Gravity compensation for leachate grid cleaning robots in waste-to-energy plants: A modeling and simulation study

Leachate grid clogging in waste-to-energy plants severely reduces combustion efficiency by up to 42% and may cause unplanned shutdowns, leading to substantial economic losses, necessitating automated cleaning solutions. However, gravity-induced elastic deformation in long-reach hydraulic manipulators limits their positioning precision. This research introduces an innovative feedforward static compensation strategy for hydraulically driven weak-rigid manipulators, which leverages detailed analytical joint stiffness modeling and avoids the inherent latency of conventional feedback-based methods (relying on force sensors or parameter identification); it is validated via comprehensive Adams multibody dynamics simulations. Validated via Adams multibody dynamics simulations, the proposed method reduced the end-effector positioning errors by 97.49% (X), 92.91% (Y), and 94.84% (Z), achieving a repeatable positioning accuracy of ±0.1 mm-far exceeding the 0.5 mm requirement for automated grid cleaning. This model-based compensation strategy provides a generalizable theoretical framework for precision control of long-reach hydraulic manipulators. The current study is validated through high-fidelity Adams simulations, achieving a simulated repeatable positioning accuracy of ±0.1 mm. However, it is essential to emphasize that these results represent an idealized upper bound. Real-world hydraulic systems introduce complexities not captured in simulation-including backlash, nonlinear friction, valve dynamics, hysteresis, leakage, and sensor quantization-all of which will degrade practical accuracy. Therefore, this work establishes a theoretical foundation requiring experimental validation on physical hardware. Future work will focus on physical prototyping and on-site testing to address real-world challenges.