A TBM pose calculation system combining forward kinematics of propulsion cylinder and laser measurement

Abstract

The present invention discloses a TBM pose measurement and calculation system combining the forward solution of a propulsion cylinder and laser measurement, which includes: a laser absolute measurement device for obtaining the absolute pose of the support shield through a total station installed on the rock wall and a laser target on the support shield; a forward solution measurement device for the propulsion system, which constructs a parallel mechanism model of the TBM propulsion system, takes the cylinder elongation obtained by a stroke sensor and the articulated angle obtained by an angle encoder as inputs, and uses an analytical algorithm based on singular value decomposition to solve for the relative pose of the front shield with respect to the support shield; and a central control device for performing coordinate transformation and data fusion on the absolute pose of the support shield and the relative pose of the front shield with respect to the support shield to obtain the pose of the front shield in the global coordinate system. By adopting the technical solution of the present invention, the technical problems in the existing TBM guidance system, such as the visual measurement link being susceptible to environmental interference, having poor stability, and large errors, are overcome.

Description

Technical Field

[0001] This invention belongs to the technical field of full-face tunnel boring machine (TBM), specifically relating to a TBM pose calculation system that combines forward kinematics of propulsion cylinder with laser measurement. Background Technology

[0002] Currently, the automatic guidance system of full-face tunnel boring machines (TBMs) widely adopts a combined measurement scheme of "total station + visual recognition". This system uses a total station fixed at a known reference point on the tunnel sidewall to continuously observe a laser target or prism installed at the rear of the TBM support shield, thereby accurately calculating the absolute pose of the support shield, including its three-dimensional spatial coordinates and azimuth. To obtain the pose of the front shield relative to the support shield, an industrial camera is typically installed at the front of the support shield to acquire images of a specific visual target (such as a photoelectric target with high-contrast feature points) fixed at the rear of the front shield. Using photogrammetry and computer vision technology, the system employs pose estimation algorithms such as EPnP to calculate the spatial pose of the target relative to the camera based on the projection position of the target's feature points in the image. Combined with pre-calibrated mechanical installation parameters, the system calculates the pose of the front shield in real time through a coordinate transformation chain, and further obtains the three-dimensional coordinates of the cutterhead center in the engineering coordinate system. This non-contact measurement method boasts high measurement accuracy and real-time performance under ideal working conditions. The system, through a complete coordinate transformation model, can adapt to the complex movements of the TBM articulated system, providing continuous and accurate guidance data for tunnel axis control. This technical solution has been validated through years of engineering practice and has become the mainstream configuration for current TBM guidance systems, achieving excellent application results in numerous tunnel projects.

[0003] Although the TBM guidance scheme of "total station + visual recognition" performs excellently under ideal conditions, it still has obvious limitations in actual tunnel engineering applications, especially in the visual measurement stage. Specifically, the issues manifest in the following ways: 1) The vision system is extremely sensitive to environmental disturbances during tunnel excavation. The large amounts of dust and water vapor generated during construction severely degrade image quality, leading to decreased feature point contrast, image blurring, and even temporary target loss, directly reducing the accuracy and reliability of pose calculation. 2) Strong mechanical vibrations can cause relative motion between the camera and the target, resulting in image blurring and pixel-level errors in feature point positioning. These dynamic errors are transmitted and amplified through algorithms such as EPnP, ultimately affecting the final position and pose calculation results. 3) This solution relies on harsh on-site lighting conditions. Complex lighting changes, shadows, and glare generated by the equipment itself within the tunnel can cause incomplete feature point extraction or mismatches, introducing significant errors. 4) The deployment and maintenance of the vision system are also complex. The relative positional relationship between the industrial camera and the vision target requires high-precision initial calibration, and may change due to vibration and impact during long-term operation, leading to measurement reference drift. The system lacks an effective online monitoring and compensation mechanism for this. Therefore, the vulnerability of the vision component has become a key bottleneck restricting the robustness and stability of this guidance system in harsh tunneling environments. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a TBM pose calculation system that combines forward propulsion of hydraulic cylinders with laser measurement. This system overcomes the technical challenges of visual measurement in existing TBM guidance systems, which are susceptible to environmental interference, have poor stability, and large errors. It achieves automatic guidance that does not rely on visual recognition, has strong anti-interference capabilities, and provides stable and reliable measurement. By innovatively integrating multi-source measurement data and making full use of existing TBM sensor resources, the system effectively reduces system costs while ensuring measurement accuracy.

[0005] To achieve the above objectives, the present invention provides the following solution: A TBM pose calculation system combining forward kinematics of propulsion cylinder and laser measurement includes: A laser absolute measurement device is used to obtain the absolute position and orientation of the support shield by means of a total station mounted on the rock face and a laser target mounted on the support shield. The forward propulsion measurement device is used to construct a parallel mechanism model of the TBM propulsion system, and use the cylinder extension obtained by the stroke sensor and the hinge angle obtained by the angle encoder as inputs to solve the relative pose of the front shield relative to the support shield using an analytical algorithm based on singular value decomposition. The central control unit is used to perform coordinate transformation and data fusion of the absolute pose of the supporting shield and the relative pose of the front shield with respect to the supporting shield, so as to obtain the pose of the front shield in the global coordinate system.

[0006] As a preferred option, eight sets of propulsion cylinders are used, each set of propulsion cylinders is equipped with a stroke sensor and an angle encoder, wherein the eight stroke sensors and eight angle encoders are respectively placed in the eight propulsion cylinders and at the hinges connecting the propulsion cylinders to the support shield.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention effectively solves the reliability problem of traditional vision guidance systems under harsh working conditions by combining laser absolute measurement with forward kinematics calculations of the propulsion system. The invention utilizes laser measurement to achieve precise absolute positioning of the support shield, while simultaneously obtaining the relative pose of the front shield through forward kinematics calculations of the propulsion cylinder stroke and hinge angle. These two methods are integrated to form a complete pose perception system. This invention completely eliminates the influence of environmental factors such as dust and vibration on measurement accuracy, fully utilizes the efficiency of existing sensor resources, and significantly improves the system's anti-interference capability and reliability while ensuring measurement accuracy. In summary, this invention provides a reliable technical solution for the precise guidance of TBMs under complex geological conditions and has significant engineering application value. Attached Figure Description

[0008] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a structural diagram of a TBM pose calculation system that combines forward hydraulic cylinder measurement with laser measurement according to an embodiment of the present invention. Figure 2 To illustrate the simplified structural diagram and vector relationship of the propulsion mechanism; where (a) is the simplified structural diagram of the propulsion mechanism; and (b) is the vector relationship of the propulsion mechanism. Detailed Implementation

[0010] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0012] Example 1 This invention provides a TBM pose calculation system combining forward kinematics of propulsion cylinder and laser measurement, comprising: A laser absolute measurement device is used to obtain the absolute position and orientation of the support shield by means of a total station mounted on the rock face and a laser target mounted on the support shield. The forward propulsion measurement device is used to construct a parallel mechanism model of the TBM propulsion system, and use the cylinder extension obtained by the stroke sensor and the hinge angle obtained by the angle encoder as inputs to solve the relative pose of the front shield relative to the support shield using an analytical algorithm based on singular value decomposition. The central control unit is used to perform coordinate transformation and data fusion of the absolute pose of the supporting shield and the relative pose of the front shield with respect to the supporting shield, so as to obtain the pose of the front shield in the global coordinate system.

[0013] The TBM automated guidance system has three significant advantages: First, it completely eliminates the dependence of the visual measurement process on environmental conditions, ensuring stable operation of the system under harsh working conditions; second, by making full use of the existing sensor resources of the TBM, it significantly reduces the system modification cost; and third, through the serial collaboration mode of "absolute positioning + relative positioning", it constructs a complete pose perception chain. This chain has a clear structure and reliable data source, avoiding the uncertainty introduced by relying solely on visual data from the system principle, thereby fundamentally improving the overall reliability of the guidance system.

[0014] Furthermore, such as Figure 1 As shown, the TBM automatic guidance system also includes: a cutterhead 1, a front shield 2, a support shield 3, a laser target 4, a total station 5, a stroke sensor 6, eight sets of propulsion cylinders 7, a hinge 8, and an angle encoder 9. The pose of the support shield 3 is determined by the total station 5 and the laser target 4 fixed on the support shield 3. Eight sets of propulsion cylinders are used, each equipped with a stroke sensor and an angle encoder, thus requiring a total of eight stroke sensors and eight angle encoders. These are placed at the eight propulsion cylinders and at the hinges connecting the propulsion cylinders to the support shield, directly obtaining the pose of each rod vector in the static coordinate system (fixed in the support shield's coordinate system), thereby uniquely determining the pose in the moving coordinate system (fixed in the front shield) relative to the static coordinate system. Combining absolute laser measurement with forward relative measurement of the propulsion system allows for the determination of the poses of the support shield and the front shield, thus achieving TBM guidance.

[0015] The dual-shield TBM guidance system can be simplified to Figure 2 In the structure shown in (a), the front shield and the support shield are regarded as the moving platform and the stationary platform of the parallel robot, respectively, and the propulsion cylinder is regarded as the branch connecting the moving platform and the stationary platform. Coordinate systems O are established on the moving platform and the stationary platform, respectively. d -X d Y d Z d Ot -X t Y t Z t , origin O d O t They are located at the geometric centers of the moving platform and the static platform, respectively. Coordinate system O d -X d Y d Z d It can be viewed as being based on coordinate system O t -X t Y t Z t Origin t Translate to point O d Then rotate about the x-axis, y-axis, and z-axis respectively. The angle is obtained after that. Therefore, the moving coordinate system O is solved. d -X d Y d Z d Relative to the static coordinate system O t -X t Y t Z t To determine the pose, a 3×1 position vector O needs to be calculated. t O d That is, the origin O of the static coordinate system t To the origin O of the moving coordinate system d The position vector and rotation matrix represented in the static coordinate system. ,in: (1) Where R is the moving coordinate system O d -X d Y d Z d Relative to the static coordinate system O t -X t Y t Z t The rotation matrix, Coordinate system O d -X d Y d Z d From coordinate system O t -X t Y t Z t Origin t Translate to point O d After rotating around the translated coordinate system along the x, y, and z axes The rotation matrix of the angle. When the thrust hydraulic cylinder drives the moving platform to a certain position in space, the moving coordinate system O... d -X dY d Z d With static coordinate system O t -X t Y t Z t Existence such as Figure 2 The position vector relationship shown in (b) indicates that point B i and point b i These are the center points of the ball joint at the end of the i-th propulsion cylinder chain and the ball joint at the output end, respectively. Let the radius of the static platform be R. t The radius of the moving platform is R d The length of the i-th propulsion cylinder is obtained from the stroke sensor. i The angle encoder obtains the position of the i-th propulsion cylinder relative to coordinate system O. t -X t Y t Z t The x-axis rotation by an angle ε, i.e., the pitch angle, is ε; the y-axis rotation by an angle η, i.e., the yaw angle, is η. Based on the vector summation relationship, the following vector relationship can be obtained: (2) Among them, O t b i O is the origin of the static coordinate system t The vector from the center point of the ball joint at the output end of the i-th propulsion cylinder in the static coordinate system, O t B i Point B i Position vector in the static coordinate system; B i b i Let O be the vector representation in the static coordinate system from the center point of the ball joint at the end of the i-th propulsion cylinder chain to the center point of the ball joint at the output end; d b i O is the origin of the moving coordinate system d The vector to the center point of the ball joint at the output end of the i-th propulsion cylinder is represented in the static coordinate system; O is the origin of the moving coordinate system d The position vector in the static coordinate system.

[0016] Point B i Position vector in the static coordinate system: (3) in, B ix 、B iy 、B iz Point B i The projections of the position vector onto the x-axis, y-axis, and z-axis in a static coordinate system. Rt For the radius of the static platform, i For O t B i The angle between the projection of the object onto the oxy plane in the static coordinate system and the x-axis, where T is the transpose.

[0017] Length and direction vector of the propulsion cylinder: (4) in, l i To extend the length of the hydraulic cylinder, s i To propel the hydraulic cylinder's directional vector, Rot(x,e) , Rot(y,n) These are the rotation vectors of the propulsion cylinder relative to the x-axis of the static coordinate system by an angle ε and around the y-axis by an angle η, respectively.

[0018] Point b i Position vector in the moving coordinate system: (5) Where R is the moving coordinate system O d -X d Y d Z d Relative to the static coordinate system O t -X t Y t Z t The rotation matrix, D b ix 、 D b iy 、 D b iz Point b i The projections of the position vector onto the x-axis, y-axis, and z-axis in a moving coordinate system. R d For the radius of the moving platform, For O d b i The angle between the projection of the object onto the oxy plane in the moving coordinate system and the x-axis.

[0019] From formula (2), it can be seen that, based on the known vector matrix... , It can be confirmed This allows us to determine the output ball joint b. i In the static coordinate system O t -X t Y t Z tThe coordinates in the coordinate system. The origin O of the moving coordinate system can be calculated from the positions of the eight output ball joints. d In the static coordinate system (O) t -X t Y t Z t The coordinates in the diagram can be used to determine the location. Point O d The coordinates in the static coordinate system are p: (6) in, Let b be the center point of the ball joint at the output end of the i-th propulsion cylinder. i Coordinates in a static coordinate system; p x 、p y 、p z Point O d The projections of the position vector onto the x-axis, y-axis, and z-axis in a static coordinate system. b ix 、b iy 、b iz b i The projection of the position vector onto the x-axis, y-axis, and z-axis in a static coordinate system.

[0020] For ease of calculation, a vector is defined. Origin of the dynamic platform d Point B i The representation of the vector in the static coordinate system, then (7) in, Let b be the center point of the ball joint at the output end of the i-th propulsion cylinder. i Coordinates in a moving coordinate system.

[0021] Differentiate both sides of the equation with respect to time: (8) (9) (10) Where Ω is the antisymmetric matrix of the angular velocity, ω x ω y ω z These are the angular velocities of the moving coordinate system rotating about the x-axis, y-axis, and z-axis of the stationary coordinate system, respectively.

[0022] According to the properties of antisymmetric matrices, for any vector ,have ,in, Therefore, substituting into equation (10) yields: (11) Let L i Let B be the vector in the static coordinate system representing the distance from the center point of the ball joint at the end of the i-th propulsion cylinder chain to the center point of the ball joint at the output end. i Let B be the center point of the ball joint at the end of the i-th propulsion cylinder chain. i The coordinates in the static coordinate system are then (12) The direction vector of the hydraulic cylinder is: (13) Among them, ||L i|| This indicates the length of the hydraulic cylinder.

[0023] The rate of change of the propulsion cylinder length is: (14) in, L i Let be the length of the i-th propulsion cylinder. To increase the rate of change of cylinder length.

[0024] because Taking the derivative with respect to time, we have: (15) Where v is the linear velocity of the origin of the moving coordinate system.

[0025] because ,but: (16) Because of s i For a unit vector, multiply both sides by an s. i ,have: (17) in, All are known quantities, let Equation (17) can be written as: (18) The system of equations is nonlinear with respect to the rotation matrix R, requiring numerical solutions. The following definition applies: (19) in, F ( a,b,c, ω) is about the unknown number a、b、c、 A function of ω.

[0026] Solve using the gradient descent method, that is, find .right F Partial derivatives of each term: (20) in, For function F ( a,b,c, The partial derivative of ω), For the residual, R x ( α ), R y ( β ), R z ( c The rotations of the moving coordinate system around the x-axis, y-axis, and z-axis of the stationary coordinate system are respectively... α , β , c Rotation matrix of angle.

[0027] Let the parameter vector be Based on the initial position of the front shield, the initial vector is set as follows: Where x0 represents the parameter vector when the front shield is in its initial position. These represent the degrees of rotation of the moving coordinate system around the x-axis, y-axis, and z-axis of the stationary coordinate system when the front shield is in its initial position. These represent the angular velocities of the moving coordinate system rotating about the x-axis, y-axis, and z-axis of the stationary coordinate system when the front shield is in its initial position. The rotation matrix is ​​calculated based on the initial vectors. , e i , F , and according to and formula Update parameters, where, These are the parameter vectors after the k-th and (k+1)-th iterations, respectively. l The learning rate is typically set to 0.001 to 0.1. The algorithm iterates until the convergence condition is met and then outputs the final result, which is the optimal rotation matrix R and the angular velocity ω.

[0028] (twenty one) Where k and k+1 represent the number of iterations, The objective function after the k-th iteration F ( a,b,c, The function value of ω). Let be the partial derivative of the objective function after the k-th iteration. Let the gradient norm be the partial derivative of the objective function. These are the parameter vectors after the k-th and (k+1)-th iterations, respectively. For parameter changes, This is the convergence threshold.

[0029] The kinematics solution is complete, and the position vector O is obtained. t O d and rotation matrix The position of the moving platform can be determined, and the position of the front shield of the dual-shield TBM relative to the supporting shield can be determined.

[0030] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A TBM pose calculation system combining forward kinematics of a propulsion cylinder and laser measurement, characterized in that, include: A laser absolute measurement device is used to obtain the absolute position and orientation of the support shield by means of a total station mounted on the rock face and a laser target mounted on the support shield. The forward propulsion measurement device is used to construct a parallel mechanism model of the TBM propulsion system, and use the cylinder extension obtained by the stroke sensor and the hinge angle obtained by the angle encoder as inputs to solve the relative pose of the front shield relative to the support shield using an analytical algorithm based on singular value decomposition. The central control unit is used to perform coordinate transformation and data fusion of the absolute pose of the supporting shield and the relative pose of the front shield with respect to the supporting shield, so as to obtain the pose of the front shield in the global coordinate system.

2. The TBM pose calculation system combining forward kinematics of the propulsion cylinder and laser measurement as described in claim 1, characterized in that, Eight sets of propulsion cylinders are used, and each set of propulsion cylinders is equipped with a stroke sensor and an angle encoder. The eight stroke sensors and eight angle encoders are respectively placed in the eight propulsion cylinders and at the hinges connecting the propulsion cylinders to the support shield.

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