From time to time, I decide (more likely force myself) to extend my creation a bit. This was also the case during creating DominoBot. I wanted to create a robotic toy that can build domino bricks and follows the line on the floor at the same time. I chose Lego Technic as my primary kit due to its light weight and ability to create more difficult mechanisms
I built the robot twice totally. I completely disassembled the finished and fully programmed robot. I decided to rebuild it because I did not like it much. The reason was that some of the motors rubbed the floor and the brick release mechanism did not work properly as well.
Standardly, I started the building from the most difficult part. I build a stack for bricks and a belt on which the bricks are continuously pushed. I have considered many different ways to rotate the brick by 90 degrees and leaving in on the floor. The final solution was using a gravity force. The brick falls through mechanism that is continuously getting tighter from mall sides after the end of the belt. The brick is thus properly fixed before its release. The release mechanism is done as a barrier (gate) opening to the both sides.
The next step was to create a mechanism to select and push the bricks. It is constructed using two servo motors. Hitec (weaker one) retracts a lever under the brick stack which pushes single brick on the belt. This entire mechanism is further linearly moving from one stack to another. This move is done using Lego PF servo and plenty on gear ratios.
Then, I finished the construction of the robot. The drive is done through differential and rear wheels. Front wheels are rotated using another motor. I should have used another servo to control the steer radius instead of motor. Using only motor with no feedback made the entire steer logic quite difficult.
Another difficult part was done as last. I am referring of course to the line following. This part delayed the construction since I had to design and create new peripheral with sensors to detect the line. Nevertheless, I find the entire robot as a great success. It drives, builds domino bricks and follows the line at the same time. I must add that this was my first line following creation. So this is even greater triumph for me. See for yourself in the attached video or source codes.
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Source codesClick the label to show the source code
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