In the fields of intelligent manufacturing and high-end equipment, there is an increasing demand for precise control of mechanical systems. The parallel three degree of freedom platform force control system, as an advanced control technology, can simulate the force situation in complex environments and is widely used in fields such as CNC machine tools and aerospace. This article will introduce our project cases in this field, including the problems and challenges encountered in the early stages of the project, solutions, and final results.

Problems and challenges:

With the rapid development of industrial automation and intelligent manufacturing, the reliability and stability requirements for high-end equipment such as CNC machine tools are becoming increasingly high. The traditional "time-based experimental method" has problems such as material waste, long time, and difficult control in machine tool reliability testing. To address these issues, we have initiated the development of a parallel three degree of freedom platform force control system project.

• Complex dynamic modeling: The dynamic model of parallel mechanisms is complex, and parameters such as inertia tensor and friction coefficient are difficult to measure directly.
  
• Difficulty in designing control algorithms: Traditional PID control algorithms are difficult to adapt to complex nonlinear systems, and parameter adjustment is also challenging.
  
• Hardware platform construction: It is necessary to meet the requirements of high precision and high dynamic response, while considering cost and reliability.
  
• Software platform implementation: Real time display of control effects is required, while also facilitating parameter adjustment and system monitoring.
  

Solution:

Hardware design and manufacturing: Based on project requirements, carry out hardware design and manufacturing of a parallel three degree of freedom motion platform, including structural design, sensor selection, actuator selection, etc. Both the upper and lower platforms are made of high-strength aluminum alloy processing. Multiple specifications of threaded holes can be designed on the platform according to requirements for easy fixation of test loads. Choose precision servo cylinders to ensure the control accuracy and dynamic performance of the system. Accurate calibration of force sensors has been carried out to improve measurement accuracy and establish a stable and reliable hardware platform.

Control system development: Develop a control system for parallel robots, including the design and implementation of motion control algorithms, processing and integration of sensor data, etc.

Software development and integration: Developed upper computer monitoring software to achieve real-time data collection and display. At the same time, through algorithms, the measurement noise of the force sensor is reduced, the signal quality is improved, and it is convenient for system monitoring and parameter adjustment.

System testing and tuning: Conduct system testing and tuning to verify the motion control accuracy and system stability of the parallel three degree of freedom platform.

Figure 1. Parallel Three Degree of Freedom Platform in a Laboratory

Final result：

The effectiveness of the control system has been verified through a series of static and dynamic loading experiments. The experimental results show that the parallel three degree of freedom platform force control system can achieve high-precision and high dynamic response force control, meeting the testing requirements of high-end equipment such as CNC machine tools.

The landing experiment of the parallel three degree of freedom platform force control system not only provides advanced testing equipment for the reliability testing of CNC machine tools, but also provides new technological solutions for intelligent manufacturing and high-end equipment fields. Through precise force control, it is possible to simulate complex force situations in actual machining processes, improve equipment reliability and performance, and promote the development of industrial automation and intelligent manufacturing.