The Raspberry Pi is wonderful for DIY electronics. The PiCar-X is a robot kit based on this platform. It comes with various functions, including real-time video, face/color detection, line tracking, and automatic obstacle avoidance. The robot can be programmed with Blockly and Python.
The PiCar-X AI car uses the SunFounder RPi HAT as its driving module. It has a speaker for text-to-speech and sound effects. It uses an ultrasonic sensor for obstacle avoidance and auto follow.