Industrial robot trajectory planning method and controller

Abstract

The application discloses an industrial robot trajectory planning method and a controller, and the method comprises the following steps: acquiring an industrial robot motion trajectory related parameter, determining trajectory starting information and a constraint condition; dividing a trajectory model of the robot and establishing an acceleration planning model according to the trajectory model; solving optimal parameters of the trajectory according to the constraint condition, and re-integrating an acceleration formula to obtain a trajectory position planning model. In the application, a segmented exponential trajectory planning method is adopted to plan the robot trajectory. The application has the advantages that by adjusting the proportion of each stage in the industrial robot trajectory planning, especially the proportion of the deceleration stage, the impact of the trajectory planning on the robot body in the whole motion process can be reduced.

Description

Technical Field

[0001] This application relates to the field of robot motion planning technology, and in particular to an industrial robot trajectory planning method and controller. Background Technology

[0002] Trajectory planning is a crucial aspect of robot control system research. The smoothness of the robot's trajectory during motion is a key indicator of its motion planning performance, playing a critical role in improving robot performance. Therefore, trajectory planning is a significant area of ​​research in robotics.

[0003] Robot trajectory planning includes Cartesian space trajectory planning and joint space trajectory planning. Typically, to ensure smooth robot trajectories, industrial robots often employ S-curve velocity planning or trapezoidal velocity planning methods. The commonly used S-curve trajectory planning method, such as the literature "S-curve velocity planning for a six-DOF robot [J]" (Liu Lei, Zeng Hui, Liu He, et al. Computer Technology and Automation, 2015, 34(2):42-45), ensures continuous acceleration along the robot path compared to trapezoidal trajectory planning. However, the acceleration curve along the path remains discontinuous, still resulting in mechanical impact. Other commonly used trajectory planning methods include the sinusoidal acceleration and deceleration control algorithm in "Research on Pose Trajectory Planning of Industrial Robots Based on Sinusoidal Acceleration and Deceleration Control Algorithm [J]" (Huang Zhongming, Chen Aiwen, Huang Fengliang. Manufacturing Automation, 2019, 041(002):31-34). Although it ensures a smooth transition of acceleration and jerk curves between the start-up, uniform speed operation and stopping phases, it is not smooth enough in the deceleration phase. This planning method still has a certain impact on the robot body during the stopping phase. Summary of the Invention

[0004] This application provides an industrial robot trajectory planning method and controller. Its advantage is that by adjusting the proportion of each stage in the industrial robot trajectory planning, especially the proportion of the deceleration stage, the impact on the robot body caused by trajectory planning during the entire motion process can be reduced.

[0005] On the one hand, this application provides an industrial robot trajectory planning method, including the following steps:

[0006] Obtain relevant parameters of the industrial robot's motion trajectory, including the initial displacement s0, velocity v0, acceleration a0, and final displacement s. e Speed ​​v e and acceleration a e Set the constraints for trajectory velocity, trajectory acceleration, and trajectory jerk.

[0007] The trajectory model of the robot is divided into 5 stages s1-s5, namely the acceleration stage including the acceleration stage s1 and the deceleration stage s2, the constant speed stage including the constant speed stage s3, and the deceleration stage including the acceleration stage s4 and the deceleration stage s5.

[0008] An acceleration planning model is established based on the trajectory model: a segmented acceleration planning model is established for the robot trajectory model in five stages;

[0009] Solve for the optimal trajectory parameters based on the constraints: determine whether the velocity, acceleration, and jerk function planning curves satisfy the constraints; if not, recalculate.

[0010] Generate robot motion trajectory: Reintegrate the acceleration formula to obtain the trajectory position planning model.

[0011] Furthermore, the acceleration planning model for the robot trajectory model adopts an exponential acceleration function. The formula for the piecewise exponential acceleration function in the acceleration planning model is as follows:

[0012]

[0013] Among them, A acc and A dec Let t3 be the maximum and minimum acceleration and deceleration values ​​of the trajectory, t5 be the start time of the acceleration segment, t3 be the end time of the deceleration segment, and μ and σ be the end time of the acceleration segment and the proportional coefficient, respectively. By deriving the acceleration formula, the piecewise function formulas for position, velocity, and jerk are obtained. By substituting the given trajectory parameters into the calculation, the values ​​of the unknown parameters in the equations are obtained, resulting in the piecewise function trajectory formulas for position, velocity, acceleration, and jerk.

[0014] Furthermore, the robot's trajectory is determined by the following conditions:

[0015] s(t0)=0,

[0016] s(t e ) = s e ,

[0017] Where t0 is the starting time of trajectory s, t e Let be the time at which trajectory s terminates. For trajectory path speed, For trajectory path acceleration, Add acceleration to the trajectory path.

[0018] Furthermore, the robot's trajectory model is divided into the following categories according to time sequence:

[0019]

[0020] Furthermore, the constraints on the trajectory velocity, trajectory acceleration, and trajectory jerk include the maximum trajectory velocity V. max Maximum trajectory acceleration A max Maximum trajectory jerk J max ,in,

[0021]

[0022] Furthermore, when A is calculated acc Or A dec Greater than |A max |,Another A acc Or A dec The value is equal to |A max Substitute the values ​​into formula (1) and recalculate;

[0023] When the calculated jerk value is greater than J max Let the value of the jerk be equal to J. max Recalculate the values ​​of the acceleration parameters.

[0024] On the other hand, this application provides an industrial robot controller, including a memory and a processor. The memory is used to store computer programs, and when the processor calls and runs the computer programs stored in the memory, it executes the above-described industrial robot trajectory planning method.

[0025] In summary, the beneficial effects of this application are as follows:

[0026] 1. The acceleration planning method based on piecewise functions proposed in this application can change the extreme value of acceleration by adjusting the proportion of each stage in the trajectory planning of industrial robots, especially the proportion of the deceleration stage. The larger the proportion of the deceleration stage, the smaller the maximum value of acceleration, thereby reducing the impact on the robot body caused by trajectory planning during the entire motion process.

[0027] 2. The exponential function-based industrial robot trajectory planning method proposed in this application, based on segmentation, provides a smoother motion curve compared to commonly used trapezoidal and S-shaped trajectory planning models. This ensures that the position, velocity, acceleration, and jerk between the start and end points of the trajectory are continuous, resulting in a more stable robot operation. Attached Figure Description

[0028] Figure 1 This is a flowchart of the piecewise exponential trajectory planning method of the present invention;

[0029] Figure 2This is a schematic diagram of the piecewise exponential trajectory model for planning motion trajectories according to the present invention, wherein pos is the trajectory path curve, vel is the trajectory velocity curve, acc is the trajectory acceleration curve, and jerk is the trajectory jerk curve.

[0030] Figure 3 This is a comparison chart of the piecewise exponential trajectory planning acceleration planning curve of this invention and the conventional acceleration planning curve. Detailed Implementation

[0031] The specific embodiments of this application are described in detail below with reference to the accompanying drawings.

[0032] Example: On one hand, this example provides an industrial robot trajectory planning method, such as... Figure 1 As shown, it includes the following steps:

[0033] (1) Obtain relevant parameters of the industrial robot's motion trajectory and determine the trajectory start information and constraints:

[0034] Includes the initial displacement s0, velocity v0, acceleration a0, and final displacement s of the trajectory. e Speed ​​v e and acceleration a e The above parameters can be obtained from robot teaching, and the robot's motion trajectory is determined by the following conditions:

[0035] s(t0)=0,

[0036] s(t e ) = s e ,

[0037] Where t0 is the starting time of trajectory s, t e Let be the time at which trajectory s terminates. For trajectory path speed, For trajectory path acceleration, Add acceleration to the trajectory path.

[0038] Set constraints for trajectory velocity, trajectory acceleration, and trajectory jerk; including the maximum trajectory velocity V. max Maximum trajectory acceleration A max Maximum trajectory jerk J max The above parameters can be obtained from the robot controller, where,

[0039]

[0040] (2) Divide the robot's trajectory model and establish an acceleration planning model based on the trajectory model:

[0041] The robot's trajectory model is divided into five stages, s1-s5: an acceleration stage (s1 including jerk and s2), a constant velocity stage (s3 including constant velocity), and a deceleration stage (s4 including jerk and s5 including jerk); these are arranged in chronological order as follows:

[0042]

[0043] To ensure smoother robot operation, the proportion of the trajectory planning model in the deceleration phase, especially the deceleration phase, can be adjusted according to actual needs, thereby reducing body jitter when the robot stops. The piecewise acceleration planning model method in this application specifically describes the acceleration and deceleration phases separately using piecewise exponential functions. Taking the robot deceleration phase as an example, the known trajectory parameters given by the system include the initial displacement s0 and the ending position s0 of the deceleration phase. e Initial velocity v max With the default final velocity set to 0, the formula for the piecewise exponential acceleration function in trajectory planning is:

[0044]

[0045] Among them, A acc and A dec These represent the trajectory acceleration and deceleration values, respectively. t4 is the start time of the acceleration segment, t5 is the end time of the deceleration segment, and μ and σ are the end time of the acceleration segment and the proportional coefficient, respectively. The piecewise function formulas for position, velocity, and jerk are derived from the acceleration formula. Substituting the given trajectory parameters into the calculations yields the values ​​of the unknown parameters in the equations, resulting in the piecewise function trajectory formulas for position, velocity, acceleration, and jerk, thus establishing the trajectory planning curve. The value of parameter k controls the proportion of deceleration time; a larger value of k results in a larger proportion of deceleration segments, smaller maximum and minimum deceleration values, and a smoother robot deceleration process with less impact.

[0046] (3) Solve for the optimal trajectory parameters based on the constraints:

[0047] Based on the robot controller's maximum and minimum constraints, determine whether the velocity, acceleration, and jerk function planning curves obtained in step (2) exceed their maximum or minimum values. If they do, recalculate the optimal trajectory parameters. Taking jerk as an example, when the calculated A... acc Or A dec Greater than |A max |,Another A acc Or A dec The value is equal to |A max Substitute the values ​​into formula (1) and recalculate;

[0048] When the calculated jerk value is greater than J maxLet the value of the jerk be equal to J. max Recalculate the values ​​of the acceleration parameters.

[0049] (4) Generate robot motion trajectory:

[0050] Based on the constraints in step (3), all unknown parameters A, μ, k, and t in the acceleration programming model are finally confirmed. e Then, the acceleration formula is re-integrated to obtain the trajectory position planning model. Finally, the positions from the starting point to the ending point at each time step are output in real time, completing the trajectory planning along the path.

[0051] In one specific embodiment, the planned robot motion trajectory is as follows: Figure 2 As shown, pos is the trajectory path curve, vel is the trajectory velocity curve, acc is the trajectory acceleration curve, and jerk is the trajectory jerk curve.

[0052] This embodiment changes the extreme value of acceleration by adjusting the proportion of the deceleration segment. The larger the proportion of the deceleration segment, the smaller the maximum value of acceleration. Figure 3 As shown, this reduces the impact on the robot body caused by trajectory planning throughout the entire motion process.

[0053] This embodiment also provides an industrial robot controller, including a memory and a processor. The memory is used to store computer programs. When the processor calls and runs the computer programs stored in the memory, it executes the industrial robot trajectory planning method in the above embodiment.

[0054] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of this application, and these all fall within the protection scope of this application.

Claims

1. A method for trajectory planning of an industrial robot, characterized in that, Includes the following steps: Obtain relevant parameters of the industrial robot's motion trajectory, including the initial displacement s0, velocity v0, acceleration a0, and final displacement s. e Speed ​​v e and acceleration a e Set the constraints for trajectory velocity, trajectory acceleration, and trajectory jerk. The trajectory model of the robot is divided into 5 stages s1-s5, namely the acceleration stage including the acceleration stage s1 and the deceleration stage s2, the constant speed stage including the constant speed stage s3, and the deceleration stage including the acceleration stage s4 and the deceleration stage s5. An acceleration planning model is established based on the trajectory model: a piecewise acceleration planning model is established for the robot trajectory model in five stages; the acceleration planning model of the robot trajectory model adopts an exponential acceleration function, and the formula for the piecewise exponential acceleration function of the acceleration planning model is as follows: （1） Among them, A acc and A dec Let t3 be the maximum and minimum acceleration and deceleration values ​​of the trajectory, t5 be the start time of the acceleration segment, t3 be the end time of the deceleration segment, and μ and σ be the end time of the acceleration segment and the proportional coefficient, respectively. By deriving the acceleration formula, the piecewise function formulas for position, velocity, and jerk are obtained. By substituting the given trajectory parameters into the calculation, the values ​​of the unknown parameters in the equations are obtained, resulting in the piecewise function trajectory formulas for position, velocity, acceleration, and jerk. Solve for the optimal trajectory parameters based on the constraints: determine whether the velocity, acceleration, and jerk function planning curves satisfy the constraints; if not, recalculate. Generate robot motion trajectory: Reintegrate the acceleration formula to obtain the trajectory position planning model.

2. The industrial robot trajectory planning method according to claim 1, characterized in that, The robot's trajectory is determined by the following conditions: Where t0 is the starting time of trajectory s, t e Let be the time at which trajectory s terminates. For trajectory path speed, For trajectory path acceleration, Add acceleration to the trajectory path.

3. The industrial robot trajectory planning method according to claim 1, characterized in that, The robot's trajectory model is divided into the following categories according to time sequence: 。 4. The industrial robot trajectory planning method according to claim 1, characterized in that, The constraints on trajectory velocity, trajectory acceleration, and trajectory jerk include the maximum trajectory velocity V. max Maximum trajectory acceleration A max Maximum trajectory jerk J max ,in, 。 5. The industrial robot trajectory planning method according to claim 4, characterized in that, When the calculated A acc Or A dec Greater than |A max |, let A acc Or A dec The value is equal to |A max Substitute the values ​​into formula (1) and recalculate; When the calculated jerk value is greater than J max Let the value of the jerk be equal to J. max Recalculate the values ​​of the acceleration parameters.

6. An industrial robot controller, characterized in that, The method includes a memory and a processor, wherein the memory is used to store computer programs, and when the processor calls and runs the computer programs stored in the memory, it performs the method as described in any one of claims 1-5.

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