Case Study on IV&V of Attitude and Heading Reference System
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The document outlines the Independent Verification and Validation (IV&V) process for an Attitude and Heading Reference System (AHRS) developed by Oak Systems Pvt. Ltd. It details the system's functionalities, architecture, compliance with DO-178B guidelines, and the extensive testing and verification performed, including discovering critical defects. The outcome includes comprehensive documentation and reports demonstrating full requirement coverage and successful regulatory clearance.
Case Study on IV&V of Attitude and Heading Reference System
- 1. AVIONICS CASE STUDY – IV&V OF ATTITUDE AND HEADING REFERENCE SYSTEM (AHRS) Oak Systems Pvt. Ltd.
- 2. Salient features of the System v AHRS is a subsystem of Jaguar Darin-III upgrade with focus on indegenisation with following features – Provide Attitude (Roll, Pitch) and magnetic heading data to the ADIU. – Provide body accelerations and body angular rates data to ADIU. – Provide BIT health status data to the ADIU. – Accept external magnetometer input data from ADIU as an input to AHRS. – Accept True air speed and pressure-altitude data from ADIU for aiding of AHRS data. – Use internal algorithm for estimation of output parameters. – Perform Magnetometer Calibration Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 2
- 3. Architecture Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 3
- 4. Major System Functionalites v Two major independent functional blocks v Inertial computational Unit (IMU) v Navigational Unit (NAV) v Each having its own Built-in tests Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 4
- 5. About IMU v IMU handles complex inertial data computations like acceleration biases using Temperature coefficients, calibration coefficients with data available from accelerometers v Built in tests for checking beyond range accelerometer and gyro temperatures and also 70 others Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 5
- 6. About NAV v NAV provides calibrated Pitch, roll, Yaw data and also magnetic heading using complex calculations. v Kalman filter algorithms are applied for all NAV parameters v Has capability to switchover to internal magnetometers in case of failure to detect external magnetometer v About 60 built in tests to provide robustness to system Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 6
- 7. Trigger for IV&V As per DO-178B guidelines Independent Verification & Validation (IV&V) was mandated for DAL (Design assurance level B with MC/DC) Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 7
- 8. Scope of Work To Conduct IV&V as per RTCA - DO178B Level B compliance - v Planning phase docs review e.g. PSAC, SVP, SDP, SCMP, SQAP, SRS, SDS, SCS v High level Requirement Verification v Low level Requirement (Design) Verification v Code Evaluation (MISRA Standards) v Requirement based test case preparation (High level and Low level Tests) for 100% Requirement coverage v Source Code Coverage (100% MC/DC, 100 % Statement, 100 % Decision) v High Level and Low level Test Execution (using LDRA tool) v Traceability analysis: § Requirements ó Design ó Code § Requirement ó High level Tests § Design ó Low level Tests v Software Configuration Audit Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 8
- 9. In the Works Copyright © 2020 Oak Systems Private Limited. All Rights Reserved v 450 Functions with cyclomatic complexity ranging from 5 - 55 v Dual language software (C and C++) v 11000 Executable lines of code v Complex algorithms viz. Kalman filters, compass swing v Tight Schedule due to onset of winter for trials v Distributed Work environment across Multiple cities v Usage of Multiple testing tools involved RTRT, LDRA to speed up work v Team size ranging from 3 - 15 9 Software Size: 11 KLOC Language: C, C++
- 10. Accomplishments v Provided templates and checklists meeting DO178B guidelines v Thorough plan document review with emphasis on safety measures needed as a suggestion v Requirement and design review : Uncovered anomalies in the document in form of traceability, completeness and correctness w.r.t to DO-178B standards v Test case creation at both HSI and Unit level with emphasis on uncovering faults to make system robust by adopting testing techniques like BVA, Equivalence partitioning, arithmetic precision, fault recovery v Exhaustive test to handle complex algorithms involved in the project v Test case execution at both levels with emphasis on 100 percent requirement coverage, 100 percent MC/DC coverage, 100 percent decision coverage and 100 statement coverage v Clearance from regulators in record time with almost zero turnaround time v Uncovered 55 Critical and Major defects across HLR and LLR tests Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 10
- 11. Outcome Activity/Task Status Review report of Plan Docs: PSAC, SDP, SCMP, SRS, SDS, SCS, SQAP, SVP Delivered SRD Review report Delivered HLR SVCP Preparation Delivered SDD Review report Delivered LLR SVCP Preparation Delivered Code Review report Delivered SDD-Code Traceability Delivered LLR Test Execution Delivered HLR Test Execution Delivered IVV Reports (SCI, SECI, SAS) Delivered Copyright © 2020 Oak Systems Private Limited. All Rights Reserved 11
- 12. Thank you! Oak Systems Pvt. Ltd. #27, NGEF Lane, Off 100 Feet Road, Indira Nagar, Bengaluru – 560 038, INDIA Tel : +91-80-4126 7681 Email: contact@oaksys.net URL: www.oaksys.net We add value through engagement