Modern aircraft design has moved towards the use of computer-controlled servo-mechanisms (Fly by Wire) for Flight Control Systems. One approach for primary and secondary control circuits is the use of simple DDV (Direct Drive servo-Valves) with few moving parts (as seen in the image below).
Direct-Drive is an advanced servo control technique developed initially for multi-redundant systems in military aircraft. In the Direct-Drive hydraulic actuator, the main control valve spool is operated directly by an electrical drive (rotary or linear), thus eliminating the need for an amplification stage of conventional EHSV (electro-hydraulic servo valves).

Direct Drive Valve

Claverham began its development of DDV systems in the 1980’s. This proven technology has now been refined to the point where normal operating currents are little higher than those of typical ehsv systems. Developments in magnetic materials & power semi-conductors ensure that the DDV is becoming competitive with ehsv even in simplex systems
Claverham's ADA (Advanced Development Actuator) is a self-financed technology demonstrator. The actuator integrates three lanes of control with two independent hydraulic systems.