Question: Hi Niel.. what's the hardest motion/control model you have had to design?? :) btw where were you at the chat #prayforneil was trending ;)

Neil Dhir answered on 20 Jun 2014:

Hi Shefali!

I am so sorry to have missed the chat with such a lovely hashtag like now trending in my favour. I shall have to make sure that that does not happen again. But, as the other engineers will tell you, we have a lot of meetings, so I am usually very busy during the day but I will try to get onto a few more chats, they are a lot of fun.

Now for your actual question, once I had to design a control system for a helicopter. If you go on to study engineering, you will soon realise that this is one of the staple problems departments use to teach students about control systems. This was true for us as well.

So what they do is, they have a helicopter jig; a main rotor and a tail rotor, and it spins very erratically while you try to control it manually. And this is the point, controlling helicopters in particular is very very difficult. Which is why you need a control system to do so. Hence, what we had to do was, based on the data we got from that initial manual test run, we had to design a control system that accurately stabilised the entire system such that the main rotor was horizontally level, and that it would pitch in accordance with our user input. The same was true for the tail rotor, but it instead had to be vertical. This was a difficult project, but very interesting, and to some degree it got me very interested in control engineering. It is very mathsy, which I like, but you can do some very powerful stuff.