A small company employing around 25 people manufactures and sells anthropometric measuring equipment - equipment used mainly in hospitals to measure the height and other dimensions of human beings. Such information is required, for instance, for monitoring the growth of children/young persons suffering from abnormal growth conditions. It is a requirement of all such equipment that operation is simple by the person making the measurements, and readings are required that are accurate and repeatable to ±1.5mm.
The company's current range of equipment covers a number of instruments, all mechanical and based on a 'head' which moves driving a gear train which in turn drives a mechanical readout counter using the same principle as the wheeled instruments used by surveyors to measure road distances. The company's background is in precision mechanical engineering and it has no experience of electronics whatsoever. Experience has shown that the gear train and mechanical counter readout suffer from wear-out in under two years and therefore the mechanical reliability of the instruments has become a matter of concern. The MD of the company has become aware that one of its competitors overseas is developing an electronic version of the instrument and understands that the reliability therefore will be much improved.
The MD has asked you, as a microelectronics design consultant, to help the company in developing an electronic (or possibly a microelectronic) version of the instruments. At your initial briefing meeting he detailed the overall specification for you as follows:
- Mechanical gear train to be replaced.
- One standard measuring head for the complete range of measuring equipment with a range of 0-2000mm in increments of ±1mm with an accuracy and repeatability of ±1.5mm.
- Battery operated.
- Operation to be as simple as the current units, with no requirement for zero adjustment, etc.
- Physical size of the head preferably to be smaller and lighter than current mechanical units.
- Production costs to undercut current costs by at least 20%.
- Volume estimated at 3,000 units per annum in the first instance.
- Development costs to be £30,000 or less in total.
- Increased reliability over the current unit.
Carry out a feasibility study and propose an electronic system to meet the brief giving a project plan, timescales, and system specification.
The company is rather doubtful of any proposed electronic system on paper so suggest a possible demonstration prototype route for your proposal. Include block diagrams for any circuits you suggest, together with a proving test specification. You can assume that any mechanical work will be carried out by the company and all you need to do there is specify, in general terms, your mechanical requirements and interfaces.
Indicate possible problems, and likely solutions, with your proposal including EMC and other issues.
Give an indication of the User Interface panel you envisage together with any external switches, indicators, etc. that you intend to have on the finished product.
Give general guidance to the company as far as the choice of design house (to carry out the detailed design) and also the choice of silicon foundries if applicable.
Indicate any possible enhancements to the basic instrument that you envisage, and any advantages that would result.
Make any other recommendations that you consider relevant including personnel, or other management issues.