Hierarchical TRIZ Algorithms
Editor | On 08, Feb 2006
Hierarchical TRIZ Algorithms is a how-to TRIZ book. It is designed to assist both beginning and advanced users. Each month, the TRIZ-Journal will publish another chapter of the book. This monthâ€™s installment includes the eighth step of the 10 step algorithm (shown on the cover):
H. Turn Object Knobs (Properties) to Fix the Problem
Next monthâ€™s installation will cover the ninth process step:
I. Resolve Resulting Contradictions
In all, there will be 12 installments. Should you decide to purchase the most current edition of the complete book contact the publisher at: http://www.3mpub.com/TRIZ/
An analysis of cause and effect gives us the knobs and their settings that cause the problem. Now we must turn the knobs to create an enduring solution to our primary problem For purposes of illustration, let us assume that we are driving piles in shallow waters which will be used to support
large structures. Driving the piles is slow and expensive, due to the cost of labor and the cost of renting the pile driver. We would like to improve the speed of driving.
Letâ€™s assume that we have already performed the preceding analyses including the cause-effect analysis (not shown here). We learned that the driving speed was slow because: The ground is hard; the required depth was deep; the diameter of the pile was large; the pile sharpness is blunt. . .
Now, what if we turned these knobs to very different settings? We know that we could drive much faster if the ground was soft, the driving depth were shallow, the diameter of the pile was narrow or the pile was sharp.
However, in each case, there is a new problem that arises. The ground may be hard, or its hardness may have great variability. (If it did come soft, we would be required to drive it deeper since it gives less support). A deep driving depth is required to support the structure when there are sideward loads which arise from earthquakes or waves. The diameter of the pile must be large in order to hold up the
structure. The pile must be blunt in order to carry the vertical loads during earthquakes. Were we to use a sharpened pile, we would be required to drive deeper.
(Greater depths give greater supporting forces). Driving deeper defeats the initial gains of being able to drive faster!
Such objections are what stops people from turning knobs as far as they should. Most would rather turn the knob part way and thereby compromise. Unfortunately, compromise guarantees risk and leaves the problem to be solved later. There is only one way through this mess. We must turn the knob far enough to fix the primary problem. (In doing this, we do not ignore the resulting problems, instead, we will use them to form a clear contradiction that we will later resolve).
There is a natural eagerness to turn some knobs and a reluctance to turn others. This tendency limits us in the range of solutions that are possible. Letâ€™s take a closer look at different types of knobs. (See the illustration on the following page). The first type of knob is one that is easily turned. For instance, we could consider getting a larger pile driver. If the piles do not splinter, we could
increase the power of the driver until we are satisfied.
This solution might work if we started with an underpowered driver.
Another type of knob is one that has little effect when we turn it. The pile has many knobs or attributes which have little or no effect on driving speed. For instance, the color or temperature of the pile.
The next type of knob is usually a design feature that we have control over. When we turn this knob to fix our primary problem, something else gets worse. Examples that we have mentioned are the sharpness and diameter. We have design control over these knobs, but another requirement dictates that we not change these knob settings.
The next kind of knob is one that may only come in limited â€œflavorsâ€. Most people would be very reluctant to turn these knobs. Objects may be required to have certain characteristics because of customer requirements or natural circumstances. A good example of this is the ground hardness where we are driving piles.
The last type of knob is the outcome knob. This is the Y for each equation. In effect, we say that in spite of all the Xâ€™s and their settings, the Y will be OK. In the pile driver problem, the Y is the speed of driving. The driving speed must be fast in order to increase productivity and it must be slow, because all the inputs will remain unchanged.
These last three knobs â€œsomething gets worseâ€ â€œone flavorâ€ and â€œoutcomeâ€ are the least likely to be turned, but turning them often allows us to find very satisfying but unconventional solutions. Remember, every knob in our cause-effect chain should be tried. The output of this step is either a solution (if the knob is easily turned) or a contradiction. Going back to our illustration, let us choose one of the knobs, pile sharpness, and insist that the pile must be quite sharp in order to drive faster. Now we form the contradiction:
In order to drive fast, the pile must be sharp. In order to provide adequate support the pile must be
blunt. (Do not worry that this seems impossible. We will overwhelm this contradiction in the next step and resolve it).