Model selection method of additional shaft servo motor for robot

Abstract

The invention relates to the field of robot additional shafts, in particular to an additional shaft servo motor type selection method for a robot, which comprises the following specific steps of: S1, determining a transmission system structure at a load end of an additional shaft motor; s2, determining a mechanical structure and motion characteristic parameters of the transmission system; s3, importing into a motor library; s4, performing calculation; s5, judging and checking; s6, model selection is completed; for three mainstream transmission systems of a gear rack, a ball screw and a belt at a load end of a robot additional shaft motor, calculation and accurate model selection are performed on parameters of the motor, and the dynamic response characteristic of the motor and the system compatibility of the model selection method are improved; the model selection tool can support a user to import and modify a motor database by himself / herself, and quickly and conveniently recommend an accurate model selection result from the motor database according to the rotation speed, torque, power and load inertia ratio judgment and check conditions of the motor, thereby improving the model selection efficiency of the servo motor and improving the user experience. And resource redundancy and manufacturing cost caused by a traditional empirical selection method are reduced.

Description

Technical Field

[0001] This invention relates to the field of robot additional axes, specifically a method for selecting servo motors for robot additional axes. Background Technology

[0002] Robot add-on axes, a significant technological innovation in industrial automation, primarily refer to auxiliary actuators that extend the motion degrees of freedom of multi-degree-of-freedom industrial robots. These devices significantly extend the robot's workspace and operational flexibility by adding linear or rotational motion dimensions, enabling it to adapt to more complex application scenarios. As the core drive unit of the add-on axis, the performance of the servo motor directly affects the operational accuracy, response speed, and stability of the entire robot system. When selecting an add-on axis motor, multiple factors need to be considered, such as motor torque, inertia, power matching, and load characteristics. Especially under high-load, high-acceleration, and frequent start-stop conditions, selecting a suitable servo motor is crucial to ensuring system performance; therefore, how to quickly and accurately select the right servo motor for robot add-on axes is a core problem to be solved.

[0003] Current servo motor selection methods primarily rely on a combination of empirical formulas and manual calculations. Engineers need to progressively calculate various parameters and repeatedly verify the selected motor by consulting tables. This method is inefficient, rarely considering the design of the motor's motion trajectory characteristics during calculations, and often selects oversized motors for safety, resulting in wasted resources and increased manufacturing costs for the servo motor. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a method for selecting additional axis servo motors for robots.

[0005] A method for selecting an additional axis servo motor for a robot, the specific steps of which are as follows: S1. Determine the structure of the transmission system at the load end of the auxiliary shaft motor: the models include gear rack, ball screw and belt drive commonly used in industry; S2. Determine the mechanical structure and motion characteristic parameters of the transmission system: Determine the mechanical structure dimensions of the transmission system and design its motion characteristic trajectory according to the actual processing requirements of the auxiliary shaft motor; S3. Import Motor Library: Import a user-defined motor database. The import results are used to determine whether there are any materials that can be recommended in the current motor database. S4. Calculation: Based on the mechanical structure dimensions and motion characteristic trajectory parameters of the transmission system determined in steps S1 and S2, calculate the maximum speed, torque, load inertia, acceleration power and travel power of the selected motor at the motor end. S5. Judgment and Verification: Perform preliminary motor judgment and verification on the maximum speed, torque, inertia, travel power and acceleration power parameters calculated in step S4. If it passes, proceed to step S6. If the judgment or verification fails, return to step S2 and the design parameters and motion characteristic trajectory need to be re-determined. S6. Complete the selection: Based on the judgment and verification conditions in step S5, recommend a suitable final motor model from the motor database imported in step S3, and complete the selection.

[0006] The mechanical structural dimensions of the transmission system involved in step S2 specifically include: the maximum speed of the traveling shaft, the diameter of the drive gear, the transmission efficiency, the reduction ratio, the coefficient of friction of the slide rail, the total mass of the slide table, the positive additional force, the additional force in the direction of motion, the inertia of the reducer, the driving wheel, and other inertia; the motion characteristic trajectory parameters include: the acceleration and deceleration time, the positioning time, the stopping and setting time, and the running cycle of the motor running speed curve; the inertia of the reducer is the value relative to the input end of the motor, and the inertia of the driving wheel and other inertia is the value relative to the output end of the motor.

[0007] The motor library imported in step S3 is in the common Excel spreadsheet format, specifically including motor model, rated speed, rated torque, motor inertia, maximum torque and rated power parameters.

[0008] In step S4, the maximum speed of the motor in the ball screw drive system is... n m The calculation formula is: in, V m This is the maximum speed of the motor's traveling shaft. The reduction ratio, P b This refers to the lead of the ball screw.

[0009] The formula for calculating the load's moment of inertia in step S4 is as follows: ; in, J 0 represents the coupling inertia. , m p For the quality of the coupling, R p The radius of the coupling; J g Let be the moment of inertia of the worktable and the workpiece. , M k For the quality of the worktable and the workpiece, J B Let be the moment of inertia of the ball screw. , ρ It refers to the density of the ball screw material.L B The length of the ball screw. D B The diameter of the ball screw; J Q This is the moment of inertia of the speed reducer.

[0010] The moment of inertia can be found in the manual. To meet the requirements, a corresponding reducer can be customized, and the calculation can be performed according to the following formula: ; in, J i Let n be the moment of inertia of the nth gear. i This represents the transmission ratio of the nth stage.

[0011] The load torque on the motor side in step S4 T L The calculation formula is as follows: in, P The distance traveled by the actuator for one revolution of the motor shaft. , M The total mass of the slide table, F It is an external force acting on the load. For transmission efficiency, denoted as the coefficient of friction of the slide rail.

[0012] In step S4, the highest speed of the gear and rack transmission system is... n m The calculation formula is: in, D This is the diameter of the drive gear.

[0013] The load rotational inertia in step S4 J L The calculation is as follows: ; in, J 主 For the moment of inertia of the active wheel, , m 0 represents the mass of the drive wheel. R 0 represents the pitch circle radius of the driving gear; J 齿 The moment of inertia of the rack and the load referred to the gear shaft. , M e The mass of the rack and pinion and the load, and the load torque on the motor side. T L The load shaft torque can be obtained by converting the reduction ratio and transmission efficiency: ; in, FV For positive additional force, , m r It is an additional load besides the slide table. F H It is an additional force in the direction of motion, equal to the external force acting on the load. , a The acceleration / deceleration of the load movement. M T For load quality.

[0014] For the belt drive system, the calculation method for the maximum speed and load torque in step S4 is consistent with that of the gear and rack system. The formula for calculating the load moment of inertia is as follows: ; in, J 主 The calculation method for the moment of inertia of the driving wheel is the same as that for gears and racks; J 带 For the pulley inertia, , m c For the pulley mass, R c The pitch circle radius of the pulley gear; J 皮 The moment of inertia of the belt can be equivalent to the moment of inertia about the driving pulley. , m 1 represents the belt mass. D 0 represents the pitch circle diameter of the driving gear.

[0015] The load travel power of the three transmission systems in step S4 P The formula for calculating 0 is as follows: ; The load acceleration power of the three transmission systems in step S4 P a The calculation formula is as follows: ; in, t p Indicates acceleration / deceleration time and required torque. T b The calculation formula is: , T a To ensure adequate acceleration torque and proper initial motor selection, an acceleration torque of 0.5 times the rated torque can be used here. T L .

[0016] In step S5, the speed trapezoidal curve of the designed motor is obtained based on the parameters input in step S2, thereby observing the motor's motion characteristic trajectory. Furthermore, considering both the motor's dynamic response characteristics and operational stability, the initial selection criteria in S5 are as follows: ; in, n e To temporarily select the rated speed of the motor, T e The rated torque of the motor is temporarily selected. T max To temporarily select the maximum torque of the motor, P e This is the rated power of the temporarily selected motor.

[0017] The verification conditions for the motor in step S5 are as follows: ; in, J M For motor load inertia, T e The rated torque of the motor. T u The acceleration torque of the motor is calculated using the following formula: ; T d The formula for calculating the motor reduction torque is as follows: ; T r The effective load torque of the motor is calculated using the following formula: ; in, t c This refers to the time of uniform velocity during the positioning process. t 0 indicates the positioning time. t s Indicates the stop setting time; The safety factor is defined as the ratio of the rated torque of the selected motor to the effective load torque of the system. A The formula is as follows: in, T m This is the rated torque of the final selected motor. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a schematic diagram of the process of the present invention; Figure 2 This is a reference diagram of the custom motor database of the present invention; Figure 3This is a schematic diagram of the motor speed trapezoidal curve of the present invention. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below.

[0021] like Figures 1 to 3 As shown, a method for selecting an additional axis servo motor for a robot includes the following steps: S1. Determine the transmission system structure of the load end of the auxiliary axis motor. Currently, the selection tool supports three major transmission system structures for the load end of common servo motors in industry: gear rack, ball screw, and belt. This example takes the selection of motors using the gear rack transmission system as an example. S2. Determine the mechanical structural dimensions of the gear and rack transmission system, mainly including: the maximum speed of the traveling shaft, the diameter of the drive gear, the transmission efficiency, the reduction ratio, the coefficient of friction of the slide rail, the total mass of the slide, the positive additional force, the additional force in the direction of motion, the inertia of the reducer, the driving wheel and other inertia, and the motor motion characteristic trajectory parameters, including: the motor's acceleration and deceleration time, positioning time, stopping and setting time, and running cycle. When confirming the parameters, it should be noted that the maximum speed of the traveling shaft refers to the maximum speed at which the slide moves within one complete motion cycle, and can be filled in according to the actual processing requirements; the total mass of the slide refers to the total mass of the movable parts, including the belt and chain; the calculation of the driving wheel and other inertia is the cumulative inertia converted to the output of the motor. The formula for calculating the inertia of the driving wheel is: , m 0 For the mass of the driving wheel, R 0 The pitch circle radius of the driving gear is given; other moments of inertia are the rotational inertia of the rack and load referred to the gear shaft. The formula for calculating these moments is: , M e This represents the mass of the rack and pinion and the load. If a speed reducer is used, the calculation is based on the speed reducer inertia referred to the motor input. This can be filled in according to the manual or calculation formula, as follows: ; in, J i Let n be the moment of inertia of the nth gear. i This represents the transmission ratio for the nth stage. The reduction ratio can be filled in based on the ratio of the number of driven gears to the number of driving gears. Positive additional force usually refers to the additional force exerted on the slide and load in the vertical direction. If there is only slide translation without other loads, the positive additional force can be ignored. If other external loads exist, the calculation formula is: , m rThis refers to the additional load besides the slide table. The additional force in the direction of motion usually refers to the external force on the load due to acceleration or sudden change in direction. It needs to be calculated in conjunction with acceleration and deceleration parameters. The calculation formula is: , a The acceleration / deceleration of the load movement. M T For load mass, transmission Efficiency refers to the efficiency between the motor and the lead screw, which can be determined based on experience or actual measurement. In this example, we take 80%.

[0022] In this embodiment, the mechanical structure parameters and motor motion characteristic trajectory parameters of the gear and rack transmission system are set as shown in Table 1: Table 1 Parameter Settings ; S3. Import user-defined motor database. The import results are used to determine if there are any recommended motors in the current database. The database import format can be found in the reference section. Figure 2 If the import fails, it will return to S2, where you can re-import after confirming the parameters and format. S4. Based on the gear and rack transmission system structure, mechanical structure, and motor speed motion characteristic trajectory parameters determined in steps S1 and S2, calculate the maximum speed of the selected motor using the following formula: ; in, D The diameter of the drive gear; the moment of inertia of the load. J L The calculation is as follows: ,in, , Motor-side load torque T L The calculation formula is as follows: ; in, F V For positive additional force, , F H It is an additional force in the direction of motion, equal to the external force acting on the load. .

[0023] Load walking power P The formula for calculating 0 is as follows: ; Load acceleration power P a The calculation formula is as follows: ; in, t pIndicates the acceleration / deceleration time.

[0024] Required torque T b The calculation formula is: , T a To ensure adequate acceleration torque and proper initial motor selection, an acceleration torque of 0.5 times the rated torque is chosen. T L .

[0025] In this embodiment, the maximum speed of the selected motor calculated based on the parameters is 955.414 r / min, and the load moment of inertia is 0.001534. The motor-side load torque is 0.7350 W, the load travel power is 73.50 W, the load acceleration power is 306.99 W, and the required torque is 1.1025 W. .

[0026] S5. Based on the maximum speed, torque, moment of inertia, traveling power, acceleration power, and necessary torque parameters calculated in step S4, perform initial motor selection and verification. The motor's speed trapezoidal curve can be obtained based on the parameters input in step S2, as shown below. Figure 3 As shown, the motion characteristic trajectory of the motor is observed accordingly; in addition, considering the dynamic response characteristics and operational stability of the motor, the initial selection criteria in S5 are as follows: ; in, J M For motor load inertia, T u The acceleration torque of the motor is calculated using the following formula: ; T d The formula for calculating the motor reduction torque is as follows: ; T r The effective load torque of the motor is calculated using the following formula: ; in, t c This refers to the time of uniform velocity during the positioning process. t 0 indicates the positioning time. t s Indicates the stop setting time; S6. Based on the judgment and verification conditions in step S5, recommend a suitable final motor model from the motor database imported in step S3 to complete the motor selection.

[0027] In S6, the safety factor is defined as the ratio of the rated torque of the selected motor to the effective load torque of the system. A , ,in, T m To determine the rated torque of the final selected motor, when recommending motor models, the safety factor of the motor will be considered. A safety factor between 1.2 and 3.0 can balance the dynamic response and economy of the motor, and the resource rationality of the final selected motor will be judged to avoid waste caused by over-selection.

[0028] In this example, a rated motor speed of 2000 rpm and a motor inertia of 0.000233 are recommended. The rated torque is 3.18. The maximum torque is 9.55. The rated power is 1000W, the load inertia ratio is 6.59, and the accelerating torque is 5.04. The reduction torque is 2.18. The effective load torque of the motor is 1.13. The safety rate is 2.815.

[0029] Therefore, the recommended servo motor meets all the operating requirements of the gear and rack transmission system and is a reasonable selection. The selection steps for the other two transmission systems are similar.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely prisms of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for selecting an additional axis servo motor for a robot, characterized in that: The specific steps are as follows: S1. Determine the structure of the transmission system at the load end of the auxiliary shaft motor: the models include gear rack, ball screw and belt drive commonly used in industry; S2. Determine the mechanical structure and motion characteristic parameters of the transmission system: Determine the mechanical structure dimensions of the transmission system and design its motion characteristic trajectory according to the actual processing requirements of the auxiliary shaft motor; S3. Import Motor Library: Import a user-defined motor database. The import results are used to determine whether there are any materials that can be recommended in the current motor database. S4. Calculation: Based on the mechanical structure dimensions and motion characteristic trajectory parameters of the transmission system determined in steps S1 and S2, calculate the maximum speed, torque, load inertia, acceleration power and travel power of the selected motor at the motor end. S5. Judgment and Verification: Perform preliminary motor judgment and verification on the maximum speed, torque, inertia, travel power and acceleration power parameters calculated in step S4. If it passes, proceed to step S6. If the judgment or verification fails, return to step S2 and the design parameters and motion characteristic trajectory need to be re-determined. S6. Complete the selection: Based on the judgment and verification conditions in step S5, recommend a suitable final motor model from the motor database imported in step S3, and complete the selection.

2. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: The mechanical structural dimensions of the transmission system involved in step S2 specifically include: the maximum speed of the traveling shaft, the diameter of the drive gear, the transmission efficiency, the reduction ratio, the coefficient of friction of the slide rail, the total mass of the slide table, the positive additional force, the additional force in the direction of motion, the inertia of the reducer, the driving wheel, and other inertia; the motion characteristic trajectory parameters include: the acceleration and deceleration time, the positioning time, the stopping and setting time, and the running cycle of the motor running speed curve; the inertia of the reducer is the value relative to the input end of the motor, and the inertia of the driving wheel and other inertia is the value relative to the output end of the motor.

3. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: The motor library imported in step S3 is in the common Excel spreadsheet format, specifically including motor model, rated speed, rated torque, motor inertia, maximum torque and rated power parameters.

4. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: In step S4, the maximum speed of the ball screw drive system motor is... n m The calculation formula is: ； in, V m This is the maximum speed of the motor's traveling shaft. The reduction ratio, P B This refers to the lead of the ball screw.

5. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: The formula for calculating the load's moment of inertia in step S4 is as follows: ； in, J 0 represents the coupling inertia. , m p For the quality of the coupling, R p The radius of the coupling; J g Let be the moment of inertia of the worktable and the workpiece. , M k For the quality of the worktable and the workpiece, J B Let be the moment of inertia of the ball screw. , ρ It refers to the density of the ball screw material. L B The length of the ball screw. D B The diameter of the ball screw; J Q The moment of inertia of the speed reducer; The moment of inertia can be found in the manual. To meet the requirements, a corresponding reducer can be customized. In this case, it can be calculated using the following formula: ； in, J i Let n be the moment of inertia of the nth gear. i The transmission ratio of the nth stage; The load torque on the motor side in step S4 T L The calculation formula is as follows: ； in, P The distance traveled by the actuator for one revolution of the motor shaft. , M The total mass of the slide table, F It is an external force acting on the load. For transmission efficiency, denoted as the coefficient of friction of the slide rail.

6. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: In step S4, the highest speed of the gear and rack transmission system is... n m The calculation formula is: ; in, D The diameter of the driving gear; The load rotational inertia in step S4 J L The calculation is as follows: ； in, J 主 For the moment of inertia of the active wheel, , m 0 represents the mass of the driving wheel. R 0 represents the pitch circle radius of the driving gear; J 齿 The moment of inertia of the rack and the load referred to the gear shaft. , M e The mass of the rack and pinion and the load, and the load torque on the motor side. T L The load shaft torque can be obtained by converting the reduction ratio and transmission efficiency: ； in, F V For positive additional force, , m r It is an additional load besides the slide table. F H It is an additional force in the direction of motion, equal to the external force acting on the load. , a The acceleration / deceleration of the load movement. M T For load quality; For the belt drive system, the calculation method for the maximum speed and load torque in step S4 is consistent with that of the gear and rack system. The formula for calculating the load moment of inertia is as follows: ； in, J 主 The calculation method for the moment of inertia of the driving wheel is the same as that for gears and racks; J 带 For the pulley inertia, , m c For the pulley mass, R c The pitch circle radius of the pulley gear; J 皮 The moment of inertia of the belt can be equivalent to the moment of inertia about the driving pulley. , m 1 represents the belt mass. D 0 represents the pitch circle diameter of the driving gear.

7. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: The load travel power of the three transmission systems in step S4 P The formula for calculating 0 is as follows: 。 8. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: The load acceleration power of the three transmission systems in step S4 P a The calculation formula is as follows: ； in, t p Indicates acceleration / deceleration time and required torque. T b The calculation formula is: , T a To accelerate torque.

9. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: In step S5, the speed trapezoidal curve of the designed motor is obtained based on the parameters input in step S2, thereby observing the motor's motion characteristic trajectory. Furthermore, considering both the motor's dynamic response characteristics and operational stability, the initial selection criteria in S5 are as follows: ； in, n e To temporarily select the rated speed of the motor, T e The rated torque of the motor is temporarily selected. T max To temporarily select the maximum torque of the motor, P e This is the rated power of the temporarily selected motor.

10. The method for selecting an additional axis servo motor for a robot according to claim 1, characterized in that: The verification conditions for the motor in step S5 are as follows: ； in, J M For motor load inertia, T u The acceleration torque of the motor is calculated using the following formula: ； T d The formula for calculating the motor reduction torque is as follows: ； T r The effective load torque of the motor is calculated using the following formula: in, t c This refers to the time of uniform velocity during the positioning process. t 0 indicates the positioning time. t s Indicates the stop setting time; The safety factor is defined as the ratio of the rated torque of the selected motor to the effective load torque of the system. A The formula is as follows: in, T m This is the rated torque of the final selected motor.

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