Article from CADUser Magazine
Courtesy of CADUser Australia, May 1997, by Steve Hunter.

Colin Johanson has always loved the design process - the concept of starting with an idea then progressing this through to a working model and tinkering with it until the idea has a finished form. When he became a quadriplegic in 1977, he began directing this design passion at the development of a number of items that would make his life and the lives of others both easier and more enjoyable.

"There were many items that I wanted to build or have built to suit my disability requirements - things that just weren't available. So I bought a lathe and started manufacturing plastic and steel components " says Colin. "When the aids I designed started exceeding my manufacturing capabilities, I had to start drafting to get my ideas down on paper."

In 1978, working on a drawing board, he began designing aids and appliances for people with disabilities. Working with TADVIC (Technical Aids for the Disabled in Victoria), he helped develop a number of one-off designs and began to recognise the importance of ergonomics in design. This led him to undertake postgraduate studies in ergonomics at Lincoln Institute (now Latrobe University) in 1981, after which he began lecturing and consulting on the application of ergonomic design in the workplace.

At this time RSI (repetitive strain injury) was topical and, as today, a great deal of ergonomic design related to the use of computers. Colin found that he was often discussing ergonomics and computers and decided to learn more about using a computer himself. After purchasing a Commodore 64 his interest in computers grew and he started developing programs with the BASIC programming language.

But the consultative process was frustrating. Thorough assessments were often ignored by employers and little was being done to change the design of the workplace. Motivated by a desire to become more involved, Colin started working with a commercial office company, Executive Office Interiors, to design office layouts and furniture.

Autocad Comes on Board

At this time the company was also looking to improve its design and visualisation service by introducing CAD and was evaluating VersaCAD and Autocad.

In 1985, Autocad was not the industry standard that it has become today and, Colin admits, it was as much good luck as good judgement that saw him and the company start with Autocad 1.15. The NEC APC IV purchased to run Autocad at this time was equipped with two 730 kb floppy disk drives: one disk for the program and one for data - a far cry from the Pentium Pro systems of today, sporting gigabytes of hard disk space.

Colin soon became enthusiastic about Autocad and helped start VICAUG, the Victorian Autocad User Group. He customised Autocad's menus and built libraries of standard parts - ultimately developing more than a thousand standard components.

As Autocad progressed to 2.5D and later 3D, Colin started producing 3D office layouts and modular furniture designs. "The introduction of 3D was amazing," says Colin. "It meant we could draw something once and create several views. Instead of producing a simple office floor plan, we could show a client their new office as seen from their office door or from their desk. This was valuable in helping clients to understand layouts and respond immediately."

He also developed a number of interactive macros that allowed design variation based on user input. During eight and a half years spent on commercial office design, during which time Autocad progressed to Release 11, Colin developed a deep understanding of the product. Now, no matter what he's designing, Colin uses Autocad. When his house had to be modified to facilitate wheelchair access, Colin drew the plans himself in Autocad and submitted them for approval.

In 1988 Colin was introduced to skiing by George McPherson of Myrtleford in Victoria. Colin says, "I was looking for a sport that gave me control. With my limited arm and hand movement, there weren't too many sports that I could get involved in that weren't specifically disabled sports. Skiing has a risk component but still affords a measure of control. I also wanted something that I could do with my friends - something that had a social as well as a sporting aspect and I found that skiers just accepted me immediately as another fanatical skier."

George had designed and built Australia's first sit-ski to allow his son David, a paraplegic, to enjoy the thrill of downhill skiing. David went on to be selected for the Australian paralympic team in 1994 after competing on a traditional mono-ski.

Soon after experiencing the thrill of the sport, Colin purchased a bi-ski from George. Where a mono-ski is suitable for paraplegics, quadriplegics must sacrifice speed for the improved stability of a bi-ski. The bi-ski makes use of a Swing-bo snow board which combines two skis that articulate for increased manoeuvrability. "It's aimed at the quadriplegic and cerebral palsy level of disability where there is limited arm strength," says Colin. "It's also quite safe because it doesn't run away from you. When you lose balance it simply lays to one side and it tends to fall uphill."

Colin became involved with George in the development of the design and spent a few weekends in Myrtleford working on improvements to the ski. Rather than trying ideas by tacking tube together in a cold factory, Colin showed George how Autocad could be used as a tool to define geometry and develop construction drawings. As a result, less material was wasted and designs could incorporate difficult elements like gas struts that assisted in lifting and made the ski easier to load onto a chair lift.

Colin won a Houston Instruments plotter for the "most innovative use of Autocad" in a competition in 1990.

His drawings showed the proposed design of linkages and gas struts, allowing the sit-ski to change between low skiing mode and high chair lift-mounting mode. With the release of a lever the sit-ski requires little effort to rise into high mode with the assistance of gas struts. When leaving a chair lift, the skier's own weight forces the sit-ski to return to the standard (low) skiing position (see figure below).

Copying and rotating the sit-ski within the CAD drawing allows the lifting mechanism to be plotted at different stages and critical clearances measured between the mechanism and the chair lift seat.

"The design of the lifting mechanism, incorporating the gas struts, would have been a nightmare without CAD," says Colin. "Without the ability to accurately plot angles and see the relative positions of the lifting components, design optimisation would have involved a lot of trial and error." As both Colin and George understood what they were building, it was only necessary to produce 2D drawings to exchange ideas and test scenarios.

George McPherson has received a Tattersalls Award for his dedication and work in designing and building equipment for disabled skiers. He nominated the ADSF (Australian Disabled Skiers Federation), now known as Disabled Wintersports Australia, as the recipients of a $2,500 prize which was used to purchase a mono-ski for the VDSA (Victorian Disabled Skiers Association, now known as Disabled Wintersports Victoria).

Soon after seeing the potential of CAD in the design process, George also became a CAD enthusiast and Colin spent time teaching him Autocad. The two could then exchange ideas visually and regularly mailed each other floppy disks containing drawing files - a big improvement on the 300 km drive between their homes. George recently undertook a course in 3D modeling and upgraded to Autocad Release 13 for Windows.

Frame by Frame

From 1989 through to 1993, Colin developed an improved frame each year. Sorting out bugs is still a practical process that is not without cost. While testing modifications Colin has been jammed on chair lifts and skied into holes - once resulting in a broken nose.

Manufacturing rights for the quadriplegic bi-ski, using the Swing-bo snow board, have been sold to a company in the US and Colin has seen his frame being used by injured gridiron footballer, Mike Utley. The company was given all drawing files, in digital and hardcopy formats, as well as a new sit-ski. The sit-ski is not a commercial proposition in Australia, but the US has a longer ski season and larger population, making manufacture feasible. Most ski resorts in the US also offer better access to disabled skiers - something that Australian resorts have been only slowly improving.

The design of the Sit-Bo, that would now be referred to as a bi-ski, has not been altered since 1993 but Colin has already made a mould for a new, custom-sized seat bucket that will be part of the monocoque design, instead of being bolted to a stainless steel frame.

Colin is surface modeling the seat in 3D to allow the seat contours to be optimised. He is developing a lighter ski that has a totally new geometry and makes greater use of composite materials - reducing weight while still supplying the necessary rigidity. The various new frame configurations are being developed using Autocad, allowing new ideas and concepts to be trialed and refined on screen.

From Snow to Sea

The new venture that Colin and George got enthusiastic about last year was the development of a water-ski for quadriplegics. While similar designs are available overseas, Colin has modified and improved the design to provide additional lower-back support. The water-ski design, incorporating a tubular aluminium frame, was tested on the Murray River last summer by Colin and he says that, after seeing how much fun it was, all his mates just had to have a turn too.

To Colin, a person who has enjoyed hang-gliding, propelling himself down a ski slope provides an adrenalin rush not experienced in years and represents the fastest he can go under his own steam. At the same time, the sit-ski is quite safe and provides a controlled risk that allows him to engage in a social activity with friends. The sit-ski has also proved to be a great confidence builder with young children. Through its use, those as young as eight have enjoyed a sense of freedom and movement never before experienced and have gained improved confidence and self-esteem.

Article courtesy of CadUser Australia, May 1997, by Steve Hunter.

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