The robot can take the cargo from the ground or a shelf and move it following the line to the destinated shelf. Also you can anime its "face" using the LED display.
Ultrasonic Sensor
Ultrasonic Sensor. Limits
Color Sensor
Two-motor Chassis
Color Sensor. Height.
Color Sensor. Reflected light
Parallel motion linkage
Levers
Torque
Rubber bands as compensators
Introduction to software