| Precision carbon potentiometer can be used in feedback system to monitoring the change of displacement through the voltage measurement because of a homogeneous distribution of its resistance. It is often used as position feedback device in aerospace technology and precision machinery and other industries. Potentiometer linearity directly influences the accuracy of the displacement feedback, the main method of improving potentiometer linearity is to trim carbon-film at points sampled with equal interval, either manual or automated trimming methods, trimming principles are same, it needs to measure the voltage while trimming to decide whether to stop or continue, because it trims carbon- film point by point, so this method also called discrete trimming. However, we find some defects of the discrete trimming method in the process of application. For example, the biggest problem is the linearity measured by different interval point are not same, it also has problems of low efficiency and low precision. Based on this phenomenon, this dissertation presents a continuous trimming algorithm, carries on preliminary research and put forward the further research direction for trimming. This algorithm is expected to make linearity of potentiometer measured by different interval point same, and improve the trimming efficiency.Firstly, this dissertation explores the existing production technology and trimming level of potentiometer. Then, it puts forward the preliminary conception of continuous trimming algorithm under the assumed condition. In this dissertation, the theoretical basis of trimming system is consist of working principle, measuring algorithm and data processing method.Secondly, this dissertation designed a potentiometer continuous trimming system based on the system algorithm and technical requirements, the main content include the construction of the experimental platform and control system program. The experimental system includes three aspects: structural design, electrical design and program design. The structure design includes the design of the experimental platform, potentiometer fixture design and measuring mechanism design. Electrical design mainly includes the design of the control box, the design of the data acquisition box and control circuit design. Programming design based on Lab VIEW development platform, uses graphical G language to write program and complete the human-computer interaction interface. Software system can realize common function, like information input, data acquisition, processing, and report forms printing, etc.Finally, this dissertation conducts system precision testing experiment; conducts the continuous time algorithm validation experiments to exam the preliminary continuous trimming algorithm, analyze error causes and proposed further direction of improved algorithm; it also conducts some process parameters experiment to optimize the program structure. Experiment consult shows that the continuous trimming algorithm can well improve the potentiometer linearity measured at arbitrary point, and shorten the trimming time, the consult also reflects the theoretical model of continuous trimming is correct and feasible, in this dissertation, further research direction of continuous trimming algorithm is put forward. |
