Method, device and equipment for safety evaluation of collaborative robot operation path

Abstract

The application relates to the technical field of robots, in particular to a safety evaluation method, device and equipment for an operation path of a collaborative robot, wherein the method comprises the following steps: establishing an elastic mechanics model based on deformation energy of a flexible line, gravitational potential energy and calculation error; acquiring a pose of each robot in a collaborative robot system, inputting the pose of each robot into the elastic mechanics model, and outputting deformation information and stress information of the flexible line by the elastic mechanics model; and evaluating the safety of an operation path of each robot according to the deformation information and the stress information. Thus, the safety problem caused by the deformation or excessive internal stress of the flexible line part is considered, and the problem that the prior art depends on visual hardware, the cost and the computing resource are high is solved.

Description

Technical Field

[0001] The present application relates to the field of robotics technology, and in particular to a method, device, and equipment for safety assessment of an operating path of a collaborative robot. Background Art

[0002] Railway overhead contact systems contain numerous flexible components, such as catenary cables, contact wires, and dropper strings (hereinafter collectively referred to as flexible wires). These components are prone to deformation, aging, and other failures in the natural environment. Replacement and maintenance work is labor-intensive and ergonomically challenging. Therefore, to improve efficiency, a robot-assisted automated system has been introduced into railway overhead contact system maintenance operations.

[0003] Compared to traditional manipulation objects like bolts and rails, linear components in the catenary are significantly more flexible and subject to deformation during operation. Therefore, automated catenary maintenance systems typically require the integration of multiple robots working together to grasp the flexible wires and perform replacement and installation operations on these highly flexible and easily deformed components. During maintenance, two robots typically grasp the flexible wire at each end, using tooling to remove it from its initial position. Their arms then work together to transport it to a storage depot. A new flexible wire is then retrieved from the depot, transported to a designated location on the catenary, and secured using specialized tooling.

[0004] Current safety strategies for multi-robot collaboration typically focus on the robot itself. Common safety strategies include using sensors (such as visual sensors, infrared sensors, and lidar) to monitor the robot's surroundings in real time, discretizing the data collected by other robots into point clouds, and further fitting them into envelope boxes composed of convex polyhedrons. When the shortest distance between the envelope boxes is detected to exceed the safety threshold, the safety mechanism is triggered, causing the robot to slow down or trigger an emergency stop to avoid interference, collision, and damage. However, due to the high cost of hardware and the significant time and computing resources required to process two-dimensional and three-dimensional images, there is a mismatch between motion control and visual processing efficiency, which affects the efficiency of the collaborative robot system. Furthermore, safety issues arising from deformation of the flexible wire parts themselves or excessive internal stress are not considered. Summary of the Invention

[0005] The present application provides a safety assessment method, device and equipment for the operation path of a collaborative robot to solve the safety problems caused by the existing technology relying on visual hardware, high cost and computing resources, and not considering the deformation of the flexible wire parts themselves or excessive internal stress.

[0006] The first aspect of the present application provides a method for evaluating the safety of a collaborative robot operation path, comprising the following steps: establishing an elastic mechanics model based on the deformation energy, gravitational potential energy and calculation error of a flexible line, wherein the calculation error is based on the position of each different robot in the collaborative robot system operating the flexible line grasping the flexible line as the initial point, and calculating the difference between the positions of the same point on the flexible line; obtaining the posture of each robot in the collaborative robot system, inputting the posture of each robot into the elastic mechanics model, and the elastic mechanics model outputting the deformation information and force information of the flexible line; and evaluating the safety of each robot operation path based on the deformation information and force information.

[0007] Optionally, the elastic mechanics model is:

[0008]

[0009] F OD =∫||r f (s)-r i (s)||2ds;

[0010]

[0011] dQ(s) / ds=g4(q(s),Q(s),F(s));

[0012]

[0013] Among them, F oE is the total energy, E dtotal is the bending deformation energy of the flexible wire, E g is the gravitational potential energy of the flexible line, ω(s)=[ω1(s),ω2(s),ω3(s)] is the bending vector of any point of the flexible line, r(s) is the shape of the flexible line, ρ is the density of the flexible line, g is the acceleration of gravity, F OD is the calculation error, r f (s) is the coordinates of each point on the flexible line calculated from the position where the first robot in the collaborative robot system grasps the flexible line as the initial point, r i (s) is the coordinate of each point on the flexible line calculated from the position where the second robot in the collaborative robot system grasps the flexible line as the initial point, r(s) is the coordinate of the center line of the flexible line between the two ends of the flexible line operated by the robot, and r is usually taken in the calculation. i(s) is a quaternion representing the pose of each micro-element on the flexible line, g1 is an expression representing the functional relationship between the coordinates of each point on the flexible line and the pose of each micro-element, Q(s) is the result of differentiating q1(s)-q4(s) with respect to the arc length s, g2(s) is an expression representing the functional relationship of differentiating q1(s)-q4(s) with respect to the arc length s, F(s)=[F1(s),F2(s),F3(s)] T is the force borne by a point on the flexible line, f(s) is the distributed force borne by the flexible line except the operating force at the two ends, f1(s)-f3(s) are the components of f(s) in three directions in the Euclidean space, g3 is an expression representing the functional relationship between the force borne by each point on the flexible line and q, Q, F, and f, g4 is an expression representing the functional relationship between the second-order differentiation of the pose of each micro-element on the flexible line and q, Q, F, and s is the arc length of the flexible line between a point on the flexible line and the end point of the flexible line.

[0014] Optionally, the safety of each robot operation path is evaluated according to the deformation information and the force information, including: evaluating the interference danger of each robot operation path according to the deformation information; and evaluating the compliance safety of each robot operation path according to the force information.

[0015] Optionally, the interference danger of each robot operation path is evaluated according to the deformation information, including: obtaining the position and pose of each link of each robot; calculating the deformation information and the shortest distance between each link, and generating an interference danger index based on the shortest distance; and evaluating the interference danger of each robot operation path based on the interference danger index.

[0016] Optionally, the compliance safety of each robot operation path is evaluated according to the force information, including: identifying the force and torque in the force information; constructing a compliance safety index based on the force and torque; and evaluating the compliance safety of each robot operation path based on the compliance safety index.

[0017] Optionally, the interference danger index is:

[0018] C1(r(s))=min({r(s)},Robot);

[0019] wherein r(s) is the linear arc length between a point on the flexible line and the end point of the flexible line, Robot is the set of the current position and pose of each link of the robot, and C1(r(s)) is the interference danger index.

[0020] Optionally, the compliance safety index is:

[0021] C2(r(s))=w F (||F(s1)||2+||F(s t)||2)+w M (||M(s1)||2+||M(s t )||2);

[0022] Among them, w F and w M are the safety weight coefficients of force and moment respectively, F(s1) is the force borne by the starting end of the flexible line, and F(s t ) is the force borne by the end of the flexible line, M(s1) is the torque borne by the starting end of the flexible line, and M(s t ) is the torque borne by one end of the flexible line.

[0023] The second aspect of the present application provides a safety assessment device for the operation path of a collaborative robot, including: an establishment module for establishing an elastic mechanics model based on the deformation energy, gravitational potential energy and calculation error of the flexible line, wherein the calculation error is based on the position of each different robot in the collaborative robot system that operates the flexible line grasping the flexible line as the initial point, and calculating the difference between the positions of the same point on the flexible line; an input module for obtaining the posture of each robot in the collaborative robot system, inputting the posture of each robot into the elastic mechanics model, and the elastic mechanics model outputting the deformation information and force information of the flexible line; an evaluation module for evaluating the safety of each robot's operation path based on the deformation information and force information.

[0024] Optionally, the elastic mechanics model is:

[0025]

[0026] F OD =∫||r f (s)-r i (s)||2ds;

[0027]

[0028]

[0029] dQ(s) / ds=g4(q(s),Q(s),F(s));

[0030]

[0031] Among them, E OE is the total energy, E dtotal is the bending deformation energy of the flexible wire, E g is the gravitational potential energy of the flexible line, ω(s)=[ω1(s),ω2(s),ω3(s)] is the bending vector of any point of the flexible line, r(s) is the shape of the flexible line, ρ is the density of the flexible line, g is the acceleration of gravity, F ODis the calculation error, r f (s) is the coordinates of each point on the flexible line calculated from the position where the first robot in the collaborative robot system grasps the flexible line as the initial point, r i (s) is the coordinate of each point on the flexible line calculated from the position where the second robot in the collaborative robot system grasps the flexible line as the initial point, r(s) is the coordinate of the center line of the flexible line between the two ends of the flexible line operated by the robot, and r is usually taken in the calculation. i (s) and r f (s), q(s) = q1(s) - q4(s) is the quaternion that expresses the posture of each microelement on the flexible line, g1 is the functional relationship between the coordinates of each point on the flexible line and the posture of each microelement, Q(s) is the result of differentiating the arc length s in q1(s) - q4(s), g2(s) is the functional relationship expression representing the differential of the arc length s in q1(s) - q4(s), and F(s) = [F1(s), F2(s), F3(s)] T is the force acting on a point on the flexible line, f(s) is the distributed force acting on the flexible line except the operating forces at both ends, f1(s)-f3(s) are the components of f(s) in the three directions in Euclidean space, g3 is the functional expression representing the relationship between the force acting on each point on the flexible line and q, Q, F, f, g4 is the functional expression representing the relationship between the quadratic differential of each infinitesimal posture on the flexible line and q, Q, F, s is the arc length of the flexible line between a point on the flexible line and the endpoint of the flexible line.

[0032] Optionally, the evaluation module is further used to: evaluate the interference risk of each robot operation path based on the deformation information; and evaluate the compliance safety of each robot operation path based on the force information.

[0033] Optionally, the evaluation module is further used to: evaluate the interference risk of each robot operation path based on the deformation information, including: obtaining the position and posture of each link of each robot; calculating the shortest distance between the deformation information and each link, and generating an interference risk index based on the shortest distance; and evaluating the interference risk of each robot operation path based on the interference risk index.

[0034] Optionally, the evaluation module is further used to: identify forces and torques in the force information; construct a compliance safety index based on the forces and torques; and evaluate the compliance safety of each robot operation path based on the compliance safety index.

[0035] Optionally, the interference risk index is:

[0036] C1(r(s))=min({r(s)},Robot);

[0037] Among them, r(s) is the arc length between a point on the flexible line and the endpoint of the flexible line, Robot is the set of the current position and posture of each link of the robot, and C1(r(s)) is the interference risk index.

[0038] Optionally, the compliance safety index is:

[0039] C2(r(s))=w F (||F(s1)||2+||F(s t )||2)+w M (||M(s1)||2+||M(s t )||2);

[0040] Among them, w F and w M are the safety weight coefficients of force and moment respectively, F(s1) is the force borne by the starting end of the flexible line, and F(s t ) is the force borne by the end of the flexible line, M(s1) is the torque borne by the starting end of the flexible line, and M(s t ) is the torque borne by one end of the flexible line.

[0041] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to perform a safety assessment method for the operation path of a collaborative robot as described in the above embodiment.

[0042] The fourth aspect of the present application provides a computer-readable storage medium having a computer program or instructions stored thereon, and the computer program or instructions are executed by a processor to perform a safety assessment method for the collaborative robot operation path as in the above-mentioned embodiment.

[0043] Therefore, this application has at least the following beneficial effects:

[0044] The embodiment of the present application can establish an elastic mechanics model based on the deformation energy, gravitational potential energy, and calculation error of the flexible wire. The elastic mechanics model can be used to predict the deformation information and force information of the flexible wire only when the robot's position is known. Then, the safety of the robot's operation path can be evaluated based on the deformation information and force information. There is no need to introduce additional visual hardware, which reduces computing resources and hardware costs. It also avoids interference collisions caused by missed detection of the operating object due to visual hardware occlusion and fitting and registration failure during operation. This solves the safety problem of the existing technology that relies on visual hardware, has high costs and computing resources, and does not take into account the deformation of the flexible wire parts themselves or excessive internal stress.

[0045] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0047] Figure 1 Flowchart of a method for safety assessment of a collaborative robot operation path according to an embodiment of the present application;

[0048] Figure 2 Schematic diagram of the relationship between the postures of the two ends of the flexible wire and the postures of robots 1 and 2 according to an embodiment of the present application;

[0049] Figure 3 A schematic diagram of the calculation relationship between the position and posture of a point on a flexible line provided according to an embodiment of the present application;

[0050] Figure 4 A specific flow chart of a method for safety assessment of a collaborative robot operation path according to one embodiment of the present application;

[0051] Figure 5 This is an example diagram of a safety assessment device for a collaborative robot operation path provided in accordance with an embodiment of the present application;

[0052] Figure 6 A schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0053] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0054] Before describing the solution of this application, we first briefly introduce how related technologies can achieve safety assessment of collaborative robot operation paths, as follows:

[0055] In related technologies, collaborative robot safety strategies rely on sensor-based measurements of the operating object and the robot to determine safety. This requires the use of numerous sensors, including planar and depth cameras. This solution incurs high hardware costs, consumes significant time and computing resources for processing two-dimensional and three-dimensional images, and suffers from a mismatch between motion control and visual processing efficiency, impacting the efficiency of collaborative robot systems.

[0056] After obtaining visual image data of the robot and the manipulated object, it is necessary to fit the point cloud or pixel collection into a regular enveloping sphere or convex polyhedron enveloping box based on prior information about these objects, and then calculate the distance between these enveloping boxes. However, in railway catenary maintenance scenarios, manipulated objects such as droppers and contact wires are linear flexible bodies whose shapes change with the robot's operation, making them difficult to visually identify using templates. Moreover, such objects often exhibit curved shapes, making them difficult to fit using convex polyhedra or spheres. Therefore, the recognition results for such manipulated objects may miss detections. In the working environment, these linear components occupy a large amount of space in the axial direction, making it extremely easy for robots in multi-machine collaborative systems to obstruct and interfere with the manipulated objects.

[0057] Related technologies rely primarily on visual information, using only the physical distance between the object being manipulated and the robot as a safety criterion. When a flexible linear part being gripped by a robot twists, its deformation stress rapidly increases, increasing the probability of instability. Even in the absence of interference, sudden changes in shape can cause collisions with other robots, or excessive internal stress can lead to self-injury. This is a factor currently not considered in collaborative robot safety strategies.

[0058] In addition, it should be noted that during the maintenance of the contact network, a collaborative robot system consisting of N robotic arms (usually N=2) is usually required to grasp the two ends of a flexible line and transport it from the initial position to the target position according to a certain posture and trajectory. During the transportation process, there should be no collision or interference between the flexible line and the robot, and the flexible line should not be overstretched or over-twisted. Therefore, the embodiment of the present application takes into account the flexibility and safety requirements during the operation process. Before the robot is executed to operate according to the set trajectory and posture, the robot's operation path needs to be evaluated. If there is interference with the operating object or excessive operating force in the operation task, an early warning is required.

[0059] Specifically, this application provides a safety assessment method for collaborative robot operation paths. This method evaluates the safety of a collaborative robot operating a flexible component based on the predicted deformation of the object being operated. This method provides an early warning of potentially dangerous robot operation paths before the operation is performed. This addresses the safety issues inherent in existing technologies, which rely on visual hardware, are costly and require high computing resources, and fail to account for deformation or excessive internal stress in flexible wire components.

[0060] Figure 1 A flowchart of a method for safety assessment of a collaborative robot operation path provided in an embodiment of the present application.

[0061] like Figure 1As shown, the safety evaluation method of the collaborative robot operation path includes the following steps:

[0062] In step S101, an elastic mechanics model is established based on the deformation energy of the flexible line, the gravitational potential energy and the calculation error.

[0063] The calculation error is the difference between the positions of the same point on the flexible line calculated from the different robots in the collaborative robot system that operates the flexible line.

[0064] It can be understood that the embodiments of the present application can establish an elastic mechanics model based on the deformation energy of the flexible line, the gravitational potential energy and the calculation error, wherein the calculation error is the difference between the positions of the same point on the flexible line calculated from each robot in the collaborative robot system that operates the flexible line. OD .

[0065] Taking two robots in the collaborative robot system as an example, the calculation error is the difference between the position of a point on the flexible line calculated from the forward direction of the operating end of robot 1 and the position of the same point on the flexible line calculated from the reverse direction of the operating end of robot 2.

[0066] In the embodiments of the present application, the elastic mechanics model is:

[0067]

[0068] F OD =∫||r f (s)-r i (s)||2ds;

[0069]

[0070] dQ(s) / ds=g4(q(s),Q(s),F(s));

[0071]

[0072] wherein E OE is the total energy, E dtotal is the bending deformation energy of the flexible line, E g is the gravitational potential energy of the flexible line, ω(s)=[ω1(s),ω2(s),ω3(s)] is the bending vector of any point on the flexible line, r(s) is the shape of the flexible line, ρ is the density of the flexible line, g is the gravitational acceleration, F OD is the calculation error, r f (s) is the coordinates of each point on the flexible line calculated from the position of the flexible line held by the first robot (i.e. robot 1) in the collaborative robot system as the initial point, and r i(s) is the coordinate of each point on the flexible line calculated from the position where the second robot (i.e., robot 2) in the collaborative robot system grasps the flexible line as the initial point, and r(s) is the coordinate of the center line of the flexible line between the two ends of the flexible line operated by the robot. In the calculation, r is usually taken as i (s) and r f (s), q(s) = q1(s) - q4(s) is the quaternion that expresses the posture of each microelement on the flexible line, g1 is the functional relationship expression between the coordinates of each point on the flexible line and the posture of each microelement, Q(s) is the result of differentiating the variable (arc length s) in q1(s) - q4(s), g2(s) is the functional relationship expression representing the differential of the variable (arc length s) in q1(s) - q4(s), F(s) = [F1(s), F2(s), F3(s)] T is the force acting on a point on the flexible line, f(s) is the distributed force acting on the flexible line except the operating forces at both ends, f1(s)-f3(s) are the components of f(s) in the three directions in Euclidean space, g3 is the functional expression representing the relationship between the force acting on each point on the flexible line and q, Q, F, f, g4 is the functional expression representing the relationship between the quadratic differential of each infinitesimal posture on the flexible line and q, Q, F, s is the arc length of the flexible line between a point on the flexible line and the endpoint of the flexible line.

[0073] Among them, g1~g4 are used to express that the differential term on the far left is only related to several variables in the brackets after g, and a system of differential equations can be constructed to solve it.

[0074] Specifically, the process of constructing the elastic mechanics model in the embodiment of the present application, taking two robots as an example, is as follows:

[0075] In the collaborative robot system, the end effector path of robot 1 is set to P1 = {p1 1 ,p2 1 ,…,p n 1}, the end effector path of robot 2 is P2={p1 2 ,p2 2 ,…,p n 2}, where p i j =[r i j ,θ i j ],t i j is the robot end position vector, θ i j is the posture vector of the robot end effector, expressed as a quaternion. The posture sequence of the two ends of the flexible line is also determined by the robot actuator, which are T0 = {t10 ,t2 0 ,…,t n 0}=P1,T t ={t1 t ,t2 t ,…,t n t}=P2.

[0076] Under the conditions of the positions and postures of the two ends of a straight flexible line, an elastic mechanics model can be established based on Cosserat's elastic rod theory.

[0077] Assume that the linear density of the flexible wire is ρ, the bending stiffness is C1, and the torsional stiffness is C3.

[0078] At time i, the positions of robot 1 and robot 2 are given as p i 1 =[r i 1 ,θ i 1 ] and p i 2 =[r i 2 ,θ i 2 ], the poses at both ends of the flexible line are t i 0 =[r0,q0]=p i 1 and t i t =[r t ,q t ]=p i 2 The coordinates of the center line of the flexible line between the two ends are r(s), where r(0) = r0, r(L) = r t , s∈[0,L] is the length variable of the flexible line, and L is the total length of the flexible line. The posture of each microelement on the flexible line is q(s)=[q1(s),q2(s),q3(s),q4(s)], where q(0)=q0, q(L=q t , where the relationship between the postures of the two ends of the flexible line and the postures of robot 1 and robot 2 is as follows: Figure 2 shown.

[0079] Assume that the bending vector at any point on the flexible line is ω(s) = [ω1(s), ω2(s), ω3(s)], and the derivation formula is as shown in (1).

[0080]

[0081] Flexible wire bending deformation energy C=diag(C1,C1,C3). The gravitational potential energy of the flexible line is E g =∫r(s)ρgds=∫∫(dr(s) / ds)ρgds 2 For stability reasons, the shape of the flexible line after the operation should be the lowest point of the comprehensive potential energy. Therefore, when calculating the shape of the flexible line, the q(s) function is obtained so that F OE Minimum.

[0082]

[0083] In order to reduce the influence of discrete error, the calculation error term F is added to the objective function OD As shown in (3). That is, the difference between the position of a point on the flexible line calculated from the forward direction of the robot 1 operating end and the position of the same point on the flexible line calculated from the reverse direction of the robot 2 operating end. Where d3 is the direction vector of the flexible line axis, and the calculation relationship between the position of a point on the flexible line and the posture is as follows: Figure 3 shown.

[0084] F OD =∫||r f (s)-r i (s)||2ds; (3)

[0085]

[0086] By optimizing and calculating the minimum q(s) value of FOE+FOD and combining it with formula (4), the shape of the entire flexible line and the posture of any point, i.e., r(s) and q(s), can be predicted and calculated under the condition that the robot operation conditions at both ends of the flexible line are known.

[0087] Under the premise of obtaining the flexible line shape, assume that the moment at any point on the line is M(s) = [M1(s), M2(s), M3(s)] T , M(s)=[c1ω1(s), c1ω2(s), c3ω3(s)]. F(s)=[F1(s),F2(s),F3(s)] T is the force at a point on the flexible line. Combining Kirchhoff theory, the differential equation that characterizes the relationship between the deformation of the flexible line and the force is established as shown in (6). The force F(s) on the flexible line can be obtained according to equation (6.3).

[0088]

[0089] dQ(s) / ds=g4(q(s),Q(s),F(s)); (6.4)

[0090]

[0091] In step S102, the pose of each robot in the collaborative robot system is acquired, the pose of each robot is input into an elastomechanics model, and the elastomechanics model outputs deformation information and force information of the flexible line.

[0092] The deformation information can also be understood as shape information.

[0093] It can be understood that the embodiments of the present application can acquire the pose of each robot in the collaborative robot system, and input the pose of each robot into an elastomechanics model, and the elastomechanics model outputs deformation information and force information of the flexible line.

[0094] In step S103, the safety of each robot operation path is evaluated according to the deformation information and the force information.

[0095] It can be understood that the embodiments of the present application can evaluate the safety of each robot operation path according to the deformation information and the force information, thereby preventing dangerous phenomena such as collision, overstretching, and over-torsion of the flexible line in maintenance operation, and only the pose of the robot is required to obtain the deformation information and the force information of the flexible line by using the elastomechanics model, without using visual hardware, reducing the computing resources, and reducing the hardware cost.

[0096] In the embodiments of the present application, evaluating the safety of each robot operation path according to the deformation information and the force information includes: evaluating the interference danger of each robot operation path according to the deformation information; and evaluating the compliance safety of each robot operation path according to the force information.

[0097] It can be understood that the embodiments of the present application can evaluate the interference danger of each robot operation path according to the deformation information, and evaluate the compliance safety of each robot operation path according to the force information, and the specific evaluation method is as follows.

[0098] In the embodiments of the present application, evaluating the interference danger of each robot operation path according to the deformation information includes: acquiring the position and pose of each link of each robot; calculating the shortest distance between the deformation information and each link, and generating an interference danger index based on the shortest distance; and evaluating the interference danger of each robot operation path based on the interference danger index.

[0099] It can be understood that the embodiments of the present application can design the interference danger index according to the deformation information, and specifically: the current position and pose of each link of the robot are determined through the joint encoders of the robot, and the set is denoted as Robot. The interference danger criterion C1 of the flexible line at the current time can be obtained by calculating the distance between the flexible line curve and the link, and then the interference danger of each robot operation path is evaluated based on the interference danger. If C1 < T D(safety threshold), it means that during the operation, there is a high risk of collision and interference between the flexible line and the robot, and the robot's operating path needs to be adjusted.

[0100] In the embodiment of the present application, the interference risk index is:

[0101] C1(r(s))=min({r(s)},Robot); (7)

[0102] Among them, r(s) is the arc length between a point on the flexible line and the endpoint of the flexible line, Robot is the set of the current position and posture of each link of the robot, and C1(r(s)) is the interference risk index.

[0103] In an embodiment of the present application, the compliance safety of each robot operation path is evaluated based on the force information, including: identifying the forces and moments in the force information; constructing a compliance safety index based on the forces and moments; and evaluating the compliance safety of each robot operation path based on the compliance safety index.

[0104] It should be noted that since another requirement for robot operation safety is that the operating force must not exceed the limit during the maintenance process, which would cause over-stretching or over-twisting of the operated object, the embodiment of the present application designs a compliance safety index C2 to characterize compliance safety. By identifying the force and torque in the force information, a compliance safety index is constructed based on the force and torque, and the compliance safety of each robot operation path is evaluated based on the compliance safety index.

[0105] For the planned robot operation path, it is required to satisfy C2(r(s)) <T S ,max(||F(s1)||2,||F(s t )||2)≤T F and max(||M(s1)||2,||M(s t )||2)≤M F Otherwise, there is a risk that the robot and the object being operated may be damaged due to excessive force. s is the comprehensive stress safety threshold, T F is the force component safety threshold, M F is the torque component safety threshold, w f and w M are the safety weight factors of force and moment respectively.

[0106] In the embodiment of the present application, the compliance safety index is:

[0107] C2(r(s))=w F (||F(s1)||2+||F(s t )||2)+w M(||M(s1)||2+||M(s t )||2);(8)

[0108] Among them, w F and w M are the safety weight coefficients of force and moment respectively, F(s1) is the force borne by the starting end of the flexible line, and F(s t ) is the force borne by the end of the flexible line, M(s1) is the torque borne by the starting end of the flexible line, and M(s t ) is the torque borne by one end of the flexible line.

[0109] The following describes the safety assessment method of the collaborative robot operation path of the embodiment of the present application through a specific embodiment. The specific process is as follows: Figure 4 Shown, including:

[0110] In the collaborative robot system, the end effector path of robot 1 is set to P1 = {p1 1 ,p2 1 ,…,p n 1}, the end effector path of robot 2 is P2={p1 2 ,p2 2 ,…,p n 2}, where p i j =[r i j ,θ i j ],t i j is the robot end position vector, θ i j is the posture vector of the robot end effector, expressed as a quaternion. The posture sequence of the two ends of the flexible line is also determined by the robot actuator, which are T0 = {t1 0 ,t2 0 ,…,t n 0}=P1,T t ={t1 t ,t2 t ,…,t n t}=P2.

[0111] Under the condition that the positions and postures of the two ends of the flexible line are known, an optimization model can be established based on the Cosserat elastic rod theory to predict and calculate the shape and force conditions of the flexible line during robot operation, and then an evaluation index function can be designed to evaluate the safety of each step in the collaborative robot operation. If the index function deviates from the threshold, the path planning is re-performed to prevent the occurrence of dangerous phenomena such as collision, over-stretching, and over-twisting of the flexible line during maintenance operations.

[0112] Assume that the linear density of the flexible wire is ρ, the bending stiffness is C1, and the torsional stiffness is C3.

[0113] At time i, the positions of robot 1 and robot 2 are given as p i 1 =[r i 1 ,θ i 1 ] and p i 2 =[r i 2 ,θ i 2 ], the poses at both ends of the flexible line are t i 0 =[r0,q0]=p i 1 and t i t =[r t ,q t ]=p i 2 The coordinates of the center line of the flexible line between the two ends are r(s), where r(0) = r0, r(L) = r t , s∈[0,L] is the length variable of the flexible line, and L is the total length of the flexible line. The posture of each microelement on the flexible line is q(s)=[q1(s),q2(s),q3(s),q4(s)], where q(0)=q0, q(L=q t .

[0114] Minimize the objective function FOE+FOD, and predict and calculate the shape of the entire flexible line and the posture of any point, i.e., r(s) and q(s), through formulas (1)-(5).

[0115] Under the premise of obtaining the flexible line shape, assume that the moment at any point on the line is M(s) = [M1(s), M2(s), M3(s)] T , M(s)=[c1ω1(s), c1ω2(s), c3ω3(s)]. F(s)=[F1(s),F2(s),F3(s)] Tis the force at a point on the flexible line. Combining Kirchhoff theory, the differential equation that characterizes the relationship between the deformation of the flexible line and the force is established as shown in formula (6). The force F(s) on the flexible line can be obtained according to formula (6.3), where f(s) is the distributed force on the flexible line in addition to the operating forces at both ends, which is usually the gravity caused by the density of the flexible line.

[0116] The safety of the robot's operation path is evaluated by C1(r(s)) and C2(r(s)). If C1(r(s)) is less than TD, or C2(r(s)) is greater than or equal to TS, an alarm message is issued and the robot's operation path is replanned.

[0117] In summary, the embodiment of the present application establishes an elastic mechanics model, takes into account deformation energy, gravitational potential energy and calculation errors, models the flexible lines in the maintenance process, predicts their shape and force conditions, and designs interference and force criteria to characterize operational safety based on the modeling prediction results. When only the robot operation path is known, it can be determined whether collisions and damage to the operation object will occur during the operation. Before the operation path planning is completed and executed, the safety of the task can be evaluated, avoiding interference collisions caused by missed detection of the operation object due to occlusion of the visual sensor and fitting and registration failure during the operation. Compared with the existing technology, no visual sensor needs to be introduced, the cost is lower, and there is no need to process image and point cloud data, which consumes less computing resources.

[0118] According to the safety assessment method of the collaborative robot operation path proposed in the embodiment of the present application, an elastic mechanics model can be established based on the deformation energy, gravitational potential energy and calculation error of the flexible line. The elastic mechanics model can be used to predict the deformation information and force information of the flexible line only when the robot's posture is known, and then the safety of the robot's operation path can be assessed based on the deformation information and force information. There is no need to introduce additional visual hardware, which reduces computing resources and hardware costs, and avoids interference collisions caused by missed detection of the operation object due to occlusion of visual hardware and failure of fitting and registration during operation.

[0119] Next, a safety assessment device for the operation path of a collaborative robot proposed in an embodiment of the present application will be described with reference to the accompanying drawings.

[0120] Figure 5 It is a block diagram of a safety assessment device for a collaborative robot operation path according to an embodiment of the present application.

[0121] like Figure 5 As shown, the safety assessment device 10 for the collaborative robot operation path includes: an establishment module 100, an input module 200 and an assessment module 300.

[0122] Among them, the establishment module 100 is used to establish an elastic mechanics model based on the deformation energy, gravitational potential energy and calculation error of the flexible line, wherein the calculation error is based on the position of each different robot in the collaborative robot system that operates the flexible line grasping the flexible line as the initial point, and calculates the difference between the positions of the same point on the flexible line; the input module 200 is used to obtain the posture of each robot in the collaborative robot system, input the posture of each robot into the elastic mechanics model, and the elastic mechanics model outputs the deformation information and force information of the flexible line; the evaluation module 300 is used to evaluate the safety of each robot's operating path based on the deformation information and force information.

[0123] In the embodiment of the present application, the elastic mechanics model is:

[0124]

[0125] F OD =∫||r f (s)-r i (s)||2ds;

[0126]

[0127]

[0128] dQ(s) / ds=g4(q(s),Q(s),F(s));

[0129]

[0130] Among them, E OE is the total energy, E dtotal is the bending deformation energy of the flexible wire, E g is the gravitational potential energy of the flexible line, ω(s)=[ω1(s),ω2(s),ω3(s)] is the bending vector of any point of the flexible line, r(s) is the shape of the flexible line, ρ is the density of the flexible line, g is the acceleration of gravity, F OD is the calculation error, r f (s) is the coordinates of each point on the flexible line calculated from the position where the first robot in the collaborative robot system grasps the flexible line as the initial point, r i(s) is the coordinate of each point on the flexible line calculated from the position where the second robot in the collaborative robot system grasps the flexible line as the initial point, r(s) is the coordinate of the center line of the flexible line between the two ends operated by the robot, q(s) = q1(s) - q4(s) is the quaternion expressing the posture of each microelement on the flexible line, g1 is the functional relationship between the coordinates of each point on the flexible line and the posture of each microelement, Q(s) is the result of differentiating the arc length s in q1(s) - q4(s), g2(s) is the functional relationship expression representing the differential of the arc length s in q1(s) - q4(s), and F(s) = [F1(s), F2(s), F3(s)]. T is the force acting on a point on the flexible line, f(s) is the distributed force acting on the flexible line except the operating forces at both ends, f1(s)-f3(s) are the components of f(s) in the three directions in Euclidean space, g3 is the functional expression representing the relationship between the force acting on each point on the flexible line and q, Q, F, f, g4 is the functional expression representing the relationship between the quadratic differential of each infinitesimal posture on the flexible line and q, Q, F, s is the arc length of the flexible line between a point on the flexible line and the endpoint of the flexible line.

[0131] In the embodiment of the present application, the evaluation module 300 is further used to: evaluate the interference risk of each robot operation path based on the deformation information; and evaluate the compliance safety of each robot operation path based on the force information.

[0132] In an embodiment of the present application, the evaluation module 300 is further used to: evaluate the interference risk of each robot operation path based on the deformation information, including: obtaining the position and posture of each link of each robot; calculating the shortest distance between the deformation information and each link, and generating an interference risk index based on the shortest distance; and evaluating the interference risk of each robot operation path based on the interference risk index.

[0133] In an embodiment of the present application, the evaluation module 300 is further used to: identify forces and torques in the force information; construct a compliance safety index based on the forces and torques; and evaluate the compliance safety of each robot operation path based on the compliance safety index.

[0134] In the embodiment of the present application, the interference risk index is:

[0135] C1(r(s))=min({r(s)},Robot);

[0136] Among them, r(s) is the arc length between a point on the flexible line and the endpoint of the flexible line, Robot is the set of the current position and posture of each link of the robot, and C1(r(s)) is the interference risk index.

[0137] In the embodiment of the present application, the compliance safety index is:

[0138] C2(r(s))=w F (||F(s1)||2+||F(s t )||2)+w M (||M(s1)||2+||M(s t )||2);

[0139] Among them, w F and w M are the safety weight coefficients of force and moment respectively, F(s1) is the force borne by the starting end of the flexible line, and F(s t ) is the force borne by the end of the flexible line, M(s1) is the torque borne by the starting end of the flexible line, and M(s t ) is the torque borne by one end of the flexible line.

[0140] It should be noted that the above explanation of the embodiment of the method for safety assessment of the operation path of a collaborative robot is also applicable to the safety assessment device for the operation path of a collaborative robot in this embodiment, and will not be repeated here.

[0141] According to the safety assessment device for the collaborative robot operation path proposed in the embodiment of the present application, an elastic mechanics model can be established based on the deformation energy, gravitational potential energy and calculation error of the flexible line. The elastic mechanics model can be used to predict the deformation information and force information of the flexible line only when the robot's posture is known, and then the safety of the robot's operation path can be assessed based on the deformation information and force information. There is no need to introduce additional visual hardware, which reduces computing resources and hardware costs, and avoids interference collisions caused by missed detection of the operation object due to occlusion of visual hardware and failure of fitting and registration during operation.

[0142] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0143] A memory 601 , a processor 602 , and a computer program stored in the memory 601 and executable on the processor 602 .

[0144] When the processor 602 executes the program, the safety assessment method of the collaborative robot operation path provided in the above embodiment is implemented.

[0145] Furthermore, the electronic device further includes:

[0146] The communication interface 603 is used for communication between the memory 601 and the processor 602 .

[0147] The memory 601 is used to store computer programs that can be run on the processor 602 .

[0148] The memory 601 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0149] If the memory 601, processor 602, and communication interface 603 are implemented independently, the communication interface 603, memory 601, and processor 602 can be interconnected via a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0150] Optionally, in a specific implementation, if the memory 601, the processor 602 and the communication interface 603 are integrated on a chip, the memory 601, the processor 602 and the communication interface 603 can communicate with each other through an internal interface.

[0151] The processor 602 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0152] An embodiment of the present application also provides a computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed by a processor, the safety assessment method of the collaborative robot operation path as described above is implemented.

[0153] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0154] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0155] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing a custom logical function or process step, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0156] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, it can be implemented using any one or a combination of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0157] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

Claims

1. A safety assessment method for a collaborative robot operation path, characterized in that: The following steps are involved: An elastic mechanics model is established based on the deformation energy, gravitational potential energy, and calculation error of the flexible wire, wherein the calculation error is the difference between the positions of the same point on the flexible wire, starting from the position where different robots in the collaborative robot system operating the flexible wire grasp the flexible wire; The posture of each robot in the collaborative robot system is obtained, and the posture of each robot is input into the elastic mechanics model, and the elastic mechanics model outputs the deformation information and force information of the flexible line; the elastic mechanics model is: ； F OD = ； dr(s) / d s = = g 1(q( s )); dq(s) / d s = =Q(s) = g 2( s ); dF(s) / d s = = g 3(q( s ), Q( s ), F( s ), f( s )); dQ(s) / d s = g 4(q( s ), Q( s ), F( s )); df( s ) / d s = = 0; in, is the total energy, is the bending deformation energy of the flexible line, is the gravitational potential energy of the flexible line, =[ω1( s ), ω2( s ), ω3( s )] is the bending vector of any point on the flexible line, In the form of a flexible line, is the density of the flexible line, is the acceleration due to gravity, F OD is the calculation error, The coordinates of each point on the flexible line are calculated starting from the position where the first robot in the collaborative robot system grasps the flexible line. The coordinates of each point on the flexible line are calculated starting from the position where the second robot in the collaborative robot system grasps the flexible line. r(s) is the coordinate of the center line of the flexible line between the two ends operated by the robot. q( s )= - The quaternion expresses the posture of each microelement on the flexible line. g 1 is the functional relationship expression between the coordinates of each point on the flexible line and the posture of each microelement, Q(s) is the - The result of differentiating the arc length s is, g 2( s ) is the representation - The functional relationship expression for the differential of arc length s is F(s)=[ F 1( s ), F 2( s ), F 3( s )] T is the force on a point on the flexible line, f( s ) is the distributed force on the flexible line in addition to the operating forces at both ends, - is f( s ) in the three directions in Euclidean space, g 3 is the functional expression that represents the relationship between the force at each point on the flexible line and q, Q, F, f. g 4 is the functional expression for the relationship between the second differential of each infinitesimal element posture on the flexible line and q, Q, F. The arc length of the flexible line between a certain point on the flexible line and the endpoint of the flexible line; The safety of each robot operation path is evaluated according to the deformation information and the force information.

2. The safety assessment method for collaborative robot operation paths according to claim 1, characterized in that: The evaluating the safety of each robot operation path according to the deformation information and the force information includes: evaluating the interference risk of each robot operation path according to the deformation information; The compliance safety of each robot operation path is evaluated according to the force information.

3. The safety assessment method for collaborative robot operation paths according to claim 2, characterized in that: The step of evaluating the interference risk of each robot operation path according to the deformation information includes: Obtaining the position and posture of each link of each robot; calculating the shortest distance between the deformation information and each connecting rod, and generating an interference risk index based on the shortest distance; The interference risk of each robot operation path is evaluated based on the interference risk index.

4. The safety assessment method for collaborative robot operation paths according to claim 2, characterized in that: The evaluating the compliance safety of each robot operation path according to the force information includes: Identifying forces and moments in the force information; constructing a compliance safety index based on the force and the moment; The compliance safety of each robot operation path is evaluated based on the compliance safety index.

5. The safety assessment method for collaborative robot operation path according to claim 3, characterized in that: The interference risk index is: C 1(r( s )) = min({r( s )}, Robot); Among them, r( s ) is the arc length between a point on the flexible line and the endpoint of the flexible line, Robot is the set of the current position and posture of each link of the robot, C 1(r( s )) is an interference risk indicator.

6. The safety assessment method for collaborative robot operation paths according to claim 4, characterized in that: The compliance safety index is: C 2(r( s )) = w F (||F( s 1)||2+||F( s t )||2)+ w M (||M( s 1)||2+||M( s t )||2); in, w F and w M are the safety weight factors of force and moment, F( s 1) is the force borne by the starting end of the flexible line, F( s t ) is the force borne by one end of the flexible line, M( s 1) is the moment borne by the starting end of the flexible line, M( s t ) is the torque borne by one end of the flexible line.

7. A safety assessment device for a collaborative robot operation path, characterized in that: include: Establishing a module for establishing an elastic mechanics model based on the deformation energy, gravitational potential energy, and a calculated error of the flexible wire, wherein the calculated error is the difference between the positions of the same point on the flexible wire, starting from the position where each different robot in the collaborative robot system operating the flexible wire grasps the flexible wire; An input module is used to obtain the position and posture of each robot in the collaborative robot system, input the position and posture of each robot into the elastic mechanics model, and the elastic mechanics model outputs the deformation information and force information of the flexible line; the elastic mechanics model is: ； F OD = ； dr(s) / d s = = g 1(q( s )); dq(s) / d s = =Q(s) = g 2( s ); dF(s) / d s = = g 3(q( s ), Q( s ), F( s ), f( s )); dQ(s) / d s = g 4(q( s ), Q( s ), F( s )); df( s ) / d s = = 0; in, is the total energy, is the bending deformation energy of the flexible line, is the gravitational potential energy of the flexible line, =[ω1( s ), ω2( s ), ω3( s )] is the bending vector of any point on the flexible line, In the form of a flexible line, is the density of the flexible line, is the acceleration due to gravity, F OD is the calculation error, The coordinates of each point on the flexible line are calculated starting from the position where the first robot in the collaborative robot system grasps the flexible line. The coordinates of each point on the flexible line are calculated starting from the position where the second robot in the collaborative robot system grasps the flexible line. r(s) is the coordinate of the center line of the flexible line between the two ends operated by the robot. q( s )= - The quaternion expresses the posture of each microelement on the flexible line. g 1 is the functional relationship expression between the coordinates of each point on the flexible line and the posture of each microelement, Q(s) is the - The result of differentiating the arc length s is, g 2( s ) is the representation - The functional relationship expression for the differential of arc length s is F(s)=[ F 1( s ), F 2( s ), F 3( s )] T is the force on a point on the flexible line, f( s ) is the distributed force on the flexible line in addition to the operating forces at both ends, - is f( s ) in the three directions in Euclidean space, g 3 is the functional expression that represents the relationship between the force at each point on the flexible line and q, Q, F, f. g 4 is the functional expression for the relationship between the second differential of each infinitesimal element posture on the flexible line and q, Q, F. The arc length of the flexible line between a certain point on the flexible line and the endpoint of the flexible line; An evaluation module is used to evaluate the safety of each robot operation path based on the deformation information and the force information.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the safety assessment method for the collaborative robot operation path as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: The computer program or instructions are executed by a processor to implement the safety assessment method for the collaborative robot operation path as described in any one of claims 1 to 6.

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