Fluid-working machine and method of operating a fluid-working machine

A method of operating a fluid-working machine for a plurality of cycles, the fluid-working machine comprising a plurality of working chambers of cyclically variable volume, each said working chamber being operable to displace a selectable volume of working fluid during each cycle, and the method comprising:

• controlling the plurality of working chambers in aggregate so as to cause the total volume of working fluid displaced during each cycle to conform to a global demand function;
• and
• controlling the plurality of working chambers individually in accordance with a suitability function that determines the suitability of each working chamber.

A fluid-working machine comprising a controller and a plurality of working chambers of cyclically varying volume, each said working chamber operable to displace a volume of working fluid which is selectable by the controller on each cycle of working chamber volume, the controller operable to select the volume of working fluid displaced by one or more said working chambers on each cycle of working chamber volume to carry out a working function responsive to a received demand signal, characterised by the controller being operable to select the volume of working fluid displaced by a first working chamber on a cycle of working chamber volume taking into account the suitability of said first working chamber to displace fluid to carry out the working function.

A power absorbing structure comprising at least one mechanical component and further comprising a fluid working machine itself comprising a plurality of working chambers of cyclically varying volume, each said working chamber operable to displace a volume of working fluid which is selectable for each cycle of working chamber volume, the method comprising selecting the volume of working fluid displaced by one or more said working chambers during each cycle of working chamber volume to carry out a working function responsive to a received demand signal, the method further including measuring or predicting the motion of the mechanical component and selecting the volume of working fluid displaced by a first working chamber during a cycle of working chamber volume taking into account the measured or predicted motion of the mechanical component under influence of the working function.