DESIGN AND FABRICATION OF TEST BOX FOR HELICOPTER TRIM ACTUATOR

摘要

The TRIM ACTUATOR is a rotary electro mechanical actuator used in the flight control system of the Advanced Light Helicopter (Dhruv). It is connected in parallel to the mechanical flight control linkages and can be electrically operated either manually or by the Automatic Flight Control System (AFCS) to move the flight controls connected to the booster actuator which in turn controls the main rotor and tail rotor blade angle. This alteration in the blade angle controls the flight path of the helicopter. The trim act uator has the following functions: a) To provide an artificial force feel in the flight control circuit by means of a preloaded spring b) To provide a re-locatable anchor point by means of an electrically operated clutch c) To provide a means of electrically controlling the flig ht control system by means of an electrical motor and associated gear system. The actuator is equipped with the following sensors which interface with the automatic flight control system: a) RVDT: the Rotary Variable Differential Transformer gives a measure of the angular position ofthe output shaft. b) Potentiometer: gives a measure of the effort applied on the force feel spring. c) Micro Switch: is used for detecting the pilot input to the mechanical flight control against the force feel spring. The project is dealt with development of a electrical test box for the trim actuator. The test box is designed to test the proper operation of all the above said electrical components. The test box have the following features: a) Provision for testing motor operation in both auto and manual mode o f operation. b) Provision for testing clutch operation. c) Provision for testing the proper operation of the micro -switch. dj Provision for testing RVDT operation and displaying the shaft angle. e) Provision for testing potentiometer. A f) Provision for measuring t he current consumption of motor in auto and manual mode of operation. g) Provision for measuring the current consumption of clutch. The design facilitates the control of the actuator from both the pilot side and the co-pilot side. The test box design allows intuitive, simple and clear operation of the actuator. Adequate safeguards are built into the test box to ensure that the trim actuator is not inadvertently damaged by a wrong operation when connected to the test box and also to prevent damage to the test bo x in the event of connection to a defective trim actuator. This project includes elements of electrical, mechanical and electronic design along with � the fa brication, assembly and testing of the test box.