Servo system positioning error formation causes and solutions - Database & Sql Blog Articles

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In a typical servo system control process, the movement is divided into several stages: acceleration, constant speed, deceleration, and low-speed approach to the target position. Throughout this entire process, position closed-loop control is used to ensure accuracy. Among these steps, the deceleration and low-speed approach phases have the most significant impact on the final positioning precision. There are various methods for implementing deceleration control. Two commonly used approaches are exponential law and linear law acceleration/deceleration algorithms. The exponential law algorithm offers strong tracking performance, making it suitable for applications that require high response speed, such as cutting operations. However, when the speed is high, its stability may be compromised. On the other hand, the linear law algorithm provides better stability and is ideal for fast positioning scenarios where large speed variations are involved. When choosing a deceleration strategy, both stability and stopping accuracy must be taken into account. In theory, with proper selection of the deceleration point, either the exponential or linear law can achieve accurate positioning. However, determining the exact deceleration point remains a challenge. There are generally two common methods for identifying this point: 1. If the same acceleration/deceleration profile is used during both starting and stopping, the deceleration point can be calculated based on the symmetry of the speed curve and related parameters. 2. Alternatively, the deceleration point can be determined using parameters such as feed speed, deceleration time, and deceleration rate. With modern high-speed CPUs being widely available, this method is easy to implement in CNC servo systems and offers greater flexibility compared to the first approach. By carefully selecting the appropriate deceleration strategy and accurately determining the deceleration point, the overall performance and precision of the servo system can be significantly improved.