After two years of work I finished my self-driving robot-car. The robot is able to navigate and to autonomously drive around in the garden. It is equipped with different sensors and the combination of the sensors information enables the robot to drive around. The first self-driving robot was the Discoverer which is equipped with a metal detector. The challenges with the robot-car are the powertrain, the energy supply, the integration of the sensor data and the developing of the software to control the robot-car.
The following pictures shows the robot-car which I build from a floppy disc box. This robot is my prototype with which I test the software and electronics.
The next close-up shows the floppy disc box. As central processing unit or brain of my robot-car I am using a Raspberry Pi 3 model B. Above the lock of the floppy disc box you see the Raspberry Pi camera which is used for live video streaming out of the robot. With the video-stream and a simple web-interface I am possible to control the robot.
Robot-Car – component list
A list with all the components you need to build your own robot-car is available here: components list
The dc gear-motors I am using inside my robot-car are not strong enough for the rubber tires. The robot-car is turning like a tank on the sport the robot needs much power to turn the chassis in the grass. The dc-motors do not have the power to turn the robot and I bonded duct tape around the wheels. This makes the wheels slippery and enables the robot-car to turn on the spot. The pictures below shows the inside of the robot-car with the four dc-motors.
The next picture shows the robot-car from the left side. You see on the picture the gps receiver and the external WIFI-antenna which boost the signal up to 12 dB. This is important because the WIFI signal will get week very fast outside of your apartment far away from your router.
Sensors of the robot-car
I am using different sensors in my robot-car which enabling the robot-car to drive autonomously around. Above the robot-car on top of the white PVC pipe I mounted the Raspberry Pi Sense-HAT. The Sense-HAT is equipped with six sensors:
- Barometric pressure
Beside the six sensors the Sense-HAT is equipped with a 8×8 RGB LED matrix and a tiny joystick.
To protect the Sense-HAT from the environment I used an empty yoghurt cup. The yoghurt cup protects the Sense-HAT against dust and moisture.
Additional to the sensors of the Raspberry Pi Sense-HAT I am using a GPS receiver to enable the robot to drive from one waypoint to the next one. I tested a few GPS receivers and actual I am using a 167 Channel GPS receivers in this floppy disc self-driving robt.
Actual I am not using the SRF08 ultrasonic sensors I normally use for my robot-cars in this model. I do not have a workshop and to drill the holes and mounts into the plastic box isn’t easy. But it would be very interesting to use the ultrasonic sensors in this robot-car while it is driving around in the garden.
Some close-ups from inside the robot-car
The picture below shows the cardboard on which I mounted the Raspberry Pi, the motor driver and the step-down converter. Partly I mounted the electronic components to the cardboard with some rubber bands and nails I stick through the cardboard and holes of the PC boards of the electronic components.
Below the cardboard with the electronic components the rc-accus are located. I connected the two accus in series. The supply constantly the robot-car with 14.4 voltage and 5.000 mAh current. The accus are located between the four dc gear-motors. With this setup the weight distribution of the robot-car is very good. The both accus are good enough for 30 – 45 minutes of driving around with the robot car. The wheels are normal rc-car tieres which are directly mounted on the axis of the dc-motors.
Video – self-driving robot-car
A video which shows the robot-car driving around in the garden is available on YouTube. In the video you will also see the live video streaming from inside the robot-car to my desktop to control the robot-car.
I am very happy with the small robot-car and all electronic components inside the robot. The Raspberry Pi is perfect for such a robot project and to build a self-driving robot-car. The add-ons like the Raspberry Pi Sense-HAT is perfectly supported by the operation system Raspbian and very easy to program. All programs are written in Python for the robot. The GPS receiver works perfect with the gpsd tool together with LINUX / Raspbian. Now with the GPS receiver the robot is able to drive from one way point to the next one. I little soldering work was done to get the Sense-HAT running above the robot chassis.