An Advanced Reaching Law for Sliding Mode Speed Control of Electric Reel Sprinkler Irrigation Machine

The high-precision control of the electric drive system for the reel sprinkler machine is essential for ensuring efficient and stable operation. However, nonlinear friction, external disturbances, and parameter mismatches significantly degrade the performance of the system. To address these issues, this paper presents a sliding mode speed controller based on the advanced sliding mode reaching law (ASMRL) and a novel sliding mode observer (NSMO) for disturbance compensation. First, a mathematical model is developed, considering the time-varying moment of inertia and load of the reel. Next, the traditional terminal sliding mode reaching law (TSMRL) is improved by replacing the sign function with a power piecewise function, and by incorporating exponential and power terms. This method accelerates the convergence of the system to the sliding mode surface while effectively reduces chattering. A detailed theoretical analysis of ASMRL demonstrates that it achieves faster convergence and more effective chattering suppression compared to TSMRL. Furthermore, a precise NSMO is developed to estimate the total disturbance of the system, which is then compensated for within the ASMC. Experimental results demonstrate that, compared to traditional PI and TSMC methods, the ASMC+NSMO approach significantly improves control accuracy, reducing the steady-state error by 88.57% and 69.46%, respectively.