Before the selection calculation, the first thing to determine is the position and speed requirements of the end of the mechanism, and then determine the transmission mechanism. Now you can select the servo motor and the corresponding reducer.
In the selection process, the following parameters are mainly considered:
Servo motor power and speed
According to the structure and the speed and acceleration requirements of the final load, calculate the required power and speed of the motor. It is worth noting that under normal circumstances, the reduction ratio of the reducer needs to be selected according to the speed of the selected motor.
In the actual selection process, for example, the load is horizontal movement, because of the uncertainty of the friction coefficient and wind load coefficient of each transmission mechanism, the formula P=T*N/9549 often cannot be calculated clearly (it is impossible to calculate the size of the torque). In the course of practice, it is also found that the power required to use the servo motor. Most often, the acceleration and deceleration phase. Therefore, through T=F*R=m*a*R, the required motor power and the reduction ratio of the reducer can be calculated quantitatively (m: load mass; a: load acceleration; R: load rotation radius).
Servo motors need to pay attention to the following points:
a) The power surplus coefficient of the motor;
b) Consider the transmission efficiency of the mechanism;
c) Whether the input and output torque of the reducer meets the standard and has a certain safety factor;
d) Will there be the possibility of increasing the speed later.
It is worth mentioning that in traditional industries, such as cranes and other industries, ordinary induction motors are used to drive, and there is no clear requirement for acceleration. The calculation process uses empirical formulas.
Note: When the load is running vertically, take care to include the acceleration due to gravity.
4.2 Inertia matching
To achieve high-precision control of the load, it is necessary to consider whether the inertia of the motor and the system match.
Regarding the question of why inertia matching is needed, there is no saying on the Internet that dominates the world. Personal understanding is limited, so I won’t explain it here. Friends who are interested can do their own research and inform. The principle of inertia matching is: considering the system inertia converted to the motor shaft, and the inertia ratio of the motor is not greater than 10 (Siemens); the smaller the ratio, the better the control stability, but a larger motor is required, and the cost performance is lower. If you don’t understand the specific calculation method, please make up your own "Theoretical Mechanics".
4.3 Servo motor accuracy requirements
Calculate whether the control accuracy of the motor can meet the requirements of the load after the change of the reducer and the transmission mechanism. The reducer or some transmission mechanism has a certain return clearance, which needs to be considered.
4.4 Control matching
This aspect is mainly to communicate with electrical designers to confirm, such as whether the communication mode of the servo controller matches the PLC, the type of encoder, and whether data needs to be exported, etc.
5. Brand
At present, there are many brands of servo motors on the market, and their performance varies greatly. It is very important to choose the right servo motor. If you want to know more information, please pay attention to us.
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