Parallel robot pose measurement device and method based on combination of pull wire and two-dimensional tilt meter

Abstract

The present application relates to the field of robot measurement technology, and more particularly to a parallel robot pose measurement device and method based on a combination of a pull wire and a two-dimensional tilt angle instrument, the pose measurement system comprising an upper platform connecting module installed at the geometric center position of the upper platform of the parallel robot and a lower platform connecting module installed at the geometric center position of the lower platform of the parallel robot, the upper platform connecting module comprising a first gimbal, a pose measurement two-dimensional tilt angle instrument and a first gimbal measurement two-dimensional tilt angle instrument, and the lower platform connecting module comprising a second gimbal, a pull wire displacement sensor and a second gimbal measurement two-dimensional tilt angle instrument; through combined measurement of a single pull wire displacement sensor and multiple tilt angle instruments, the pose measurement of a six-degree-of-freedom parallel robot is achieved, and the system has a simple structure and a low price, and the measurement system is installed inside the parallel robot, which neither affects the movement of the parallel robot nor covers the entire movement space of the parallel robot.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of robot measurement technology, in particular to a parallel robot pose measurement device and method based on a combination of a wire and a two-dimensional inclinometer. BACKGROUND

[0002] With the continuous breakthrough and development of science and technology, robot technology plays an indispensable role in the process of social development. At present, serial industrial robots are widely used in welding, handling and other fields due to their good flexibility. However, serial industrial robots also have certain structural defects, such as low positioning accuracy and poor load capacity. On the contrary, parallel industrial robots have high positioning accuracy and load capacity.

[0003] According to the degrees of freedom of parallel industrial robots, they are divided into three degrees of freedom, four degrees of freedom, five degrees of freedom and six degrees of freedom. The typical structure of six degrees of freedom parallel industrial robots is Stewart parallel robot. The robot mainly connects the upper platform and the lower platform through six telescopic connecting rods, and the controller drives the six connecting rods to perform telescopic movement to make the moving platform reach different poses.

[0004] However, the Stewart parallel robot is also a semi-closed loop control system, which mainly controls the position of the electric cylinder in the controller, and does not pay attention to whether the end pose of the Stewart parallel robot reaches the target pose. By optimizing the resolution of the motor encoder or grating ruler in the electric cylinder, the control accuracy of the electric cylinder position can be realized. However, the machining and assembly errors of the mechanical structure cannot be reflected through the position feedback of the electric cylinder, and higher precision robot pose control cannot be realized.

[0005] The current main measurement system is based on external measurement equipment, such as laser tracker, stereo vision measurement system, etc. Such equipment is not only expensive, but also its measurement range cannot cover the full motion range of the robot. At the same time, some external measurement devices need to be additionally clamped, such as the target ball of the laser tracker, the marker point of the stereo vision measurement system, etc. At present, six wire sensors are used to realize the pose measurement of the robot, but this measurement system also depends on the accuracy of the forward kinematics algorithm, and three wire sensors are used to realize the position measurement of the robot, but the attitude data cannot be obtained. SUMMARY

[0006] The first aspect of the present application proposes a technical solution, a parallel robot pose measurement device based on a combination of a wire and a two-dimensional inclinometer, comprising a pose measurement system installed on a parallel robot, the pose measurement system comprising an upper platform connection module installed at the geometric center position of the upper platform of the parallel robot and a lower platform connection module installed at the geometric center position of the lower platform of the parallel robot, wherein,

[0007] The upper platform connecting module comprises:

[0008] The first gimbal comprises a first gimbal upper part and a first gimbal lower part which can rotate relative to each other, the first gimbal upper part is arranged to move synchronously with the upper platform of the parallel robot, a coordinate system of the first gimbal is defined as {F1}, and a distance L1 between a center point of the first gimbal and the upper platform of the parallel robot;

[0009] A posture measurement two-dimensional inclinometer is arranged to move synchronously with the first gimbal upper part and is used to detect a two-dimensional inclination of the upper platform of the parallel robot;

[0010] A first gimbal measurement two-dimensional inclinometer is arranged to be fixed to the first gimbal lower part and is used to detect a two-dimensional inclination of the first gimbal lower part;

[0011] The lower platform connecting module comprises:

[0012] The second gimbal comprises a second gimbal upper part and a second gimbal lower part which can rotate relative to each other, the second gimbal lower part is arranged to be fixed to a top of the lower platform of the parallel robot, a coordinate system of the second gimbal is defined as {F2}, and a distance L2 between a center point of the second gimbal and the lower platform of the parallel robot;

[0013] A wire displacement sensor is arranged to be fixed to the second gimbal upper part, a wire is elastically wound on the wire displacement sensor, the other end of the wire is fixed to the first gimbal lower part, and the wire displacement sensor is used to detect a distance L between the rotation center of the first gimbal and the rotation center of the second gimbal;

[0014] A second gimbal measurement two-dimensional inclinometer is arranged to be fixed to the wire displacement sensor and is used to detect a two-dimensional inclination of the wire displacement sensor;

[0015] A base coordinate system of the parallel robot is defined as {B}, a measurement coordinate system of the posture measurement system is defined as {M}, a conversion matrix between the measurement coordinate system {M} and the coordinate system {F1} is H1, a conversion matrix between the base coordinate system {B} and the coordinate system {F2} is H2, and a posture matrix T12 of the coordinate system {F1} relative to the coordinate system {F2} is obtained according to a relative angle between the first gimbal or the second gimbal and the wire and a length of the wire;

[0016] A posture matrix TB of the coordinate system {M} relative to the base coordinate system {B} is H1·T12·H2.

[0017] Preferably, the first gimbal and the second gimbal comprise a cross gimbal.

[0018] Preferably, the cross shafts of the first gimbals are x, y direction distribution, and the cross shafts of the second gimbals are x, y direction distribution.

[0019] The upper part of the first gimbals can only move along the x-axis in the y-z plane, and the attitude measuring two-dimensional inclinometer is arranged to detect the first inclination (0, y, z) of the upper part of the first gimbals relative to the coordinate system {F1}, the first inclination (0, y, z) being in the y F1 -z F1 plane;

[0020] The lower part of the first gimbals can only move along the y-axis in the x, z plane, and the first gimbals measuring two-dimensional inclinometer is arranged to detect the second inclination (x1, 0, z1) of the lower part of the first gimbals relative to the coordinate system {F1}, the second inclination (x1, 0, z1) being in the x F1 -z F1 plane;

[0021] The upper part of the second gimbals can only move along the y-axis in the x, z plane, and the attitude measuring two-dimensional inclinometer is arranged to detect the third inclination (x2, 0, z2) of the upper part of the second gimbals relative to the coordinate system {F1}, the third inclination (x2, 0, z2) being in the x F1 -z F1 plane.

[0022] Preferably, a lower connecting plate is fixedly arranged at the middle position of the top surface of the lower platform of the parallel robot, and the lower part of the second gimbals is fixedly installed on the lower connecting plate.

[0023] Preferably, a bracket seat is fixedly arranged at the middle position of the bottom surface of the upper platform of the parallel robot, and the upper part of the first gimbals is fixedly installed at the bottom of the bracket seat.

[0024] Preferably, the bracket seat comprises an upper connecting plate fixed to the bottom surface of the upper platform of the parallel robot and a bracket plate fixed to the bottom of the upper connecting plate, the upper part of the first gimbals is fixed to the bottom of the bracket plate, and the attitude measuring two-dimensional inclinometer is fixedly installed between the upper connecting plate and the bracket plate.

[0025] The second aspect of the present application proposes a technical solution, a parallel robot pose measurement method based on the combination of a wire and a two-dimensional inclinometer, using the parallel robot pose measurement device based on the combination of a wire and a two-dimensional inclinometer described above, comprising the following steps:

[0026] Step 1: Establish coordinate systems: Define the base coordinate system of the parallel robot as {B}, the measurement coordinate system of the pose measurement system as {M}, and the measurement coordinate system of {M} of the pose measurement system is aligned with the base coordinate system of {B} of the parallel robot. Define the coordinate system of the first gimbal as {F1} and the coordinate system of the second gimbal as {F2}, and set the origin of the coordinates of {F1} and {F2} at the center point of the first gimbal and the second gimbal.

[0027] Step 2: Calculate the attitude angle of the parallel robot on the platform: After the parallel robot moves to the target pose, the attitude measurement two-dimensional inclinometer obtains the first inclinometer angle (0, y, z) of the parallel robot on the platform and calculates the attitude angle as (α, β, γ).

[0028] Step 3: Calculate the distance between the center points of the first universal joint and the second universal joint: After the parallel robot moves to the target pose, the cable displacement sensor obtains the length value of the cable, denoted as La, and calculates the distance between the center points of the first universal joint and the second universal joint, denoted as Lb, based on the known length of the cable displacement sensor and the length data of the lower part of the first universal joint and the upper part of the second universal joint.

[0029] Step 4: Calculate the attitude angles of the first gimbal measuring two-dimensional inclinometer and the second gimbal measuring two-dimensional inclinometer: Read the measured values ​​of the second inclinometer (x1, 0, z1) and the third inclinometer (x2, 0, z2), and calculate the corresponding attitude angles, which are denoted as (α1, β1, γ1) and (α2, β2, γ2) respectively. Take the average value of the two attitude angles as the angle of the rope space inclinometer. According to the base coordinate system theorem, calculate the pose matrix T12 of coordinate system {F1} relative to coordinate system {F2}.

[0030] Step 5: Obtain the transformation relationship between coordinate system {F1} and the upper platform of the parallel robot, and the transformation relationship between coordinate system {F2} and the lower platform of the parallel robot: Based on the known distance L1 between the center point of the first gimbal and the upper platform of the parallel robot, calculate the transformation relationship between coordinate system {F} and the upper platform of the parallel robot and denote it as H1;

[0031] Based on the known distance L2 between the center point of the second gimbal and the lower platform of the parallel robot, calculate the transformation relationship between the coordinate system {F} and the lower platform of the parallel robot, and denote it as H2;

[0032] Step 6: Based on the two transformation relationships H1 and H2 in Step 5, calculate the pose matrix TB of coordinate system {M} relative to base coordinate system {B} as: H1·T12·H2, and complete the pose measurement of the parallel robot.

[0033] Preferably, the first and second universal joints in the reset state are located on the central axis of the parallel robot.

[0034] Preferably, the pull rope is located on the line connecting the center points of the first universal joint and the second universal joint, and the pull rope is always in a taut state.

[0035] Preferably, the parallel robot includes a three-degree-of-freedom, four-degree-of-freedom, five-degree-of-freedom, or six-degree-of-freedom parallel robot.

[0036] Compared with the prior art, the advantages of the present invention are as follows:

[0037] This invention achieves pose measurement of parallel robots, especially for widely used six-DOF parallel robots, through a combination of a single wire displacement sensor and multiple inclinometers. The system has a simple structure and low cost. Furthermore, the measurement system is installed inside the parallel robot, which does not affect the robot's movement and can cover the entire motion space of the robot, resulting in high measurement accuracy. Attached Figure Description

[0038] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0039] Figure 1 This is a three-dimensional structural diagram of the parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer, as shown in an embodiment of the present invention, in its installation state.

[0040] Figure 2 This is a front view structural diagram of the parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer, as shown in an embodiment of the present invention, in its installation state.

[0041] Figure 3 This is a front view schematic diagram of the parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer, as shown in an embodiment of the present invention.

[0042] Figure 4 This is a three-dimensional structural schematic diagram of a parallel robot pose measurement device based on a combination of a pull wire and a two-dimensional tilt meter, as shown in an embodiment of the present invention.

[0043] Figure 5This is a schematic diagram of the relative coordinate system of a parallel robot pose measurement device based on a combination of a pull wire and a two-dimensional inclinometer, as shown in an embodiment of the present invention.

[0044] Figure 6 This is a schematic diagram of the relative relationship of the coordinate system in the tilted state of the upper platform in the parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer, as shown in an embodiment of the present invention. Detailed Implementation

[0045] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0046] Currently, most measurement systems for the motion posture of parallel robots are based on external measurement equipment, which are not only expensive, but also cannot cover the full range of motion of the robot. There are also systems that use six wire sensors to measure the robot's pose, but this measurement system depends on the accuracy of the forward kinematics algorithm. Furthermore, while three wire sensors can measure the robot's position, they cannot acquire posture data.

[0047] Therefore, there is an urgent need to design a combined parallel robot pose measurement device and method based on a pull wire and a two-dimensional inclinometer. This measurement system can be installed inside the parallel robot without affecting the robot's movement, can cover the movement range of the parallel robot, and has high measurement accuracy.

[0048] [Parallel Robot Pose Measurement Device Based on a Combination of Wire and 2D Inclinometer]

[0049] like Figure 1 The first aspect of the present invention provides a parallel robot pose measurement device based on a combination of a pull wire and a two-dimensional inclinometer, which mainly includes a pose measurement system 10 installed on a parallel robot 100.

[0050] Combination Figure 2 The pose measurement system 10 includes an upper platform connection module 101 installed at the geometric center of the upper platform of the parallel robot 100 and a lower platform connection module 102 installed at the geometric center of the lower platform of the parallel robot 100. The base coordinate system of the parallel robot 100 is defined as {B}, and the measurement coordinate system of the pose measurement system 10 is defined as {M}. The measurement coordinate system of the pose measurement system 10, {M}, is aligned with the base coordinate system of the parallel robot 100, {B}.

[0051] Up platform connection module

[0052] The upper platform connection module 101 includes a first universal joint 3, an attitude measurement two-dimensional inclinometer 4, and a first universal joint measurement two-dimensional inclinometer 5.

[0053] Further, the first universal joint 3 includes an upper part and a lower part of the first universal joint that can rotate relative to each other. At the same time, the coordinate system of the first universal joint 3 is set as {F1}, and the origin of the coordinate system {F1} is set at the center point of the first universal joint 3.

[0054] In a specific embodiment, as Figure 3 and Figure 4 shown, a bracket seat is fixedly provided at the middle position of the bottom surface of the upper platform of the parallel robot 100. The bracket seat includes an upper connecting plate 1 fixed to the bottom surface of the upper platform of the parallel robot 100 and a bracket plate 2 fixed to the bottom of the upper connecting plate 1. The upper part of the first universal joint is fixed to the bottom of the bracket plate 2. Since the bracket plate 2 is rigidly connected to the upper platform of the parallel robot 100 through the upper connecting plate 1, the upper part of the first universal joint is set to move synchronously with the upper platform of the parallel robot 100, and the distance between the center point of the first universal joint 3 and the upper platform of the parallel robot 100 is L1, which includes the length of the upper part of the first universal joint and the height of the bracket seat.

[0055] Specifically, both the upper connecting plate 1 and the bracket plate 2 are made of stainless steel or aluminum alloy. The bracket plate 2 is set in a "C" - shaped frame, forming a rectangular installation space with the upper connecting plate 1. The attitude - measuring two - dimensional inclinometer 4 is fixedly installed in the space between the upper connecting plate 1 and the bracket plate 2 and remains relatively fixed with respect to the bracket plate 2.

[0056] In this way, the attitude - measuring two - dimensional inclinometer 4 can move synchronously with the upper part of the first universal joint, and the upper part of the first universal joint moves synchronously with the upper platform of the parallel robot 100, enabling the attitude - measuring two - dimensional inclinometer 4 to detect the two - dimensional attitude of the upper platform of the parallel robot 100.

[0057] Combined with Figure 4 shown, it is defined that the cross - axes of the first universal joint 3 are distributed in the x and y directions, and the cross - axes of the second universal joint 7 are also distributed in the x and y directions. Thus, the upper part of the first universal joint can only move along the x - axis in the y - z plane. The attitude - measuring two - dimensional inclinometer 4 is set to detect the first inclination angle (0, y, z) of the upper part of the first universal joint relative to the coordinate system {F1}, and the first inclination angle (0, y, z) is in the y F1 -z F1 plane.

[0058] Further, a first universal - joint - measuring two - dimensional inclinometer 5 is fixedly provided on the side wall of the lower part of the first universal joint, enabling the first universal - joint - measuring two - dimensional inclinometer 5 to move synchronously with the lower part of the first universal joint for detecting the two - dimensional attitude of the lower part of the first universal joint. The lower part of the first universal joint can only move along the y - axis in the x and z planes. The first universal - joint - measuring two - dimensional inclinometer 5 is set to detect the second inclination angle (x1, 0, z1) of the lower part of the first universal joint relative to the coordinate system {F1}, and the second inclination angle (x1, 0, z1) is in the xF1 -z F1 In the plane.

[0059] By combining the first tilt angle (0, y, z), the second tilt angle (x1, 0, z1), and the clamp of the tilt meter between the centers of the cross shafts, the corresponding attitude angles can be calculated and denoted as (α, β, γ) and (α1, β1, γ1), respectively.

[0060] Lower platform connection module

[0061] like Figure 3 and Figure 4 As shown, the lower platform connection module 102 includes a second universal joint 7, a wire displacement sensor 8, and a two-dimensional inclinometer 9 for measuring the second universal joint.

[0062] The second universal joint 7 includes an upper part and a lower part of the second universal joint that can rotate relative to each other. The coordinate system of the second universal joint 7 is set as {F2}, and the origin of the coordinate system of {F2} is set at the center point of the second universal joint 7.

[0063] In a specific embodiment, a lower connecting plate 6 is fixedly provided at the middle position of the top surface of the lower platform of the parallel robot 100. The lower part of the second universal joint is fixedly installed on the lower connecting plate 6, so that the lower part of the second universal joint is rigidly connected to the lower platform of the parallel robot 100 and keeps the position fixed. At the same time, the distance between the center point of the second universal joint 7 and the lower platform of the parallel robot 100 is L2, which includes the length of the lower part of the second universal joint and the thickness of the lower connecting plate 6.

[0064] Furthermore, the cable displacement sensor 8 is fixedly mounted on the top of the upper part of the second universal joint, so that the cable displacement sensor 8 can move synchronously with the upper part of the second universal joint. The cable displacement sensor 8 has a cable 81 elastically wound on it, and the other end of the cable 81 is fixed to the lower part of the first universal joint. It is used to detect the distance between the rotation center of the first universal joint 3 and the rotation center of the second universal joint 7, and the distance between the center points of the first universal joint 3 and the second universal joint 7 is set as L.

[0065] Furthermore, the second universal joint measuring two-dimensional inclinometer 9 is fixed to one side of the housing of the wire displacement sensor 8, and can move synchronously with the wire displacement sensor 8 to detect the two-dimensional attitude of the wire displacement sensor 8. The upper part of the second universal joint can only move along the y-axis in the x and z planes. The attitude measuring two-dimensional inclinometer 7 is configured to detect the third tilt angle (x2, 0, z2) of the upper part of the second universal joint relative to the coordinate system {F1}. The third tilt angle (x2, 0, z2) is measured in the x-axis. F1 -z F1 In the plane.

[0066] By combining the second tilt angle (x1, 0, z1), the third tilt angle (x2, 0, z2), and the distance between the center points of the first universal joint 3 and the second universal joint 7, which is set to L, the corresponding attitude angles can be calculated and denoted as (α1, β1, γ1) and (α2, β2, γ2), respectively.

[0067] After the parallel robot 100 moves to the target posture, the attitude measurement 2D inclinometer 4 acquires the attitude angle data of the upper platform of the parallel robot 100, the first gimbal measurement 2D inclinometer 5 acquires the attitude angle data of the lower part of the first gimbal, the wire displacement sensor 8 acquires the distance between the center points of the first gimbal 3 and the second gimbal 7, and the second gimbal measurement 2D inclinometer 9 acquires the attitude angle data of the wire displacement sensor 8. The pose matrix T12 of coordinate system {F1} relative to coordinate system {F2} is obtained. Combined with the distance between the center point of the first gimbal 3 and the upper platform of the parallel robot 100 and the distance between the center point of the second gimbal 7 and the lower platform of the parallel robot 100, the transformation matrix between the measurement coordinate system {M} and coordinate system {F1} is calculated as H1, the transformation matrix between the base coordinate system {B} and coordinate system {F2} is H2, and the pose matrix TB of coordinate system {M} relative to base coordinate system {B} is: H1·T12·H2.

[0068] In an optional embodiment, the first universal joint 3 and the second universal joint 7 are cross universal joints, which have the characteristics of simple structure and stable transmission.

[0069] A Parallel Robot Pose Measurement Method Based on a Combination of Wire and 2D Inclinometer

[0070] Combination Figure 5 and Figure 6 As shown, a method for measuring the pose of a parallel robot based on a combination of a string and a two-dimensional inclinometer, using the aforementioned parallel robot pose measurement device based on a combination of a string and a two-dimensional inclinometer, includes the following steps:

[0071] Step 1: Establish coordinate systems: Define the base coordinate system of the parallel robot 100 as {B}, and the measurement coordinate system of the pose measurement system 10 as {M}. In the reset state, the first universal joint 3 and the second universal joint 7 are located on the central axis of the parallel robot 100, so that the measurement coordinate system of the pose measurement system 10 as {M} is consistent with the base coordinate system of the parallel robot 100 as {B}. Define the coordinate system of the first universal joint 3 as {F1} and the coordinate system of the second universal joint 7 as {F2}, and set the origin of the coordinates of {F1} and {F2} at the center point of the first universal joint 3 and the second universal joint 7.

[0072] Step 2: Calculate the attitude angles of the platform on the parallel robot 100: After the parallel robot 100 moves to the target pose, the attitude measurement two-dimensional inclinometer 4 acquires the attitude angle data of the platform on the parallel robot 100 and calculates the attitude angles as (α, β, γ). Since the attitude measurement two-dimensional inclinometer 4 is rigidly connected to the platform on the parallel robot 100 through the support, it can move synchronously with the platform on the parallel robot 100, representing the motion attitude of the platform on the parallel robot 100.

[0073] Step 3: Calculate the distance between the center points of the first universal joint 3 and the second universal joint 7: After the parallel robot 100 moves to the target pose, the cable displacement sensor 8 acquires the length value of the cable 81, which is recorded as La. Based on the known length of the cable displacement sensor 8 and the length data of the lower part of the first universal joint and the upper part of the second universal joint, which are recorded as Lb, the distance between the center points of the first universal joint 3 and the second universal joint 7 is calculated and recorded as L. The coil spring inside the cable displacement sensor 8 has a large winding force, and because the cable displacement sensor 8 itself is lightweight, it can keep the cable 81 in a taut state at all times, so that the cable 81 is on the line connecting the center points of the first universal joint 3 and the second universal joint 7, thereby reducing the error of La. The length of the cable displacement sensor 8 and the length data of the lower part of the first universal joint and the upper part of the second universal joint are all measured in advance and the sum is recorded as Lb. The sum of La and Lb is L.

[0074] Step 4: Calculate the attitude angles of the first gimbal measuring two-dimensional inclinometer 5 and the second gimbal measuring two-dimensional inclinometer 9: Read the data of the first gimbal measuring two-dimensional inclinometer 5 and the second gimbal measuring two-dimensional inclinometer 9, calculate the corresponding attitude angles respectively, and denot them as (α1, β1, γ1) and (α2, β2, γ2), and take the average of the above two attitude angles as the angle of the spatial tilt of the rope 81. According to the base coordinate system theorem, calculate the pose matrix T12 of coordinate system {F1} relative to coordinate system {F2}.

[0075] Step 5: Obtain the transformation relationship between coordinate system {F1} and the upper platform of parallel robot 100 and coordinate system {F2} and the lower platform of parallel robot 100: Based on the known distance L1 between the center point of the first universal joint 3 and the upper platform of parallel robot 100, calculate the transformation relationship between coordinate system {F1} and the upper platform of parallel robot 100 and denote it as H1.

[0076] Based on the known distance L2 between the center point of the second universal joint 7 and the lower platform of the parallel robot 100, calculate the transformation relationship between the coordinate system {F2} and the lower platform of the parallel robot 100, and denote it as H2;

[0077] Step 6: Based on the two transformation relationships H1 and H2 in Step 5, the pose matrix TB of coordinate system {M} relative to base coordinate system {B} is: H1·T12·H2, thus completing the pose measurement of the parallel robot 100.

[0078] Combining the above embodiments, the pose measurement of parallel robots is realized by combining a single wire displacement sensor 8 and multiple inclinometers, especially for widely used six-degree-of-freedom parallel robots. The system has a simple structure and low cost. At the same time, the measurement system is installed inside the parallel robot, which does not affect the movement of the parallel robot and can cover the entire movement space of the parallel robot, thus having high measurement accuracy.

[0079] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A parallel robot pose measurement device based on a combination of a pull-string and a two-dimensional inclinometer, characterized in that, The system includes a pose measurement system (10) mounted on a parallel robot (100). The pose measurement system (10) includes an upper platform connection module (101) mounted at the geometric center of the upper platform of the parallel robot (100) and a lower platform connection module (102) mounted at the geometric center of the lower platform of the parallel robot (100). The upper platform connection module (101) includes: The first universal joint (3) includes an upper part and a lower part of the first universal joint that can rotate relative to each other. The upper part of the first universal joint is fixedly connected to the parallel robot (100). The coordinate system of the first universal joint (3) is defined as {F1}. The distance L1 between the center point of the first universal joint (3) and the platform of the parallel robot (100) is 1. A two-dimensional tilt meter (4) for attitude measurement is set to move synchronously with the upper part of the first universal joint to detect the two-dimensional tilt angle of the platform on the parallel robot (100); The first universal joint measuring two-dimensional inclinometer (5) is fixed at the lower part of the first universal joint and is used to detect the two-dimensional inclinometer at the lower part of the first universal joint. The lower platform connection module (102) includes: The second universal joint (7) includes an upper part and a lower part of the second universal joint that can rotate relative to each other. The lower part of the second universal joint is fixed to the top of the lower platform of the parallel robot (100). The coordinate system of the second universal joint (7) is defined as {F2}. The distance L2 between the center point of the second universal joint (7) and the lower platform of the parallel robot (100) is 100. A pull-wire displacement sensor (8) is fixed on the upper part of the second universal joint. A pull-wire displacement sensor (8) is elastically wound with a pull rope (81). The other end of the pull rope (81) is fixed on the lower part of the first universal joint. It is used to detect the distance between the rotation center of the first universal joint (3) and the rotation center of the second universal joint (7), and is positioned as L. The second universal joint measuring two-dimensional inclinometer (9) is fixed on the wire displacement sensor (8) and is used to detect the two-dimensional inclinometer of the wire displacement sensor (8); Define the base coordinate system of the parallel robot (100) as {B}, the measurement coordinate system of the pose measurement system (10) as {M}, the transformation matrix between the measurement coordinate system {M} and the coordinate system {F1} as H1, and the transformation matrix between the base coordinate system {B} and the coordinate system {F2} as H2. Obtain the pose matrix T12 of the coordinate system {F1} relative to the coordinate system {F2} based on the relative angle between the first or second universal joint and the pull rope (81) and the length of the pull rope (81). The pose matrix TB of coordinate system {M} relative to base coordinate system {B} is: H1·T12·H2.

2. The parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer as described in claim 1, characterized in that, The first universal joint (3) and the second universal joint (7) include cross universal joints.

3. The parallel robot pose measurement device and method based on the combination of a pull wire and a two-dimensional inclinometer as described in claim 2, characterized in that, The cross-shaped rotation axis of the first universal joint (3) is defined as being distributed in the x and y directions, and the cross-shaped rotation axis of the second universal joint (7) is also distributed in the x and y directions. The upper part of the first universal joint can only move along the x-axis in the yz plane. The attitude measurement two-dimensional inclinometer (4) is configured to detect the first tilt angle (0, y, z) of the upper part of the first universal joint relative to the coordinate system {F1}. The first tilt angle (0, y, z) is in the y-axis direction. F1 -z F1 In the plane; The lower part of the first universal joint can only move along the y-axis in the x and z planes. The two-dimensional inclinometer (5) measuring the first universal joint is set to detect the second tilt angle (x1, 0, z1) of the lower part of the first universal joint relative to the coordinate system {F1}. The second tilt angle (x1, 0, z1) is in the x-axis. F1 -z F1 In the plane; The upper part of the second universal joint can only move along the y-axis in the x and z planes. The attitude measurement two-dimensional inclinometer (4) is configured to detect the third tilt angle (x2, 0, z2) of the upper part of the second universal joint relative to the coordinate system {F1}. The third tilt angle (x2, 0, z2) is located at x... F1 -z F1 In the plane.

4. The parallel robot pose measurement device and method based on the combination of a pull wire and a two-dimensional inclinometer as described in claim 1, characterized in that, A lower connecting plate (6) is fixedly provided at the middle position of the top surface of the lower platform of the parallel robot (100), and the lower part of the second universal joint is fixedly installed on the lower connecting plate (6).

5. The parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer according to claim 1, characterized in that, A support base is fixedly provided at the middle position of the bottom surface of the platform of the parallel robot (100), and the upper part of the first universal joint is fixedly installed at the bottom of the support base.

6. The parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer according to claim 5, characterized in that, The support base includes an upper connecting plate (1) fixed to the bottom surface of the platform on the parallel robot (100) and a support plate (2) fixed to the bottom of the upper connecting plate (1). The upper part of the first universal joint is fixed to the bottom of the support plate (2). The attitude measurement two-dimensional tilt meter (4) is fixedly installed between the upper connecting plate (1) and the support plate (2).

7. A method for measuring the pose of a parallel robot based on a combination of a string and a two-dimensional inclinometer, characterized in that, The parallel robot pose measurement device based on the combination of a pull wire and a two-dimensional inclinometer as described in claim 3 includes the following steps: Step 1: Establish coordinate system: Define the base coordinate system of the parallel robot (100) as {B}, the measurement coordinate system of the pose measurement system (10) as {M}, the measurement coordinate system of the pose measurement system (10) as {M} is consistent with the base coordinate system of the parallel robot (100) as {B}, define the coordinate system of the first universal joint (3) as {F1}, the coordinate system of the second universal joint (7) as {F2}, and set the origin of the coordinates of {F1} and {F2} at the center point of the first universal joint (3) and the second universal joint (7); Step 2: Calculate the attitude angle of the platform on the parallel robot (100): When the parallel robot (100) moves to the target pose, the attitude measurement two-dimensional tilt meter (4) obtains the first tilt angle (0, y, z) of the platform on the parallel robot (100) and calculates the attitude angle as (α, β, γ). Step 3: Calculate the distance between the center points of the first universal joint (3) and the second universal joint (7): When the parallel robot (100) moves to the target pose, the pull cable displacement sensor (8) obtains the length value of the pull cable (81) as La, and calculates the distance between the center points of the first universal joint (3) and the second universal joint (7) as L based on the known length of the pull cable displacement sensor (8) and the length data of the lower part of the first universal joint and the upper part of the second universal joint as Lb; Step 4: Calculate the attitude angles of the first gimbal measuring two-dimensional inclinometer (5) and the second gimbal measuring two-dimensional inclinometer (9): Read the measured values ​​of the second inclinometer (5) (x1, 0, z1) and the measured values ​​of the third inclinometer (9) (x2, 0, z2), and calculate the corresponding attitude angles, which are recorded as (α1, β1, γ1) and (α2, β2, γ2) respectively. Take the average value of the two attitude angles as the angle of the spatial inclinometer of the pull rope (81), and calculate the pose matrix T12 of coordinate system {F1} relative to coordinate system {F2}. Step 5: Obtain the transformation relationship between coordinate system {F1} and the upper platform of the parallel robot (100) and the transformation relationship between coordinate system {F2} and the lower platform of the parallel robot (100): Based on the distance L1 between the center point of the first universal joint (3) and the upper platform of the parallel robot (100), calculate the transformation relationship between coordinate system {F1} and the upper platform of the parallel robot (100) and record it as H1; Based on the known distance L2 between the center point of the second universal joint (7) and the lower platform of the parallel robot (100), calculate the transformation relationship between the coordinate system {F2} and the lower platform of the parallel robot (100) and denote it as H2; Step 6: Based on the two transformation relationships H1 and H2 in Step 5, calculate the pose matrix TB of coordinate system {M} relative to base coordinate system {B} as: H1·T12·H2, and complete the pose measurement of the parallel robot (100).

8. The method for measuring the pose of a parallel robot based on a combination of a pull-string and a two-dimensional inclinometer as described in claim 7, characterized in that, In the reset state, the first universal joint (3) and the second universal joint (7) are located on the central axis of the parallel robot (100).

9. The method for measuring the pose of a parallel robot based on a combination of a pull wire and a two-dimensional inclinometer as described in claim 7, characterized in that, The pull rope (81) is located on the line connecting the center points of the first universal joint (3) and the second universal joint (7), and the pull rope (81) is always in a taut state.

10. The method for measuring the pose of a parallel robot based on a combination of a pull wire and a two-dimensional inclinometer as described in claim 7, characterized in that, The parallel robot (100) includes a three-degree-of-freedom, four-degree-of-freedom, five-degree-of-freedom, or six-degree-of-freedom parallel robot.

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