Think what if you are an engineer and you want to design a machine? ...
Firstly you make a sketch then a model and then a machine if the model works properly. And what will you do if the model is a failure - you again start from step one.
The solution to this problem is given by (Video) MIT's Assist Sketch Understanding System. The system allows you to sketch a mechanical system and you can interact with the sketch just like simulation which reduces a lot of effort and even saves ur time and money. This is one of the best tool designed for your convenience.
Via: techeblog