Ardunio Self Balancing Robot
Project Equipment:
18650 Battery Holder (holds 3 x batteries)
3 X 18650 2100mA batteries
Arduino Uno R2 (Running a PID ProportionalIntegralDerivative motor control sketch)
MPU-6050 3-axis gyroscope and accelerometer
L298N Dual Bridge DC Stepper Motor Driver
2 X N20 DC 100RPM Geared Motor with press fit Rubber Tires
3 X 0.75mm Brass Sheet, 140mm X 80mm
M2 Brass Stand-off / Screw / nut & bolt kit
Male/Female Jumper Wires & 1mm wire (50cm)
Two-Pole Power switch
Overview:
This is my first project to be published on the Instructables site. It is the first version of this robot with subsequent versions having Bluetooth control, via an Android App which I will be developing on Android Studio, IR sensors for object detection and LCD display.
My philosophy when building robots is to ensure that they not only work in the way required but also that they look aesthetically correct with clean lines and good construction methods. I used a number of internet-based resources both for the electronics and Arduino code and for that I offer my thanks to those contributors.
The choice of the 18650 batteries was based on their power rating and ease of obtaining good quality second hand batteries usually from old laptops. The Arduino board is a standard clone, as is the L298N Dual Bridge motor controller. The N20 DC motors are adequate for the project but I felt that larger 6V DC motors with direct drive would perform better, this being a possible future upgrade to the project.
The basic construction consisted of three 140mmX80mm 0.75mm brass rectangles with holes drilled for the M2 stand-offs, holes for the L298N, MPU-6050, and Arduino Uno supports and four 2mm holes to attach the N20 motor supports. I added two out riders to catch the robot should it topple over, these had the added advantage in that they provided a stand for the robot, while it was switched off, and which the robot could start from when switched on. While the jumper wires were adequate, I have found that the connections are weak and that fully soldered connections are better, such as those to the MPU-6050.”

Link