Session: Controls 1

Paper Number: 111492

111492 - Projection Method for Hydraulic Piston Motor Torque Control 

Hydraulic systems are mostly known for their high-power density and their ability to precisely modulate the ratio of the power transmission between a prime mover and other actuators. This power modulation is generally achieved by controlling the displacement of the pump/motors implemented in the hydraulic system. Several component architectures and/or control strategies have been developed in this sense, as described in (Darnet & Bideaux, 2022). However, for hydrostatic transmissions, beyond the displacement control, a precise and efficient torque control of hydraulic motors is often preferable in order to optimize the driveability and/or the energy consumption. This constitutes a major technological problem, which could be addressed step-by-step by simplifying the architecture of the hydraulic motor studied and dividing the control in elementary bricks.

This paper proposes a new general framework to control the torque in hydraulic piston motors based on an analogy with multiphase electric motors. By assuming an ideal control of each piston inlet or outlet flow rates, the torque control requires the regulation of the pressure in each piston according to the angular position of the rotor and the motor kinematic. However, this leads to a large dimension of state and input vectors, depending on the number of pistons in the motor, which complicates the synthesis of command laws. The methodology described in this study proposes to facilitate the control of the torque by projecting state and input vectors in new specific bases that permit the separation of the dynamics driving the torque from the other internal dynamics of the motor. Then, when the projections are chosen properly, the torque could be controlled through a single component of the new state vector regardless of the number of pistons. The other components may be used to satisfy physical constraints and optimization criteria and to constraint the control algorithm based on requirements coming from the hydraulic system.

The paper presents an application of this early torque control strategy to a 3-pistons hydraulic motor. A simplified model of such a motor leads to a state-space representation, which is then transformed using specific projections that enable a direct torque control in closed loop. Simulation will illustrate the potential of this approach before concluding.

Refrences :

Justin Darnet, Éric Bideaux. State-of-the-art of Variable Displacement Technologies for Radial Piston Hydraulic Machines. Proceedings of the Bath/ASME Symposium on Fluid Power and Motion Control (FPMC) 2022, Sep 2022, Bath, United Kingdom.

Presenting Author: Justin Darnet Ampère (UMR5005), Univ Lyon, INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale de Lyon, CNRS

Presenting Author Biography: Justin Darnet is in the second year his PhD. He is doing his research at Laboratoire Ampère (INSA Lyon, France) under the supervision of Professor Eric Bideaux and Jean-François Trégouët. His main research area is the control of hydraulic pumps/motors. He obtained his degree in mechanical engineering from the UTC (Université de Technologie de Compiègne) in 2021.