Wheels, Tracks, or Legs?
Considering I want my robot to look similar to Wall-E and be able to live a long life and go many places, I decided to use tracks. I know there are sociable robots that are stationary, but with people always on the go, I feel a robot should be too.
What is locomotion?
Locomotion involves the conversion of some source of energy — electricity, air pressure, steam, nuclear power. — into a mechanical action that moves a vehicle or other carriage.Mobile robots use a variety of techniques to achieve motion. Most use an electric power source (usually a battery) that operates an electric motor. In the typical arrangement the direction of the motors can be changed, allowing the robot to be propelled forward or backward. There are other power train techniques used for robots, but the battery and motor pair is by far the most common.
After reading from Society of Robots, I decided to use 4 batteries and 2 motors for my robot. I decided to keep the DC motors that came with the kit because they were 3V-6V.
Where?
After deciding how I wanted my robot to move, I needed to figure out where I would get the tools to make it move. I felt that a kit would be the ideal approach since this will be my first robot, so I went on the hunt for a “Tracked Vehicle Chassis Kit.” I went to Amazon first, but I saw that the prices were pretty high, so I decided to check on Google and search by lowest to highest price. I immediately found the perfect kit I wanted to use. The kit was from Tower Hobbies and it includes everything I need to build the mobility for my robot. Such as wheels, tracks, a platform, grease, etc.
However, even though the kit included a gearbox and a motor, I wanted to improve the mobility of my robot. So I went ahead and searched for another gearbox and motor. To my surprise, I found a twin gearbox kit that included 2 motors that was cheaper than a single gearbox and motor. I also found a Universal Plate set that I felt would work better than the wooden platform because it would allow me to have more room. I also had to purchase a new battery compartment because the original one could only supply 2 batteries which would not have enough power for 2 motors.
How?
Again, I’m going to use 4 batteries to power my 2 motors and I’m going to use a dual channel motor driver to control my motors.
Original Parts
Additional Parts
Construction Video
Motor Control Program
After trying to implement and debug code and getting little movement from my RoboPi2, I realized that I had a power issue.
I tried adding another battery pack and a new portable power pack. I wired the battery packs together and then plugged them in as one battery and the power pack supplies the Raspberry Pi 2 with 2.4 amps (A).
After trying to run my code again, I still found that there was not enough power. 1. My robot was heavy from the LEGOs and components I used. 2. The LCD display takes up a lot of power away from the motors. I could even see the LCD screen flickering from bright to dim as I ran the motor control program.
The motor control program works when I place my robot on a box to support the weight instead of the wheels but that’s not going to help my robot go anywhere.
Future
In the future, I would like to figure out how to make a lighter but durable robot. I want to be able to improve my motorcontrol program and make it so that the robot moves towards motion. Almost like it’ll follow someone where they are going. However, I also want something that’s going to be easy to approach. I don’t want the robot to seem scary and seem like it’s chasing someone down! That’s why I did the rainbow colors. I felt that people would be more drawn to something with many colors. Nevertheless, now I have to go back to the design of the robot and back to the drawing board.
motorcontrol.py
RoboPi2 