An Investigation on the Ball Screw-Based Variable Displacement Mechanism for Axial Piston Pumps with Feedforward Differential Input Control

This paper proposes a variable mechanism structure based on a ball screw design for precise displacement control in axial piston pumps, with the objective of improving actuator position and velocity control within the displacement-controlled (DC) systems. Traditional valve-controlled cylinder variable mechanisms (VCCVM) often suffer from limited control precision over the swash plate due to numerous uncertain parameters within the hydraulic system. To address this issue, a ball screw is utilized to replace the original valve-controlled cylinder for swash plate control, enhancing accuracy and responsiveness. In addition, an in-depth analysis of the Ball Screw Variable Mechanism (BSVM) is conducted, leading to the development of a coupled mechanical–hydraulic dynamic model. Based on this model, a controller is designed to improve system performance. Finally, the effectiveness and high performance of the proposed new structure and control strategy were validated through comparative experiments and simulations. The experimental results confirm the advantages of the proposed design, demonstrating satisfactory improvements in control precision.