Background: So I'm a mechanical engineering student, we are asked to make an autonomous vehicle with regenerative breaking. Info. about the project: dimensions of vehicle to be about 25 cm long, 16 cm wide and 8 cm high should be low weight should be low cost should be fast should carry weight Competition: -In the competition day the vehicle will start on top of a ramp, the vehicle must only use gravitational potential energy to move. -The vehicle must store energy from breaking for at least 1 second at full stop, then release the energy stored to move as far as possible. - there will be 4 stages and we are allowed to tweak the vehicle between stages I haven't done a lot of research on everything, but i have some basic ideas of how to tackle this project. But I need some advice on somethings. REGENERATIVE BREAKING: since we're not allowed to use batteries to propel the vehicle, I guess the only choices are using a Flywheel or Spring to store energy. From experience which do you think will store more energy or which one is more applicable in this case? Micro-controller: I think micro-controller will be extremely helpful because we will need to control the speed the vehicle at all times. I dont have a lot of experience with micro-controllers, what micro-controller do you recommend for a beginner or what micro-controller is more applicable to use in this case? Laser Beam sensor: In the track there will be multiple laser beams in which the vehicle must slow down or propel from rest. This is the most difficult part for us, we are told the laser beam will be at a height of 1.5 - 5 cm. What type of sensor do you think will work in this case? or how will our vehicle know that it passed through the laser beam? I appreciate your help.