Vol. 10 No. 5  October 2002

REAL-TIME FLIGHT SAFETY EXPERT SYSTEM Hardware configuration of RTFLEX

       A state-of-the-art expert flight safety decision support system (DSS) software has been designed, developed and implemented in collaboration with National Aerospace Laboratory, Bangalore and Indian Statistical Institute, Kolkata for providing real-time flight safety decision during test and evaluation of aerospace flight vehicle and training to the flight personnel
                         

       The real-time range safety management requires monitoring conformity of performance of the flight vehicle by analysing the real-time positional and impact point data of the vehicle. Based on the above data, the Range Safety Officer (RSO) takes the decision whether to continue or terminate the flight. The conventional range safety aid consists of graphical display of position, impact point, and critical health parameters of the vehicle, which a RSO has to monitor visually and analyse in real-time (within 3-4 s) to take flight safety decision. The DSS developed by DRDO overcomes all the limitations of the conventional range safety practices and procedures.
       The DSS has two sub-modules:

Multi-sensor Data Fusion and Filtering (MSDF) Module
        The MSDF module receives raw data from different sensors, filters these using Kalman dynamic tracking filter, and fuses multiple sensor data to provide three sensor data input to DSS module. The MSDF module is capable of predicting data for 4 sin case of loss of tracking sensor data to the RSO for taking real-time flight safety decision.

Knowledge-based DSS Module
       The data from three sensors and health data from MSDF module is analysed in DSS module to compute different flight safety parameters for each of the three channels and then processes the Rule Base. The Rule Base selects the sensor based on majority voting and depending on the laid down flight safety criteria, and displays the flight safety decision in the form of Normal Flight/Alert/Terminate Flight.Display format for DSS
        The DSS module provides interactive graphic display and an audio alarm as output to the RSO. The graphic display provides main flight safety decision, critical vehicle state vectors (position and velocity wrt time), critical health parameters (chamber pressure, vehicle body rates, etc.), and some crucial flight safety parameters (instantaneous impact point and safety margin). Different levels of emergencies are indicated to the RSO by different colour codes, e.g., green for normal, yellow for alert, red for termination of flight, etc. , along with a persistent audio alarm.

       The system, after detailed testing and validation using post flight data and simulated test data, was successfully used during Agni flight test.

Salient Features

  •  Error free and quick flight safety decision.
  •  Immune to bias, fatigue, and panic.
  •  Ensures accurate interpretation of sensor data, even in low-resolution graphical display.
  •  Predicts data for4 sin case of loss of tracking sensor data and provides flight safety decision.
  •  Unique feature of Code Generation to check the syntax of the Rule Base whenever it  undergoes any change and allows the        Rule Base to modify/change, depending on mission requirement.
  •  Capable of processing (filtering, fusing, and Rule Base) multiple sensor data (approx. 10) simultaneously and provides flight safety decision at 100 ms update rate, to fulfill the real-time requirement of range safety decision making.

Spin-Off

  •  Fault-tolerant design for onboard computer-based control and guidance system; the software can be utilised for updating design in the future missiles.
  •  Can be used for simulated training of the Flight Safety Officers.
  •  In the user version of missiles, the proposed induction of onboard controller could be used to trigger a flight termination mechanism in case of malfunction of a missile where ground-based range safety measures are not available.
  •  The software can be used for the allotment of flight corridor to the missiles not having onboard  Command Destruct System (CDS).