HILS of auto take off system: For high Speed UAV using booster rocket

摘要

Development of auto pilot system for high-speed UAV, RKX-200TJ, started in 2013. Currently, as the guided and control system for UAV, the FPGA (Field Programmable Gate Array), in order to flexibility in management of inputs and outputs facilitate many modules, which are processed simultaneously. So the control and stability of the UAV is improved and easy to handle by the processor. Testing on this controller capacity in receiving 4 different inputs and 2 outputs module should be done in an integrated simulation with flight simulator (XPlane) to make sure that all programs run according to plan. Moreover, in this research, HILS (Hardware in the Loop Simulation) is activated to initiate IMU (inertial measurement unit), which is located on top of hexapod to illustrate the close loop programming (PID) between the vehicle attitude, which is seen in hexapod movement and IMU issuing sensor data and received by processor. Integrated development of HILS involves three computer units, i.e. dynamic computer (XPlane), monitoring computer (to control hexapod and to serve as GCS / Ground Control System) and a computer controller that is connected with the main onboard computer (NI MyRIO). All three computers are connected with the UDP (User Datagram Protocol). Meanwhile, the controller computer accesses the main board computer using the facility of `shared memory'. With these connections, the flying simulation of RKX-200TJ can run smoothly without interruption of time lag. Vehicle simulation models created in XPlane Maker. Vehicle dimensions, engine specification, control geometry and setting of weight and balance are very influential in this simulation. The vehicle model should be made as similar as possible to the actual vehicle. It should include data input of real measurement of the center of gravity (CG), with both X axis and Z axis should be used as a reference model of the vehicle. In this simulation the booster rocket is modeled in JATO (Jet Assisted Take Off) with the firing angle leads to CG, according to the result of real measurement. Simulation of auto take off and auto pilot system went well; describing RKX-200TJ hovered early with booster for 1 sec, and was subsequently taken over by the auto pilot system. The takeover happened when the vehicle speed had reached 250 km/h or 600 m altitude based on the program installed. The auto pilot system would maneuver with a maximum of 30 deg banking and stabilization that maintained speed and altitude to reach the target way point.