A4WD1 Tutorial for Autonomous Behavior v1.0

Download this file (<a href="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/wheeled-tracked/a4wd1-autonomous/WebHome/a4wd1tst2.zip" target="_blank">a4wd1tst2.zip</a>) and run it. For this program, on the Bot Board II,

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the "A" button is left channel throttle, "C" button is right channel throttle, and "B" is a speed and direction

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reset.

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This program requires the Sabertooth's Switch 1 to be flipped to the "Off" or "Independent

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Control" position.

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Upon powering up the robot, you should hear four ascending notes. Pressing A once results in a beep and slow

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forward motion (10%) on the left channel only. Pressing nine more times results in 100% power. Continuing to press A will make the motor act as

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above, except only for the right channel. The C button will control the left motor in a similar manner. Pressing the B button will reset the

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speed and direction of both left and right.

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Note: The Sabertooth's red Error LED will light to indicate overheating or current limit. The green Status1 LED

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will glow dimly when power is applied, and brightly when it's receiving pulses from the microcontroller. The green Status2 LED will flash out

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the detected number of lithium cells when lithium mode is enabled.</td>

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<td valign="top" align="left" colspan="2">Step 8.

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Throttle and Steering Mode Test (Optional)

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This program requires the Sabertooth's Switch 1 is flipped into the "On" or "Enable Mixed Mode" position!

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Download this file (<a href="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/wheeled-tracked/a4wd1-autonomous/WebHome/a4wd1tst1.zip" target="_blank">a4wd1tst1.zip</a>) and run it. For

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this program, on the Bot Board II, the "B" button is throttle and the "A" and "C" buttons are steering.

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Upon powering up the robot, you should hear four ascending notes.  Pressing B once results in a beep and

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slow forward motion (10%). Pressing nine more times results in 100% power. After the motor is at 100% power, pressing B will reduce the speed in

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10% increments until it stops. Continue to press B to make the robot move as above, only in reverse.

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Press Reset, then B twice. Now press C a few times to see the robot make a gradual left turn. Pressing A a few

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times will return to forward motion, and continuing to press A will result in gradual right turn.

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Experiment with these buttons to understand how throttle and steering can be used to control the vehicle's

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motion.

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Note: The Sabertooth's red Error LED will light to indicate overheating or current limit. The green Status1 LED

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will glow dimly when power is applied, and brightly when it's receiving pulses from the microcontroller. The green Status2 LED will flash out

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the detected number of lithium cells when lithium mode is enabled.

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When you're done with this testing program, flip the Sabertooth's Switch 1 back into the "Independent

Control" position!

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<td valign="top" align="left">Step 9.

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Now it's time to set up the A4WD1 for autonomous behavior.

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The code supports three Sharp GP2D12 sensors; two in the front and one in the back.</td>

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<td align="center" bordercolor="#808080" bgcolor="#C0C0C0" colspan="2">Bot Board Jumpers

& Connections</td>

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<td align="center" bordercolor="#808080" bgcolor="#C0C0C0">Connect</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">AX 0-3 Power Bus Jumper to 5v</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Robot's front left sensor</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Robot's front right sensor</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Rear sensor</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Sabertooth Ch1</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Sabertooth Ch2</td>

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Table 9</td>

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</center>

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<td valign="top" align="left">Step 10.

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Attach two GP2D12 sensors to the chassis as shown, using either double-sided foam tape or optional multi-purpose sensor housing brackets. The

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exact angle isn't critical, but will affect the robot's behavior. Experimentation is encouraged.

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Make sure you place the robot's right sensor on the robot's right side, facing left! Place the robot's left

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sensor on the robot's left side, facing right! This overlap ensures there isn't a blind spot in the center. If you switch the positions of the

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sensors accidentally, the robot will turn into objects, instead of away.

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Attach the other GP2D12 sensor at the rear of the robot as shown. Use double-sided foam tape to hold it in

place.</td>

Figure 10.</td>

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Schematic - Figure 11.

Schematic - Figure 11.

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<td valign="top" align="left">Step 12.

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Download this file (<a href="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/wheeled-tracked/a4wd1-autonomous/WebHome/4wd1auto.zip" target="_blank">4wd1auto.zip</a>) and

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program the Atom Pro. You will want to set the bot on something so that the wheels aren't touching the ground.

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This program allows the robot to roam around the room without bumping into things. It uses three Sharp GP2D12

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analog distance sensors to "see" things in its environment. Feel free to experiment with the variables and math in the main section of

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the program. The robot does a very good job navigating without getting stuck. The motor control is based on the GP2D12 sensors with a bias for

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forward motion. The robot will sometimes back up and turn even though there are no specific instructions to do so. Look for this and other

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emergent behaviors during your experimentation.</td>

Figure 12.</td>

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