Betty is the first prototype of our mobile robot. It has a variety of sensors and utilizes our Finger Board 68HC11 embedded processor board for control. The robot is fairly small, it stands 4.25" high by 4" in width. The construction is based on three 4" diameter boards that are stacked on top of each other. The first layer holds the modified R/C servo drive units and nicad batteries. The internal servo electronics were removed and the motors are driven by a L293 H-switch chip. Future prototypes may use small gear-head motors for greater speed. Most of the electronics are contained on the middle printed circuit board. The processor board is located in the center with the various external sensors surrounding it. The top layer holds the LCD display and Vector compass unit. The sonar driver circuitry is also located on the top layer, yet to be implemented.
Our next prototype will try to integrate more of the electronic circuitry on a single board and may have possible enhancements such as wireless data transmitter, wireless video transmitter, sonar, PIR detector and smart charging battery system.
We are thinking of developing a PCB board for those of you who are interested in owning their own Betty. E-mail us if you think we should pursue this avenue and suggestions are always welcome.
Some detailed images of
Circuit schematic of Betty in Acrobat PDF format.
Finger Board - 68HC11 based
Vector 2XG compass for direction
left and right IR line following sensors
left and right CDS light sensors
left and right microphones
left and right wheel speed sensors
left and right IR transmitters for collision avoidance
Sharp IR detector
IR data transmitter
16x2 line LCD data display
Speaker for sound output
Power monitor for low voltage battery warning
Extra I/O Menu buttons
6 cell 270mAH nicad battery for power
Modified servos for locomotion
L293 H-switch motor driver
Weight: approximately 1 pound
Runtime: Servo motors moving constantly, get a runtime of approximately 37 minutes with the 270mAH nicad battery pack.