Coaxial Optimal Electric Servo-Actuator

COESA (Coaxial, optimal electric, servo-actuator) is an actuation system for helicopter rotor blade trailing edge control surfaces, comprised of 3 major subsystem: the electromagnetic Coaxial Linear Actuator (EMCL), pulse width modulated supply, and piston control feedback system. The requirement of helicopter rotor blade control is a difficult problem cause of the constraints imposed by the main rotor and operation in a helicopter. The actuator volume must fit within the airfoil contour, the actuator must be lightweight, but withstand high centrifugal and dynamic vibratory load environment associated with the trim, primary, and HHC motion of the rotor. The actuator must have high frequency response (0-40 Hz) capability at 10's of pounds load levels, precise and dynamic travel necessary to control loads. Finally, the actuator must be efficient in its load generation, limiting prime power and power conditioning duty in order to stay within its thermal limits. COESA is a state of the art actuation technology which uses high magnetic density samarium-cobalt magnets, tightly coupled magnetic circuit, and a breakthrough commutation configuration in a low profile coaxial geometry achieve unmatched dynamic range, tightly coupled magnetic circuit, and a breakthrough commutation configuration in a low profile coaxial geometry achieve unmatched dynamic range, thermal efficiency, and a package ruggedness required for TECS actuation. The combination of commutation features of air core coilgun and submarine countermeasures launchers with the magnetic circuit efficiency, control performance and high thermal efficiency of the state of the art voice coil arrangements. The basic arrangement of the EMCL actuator is a hybrid brush fed synchrono DC linear motor made up of a helical conductor (bore), iron fiberglass shel permanent magnet/back iron modules for piston.