System Simulation Mr. George Sanders AMCOM George.A.Sanders@us.army.mil (256) 876-2301

1. System SimulationMr. George SandersAMCOMGeorge.A.Sanders@us.army.mil(256) 876-2301 Session 2 - Sanders

2. Automating System Simulation Using AMCODE Army Missile Collaborative Design Environment (AMCODE) is an electronic environment designed specifically to automate and optimize AMRDEC’s workflow process in both customer support and technology development programs. AMCODE utilizes the RDEC’s Subject Matter Experts (SME) with associated design tools and provides an environment rich with state-of-the-art development/analysis tools and electronic data/information management via a centralized object relational database. AMCODE is AMRDEC’s Collaborative Design Environment Session 2 - Sanders

3. AMCODE AMCODE is Composed of Working Simulation Technologies: ICE (Integrated Collaborative Environment) Genetic Algorithm Method Scripting Technology Remote Object Execution Common Simulation Framework (CSF) Rocket Science AMCODE Computer Science Information Technology Session 2 - Sanders

4. AMCODE is SMARTSimulation & Modeling for Acquisition, Requirements and Training Cost-Performance Trades Requirements Definition Prototyping Detailed Design AMCODE’s Role In SMART Manufacturing & Production ProgramManagement Developmental &Operational T&E Training Life Cycle Sustainment Session 2 - Sanders

5. Simulation Based Design AMRDEC TECHNOLOGY TEAM Ops Requirements SME Simulation SME System SME Force-on-Force Simulations IFS Threat Pk & Ph Genetic Algorithm 6-DOF Done? Data Subsystem Characteristics Hi-Fidelity Optimize Systems Data AMRDEC TECHNOLOGY TEAM Lethality SME Warhead/Fuze SME FC Illuminators SME RF Seekers SME IR Seekers SME Guidance SME Control & Power SME Computer Miniaturation SME Aero & Structures SME Propulsion SME FC SME Datalinks SME Networks SME BMC4I SME Subject Matter Experts Update System and Critical Technologies Human Intervention Automation Loop Session 2 - Sanders

6. Overview • Model: A physical, mathematical, or logical representation. • Simulation: A method for implementing a model(s) over time. • Model types: • Continuous model: A model that contains integrated states and is updated continuously, usually at the same rate that the simulation executes. • Discrete model: A model that is updated at a regular rate but not at the integration time step and doesn’t contain integrated variables. Comm. Link Propulsion CAS Airframe Motion & Aero Tracker Seeker Gimbals Gyros Guidance Target Atmosphere Earth Launcher Session 2 - Sanders

7. Objectives • Purpose of System Simulation is to accurately represent the missile mathematically . • Physical characteristics of the missile components and airframe • Physical environment • Required for preflight design and analyses and post flight analyses • Design of autopilot, guidance, navigation • Flight performance analysis • Stochastic analysis (requires error budget) • Range safety • Trade studies • Parametric analysis • Flight test reconstruction Session 2 - Sanders

8. Other Examples of System Simulation Users Advanced Experimentation Hardware-in-the-loop Endgame analysis Session 2 - Sanders

9. Survey • Simulations can be developed using a wide array of tools, typically dependent on the fidelity required and its intended use. • Microsoft Excel (top-level) • Mathworks MATLAB with SIMULINK (learning curve, license fees) • Other commercial tools focused on modeling and simulation • Programming languages to develop models and simulation (C++, C, FORTRAN, Python, ADA, BASIC) • Most used • Flexible and portable • Free • Total control (verification and validation) • Implement in other experiments • “cRocket” 3-degree-of-freedom (3-DOF) missile simulation developed during MAE 659 for the use by the design students. • Written in C • Easy to read, understand, modify as required • Portable Session 2 - Sanders

10. dv dh Momentum analysis (F = m G = ) dt dt Levels of Fidelity • First-Order • Closed-form solutions (ideal velocity) • 1-DOF (thrust, drag, mass) : energy study • Intermediate • 3-DOF (typically three translations or range, altitude, flight path angle) • Advanced • 6-DOF (translations and rotations) • Requires much higher fidelity models (mass, propulsion, aerodynamics, autopilot, guidance, navigation) Ideal velocity equation: Vbo = Isp * g * ln (Wi/Wbo) Session 2 - Sanders

11. Inputs Aerodynamic coefficients (wind tunnel tests, prediction codes, empirical data) Mass properties (estimates, measurements, CAD) Thrust profile (static test, prediction codes, closed form solutions) Guidance, A/P, Navigation (derived from above) Tip-off information (test, estimates, dynamic simulation) Error sources (measurement, test, estimates) Outputs Positions Velocities Rates Accelerations Closest approach Impact points … Typical Inputs/Outputs (Dependent upon fidelity of models and simulation) Simulation and Modeling Function Provides Involvement With All Disciplines Gain Working Knowledge of the Entire Missile System Session 2 - Sanders

12. Where To Begin • Identify computer(s) and compiler(s) for use of cRocket 3-DOF simulation. • Define goals and requirements • Desired max range, hit target, control effectiveness, time of flight • Minimize: weight, drag, missile dispersion (typically) • Define constraints • Maximum diameter • Missile maximum weight and length • Define error sources • Variability in aerodynamic data, mass properties, total impulse, thrust misalignment, … • Tip-off rates; pointing accuracy • Guidance errors Session 2 - Sanders

13. - missile • target • line of sight • missile velocity • target velocity • separation distance • lead angle (plus heading error) l Vm Vt L Simulation Task Vt Vm L l x y Session 2 - Sanders z

14. cRocket Overview • Straight ANSI C, commented, intuitive variable name and functions • Modular coding practice • Inputs: • Missile • Mass, initial velocity, aerodynamic properties • Launcher • Altitude, range, length, elevation, azimuth • Target • Initial range, initial altitude, initial velocity • Guidance • Proportional navigation constant, commanded acceleration limits, heading errors • Simulation • Max time • Outputs: • Any variable can be printed out in the tabular output file. Session 2 - Sanders

15. Conclusion • Simulation is a critical function in all phase of missile development (concept exploration, detailed design, flight test support, hardware-in-the-loop, lethality, …) • Begin with the fidelity needed for the current requirement. • The determination of mission requirements (which defines performance parameters) is a necessary first step in designing a missile. • Consider mission objectives and constraints on the system. • System simulation provides overview knowledge of all subsystem domains. Session 2 - Sanders