Answer: C. Errors in the error detection element itself and errors in the installation process.
Answer analysis:
The positioning error of the closed-loop control system is a complex issue, which is affected by multiple factors. For the given options, we can analyze them one by one:
A. Clearance and manufacturing errors of mechanical transmission pairs: Although the clearance and manufacturing errors of mechanical transmission pairs do affect the performance of the mechanical system, including positioning accuracy, in closed-loop control systems, these errors are usually detected and compensated by the feedback system.
The core of the closed-loop control system is to reduce or eliminate various errors through feedback mechanisms. Therefore, although these factors exist, they are not the main factors that determine the positioning error of the closed-loop control system.
B. Elastic deformation of mechanical transmission pairs: The elastic deformation of mechanical transmission pairs will also affect the positioning accuracy of the system, but in closed-loop control systems, this effect will also be considered and compensated by the feedback system. Similar to option A, it is not a decisive factor.
C. Errors in the error detection element itself and errors in the installation process: This option is closer to the main source of positioning errors in closed-loop control systems.
In closed-loop control systems, the accuracy and installation quality of detection elements (such as sensors) have a crucial impact on the positioning accuracy of the system.
The errors of the detection element itself (such as resolution, linearity, etc.) and the errors generated during the installation process (such as detection errors caused by installation tilt, self-weight deformation, short ruler extension, etc., and Abbe errors caused by the detection element being too far away from the object being measured during installation) will directly affect the positioning accuracy of the system.
These errors are the main components of the positioning error of the closed-loop control system.
D. Errors caused by thermal deformation of the ball screw pair: The thermal deformation of the ball screw pair does affect the positioning accuracy of the servo system, but this effect is relatively small in the closed-loop control system.
Because the closed-loop control system has a feedback mechanism, it can detect and compensate for errors caused by thermal deformation, etc. in real time. In addition, the thermal deformation of the ball screw pair affects the open-loop and semi-closed-loop servo systems more, while in the closed-loop system, this effect is significantly reduced.
In summary, the positioning error of the closed-loop control system mainly depends on the errors of the error detection element itself and the errors in the installation process (ie, option C).
These factors are directly related to the detection and feedback accuracy of the system to the target position, and are the main sources of positioning errors in the closed-loop control system.
It should be noted that although other factors (such as clearance and manufacturing errors of mechanical transmission pairs, elastic deformation of mechanical transmission pairs, thermal deformation of ball screw pairs, etc.) will also affect the positioning accuracy of closed-loop control systems, these effects are significantly reduced or compensated by the closed-loop control mechanism.
Therefore, when evaluating the positioning error of a closed-loop control system, key factors such as detection components and installation quality should be focused on.