Boe-Bot: Obstacle Avoidance Robot

This little robot uses his whiskers to detect obstacles. When one or both of his whiskers get triggered, he backs up and turns to a different direction. He otherwise moves forward. Powered by 4 AA batteries, the Paralax motherboard lets this little guy move.

Parts Needed: The Boe-Bot Kit (located Here)

Step 1: Chassis Elevation

For this part you'll need the main chassis, 4 1/4" 4-40 Pan head screws, a 13/32" rubber grommet 4 1" standoffs. Fit the grommet into the hole in the center of the chassis. Then take your standoffs and put them in the four screw hole corners. Put the screws in on the other side to secure the standoffs to the chassis.

Step 2: Servo Additions

Next we'll add the servos. You'll first want to remove the control horns (the X shaped piece on your servo) Take a Phillips head screwdriver and remove the screw in the center of that piece. Then pull the piece off the servo. You now have the servos we need. Save those screws you took off as we will need them later. Grab your chassis, 8 3/8" 4-40 Pan head screws and 8 4-40 Nuts. The nuts go on the inside and the screws go into the holes on the outside. Do all 4 on the corners on both servos. This will secure the servos in place. For preference you can label both servos for left and right.

Step 3: Battery Pack

Now we're going to add the battery pack. You'll need that, 2 Flat head Phillips Screws, 3/8" 4-40, 2 4-40 nuts and your chassis. Before adding any batteries to your pack put your screws into the holes by the battery spots. Pull all the cords into the grommet hole. If the cable connectors are bent it's ok. I recommend you pull the battery connecter first. Put the battery pack into the open space below the servos aligning the screws with the holes in the chassis as shown above. Flip the chassis over and add the nuts to secure the pack to the robot.

Step 4: Wheels on the Robot

Now we can add the wheels. Grab the plastic wheels, a 1/16" Cotter Pin, the servo screws you saved and the tail plastic ball. Your kit should have rubber bans to use as tires but mine didn't. Those go around the wheel like a tire. Put your plastic wheels on the servo and secure them with your horn screws. You then put the tail ball on the U shaped piece of chassis. Slide the cotter pin through both the chassis and the ball. Now your robot has modes of transport!

Step 5: Motherboard Wiring

Here comes the fun part. Take your Board of Education® and Basic Stamp 2 chip. be careful with the silver pins on your chip and put it into the rectangular slot under the Parallax™ logo. Orientate it so the big black capacitor is on the bottom as shown. Next grab two 1/4" 4-40 pan head screws and your board. Place the board on top of your standoffs. The screws go on the side with the tail ball. Grab the servos and loop them around so their above the right wheel. The colors should be from front to back: White, Red, then Black. See the image above if need be. The left servo connector goes in the back. of the 5x slot.

Now we're going to add the whiskers. Grab the weird whiskers, two 7/8" pan head 4-40 Phillips screws, two 1/2" round spacers, two nylon washers (size #4) two 3 pin m/m headers, two 220 ohm resisters (red-red-brown) and two 10k ohm resistors (brown-black-orange). With the two empty screw holes on your board put the spacers. The spacer on the left needs to have the whisker first then the spacer. The hook on the end of your whisker is used to connect it so put that on top of your spacer. Put the washer on top of that then screw the whole thing together. Now we can add the right side. The right side has this order: Spacer, washer, whisker then screw. Do your best to tighten the screws because the whiskers need to form an almost intact straight line.

To wire those bad boys you'll need to turn your robot so the white breadboard is longest vertically. Grab your 3 pins and place them so one is on the farthest left on P12. The other 3 pin is 2 holes down on P9. Take the Red-Black-Brown resistors next. One end goes right behind the 3 pins. The bottom 3 pin resistor goes to VDD up top, 3 spaces from the left. The other resistor connects the right motor to VDD slot 5, right beside the other resistor. The Red-Red-Brown resistors go behind the resistors connecting to the 3 pin. The top 3 RRB goes to P7 while the other RRB goes to P5.

If you'd like to you can add a Piezo buzzer like I did. This will play a sound whenever hitting an obstacle and starting up. Put a wire in P4 and run it to the far left row three holes up. Put the positive end of your buzzer next to the wire (you should see a positive symbol on the buzzer that shows the sides) with a hole in between. Put a wire above your positive wire with a hole apart. This is your buzzer's ground. The other end goes to the other side of your breadboard, on the P1 line, to holes from the divide. Lastly, put a wire next to the wire you just plugged in. It goes all the way up to Vss one hole from the right.

You can also add LEDs to your board to show which side detected an obstacle. You'll need 2 more RRB resistors for the LEDs. Put one RRB resistor into P1 and right below the buzzer four holes from the left. Take one LED and find the longer prong. This is your positive and goes right next to your resistor. Take your other resistor and put into P10 and four spaces to the right from P14. Finally, take your last LED and put the longer prong right next to your resistor you just put in. The other prong crosses the divide and into the first hole on the other side.

Step 6: The Code

I uploaded the code I used. There are many variables able to be tweaked at your leisure. You'll first need to install BASIC Stamp Editor v2.5.3 or better in order to open it. You should get a basic wizard for installation. But if you get confused the tutorial/help option will fill you in on how to find your Stamp. Have fun with your own Boe-Bot.

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