seen result leftPower rightPower abort abortReason area colorCandidate tx rangeInches tracking lastTx lastArea visibleFrames centeredFrames startFrontLeftTicks startBackLeftTicks startFrontRightTicks startBackRightTicks targetTicks done lossStartedAt encoderTicks runOpMode BLUE BALL APPROACH STUDY These are real Limelight, steering and motor Blocks from the deployed autonomous. This teaching excerpt omits the wall guard and is disabled; use the complete robot program to drive. {"commentPositionLeft":161,"commentPositionTop":-27} MOTORS ARE ONLY THE OUTPUT The four drive motors use encoder mode and start at zero power. The Limelight decides HOW to steer, but these motor blocks do the actual driving. This study copy is disabled because it does not include the real wall guard. front_left_driveAsDcMotor Direction {"IDENTIFIER":"front_left_drive"} REVERSE front_left_driveAsDcMotor ZeroPowerBehavior {"IDENTIFIER":"front_left_drive"} BRAKE front_left_driveAsDcMotor Mode {"IDENTIFIER":"front_left_drive"} RUN_USING_ENCODER back_left_driveAsDcMotor Direction {"IDENTIFIER":"back_left_drive"} REVERSE back_left_driveAsDcMotor ZeroPowerBehavior {"IDENTIFIER":"back_left_drive"} BRAKE back_left_driveAsDcMotor Mode {"IDENTIFIER":"back_left_drive"} RUN_USING_ENCODER front_right_driveAsDcMotor Direction {"IDENTIFIER":"front_right_drive"} FORWARD front_right_driveAsDcMotor ZeroPowerBehavior {"IDENTIFIER":"front_right_drive"} BRAKE front_right_driveAsDcMotor Mode {"IDENTIFIER":"front_right_drive"} RUN_USING_ENCODER back_right_driveAsDcMotor Direction {"IDENTIFIER":"back_right_drive"} REVERSE back_right_driveAsDcMotor ZeroPowerBehavior {"IDENTIFIER":"back_right_drive"} BRAKE back_right_driveAsDcMotor Mode {"IDENTIFIER":"back_right_drive"} RUN_USING_ENCODER leftPower 0 rightPower 0 TURN ON THE FRONT LIMELIGHT Use blue color pipeline 0 and request fresh results. This camera faces FORWARD. The rear Logitech camera is separate and is not part of this lesson. limelightAsLimelight3A {"IDENTIFIER":"limelight"} 100 limelightAsLimelight3A {"IDENTIFIER":"limelight"} 0 limelightAsLimelight3A {"IDENTIFIER":"limelight"} INIT: LOOK BEFORE MOVING During INIT, read blue contours and show the angle and estimated distance on the Driver Station. The robot must not drive toward a ball it cannot see. WHILE Phase INIT: blue ball preview; check clear path seen Blue tx (deg) tx Lens-to-ball center (in) rangeInches Blue contour (fraction) area Lens-to-ball gap est (in) MINUS rangeInches 1.4 Blue ball not detected; robot will not drive 50 visibleFrames 0 centeredFrames 0 FIRST: CENTER THE CAMERA Check several fresh frames. Turn left or right until the ball's horizontal angle is within 2 degrees for five checks. If the ball disappears or is far off-screen, stop the motors instead of guessing. WHILE AND AND AND LT 6 LT centeredFrames 5 abort AND seen LT ABS tx 25 visibleFrames ADD visibleFrames 1 GTE visibleFrames 5 LTE ABS tx 2 leftPower 0 rightPower 0 centeredFrames ADD centeredFrames 1 centeredFrames 0 GT tx 0 leftPower 0.12 rightPower -0.12 leftPower -0.12 rightPower 0.12 leftPower 0 rightPower 0 leftPower 0 rightPower 0 visibleFrames 0 centeredFrames 0 Blue tx (deg) tx Centered frames centeredFrames 25 leftPower 0 rightPower 0 THEN: DRIVE WHILE RE-CENTERING Only enter the approach after a stable center and a blue ball farther than the estimated 4.4-inch lens-to-center target. This is about a 3-inch gap to the surface of a 2.8-inch ball, not a tape-verified stopping distance. AND AND GTE centeredFrames 5 AND seen GT rangeInches 4.4 tracking TRUE lastTx tx lastArea area startFrontLeftTicks front_left_driveAsDcMotor CurrentPosition {"IDENTIFIER":"front_left_drive"} startBackLeftTicks back_left_driveAsDcMotor CurrentPosition {"IDENTIFIER":"back_left_drive"} startFrontRightTicks front_right_driveAsDcMotor CurrentPosition {"IDENTIFIER":"front_right_drive"} startBackRightTicks back_right_driveAsDcMotor CurrentPosition {"IDENTIFIER":"back_right_drive"} targetTicks MULTIPLY MINUS rangeInches 4.4 115 done FALSE abort FALSE abortReason STOPPED: 16-second approach timeout lossStartedAt -1 WHILE AND AND LT 16 AND done abort LOOK AGAIN EVERY LOOP Every 25 milliseconds, take a NEW Limelight reading. Do not steer using the ball's old position: the robot and ball can both move between frames. encoderTicks MAX ABS MINUS front_left_driveAsDcMotor CurrentPosition {"IDENTIFIER":"front_left_drive"} startFrontLeftTicks ABS MINUS back_left_driveAsDcMotor CurrentPosition {"IDENTIFIER":"back_left_drive"} startBackLeftTicks ABS MINUS front_right_driveAsDcMotor CurrentPosition {"IDENTIFIER":"front_right_drive"} startFrontRightTicks ABS MINUS back_right_driveAsDcMotor CurrentPosition {"IDENTIFIER":"back_right_drive"} startBackRightTicks DRIVE AND FIX THE ANGLE TOGETHER When the blue ball is visible and no more than 25 degrees off center, the left command is 0.18 plus a clipped correction of 0.02 times tx. The right command subtracts the same correction. Recalculate EVERY loop so the ball stays centered as the robot drives forward. AND AND seen LTE ABS tx 25 GT rangeInches 4.4 lossStartedAt -1 GTE encoderTicks targetTicks done TRUE abortReason STOPPED: encoder safety limit before 3-inch camera gap leftPower 0 rightPower 0 leftPower ADD 0.18 MULTIPLY 0.02 tx -0.18 0.18 rightPower MINUS 0.18 MULTIPLY 0.02 tx -0.18 0.18 LOST BALL? POWER ZERO NOW If the Limelight cannot confirm this ball, set BOTH power commands to zero immediately. A ball past the camera edge aborts. After 0.35 seconds without the ball, abandon the approach. Never keep driving blindly. leftPower 0 rightPower 0 seen LTE rangeInches 4.4 abortReason COMPLETE: estimated 3-inch gap from lens to ball surface done TRUE abortReason STOPPED: blue ball at camera edge (over 25 degrees) abort TRUE LT lossStartedAt 0 lossStartedAt GTE MINUS lossStartedAt 0.35 abortReason STOPPED: blue target lost abort TRUE SAFETY LIMIT IS NOT SUCCESS The wheel-encoder cap and a 16-second time limit can stop the robot BEFORE the camera thinks the ball is close. A stuck encoder also triggers a stop. Only a fresh target inside the estimated 4.4-inch lens-to-center range counts as reaching the goal. AND AND AND seen done abort AND GTE 1 LT encoderTicks 5 leftPower 0 rightPower 0 abort TRUE abortReason STOPPED: drive encoders not reporting movement Blue tx (deg) tx Lens-to-ball center (in) rangeInches Encoder travel (in) DIVIDE encoderTicks 115 Wheel encoder ticks encoderTicks 25 leftPower 0 rightPower 0 Status abortReason abortReason Status STOPPED: no blue target, not centered, or already inside 3-inch gap leftPower 0 rightPower 0 limelightAsLimelight3A {"IDENTIFIER":"limelight"} 2000 readBlue FRESH BLUE CONTOUR ONLY Accept a current result from color pipeline 0. Ignore the whole-image Ta for distance. One measured distance established the area-to-distance scale, not close-range accuracy. {"commentPositionLeft":-500,"commentPositionTop":-27} CHECK THE CAMERA FEED FIRST A result must be valid, from the blue pipeline 0, and under 250 milliseconds old. A stale frame is like an old photograph: it cannot safely guide a moving robot. seen FALSE result limelightAsLimelight3A {"IDENTIFIER":"limelight"} result Camera age (ms) Staleness result Global Ta (%) - not range Ta result Color contours ColorResults result PICK A BALL-SIZED BLUE CONTOUR Look through blue color results. Choose a contour within the camera's ball-height band (Y pixels 215 to 260) and allowed area range, not the entire blue floor. tx is the angle left or right; area estimates distance using 2.84 divided by the square root of area fraction. This estimate needs more real-world calibration. AND AND EQ IsValid result true LT Staleness result 250 AND EQ PipelineIndex result 0 GT ColorResults result 0 area 0 colorCandidate ColorResults result AND GT TargetArea colorCandidate area AND LTE TargetArea colorCandidate 0.75 AND GTE TargetYPixels colorCandidate 215 LTE TargetYPixels colorCandidate 260 area TargetArea colorCandidate tx TargetXDegrees colorCandidate GTE area 0.001 seen TRUE rangeInches DIVIDE 2.84 ROOT area STAY WITH THE SAME BALL Once following a ball, reject a sudden jump in angle or contour size. A different blue patch should not steal the steering lock. If the match fails, seen becomes false and the drive stops immediately. AND tracking OR GT ABS MINUS tx lastTx 12 OR LT area MULTIPLY lastArea 0.4 GT area MULTIPLY lastArea 2.5 seen FALSE seen lastTx tx lastArea area applyPower FOUR MOTOR OUTPUTS The full robot program checks wall sensors before these four motor writes. This teaching excerpt intentionally leaves out those checks and must not be run. LEFT AND RIGHT COMMANDS REACH THE WHEELS These four blocks send leftPower to both left motors and rightPower to both right motors. That is how a difference in power steers while moving forward. The FULL deployed mode also checks the three wall sensors here; this disabled lesson is not a substitute for the guarded robot code. front_left_driveAsDcMotor Power {"IDENTIFIER":"front_left_drive"} leftPower back_left_driveAsDcMotor Power {"IDENTIFIER":"back_left_drive"} leftPower front_right_driveAsDcMotor Power {"IDENTIFIER":"front_right_drive"} rightPower back_right_driveAsDcMotor Power {"IDENTIFIER":"back_right_drive"} rightPower