Abstract: A control system for a work machine having a hydraulic energy source, a hydraulic accumulator, a digital hydraulic system having a digital hydraulic transformer, a hydraulic actuator and a movable element. The hydraulic accumulator being fluidically couplable with the hydraulic energy source. The digital hydraulic system including a digital hydraulic transformer fluidically couplable with the hydraulic accumulator. The hydraulic actuator being fluidically couplable with the digital hydraulic transformer. The movable element being movable by the hydraulic actuator. The control system including means to estimate at least one of potential energy and kinetic energy in the movable element; means to measure a fill level of hydraulic fluid in the hydraulic accumulator; and means to vary the amount of hydraulic energy added to the hydraulic accumulator by the hydraulic energy source responsive to the potential energy, the kinetic energy and/or the fill level of the hydraulic accumulator.