2009 Control Systems Fly By Wire & Autonomous Presented By: Frank Larkin Lansdale Catholic Robotics, Team 272 Upper Darby Kickoff Jan. 2009

Development Cycle Joy Pain  Time – Lots Of It! A brief moment of optimism usually followed by a crushing downfall! Warning: DO NOT BE FOOLED!

Big Al says…

Goals Get you to another room if you think this is a beginner’s seminar. Get you to understand the Iterative Robot. Get a good understanding of multi file programming Get a good understanding of Wind River. –How to edit, debug and load new code via Flash or FTP to the robot. Learn how to make disabled mode your friend Learn how to get autonomous working Presentation and files located at…

C vs C++ A few changes have to be taken into consideration –File extensions end in.cpp and.h –C++ can use classes Bundle all of a things, things into a single thing. –Example: a joystick has, X, Y & Z variables and many buttons. Joystick->GetX(); You can get to those “things” if they are public or they can br private. You then use methods to set values, get values. start processes, stop processes etc. compressor->start(); –3 Requirements to use variables Create –Servo *my_servo; Initialize –my_servo = new Servo(5); Use –my_servo->Set( my_leftStick->GetZ() ); Bad form for C++ –Servo *my_servo= new Servo(5);

C vs C++ Pointers vs Local Declarations –Pointers – References to things in memory Possibly looks cleaner How most examples are being done. –Declarations – The things in memory No need for pointers but a little more complicated –Why do I care? You will see code described both ways. Do not be afraid embrace them. Declaration Section: class IterativeDemo : public IterativeRobot { // Declare variable for the robot drive system Servo *p_servo; } Note: * means this is a pointer! Initialization Section: IterativeDemo(void) { printf("IterativeDemo Constructor Started\n"); p_servo = new Servo(5); } Usage: p_servo->Set(.50); p_servo->Set(p_leftStick->GetZ());

Discoveries Floating point power ranges –Stated as range is -1.0 to 1.0 with 0.0 being stop. Declare: Victor p_LeftWinch;// pointer Initialize: p_LeftWinch = new Victor(2); Use: p_LeftWinch->Set(0.0); // stop –Forward and Back are relative 2 motors side set to (1.0) are running at full power. But what direction? –All relative to the motors position. –Turn one around who is forward and who is back. –Joysticks Y axis Backwards to what you might think? Push forward get a value of Pull back get 1.0 Invert (reverse) for use f_WinchPower = -(p_joystick->GetX()); –Opposite motors driving in same direction. One is reversed f_WinchPower =.50; p_RightWinch->Set(f_WinchPower); p_LeftWinch->Set(-f_WinchPower);

Discoveries Using Wind River –Put all you variables into a structure. Then the intellisense works. typedef struct { Victor *p_FrontLeftMotor; Victor *p_FrontRightMotor; Victor *p_RearLeftMotor; Victor *p_RearRightMotor; Joystick *p_RightDriverStick; Joystick *p_LeftDriverStick; int i_FrontSonar; float f_FrontLeftMotor; float f_FrontRightMotor; float f_RearLeftMotor; float f_RearRightMotor; }struct_robotVars; struct_robotVars my;

Multi File programs Allow for collaborative effort –Multiple developers taking different roles –Separate files Start with place holder functions AutonomousPeriodic() { printf(“Auton Periodic: see Jim\n”); } Developed and tested separately added to final project Use.h files to expose variables to others –START_ROBOT_CLASS Main entry point of program in cRIO. In Multi file approach move from.h file to main.cpp file. Prevent multiple instances of this function

What is fly by wire? No operator direct control of output –Inputs are processed before going to outputs Something puts in input to variables –CBU (carbon based unit) via Joy Stick my.f_LeftDrive = my.p_LeftStick->GetY(); my.f_RightDrive = my.p_RightStick->GetY(); –SBU (silicon based unit) via autonomous program my.f_LeftDrive = 0.50; my.f_RightDrive = 0.50; Variables are processed –Changes made depending upon other input my.f_LeftDrive = gyroCorrect(my.f_LeftDrive); my.f_RightDrive = gyroCorrect(my.f_RightDrive); if( sonar < 80) my.f_LeftDrive = my.f_RightDrive = 0.0; Variables drive the output –Variable set final output motors or switches my.p_LeftMotor = my.f_LeftDrive; my.p_RightMotor = my.f_RightDrive;

IterativeDemo2 Functions GetDSInputs –Get Driver station inputs and set to variables Condition inputs for everyone else to use –Reverse sticks –Convert analog to digital GetRobotSensorInputs –Get inputs from Robot Sonar, contact switches RobotThink –Process the inputs ProcessOutputs –Update the variable to outputs

Basic Idea – Giant Loop Teleop code is looped through when in teleop mode. TeleopPeriodic() { GetDSInputs(); GetRobotSensorInputs(); RobotThink(); ProcessOutputs(); } Autonomous code is looped through when in Autonomous mode. AutonomousPeriodic() { GetRobotSensorInputs(); AutoProgramx(); // set vars RobotThink(); ProcessOutputs(); }

DisablePeriodic Use Disable Mode to test and setup for run –Check sensors (sonar) Use DS LED to see if sonar is working. –Select Auto Program to Run Use joystick buttons to set mode Use trigger to increment program counter. Use DS LEDs to see what program is selected #defines set limits Other possible tests –Is joystick zeroed? –Is gyro working? –Set an autonomous delay

Autonomous Basics AutoStatus structure –Keeps all Auto vars together autoStatus.Program –What program should run? Use switch statements to select program. select(autoStatus.Program) { case 1: autoProgram1(); break; case 2: autoProgram2(); break; case 3: autoProgram3(); break; } Note: autoPrograms can be in separate files.

Autonomous State Machine autoStatus.step –What am I doing now Parts of a step –Initialize Set up the step to be performed Set flag indicating setup done. –Perform Step Change variables to make something happen –Test to see if step is complete Did I go far enough? Is a wall is in front of me? Is the timer up? –Cleanup Unset setup done flag Bump step

Final Thought Unlike baseball crying is allowed in software development… but … …when your done, get back and make it work!