The PAC-Machine

In this assignment, we were intended to make a machine that can clean the small garbage on the floor or table surface, however, it only cleans while its owner is in the room with it, after the owner leaves, the machine will pour out the garbage that it has collected immediately from its tailgate. 

We use the light to indicate whether the owner leaves the room or not. Basically, when the owner is in the room, the room has its light on, and the photoresistor on the machine will sense the light so that it will clean the garbage obediently. After the owner turns off the light and leaves, the sensor of the machine will respond to open the machine’s tailgate and release the garbage all over the place.

Electronics Parts:

Arduino UNO R3 Controller board X 2

220 Ohm Resistor

Servo Motor SG90 

Stepper Motor 

ULN2003 Stepper Motor Driver Module 

Photoresistor 

360 Degree Continuous Rotation Micro Servo Motor X 4

Arduino Micro Tire Wheel X 4

USB Cable X 2

Breadboard X 1

Jumper Wire X multiple

Other Parts:

3D Printed Roller

3D Printed Gear

3D Printed Inclined Base

3mm Basswood Structure

3mm Basswood Tailgate

Power Bank X 2

Step 1: Program & Design

In this very first step, we coded the Arduino and connected most of the electronics parts on the breadboard. Then we designed the appearance of this machine, which will be a car with four wheels and a roller in the front and a tailgate at the back. Also during this step, during the coding, we figured out what specific parts we cannot get in the kit and the parts we need to purchase online or get 3D printed, such as wheels and the roller. 

In this step, we 3D printed, laser-cut, and online purchased all the parts we need that the lit does not have. After we got all the parts, we assembled the machine.

Issues:

• Sometimes it does not do its function because the wheel would not go straight. It seems the four servo motors of the four wheels have slightly different rotation speeds so that while the machine is moving, the speed difference of the right and left wheels would cause the machine to rotate instead of going straight. 

• Sometimes the roller would be stuck with the garbage, and if the garbage is stuck between the roller and the ground, it would create large friction that causes the machine to stop moving forward.  

• The Photoresistor is not so accurate that sometimes it would not read the number correctly, and this error would cause the tailgate would not open after the light is turned off, or the tailgate would not close under the light. 

• The power issue. A single power bank would not have enough power to supply all the movements, such as the roller, the gear, the wheels, and the tailgate. So the solution we came up with is to divide all the motions into two Arduino boards and use two power banks.  

• We designed the structure parts on Rhino and then fabricated them without thinking about their weights. Physically, the 3D-printed roller is much heavier than we thought it should be. We have to change the weight of the machine in order to make the machine move.

This machine works perfectly most of the time,  when the light is on, it can clean up the garbage the size of jelly beans. While the roller rolls over the garbage, the roller brings the garbage onto the machine base and the garbage will roll towards the back of the car due to the inclined surface, then stopped by the block of the tailgate. When the light is dark, the tailgate will open but the wheels are still moving so that the garbage collected inside will be released everywhere on its path.