阅读说明：本技术 基于机械臂稳态传热模型的温度估算方法 (Temperature estimation method based on mechanical arm steady-state heat transfer model ) 是由 杨跞 杨慧新 陈宏伟 许楠 于 2021-07-23 设计创作，主要内容包括：本发明提供一种基于机械臂稳态传热模型的温度估算方法,该温度估算方法包括：对机械臂进行工况测试；建立工况和功耗模型P,并输入测试结果；基于机械臂三维模型建立热仿真模型U；工况和功耗模型P的输出结果作为热仿真模型U的输入值；热仿真模型U输出估算温度值。本发明提供的该温度估计方法的实际需要的机械臂工况测试数据少,且无需过多的测试仪器,大大降低温度估计成本。另外,该温度估计方法的模型建立快速,应对不同机械臂能够快速转变模型参数,且温度估计速度快,精确度高,能够大大降低人员成本。(The invention provides a temperature estimation method based on a steady-state heat transfer model of a mechanical arm, which comprises the following steps: carrying out working condition test on the mechanical arm; establishing a working condition and power consumption model P, and inputting a test result; establishing a thermal simulation model U based on the mechanical arm three-dimensional model; the output result of the working condition and power consumption model P is used as the input value of the thermal simulation model U; and the thermal simulation model U outputs an estimated temperature value. The temperature estimation method provided by the invention has the advantages that the actually required mechanical arm working condition test data are less, excessive test instruments are not needed, and the temperature estimation cost is greatly reduced. In addition, the temperature estimation method has the advantages of quick model establishment, quick model parameter conversion for different mechanical arms, quick temperature estimation speed, high accuracy and capability of greatly reducing personnel cost.)

1. A temperature estimation method based on a steady-state heat transfer model of a mechanical arm is characterized by comprising the following steps:

carrying out working condition test on the mechanical arm;

establishing a working condition and power consumption model P, and inputting a test result;

establishing a thermal simulation model U based on the mechanical arm three-dimensional model;

the output result of the working condition and power consumption model P is used as the input value of the thermal simulation model U;

and the thermal simulation model U outputs an estimated temperature value.

2. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm as claimed in claim 1, wherein the step of performing condition test on the mechanical arm specifically tests the speed and the load of the mechanical arm.

3. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm according to claim 2, wherein the working condition and power consumption model P is specifically as follows:

E＝a·load²+b·load+c·Vel+d，

wherein, the speed vel (deg/s); load (nm); a. b, c and d are coefficients.

4. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm as claimed in claim 3, wherein the power consumption result output by the operating condition and power consumption model P is as follows: reducer efficiency Eq, motor power consumption Em and drive plate power consumption Ed.

5. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm according to claim 4, wherein the thermal simulation model U is specifically:

T＝A·E_q+B·E_m+C·E_d+D·T_e+E，

wherein, the reducer efficiency Eq; the power consumption of the motor Em; drive plate power consumption Ed; ambient temperature Te; A. b, C, D, E are all coefficients.

6. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm as claimed in claim 5, wherein the outputting of the estimated temperature value by the thermal simulation model U comprises: the temperature of the speed reducer, the temperature of the motor, the temperature of the rod piece and the temperature of the outer frame.

7. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm according to claim 3 or 5, wherein the coefficients are all predetermined coefficients obtained by performing model identification through a least square method.

8. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm according to claim 1, wherein the step of establishing the thermal simulation model U based on the three-dimensional model of the mechanical arm specifically comprises the following steps:

inputting a structural design three-dimensional model of a mechanical arm;

defining material parameters;

establishing a thermal simulation model U;

determining boundary conditions and load values of simulation analysis according to the boundary conditions and the load values during the experimental test of the mechanical arm;

inputting the boundary conditions, the load values and the equivalent parameters into a thermal simulation model U;

comparing the output simulation result with the temperature test result of the mechanical arm;

changing boundary conditions and load values of simulation analysis, and inputting the boundary conditions and the load values into a thermal simulation model U;

carrying out actual temperature test on the mechanical arm according to the changed boundary conditions and the changed load values;

comparing the simulation result output after the boundary conditions and the load value are changed with the actual temperature test result;

and finishing the establishment of the thermal simulation model U.

9. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm according to claim 8, wherein the step of comparing the output simulation result with the temperature test result of the mechanical arm specifically comprises:

if the output simulation result is consistent with the temperature test result of the mechanical arm or within a limited error range, carrying out the next operation;

and if the output simulation result is inconsistent with the temperature test result of the mechanical arm or is out of the limited error range, the previous step of operation is carried out again.

10. The temperature estimation method based on the steady-state heat transfer model of the mechanical arm according to claim 8, wherein the step of comparing the simulation result output after the boundary condition and the load value are changed with the actual temperature test result specifically comprises:

if the output simulation result is consistent with the actual temperature test result or within a limited error range, the modeling of the steady-state thermal simulation model is considered to be completed;

and if the output simulation result is inconsistent with the actual temperature test result or is out of the limited error range, inputting the boundary condition, the load value and the equivalent parameter into the thermal simulation model U again.

Technical Field

The invention relates to the technical field of mechanical arm temperature estimation, in particular to a temperature estimation method based on a mechanical arm steady-state heat transfer model.

Background

With the development of the robot technology, the mechanical arm is widely applied to various industries, meanwhile, higher requirements are put forward on the performance of the mechanical arm, particularly for a cooperative mechanical arm, the self weight of the cooperative mechanical arm is light, the structural member is a large and multipurpose aluminum alloy, a modular joint and a mechanical arm connecting rod are mainly formed for the mechanical arm structure, and important parts such as a speed reducer, a motor, a driver and the like are integrated in the modular joint. Such a robot arm requires high precision, a high load-weight ratio, and high reliability. The factors affecting these properties are very many, wherein the temperature affects the lubrication characteristics of the lubricating oil in the mechanical arm joint, and further affects the characteristics of the joint such as friction damping. Because the inherent property of arm structure material, can have expend with heat and contract with cold phenomenon when the change of temperature, the terminal precision of arm can be influenced in expend with heat and contract with cold and then take place for the structure. Temperature also affects the service life of the gear, and is an important influence factor if a life estimation model needs to be established. Therefore, the method has innovative significance for accurately obtaining the temperature values of all parts of the mechanical arm. Factors that affect the temperature characteristics of the robot arm include the ambient temperature and heat generation of the robot arm itself, such as heat generated by friction, rolling, or sliding between gears of a reducer, heat generation of a motor itself, heat generation of a power element on a drive, and the like.

The accurate estimation of the temperature of each part of the mechanical arm has important significance for temperature compensation and friction identification of the mechanical arm, generally, temperature testing is needed for temperature compensation of the mechanical arm or establishment of a more complex friction model, a temperature sensor is designed on the concerned part to obtain a temperature value, and the obtained temperature value is reliable, but the method has the defects of high cost, large workload, high maintenance cost and the like.

Therefore, a temperature estimation method which is rapid in modeling, low in cost, rapid in speed, high in accuracy and capable of coping with different working conditions is urgently needed by the technical staff in the field.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a temperature estimation method based on a steady-state heat transfer model of a mechanical arm. The actually input working condition test data of the temperature estimation method is few, excessive test instruments are not needed, and the temperature estimation cost is low. In addition, the temperature estimation method has the advantages of quick model establishment, quick model parameter conversion for different mechanical arms, quick temperature estimation speed, high accuracy and capability of greatly reducing personnel cost.

The invention provides a temperature estimation method based on a steady-state heat transfer model of a mechanical arm, which comprises the following steps: carrying out working condition test on the mechanical arm; establishing a working condition and power consumption model P, and inputting a test result; establishing a thermal simulation model U based on the mechanical arm three-dimensional model; the output result of the working condition and power consumption model P is used as the input value of the thermal simulation model U; and the thermal simulation model U outputs an estimated temperature value.

Further, the mechanical arm is subjected to working condition testing, and the speed and the load of the mechanical arm are specifically tested.

In the embodiment of the present invention, the working condition and power consumption model P specifically includes:

E＝a·load²+ b load + c Vel + d; wherein, the speed vel (deg/s);

load (nm); a. b, c and d are coefficients.

Further, the power consumption result output by the working condition and power consumption model P is: reducer efficiency Eq, motor power consumption Em and drive plate power consumption Ed.

In the embodiment of the present invention, the thermal simulation model U specifically includes:

T＝A·E_q+B·E_m+C·E_d+D·T_e+ E; wherein, the reducer efficiency Eq; the power consumption of the motor Em; drive plate power consumption Ed; ambient temperature Te; A. b, C, D, E are all coefficients.

Further, the outputting of the estimated temperature value by the thermal simulation model U includes: the temperature of the speed reducer, the temperature of the motor, the temperature of the rod piece and the temperature of the outer frame.

In the embodiment of the invention, the coefficients are all to-be-determined coefficients obtained by performing model identification through a least square method.

In the embodiment of the invention, the step of establishing the thermal simulation model U based on the mechanical arm three-dimensional model specifically comprises the following steps:

inputting a structural design three-dimensional model of a mechanical arm;

defining material parameters;

establishing a thermal simulation model U;

determining boundary conditions and load values of simulation analysis according to the boundary conditions and the load values during the experimental test of the mechanical arm;

inputting the boundary conditions, the load values and the equivalent parameters into a thermal simulation model U;

comparing the output simulation result with the temperature test result of the mechanical arm;

changing boundary conditions and load values of simulation analysis, and inputting the boundary conditions and the load values into a thermal simulation model U;

carrying out actual temperature test on the mechanical arm according to the changed boundary conditions and the changed load values;

comparing the simulation result output after the boundary conditions and the load value are changed with the actual temperature test result;

and finishing the establishment of the thermal simulation model U.

Further, the step of comparing the output simulation result with the mechanical arm temperature test result specifically comprises: if the output simulation result is consistent with the temperature test result of the mechanical arm or within a limited error range, carrying out the next operation;

and if the output simulation result is inconsistent with the temperature test result of the mechanical arm or is out of the limited error range, the previous step of operation is carried out again.

Further, the step of comparing the simulation result output after the boundary condition and the load value are changed with the actual temperature test result specifically includes: if the output simulation result is consistent with the actual temperature test result or within a limited error range, the modeling of the steady-state thermal simulation model is considered to be completed;

and if the output simulation result is inconsistent with the actual temperature test result or is out of the limited error range, inputting the boundary condition, the load value and the equivalent parameter into the thermal simulation model U again.

According to the embodiment, the temperature estimation method based on the steady-state heat transfer model of the mechanical arm has the following advantages: compared with the existing method of designing a temperature sensor on the concerned mechanical arm part to obtain the temperature value of the corresponding part, the method has the defects of high cost, large workload, high maintenance cost and the like although the obtained temperature value is reliable. According to the temperature estimation method, excessive parameters are not required to be input, and the temperature value of the corresponding part of the mechanical arm can be estimated through the working condition, the power consumption model P and the thermal simulation model U only through the mechanical arm working condition parameters and the environment temperature. In addition, the model of the temperature estimation method is established quickly and conveniently, model parameters can be changed quickly by dealing with different mechanical arms, the temperature estimation speed is high, the accuracy is high, and the personnel cost can be greatly reduced.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a schematic flow chart of a temperature estimation method based on a mechanical arm steady-state heat transfer model provided by the invention.

FIG. 2 is a flow chart of a temperature estimation method based on a steady-state heat transfer model of a mechanical arm according to the present invention.

Fig. 3 is a flow chart for establishing a thermal simulation model U based on the temperature estimation method of the steady-state heat transfer model of the mechanical arm provided by the invention.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

The invention provides a temperature estimation method based on a steady-state heat transfer model of a mechanical arm, and a flow chart of the temperature estimation method is shown in FIG. 2. In an embodiment of the present invention, the temperature estimation method includes:

step S1: and testing the working condition of the mechanical arm. The working condition test is used for obtaining working condition data of each part of the mechanical arm under the corresponding working condition, wherein the working condition data comprises the speed, the load and the like of the joint part of the mechanical arm. This data information can be derived from existing sensors on the robotic arm.

Step S2: and establishing a working condition and power consumption model P, and inputting a test result. And establishing a working condition and power consumption model P by using the mechanical arm test data. As shown in fig. 1, by inputting data of the robot arm component under different conditions into the condition and the power consumption model P, power consumption and efficiency of the heat generating components at various positions of the robot arm under corresponding conditions can be obtained. In a specific embodiment of the present invention, the operating condition and power consumption model P specifically includes: e ═ a load²+b·load+c·Vel+d，

Wherein, the speed vel (deg/s); load (nm); a. and b, c and d are all coefficients, and the coefficients are all to-be-determined coefficients obtained by performing model identification through a least square method.

The power consumption or efficiency values of mechanical arm joint components such as reducer efficiency Eq, motor power consumption Em and drive plate power consumption Ed can be obtained through the working conditions and the power consumption model P.

Step S3: and establishing a thermal simulation model U based on the mechanical arm three-dimensional model. The thermal simulation model U is a finite element steady-state thermal simulation model which is built based on the mechanical arm three-dimensional model, and the corresponding thermal simulation models U are different in different mechanical arm three-dimensional models.

Step S4: and taking the output result of the working condition and power consumption model P as the input value of the thermal simulation model U. As shown in fig. 1, the power consumption and efficiency results obtained in step S2 are input into the thermal simulation model U, and in addition, the environmental temperature needs to be added into the thermal simulation model U and the simulation calculation needs to be performed in consideration of the environmental temperature.

In a specific embodiment of the present invention, the thermal simulation model U specifically includes:

T＝A·E_q+B·E_m+C·E_d+D·T_e+E

wherein, the reducer efficiency Eq; the power consumption of the motor Em; drive plate power consumption Ed; ambient temperature Te; A. b, C, D, E are all coefficients to be determined, which are obtained by performing model identification by the least square method. A. B, C, D, E these coefficients are boundary conditions for simulation such as thermal conductivity in the corrected simulation model by thermocouple experimental tests.

Estimating by a thermal simulation model U, wherein the finally output temperature value comprises: the temperature of the speed reducer, the temperature of the motor, the temperature of the rod piece, the temperature of the outer frame and the like.

Step S5: and the thermal simulation model U outputs an estimated temperature value. Through the thermal simulation calculation of the step S4, a temperature value of the mechanical arm under a corresponding working condition can be obtained. The temperature of the speed reducer, the temperature of the motor, the temperature of the mechanical arm connecting rod and the temperature of the joint outer frame are included.

In a specific embodiment of the present invention, as shown in fig. 3, the step of establishing the thermal simulation model U based on the three-dimensional model of the mechanical arm specifically includes:

step S301: and inputting a structural design three-dimensional model of the mechanical arm. The establishment of the thermal simulation model is based on finite element simulation, and the establishment of the three-dimensional model of the mechanical arm structure design is convenient for carrying out the finite element simulation. This also requires the necessary simplification of the three-dimensional model to remove features such as chamfers, fillets, pinholes, etc.

Step S302: material parameters are defined. The material parameters are essential parameters for finite element simulation, wherein the material parameters include thermal conductivity, density, and specific heat.

Step S303: and establishing a thermal simulation model U. The thermal simulation model is based on a finite element model, which is a finite element analysis model that is gridded and defines material parameters. When the temperature of mechanical arms with the same design principle and different models is estimated based on the model, the model is only required to be simply identified, and the purpose of identification is to determine some coefficient values in the model so as to carry out thermal simulation processing. For mechanical arms with different design principles, three-dimensional modeling needs to be carried out again and a thermal simulation model U needs to be established.

Step S304: and determining the boundary conditions and the load values of the simulation analysis according to the boundary conditions and the load values during the experimental test of the mechanical arm. The boundary conditions and the load values are ambient temperature, heat exchange coefficient with the outside, heat loss power values of all heating components and the like.

Step S305: and inputting the boundary conditions, the load values and the equivalent parameters into a thermal simulation model U. The boundary conditions and the load values are ambient temperature, heat exchange coefficient with the outside, heat loss power values of all heating components and the like. The equivalent parameters are mainly that the thermal resistance among all parts needs to be equivalent, because heat conduction is generated inside the joint, certain heat radiation and local convection heat transfer also exist, and the contact thermal resistance, namely the equivalent parameters, is equivalent by integrating the action results of the three heat transfer modes.

Step S306: and comparing the output simulation result with the temperature test result of the mechanical arm. The method specifically comprises the following steps:

and if the output simulation result is consistent with the temperature test result of the mechanical arm or within a limited error range, carrying out the next operation.

And if the output simulation result is inconsistent with the temperature test result of the mechanical arm or is out of the limited error range, the previous step of operation is carried out again. Namely, returning to the step S305, adaptively adjusting the equivalent parameters and the heat exchange coefficient, performing thermal simulation processing, and continuously comparing the result with the temperature test result of the mechanical arm.

Step S307: and changing boundary conditions and load values of simulation analysis, and inputting the boundary conditions and the load values into a thermal simulation model U. This is a further verification of the thermal simulation model, in reverse compared to the above steps. And changing the boundary conditions and the load values and inputting the changed boundary conditions and the load values and the equivalent parameters into a thermal simulation model U together to obtain a new simulation result. The boundary conditions and the load values are ambient temperature, heat exchange coefficient with the outside, heat loss power values of all heating components and the like.

Step S308: and carrying out actual temperature test on the mechanical arm according to the changed boundary conditions and the changed load values. And applying the boundary conditions and the load values in the step S307 to the actual mechanical arm, and performing actual temperature tests on each part of the mechanical arm.

Step S309: and comparing the simulation result output after the boundary condition and the load value are changed with the actual temperature test result. The method specifically comprises the following steps:

and if the output simulation result is consistent with the actual temperature test result or within a limited error range, the modeling of the steady-state thermal simulation model is considered to be completed.

And if the output simulation result is inconsistent with the actual temperature test result or is out of the limited error range, inputting the boundary condition, the load value and the equivalent parameter into the thermal simulation model U again. That is, the process returns to step S305, adaptively adjusts the equivalent parameters and the heat exchange coefficients, and then performs the thermal simulation process. And then, sequentially carrying out subsequent steps until the comparison in the step S309, wherein the output simulation result is consistent with the actual temperature test result or within a limited error range.

Step S3010: and finishing the establishment of the thermal simulation model U. And finally completing the establishment of the thermal simulation model U after two times of verification.

The temperature estimation method for the steady-state heat transfer model of the mechanical arm provided by the invention is implemented as follows. As shown in fig. 1, the mechanical arm working condition test data is input into the working condition and power consumption model P, so as to obtain power consumption data of each heating component of the mechanical arm. And inputting the power consumption data and the environment temperature data into a thermal simulation model U to finally obtain a simulation temperature value, namely a temperature value of each part of the mechanical arm. The temperature of the speed reducer, the temperature of the motor, the temperature of the mechanical arm connecting rod and the temperature of the joint outer frame are included.

The foregoing is merely an illustrative embodiment of the present invention, and any equivalent changes and modifications made by those skilled in the art without departing from the spirit and principle of the present invention should fall within the protection scope of the present invention.