I have recently become a dad, which is sometimes amazing, and sometimes suffering, such as when the baby is in a fussy mood and refusing to sleep. Some friends were very enthusiastic about a $1.5k smart crib that makes white noise and rocks your baby to sleep.
You know what also makes noise, rocks your baby to sleep, and doesn’t cost $1.5k? That’s right, this Lego model. This is already by far my most useful Lego creation, and we’re using it regularly to great effect.
At the core of this creation are two bogies, driven by Lego motors, strapped to the wheel of a stroller with rubber bands. Each bogie is driven by two motors for a total of 4 driven wheels and 4 motors for maximum traction and power.
You could honestly get away with two motors and maybe gear them down 12:20. This design has excess torque and velocity and is limited by traction. The traction is provided by the rubber bands, and kept straight with coaster wheels.
This particular design uses parts from the Lego Mindstorms Robot Inventor kit, which has been discontinued. It should however be possible to construct a similar model from Powered Up motors using the Technic Hub.