Can you complete this assignment?

Help with Assignment 1

Some people have asked for some advice on Assignment 1 and it seems only fair to offer the same advice for all, so here goes.

First some general notes:

1. This first assignment is set the way it is because the syllabus all but demands it. It’s not necessarily the way I’d choose to cover this subject. The subject as a whole is well worth including in an HND, this assignment less so. Some of the content may seem a little obvious and you need to remember this is a level 4 module and you may be looking for complexity that isn’t there.

2. It’s also worth noting that when this HND was first designed Mechatronics was on something of a mission. At the time it was common for mechanical, electrical and electronic engineers to work separately on parts of projects and this frequently led to very inefficient designs, hence the need for a module about the virtues of an integrated approach. These days it’s taken for granted that engineers with different backgrounds will work together, so one of the fundamental issues behind the module is not as big an issue as it was once.

3. There is still a role for a Mechatronic approach to systems design. Frequently, a truly integrated cross-discipline method finds solutions that are either much more efficient than could be achieved by dividing a problem into separate team tasks, and sometimes it finds solutions that could not be achieved any other way.

4. The purpose of the module is to force students of different disciplines to look at systems comprising mechanical engineering, electrical engineering, control systems and electronics (or these days more usually computing) and to take a broad approach to the solution of the overall problem not just the bit they are comfortable with.

5. This is a University-level module (albeit first-year – not second year - equivalent), so I do expect you to do a bit of web-based research around the subject and be able to think for yourself on occasion. I don’t apologise for that.

Task 1

In the case of each of the product examples below, explain which of these is inherently a mechatronic system (in that its design could not realistically be undertaken except by an interdisciplinary approach), which could be designed by other means but might benefit from a mechatronic approach and which (if any) are inherently unsuited to this approach.

• Domestic washing machine

• Heat-seeking missile

• Industrial robot

• Domestic oven

• Light aircraft

In your discussion, consider size constraints, cost of components, reduction in computing power, reduction in process delays and system compatibility.

You should consider only the overall design of the product rather than the design of small elements within it.

OK, so the key point here is that all of these systems have all of the elements described above, but which of them is dependent on a fully integrated approach to design and which not? There is no categorical right answer. What you need is a very brief discussion about each and a considered view on which are and are not mechatronic. It’s actually the discussion that matters, not the decision. By way of an example, let me illustrate with two examples not in the list.

1. The Eurofighter aircraft. Aircraft, especially simpler ones, are usually designed as separate airframes, engines and avionics. Not only is this flexible (e.g. British Airways [usually] chooses to have both its Boeing and Airbus airliners fitted with Rolls-Royce engines for the sake of consistency across its fleet) but the compromise on overall performance is not great. However, at the limits of manoeuvrability, designing the flight avionics with the engine and airframe allows performance that can’t be achieved separately. The Eurofighter airframe is highly unstable and would fall out of the sky if the avionics failed to keep it flying. The avionics need data from the engine and airframe to detect the point at which the airframe would stall and instructions to correct errors need to be given to actuators in the engine and airframe within milliseconds. That’s hugely expensive to achieve, but does allow the aircraft to do things an airliner can’t, especially to climb and turn very quickly. If you think that through in terms of “size constraints, cost of components, reduction in computing power, reduction in process delays and system compatibility” you’ll realise that this is intrinsically a mechatronic system because everything has to be fitted in to horribly tight spaces (which you can’t easily do with a black-box approach), it may appear astronomically expensive but this is actually the cheapest way of achieving these goals. The component count is much lower than any other way of doing the job. (Usually, mechatronic = lower cost.) It needs less computing power than it would had these designs not been fully integrated, has low process and manufacturing delays because of the greater integration, and has guaranteed system compatibility.

2. Compare that with a domestic tumble dryer. Would it matter much if the motor, structure and electronics were designed with minimal integration? So long as all the physical space constraints were met, the sensors and actuators used the right voltage ranges, etc. and the motor output was within limits. Who cares?

Write something about each of the items in the list. So long as what you write makes sense, it’s right.

Task 2

By reference to at least one example, explain the difference between combining separately developed mechanical, electrical / electronic and control systems to produce an overall system and developing the system in an interdisciplinary way from the outset.

You might choose from such systems as

• Industrial robots

• CNC machinery

• Fly by wire aircraft

• Suspension control on vehicles

• Brake and steer by wire on vehicles

• Domestic appliances

• Auto focus cameras

• Vending machines

or select one or more of your own choosing.

As part of your discussion, explain why an interdisciplinary approach is necessary for some engineering systems and the advantages such an approach gives over separate development.

Take my Eurofighter example: what are the chances that if you bought a stock engine, stock avionics and an airframe made by combining standard parts from several manufacturers you could make this thing fly? There’s no chance that the parts would perform together as one integrated whole in the same way as they do when designed together. For some systems, this type of interdisciplinary approach is the only way of meeting exacting specifications, for others it has benefits in reducing component costs and making it easier to achieve good outcomes. Often the product designed is better than could be achieved by separate development. Sometimes, but not always, the development cost is higher but this is usually recovered pretty quickly in manufacturing costs. Any of the items in the list could be a mechatronic system, though some are slightly more suited than others. What you need to do is to explain for one of them how designing it as a whole system provides advantages. If you get desperate, there are lots of good case studies on the net if you look hard enough.

Again, there are no categorically right answers and your reasoning is the important bit. Don’t turn this into an essay. A couple of decent paragraphs will cover the topic so long as you think clearly about the issues.

Task 3

Identify two consumer products or industrial processes that are mechatronic in nature.

In each case:

a) Justify the mechatronic nature of your choice by explaining which disciplines have been integrated in each.

b) Outline, by means of a block diagram or otherwise, how the overall system is made up of elements taken from these disciplines.

Use your grey cells, or the internet if the grey cells aren’t up to it, to identify two systems that are definitely mechatronic in nature. You’ll be surprised how many well-documented case studies there are out there. Now use the arguments laid out above to explain your decision. Almost all case studies you’ll find contain a simple block diagram of how the parts of the system link together. Have a look at some of these and draft one for your chosen systems.

I set a word limit of 1500 words for this assignment, but a really good answer can be done in 1000 well chosen words. Please don’t feel you have to write up to the word limit and don’t over think the tasks looking for something deeper than laid out above. Think level 4 and pass criteria only, but don’t miss anything out.

Hope that helps.

Steve