Once the choice of a hybrid design has been made, the choice of actuator technology follows. Since energy in a hybrid design is stored as electric charge, the most efficient pathway to convert that energy to mechanical work will be with electrical based actuators. That is, once energy has been stored as electrical charge, it would be a detour in inefficiency to first use that energy to power an electric motor that in turn drives a pneumatic or hydraulic pump that then is used to drive the corresponding actuator type.
Topic for an upcoming post: Conventional electromagnetic actuators have serious, even fatal, drawbacks when it comes to their use in agricultural robotics applications. At this point, some thinking out of the box is in order.