Team subuk raftar self balancing personal vehicle
M. Abdullah Bin Azhar
The aim of this project is to build a “Self Balancing Personal Vehicle” which can be used as a convenient way of traveling for short distances carrying a single person. This self-balancing human transporter consists of a platform with wheels attached to its sides, a physical application of a stabilized control system. It is built loosely around the design of Segway™.
The rider drives the vehicle by standing on the platform and leaning in the direction to move. The handlebar also serves as steering control of the vehicle.
It balances by detecting the tilt angle using an accelerometer and gyroscope, calculating the corrective action using a PID controller implemented on a microcontroller to move forward or backwards automatically to regain its balance.
Involves: Robotics, Control and Automation, Instrumentation and Measurement.
Subuk Raftar has two parallel wheels on the sides and is controlled by moving body weight. The rider stands on a platform between the two wheels holding on to a handlebar. To move forward/backward the rider will simply lean and the vehicle will sense and start moving in that direction. When weight is equal in both directions, it will remain static. Similarly, a left or right tilt of handlebar will turn the vehicle.
Actuators & Sensors
Two Permanent Magnet Brushed DC Motors powerful enough to carry a person’s weight. These are solely responsible for balancing, moving and braking the vehicle.
Microelectromechanical Systems (MEMS) based Inertial Measurement Unit consisting of a Single axis Accelerometer and Gyroscope.
The mechanical platform is made of plywood with electric scooter wheels attached to two 250W motors using ANSI-25 standard chain-sprocket system. Two Dry Lead Acid Batteries of 12Ah capacity are the main power source.
Four N-channel Power EMOSFETs, IRF1404 are used in a full bridge configuration for each motor. The PWM driving the MOSFET is 2.1 kHz generated by an AVR microcontroller optically isolated and fed through a MOSFET driver circuit.
The output of accelerometer and gyroscope’s integral is fused using a technique known as the complementary filter, to generate a single noise free output i.e. angle of platform.
A Proportional-Integral-Derivative Controller is implemented for tilt compensation since the mathematical model of plant is not known. The controller runs at 100 cycles per second keeping the vehicle in balance.
AVR Microcontroller, AVRStudio, MATLAB, Electronic Workbench, Inertial Measurement Units, Mechanical Workshop.
Such kinds of vehicles are already in use to travel indoors within airports, shopping malls, offices, factory floors etc. as well as outdoors on city sidewalks in many countries.
They will ultimately make way to our country as well. How our society and cities will react to it, we don’t know. The engineering community, however, encouraged and appreciated this one small step we took in this direction.