LucidTronix is a new Open-Source Electronics designer. We make
tutorials,
as well as transparent, beautiful, and lucid
devices.
Read more
about us here.
Cliff Avoider
Two proximity sensors help this bot avoid cliffs.
Proximity sensors extending out from both sides of this robot ensure there is ground to roll on. If one sensor detects a drop-off the robot turns int the other direction. If both sides detect a cliff then the robot gets very anxious. The result is a perimeter following behavior that emerges from the simple rules of turning away from edges and going striaght if no edges are detected. Like many of our
bots
, this cliff avoider makes ample use of the
binary proximity sensor
from
pololu
.
Plexi Body
-
Plexi BodyThe plexi glass body has two broad wings that house the proximity sensors. These sensors extend out in front of both wheels and ensure that the bot doesn't take a nose dive. -
The PCBNotice the silkscren graphic of a bot going over a cliff... That is what we are trying to avoid! -
PCB BacksideSymmetric PCBs are appealling. The brains of this bot is the atmega168 in an SMD package. The bot runs on top of arduino, so it is easy to hack. -
Proximity Sensor CloseupThat is the right sensor, which hopefully detects any cliffs on the right side of the bot. -
Board DesignHere is an image of the EAGLE .brd file. This is where we drew the silkscreen graphic of a bot going off of a cliff. Use the wire tool on the TPLACE layer. -
SchematicThe electrical schematic. Proximity sensors in to atmega168 and PWM out to the left and right servo motors.
The plexi glass body has two broad wings that house the proximity sensors. These sensors extend out in front of both wheels and ensure that the bot doesn't take a nose dive.
Video
This bot tries to stay on the table without any human help. Corners are tricky as the two sensors sense danger in both directions. Notice how the simple behaviors of turning to avoid edges leads to a more complex behavior of following the perimeter of a shape (as long as that shape is
convex
).
Arduino Code
Control a servo robot using differential steering based on two binary proximity sensors. The robot exhibits a somewhat
emergent
behavior of avoiding cliffs, and following convex perimeters. This arises from the interaction between three rules:
- If there are no cliffs go straight
- If there is a cliff to the right, turn left
- If there is a cliff to the left, turn right
Download File
/* LucidTronix Cliff Avoider Servo Bot * http://www.lucidtronix.com/tutorials/16 * Control a servo robot using differential * steering based on two binary proximity * sensors. avoids cliffs, and follows * convex perimeters. */#includeServo right;Servo left;int leftSensor = 0;int rightSensor = 1;void setup() { right.attach(6); left.attach(5); pinMode(leftSensor, INPUT); pinMode(rightSensor,INPUT);}void loop() { int leftIn = digitalRead(leftSensor); int rightIn = digitalRead(rightSensor); if (rightIn == HIGH){ left.write(45); right.write( 45 ); } else if (leftIn == HIGH ) { left.write( 165 ); right.write (165 ); } else { left.write( 165); right.write( 65 ); } }
Download EAGLE files and code
Zipped archive of the EAGLE files and the arduino code.
Click Here to Download: Download EAGLE files and code
Parts
| Title | Description | # | Cost | Link | Picture |
| Servo Motor | Continuous rotation servo motor. | 2 | $13.95 | Link |
|
| Proximity Sensor | Digital proximity sensor. 5vValue:5v | 2 | $6.95 | Link |
|
| Servo Wheel | Wheel that attaches easily to servo motors. | 2 | $4.0 | Link |
|
| ATMEGA168A-AU | IC MCU AVR 16K FLASH 32TQFPValue:1.8 V ~ 5.5 V 20MHz | 1 | $2.43 | Link |
|
| Crystal | CRYSTAL 16.00000 MHZ 20PF SMDValue:16MHz | 1 | $0.53 | Link |
|
| Resistor | Chip Resistor - Surface Mount RES 10K OHM 1/8W 5% 0805 SMDValue: 10k | 1 | $0.1 | Link |
|
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