the dynamic platform support seat (8); a threaded through hole is arranged in the middle of the dynamic platform support seat (8) for being fixedly connected to the test model by bolts and supporting the test model; the dynamic platform support seat (8) has at least one regular polygonal plane, and a plurality of bosses are evenly distributed on the regular polygonal plane, and the bosses are connected to corresponding sliders (3) via connecting rods (6); the number of the bosses is consistent with the number of the sliders (3).

5. The Hexaglide type posture change support device according to claim 4, characterized in that: The slider (3) is fixedly connected to the connecting flange (4), the connecting flange (4) is fixedly connected to the first ball joint pair (5), the two ends of the connecting rod (6) are respectively fixedly connected to the first ball joint pair (5) and the second ball joint pair (7), and the second ball joint pair (7) is fixedly connected to its corresponding boss, thereby fixing the slider (3) to the moving platform support seat (8).

6. The Hexaglide type posture change support device according to claim 5, characterized in that: The connecting rod (6) is provided with double-start screw threads, and both ends are respectively connected to the first ball joint pair (5) and the second ball joint pair (7) by bolts.

7. The Hexaglide type posture change support device according to claim 5, characterized in that: The connecting flange (4) has two end faces, wherein the central axis is a smoothly transitioning arc perpendicular to both end faces; a threaded through hole is arranged on the slider (3); threaded through holes are arranged on both end faces of the connecting flange (4) for respectively connecting to the slider (3) and the first ball joint pair (5) through bolts; the connecting flange (4) is obtained by 3D printing.

8. The trajectory planning method of the Hexaglide type posture transformation support device according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) Setting a global coordinate system and a local coordinate system with the fixed position of the target test model as the origin, and obtaining the target posture and target posture transformation speed of the target test model in the global coordinate system; The initial pose of the target test model is q0 = [0,0,0,0,0,0], and the target pose is q goal =[P x ,P y ,P z ,α,β,γ], the target attitude change speed includes the linear velocity V m and angular velocity W m ;P x , P y , P z are the moving distances of the origin of the local coordinate system of the target test model relative to the initial posture along the X-axis, Y-axis, and Z-axis directions in the global coordinate system, respectively; γ, β, and α are the Euler angles of the target test model around the Z-axis, Y-axis, and X-axis of the global coordinate system, respectively; and the rotation order is ZYX; 2) Based on the target posture and the target posture change speed, planning the target posture change trajectory curve of the target test model from the initial posture to the target posture; the target posture change trajectory includes a linear displacement stage and an angular displacement stage; the linear displacement stage / angular displacement stage includes a starting stage, a uniform speed running stage, and a braking stage, wherein the starting stage and the braking stage are planned using a parabolic running curve; 3) solving the target control pulse signal and direction signal of the stepper motor controller corresponding to the lead screw guide when the target test model is transformed along the target posture transformation trajectory; 4) Output the target pulse signal and direction signal of the controller to the stepper motor driver, which drives the stepper motor to move, thereby driving the slider to slide on the screw guide rail, and further drives the test model to change its posture by the slider, connecting rod and moving platform support seat.

9. The trajectory planning method according to claim 8, characterized in that: In step 2), the midline displacement phase of the target posture transformation trajectory is as follows: Start-up phase: t = 0 ~ t A ;P x,t , P y,t , Uniform speed running stage: t = t A ~t B ;P x,t , P y,t , Braking phase: t = t B ~t1;P x,t , P y,t , The angular displacement phase in the target attitude transformation trajectory is as follows: Start-up phase: t = t1 ~ t C ; α t , β t , Uniform speed running stage: t = t C ~t D ; α t , β t , Braking phase: t = t D ~t2;α t , β t , Where, t A is the moment when the linear displacement transformation speed of the target test model increases from 0 to the set transformation speed, t B is the moment when the target test model starts to decelerate during the posture transformation process at the set linear displacement transformation speed, t1 is the moment when the target test model completes the linear displacement posture transformation, and t C is the moment when the angular displacement transformation speed of the target test model increases from 0 to the set transformation speed, t D P is the moment when the target test model starts to decelerate during the posture transformation process at the set angular displacement transformation speed, and t2 is the moment when the target test model completes the angular displacement posture transformation; x,t , P y,t , P z,t are the moving distances of the origin of the local coordinate system of the target test model along the X-axis, Y-axis, and Z-axis in the global coordinate system at time t; t , β t , α t are the Euler angles of the target test model around the Z-axis, Y-axis and X-axis of the global coordinate system at time t respectively.

10. The trajectory planning method according to claim 8, characterized in that: Step 3) includes: sampling the target posture transformation trajectory curve to obtain a sampling curve; for the rotation center posture of the test model corresponding to each sampling point, according to the relationship between the local coordinate system and the global coordinate system under the initial posture, obtaining the global coordinates corresponding to the origin of the local coordinate system at the sampling point and obtaining the homogeneous transformation matrix of the hard point of the test model with respect to the local coordinates; according to the coordinates of the hard point in the local coordinate system, obtaining the global coordinates of the corresponding hard point through homogeneous transformation matrix operation, and then deriving the global coordinates of the slider through geometric relationships; finally, determining the rotation angle of the stepper motor at the sampling moment according to the position of the slider, thereby determining the pulse signal and the direction signal; The rotation angle of the stepper motor at the sampling moment is obtained by the following formula: In the formula, is the moving distance of the slider relative to the initial position on the guide rail at the sampling moment of the i-th slider; is the initial global coordinate of the ith slider; D s is the lead of the screw; is the rotation angle of the stepper motor at the sampling moment; is the global coordinate of the i-th slider; The pulse signal and direction signal of the stepper motor controller corresponding to each slider at the sampling moment are determined through the rotation angle of the stepper motor at the sampling moment.

Images