Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power'Transmission and Control;
Yanshan University;
Qinhuangdao 066004;
P.R.China;
State key Laboratory of Fluid Power and Mechatronic Systems;
Zhejiang University;
Hangzhou 310027;
P.R.China;
Key Labratory of Advanced Forging&Stamping Teclnology and Science;
Yanshan University;
Qinhuangdao O66004;
P.R.China;
Hebei Key Laboratory of Special Delivery Equipment Yanshan University;
Qinhuangdao 066004;
P.R.China;
axial piston pump; variable speed condition; order ratio variational mode decomposition(VMD)in angle domain; health status assessment;