MABEL - A Boston Dynamics inspired balancing robot

So we're back in lockdown in the UK again which means I've got some more time to work on MABEL. This time I've put the legs to use and you can see in this preliminary test that by  moving the legs using the Inverse Kinematics script (written in the previous post) we can move the legs. This changes to the centre of mass of the robot and allows us to kick the robot forwards or backwards and help accelerate and decelerate the robot much more effectively. 

At present moving the robot legs up and down is proving to be quite difficult as it tends to make the robot unstable. My solution is to write a script to smooth out the servo motion which should make the robot more stable moving in that direction.

All driving in the video is done by changing the Centre of Mass (CoM) by moving the legs. This allows the robot to accelerate more effectively than by changing motor speed alone. It still needs work but it's getting there:

UPDATE: MABEL is now able to drive around wirelessly using a Wiimote as a controller. (I'll be publishing the code later on in the main project details for anyone building along.) The Pi can now communicate to the Arduino over a USB serial connection, although I had to solder the wires directly onto the pi and Arduino solder joints, as MABELs slim frame doesn't allow a USB cable to fit. In the future I'd like to move away from the WiiMote in exchange for a newer controller like the PS4 one. Using the joysticks I will be able to have velocity control over the robot for more precise movement and control. The next step for MABEL is to get the servos to move up and down whilst balancing, by using the handy PCA9865 Servo controller and the Adafruit ServoKit python library. MABEL is still a bit wobbly, but I've found that reducing the Kd PID constant helps to reduce oscillations when balancing. If you have ant questions about the build and want to build your own, feel free to contact me on raspibotics@gmail.com, I'm happy to help!