The original version of this article unfortunately contained two mistakes. In p.406 and p.408, the titles of Figs. 2 and 3 were missing, which are given below:

Fig. 2 Schematic diagram of the pump model (a) and single piston chamber model (b). Vp is the velocity of the piston (Fig. 2a is reprinted from (Ye et al., 2014), Copyright 2014, with permission from ASME).

Fig. 3 Test rig used to measure the flow ripple of axial piston pumps (Reprinted from (Ye et al., 2014), Copyright 2014, with permission from ASME).