Position servo control of industrial heavy-load hydraulic system
工业重载液压系统的位置伺服控制

For the HMK 1800 heavy roller rough grinding machine, which is designed and manufactured for the first time in China by Tsinghua University with independent intellectual property rights, this paper introduces the modeling and the position servo control for its hydraulic system. Hydraulic system is the most critical actuator of rough grinding machine, of which the position servo control system adopts a double-loop structure. The inner loop provides a closed-loop control for the piston velocity, while the outer loop is a closed-loop for controlling the cylinder position. The setpoint value of the position loop is determined through the linear interpolation. This structure ensures the precision of position control in constant position grinding; furthermore, it performs the control for the feeding-rate when the grinding arm moves inward. Two sets of PID parameters are adjusted to deal with the variations of model parameters; and a velocity PID is employed to realize the smooth switching between the two sets of control parameters.