Robotics is an active field of research and a promising application area for digital signal processing. As an example project, we build small bipedal robots with only four servo motors for the two legs (six servo motors for an extended version), an accelerometer for balance, and an Arduino board or Servo Driver HAT board on a Raspberry Pi Zero for signal processing and control of the servo motors. With the help of a PID controller, the robot shifts the balance between left and right to walk.

Walking robot made of 3D print parts
7th generation robot
Robots don't like New Year's Eve noise either

For a version out of a 3D printer (.stl):

3D Printer Models (zip file)

A Python program to let the robot from the 3D printer parts walk, with a Raspberry Pi Zero W. Observe the correct connection of the servos to the servo board number:

3D printed parts for the 7th generation robot (.stl)