# The Seventy-six Standard Solutions, with Examples Class 4

John Terninko, john@terninko.com
Ellen Domb, ellendomb@compuserve.com
Joe Miller, jam@mcs.net

The “76 Standard Solutions” of TRIZ were compiled by G.S. Altshuller and his associates between 1975 and1985.  They are grouped into 5 large categories or classes as follows:

 1.     Improving the system with no or little change 13 standard solutions 2.     Improving the system by changing the system 23 standard solutions 3.     Transition to super-system or micro-level 6 standard solutions 4.     Detection and measurement 17 standard solutions 5.     Methods for simplification and improvement of the other standard solutions 17 standard solutions Total: 76 standard solutions

(References 1-5)

This series of articles began in the February 2000, issue of the TRIZ Journal, with a tutorial article and the Class 1 problems and solutions.  Class 2 appeared in the March, 2000, TRIZ Journal, and Class 3 appeared in May.  Class 3 is used if Classes 1, 2 or 4 were not quite adequate.  By raising the problem to the super-system or looking at micro-level changes new opportunities are created.  The references are all in the Class 1 article.

Typically, the 76 standard solutions are used as a step in ARIZ, after the Su-field model has been developed and any constraints on the solution have been identified.   The model and the constraints are used to identify the class and the specific solution.  It is useful to view the Su-field model as the zone of interest as used in ARIZ.  As in other TRIZ instructional material, examples are used to show the application of the standard solution to a wide variety of problems from many fields.

Class 4.  Detecting and Measuring.  Detection and measurement are typically for control. Detection is binary (something either happens or doesn’t happen) and measurement has some level of quantification and precision.  For example, a length measurement might be 3.24m +/-.02m.   In many cases the most innovative solution is automatic control without detection/measurement by taking advantage of physical, chemical, or geometrical effects.

4.1. Indirect Methods

4.1.1. Modify the system instead of detecting or measuring so there is no longer a need for measurement.

Examples:

Music boxes incorporate a spinning governor whose speed is limited by air resistance to control the speed of the rotor and timing of the tune.    There is no need to measure the speed, since the governor automatically adjusts to the right speed.

Gas transfer systems are sometimes required to deliver precisely metered amounts.  Rather than measuring the amount, a critical orifice may be incorporated which limits flow to an acceptable maximum regardless of driving pressure.

Self regulation of heating systems is possible by using a switch activated by a

thermocouple or a bimetallic strip.

Colors in gel coats on fiberglass boats, and in master patterns for molds:  Coloring agents are added to the sucessive coats of paint, so that as the finish is sanded to refine the shape of the object, the various layers are readily visible and serve to prevent the localized removal of excess material without the need for a mechanical measurement.

4.1.2. Measure a copy or an image, if 4.1.1 can’t be used.

Examples:

A comparator is a device to magnify and precisely measure the projected image (shadow) of items normally difficult to measure such as soft products, or item with very irregular surfaces.

Populations of military personnel and equipment, and populations of waterfowl (geese and/or ducks) are measured by counting from magnified aerial or satellite photographs.

To determine the minimum but sufficient amount of fertilizer to be applied in each specific location of a farm field, satellite scanned images of the crop’s growth patterns are used as a control reference.

4.1.3. Use 2 detections instead of continuous measurement, if 4.1.1 or 4.1.2 cannot be used.   For example, make a ring having the outer tolerance limits of a machined part, and a solid having its diameter equal to the inner tolerance limit.   The part is the right diameter when it fits through the ring (one detection) and the solid fits through it (second detection.)

Examples:

The true diameter of a flexible object must sometimes be known and matched for purposes of assembly.  The minimum axis and maximum axis dimensions can be consecutively detected (without distorting the object) and used to calculate the true diameter.

Dyed or printed items may be required to match established color standards under a variety of ambient light conditions.  Consecutive comparisons of the test item to the standard under two or more light sources of known frequency is a common way to assure the best overall match.  These simple detections are far easier for someone who is not expert in color matching.

4.2. Create or synthesize a measurement system.  Some elements or fields must be added to the existing system

4.2.1. If an incomplete Su-field system cannot be detected or measured, a single or double Su-field system with a field as an output is created.  If the existing field is inadequate, change or enhance the field without interfering with the original system.  The new or enhanced field should have an easily detectable parameter that correlates to the parameter we need to know.

Examples:

The presence and size of very small holes in plastic items may be difficult to detect.  If the item is filled with air and sealed, it may then be immersed in a liquid bath under a reduced pressure (vacuum).  The presence of air bubbles in the liquid can reveal the existence and size of leaks.

Where S1 is item air leak, S2 is test liquidS2’ is bubble, F1 is reduced pressure and F2 is visual field of light reflecting  presence of air bubbles indicating leak.  S1 is an incomplete Su-field.  Both S2 and F1 (liquid and pressure difference) have to be added to make a complete system, then F2 has to be added to enhance the performance of the system.

Plastic food storage bags are now produced with a “zipper” type seal.  Food is placed inside and the air is expelled before sealing the “zipper”.  It is difficult to know if the zipper is closed, since there is little air left inside upon which pressure could be exerted.  If the “zipper” sections are produced of two different colors,(e.g. blue and yellow) they will combine to produce a different (e.g. green) color (optical field) when properly mated.

Thoracic sounds (heart and respiratory sounds) do not have a volume and level of resolution adequate for diagnosis if heard with only the human ear.  A stethoscope produces an amplified mechanical field (acoustic pressure waves) which can easily be detected by the human ear.

4.2.2. Measure an introduced additive.  Introduce an additive, that reacts to a change in the original system, then measure the changes in the additive.

Examples:

Biological Samples (Cells, bacteria, animal or plant tissue) can be examined under a microscopic, but details are difficult to distinguish and measure.  Adding a chemical staining agent to the specimen allows its structural detail to be seen and measured.

Where S1 is specimen, S2 is microscope, F1 is light, F2 is light out, S3 is stain, F2‘ is  augmented light out of microscope.

Barium is introduced into the intestine before an x-ray exam.  The barium coats the interior surface, then the x-rays measure the density and position of the barium.

Radioactive iodine is concentrated in the thyroid, then measurements of locally emitted radiation show how well or poorly the thyroid is processing the iodine, thus indicating the state of the thyroid.

Subtle changes in the shape of aircraft and automobile surfaces can have a significant effect on the aerodynamic drag and hence performance.  If it is desired to observe and measure these effects, smoke can be introduced into a wind tunnel where the object is being tested.

4.2.3. If nothing can be added to the system, then detect or measure the system’s effect on a field created by additive(s) placed in the external environment.

Example:

A person wishes to know her exact location even when remote from any landmarks, roads or signposts.  The Global Positioning System of satellites provides continuous signals (the field) covering the entire surface of the earth..   The person can detect both absolute position and change in position (velocity) using a simple, hand-held, GPS receiver.  She is measuring her position relative to the satellites (additives, when viewed from the point of view of the earth) in order to determine her position on earth.

Where S1 is the position, S2 is the person, F1 is information, F2 are distances to at least three satellites

4.2.4. If additives cannot be introduced into the environment of the system as in 4.2.3, then create them by decomposing or changing the state of something that is already in the environment, and measure the effect of the system on these created additives.

Examples:

Bubble / cloud chambers can be used to study the properties of sub-atomic particles resulting from bombardment collisions:

In bubble chambers liquid hydrogen  is kept just below the boiling point of temperature and pressure.  Energetic particles passing through cause local boiling, forming a path of bubbles that are photographed to study the particle dynamics.

In cloud chambers a saturated alcohol vapor is maintained in a chamber.  When particles pass through, they ionize the vapor, forming a string of nucleation sites where droplets condense.  The droplets are photographed to visualize the path of the particles.

4.3. Enhancing the measurement system

4.3.1. Apply natural phenomena.  Use scientific effects that are known to occur in the system, and determine the state of the system by observing changes in the effects.

Examples:

The temperature of conductive liquid can be determined from changes in electrical conductivity.

The Hall effect (the voltage across a semiconductor depends on a magnetic field vertical to it) is used to measure and provide control for the speed of precision variable speed electric motors.  The Hall emf is the potential difference created by a magnetic field across a plate carrying electric current.  Devices used to measurement force, tension, power of an electric current, and harmonic analyzers us the Hall effect.

Mass spectroscopy is achieved by controlling the magnetic fields through which particles are accelerated.  The path of the particle also depends on its ionization state.  These allow measurement of the test particle’s mass by calculation from the trajectory.

4.3.2. If changes in a system cannot be determined directly or by passing a field, measure the excited resonant frequency of the system or an element in order to measure changes..

Examples:

Finite Element Analysis:  Usually done by simulation.  A range of frequencies of mechanical force is applied to the object at a variety of locations.  The stresses created are calculated at many locations throughout the object to evaluate the need for design changes.

Tuning a piano  with a tuning fork, that excites the strings and the entire system and allows the appropriate frequency to be matched by adjusting tension.

4.3.3. If 4.3.2 is not possible, measure the resonant frequency of the object joined to another of known properties.

Examples:

Instead of directly measuring capacitance, insert the object of unknown capacitance into a circuit of known inductance, then vary the frequency of the applied voltage to find the resonant frequency of the combined circuit, then calculate the capacitance of the added object.

4.4.  Measure Fe-field:  The introduction of ferromagnetic materials for measurement  was popular before the development of remote sensing, miniature devices, fiber optics, microprocessors, etc.

4.4.1. Add or make use of a ferromagnetic substance and a magnetic field in a system (by means of permanent magnets or loops of electric current) to facilitate measurement.

Examples:

Traffic control is routinely accomplished with traffic lights to stop vehicles.  If it is desired to know when a vehicle is waiting to proceed, or to know how long a queue of vehicles stretches, conductors in loops buried under the pavement in key locations can easily detect vehicles (containing ferromagnetic components).

4.4.2. Add magnetic particles to a system or change a substance to ferromagnetic particles to facilitate measurement by detection of the resulting magnetic field.

Example:

Ferromagnetic particles are incorporated into certain inks used on currency to aid verification of authenticity.

4.4.3. If ferromagnetic particles cannot be added directly to the system or a substance cannot be replaced with ferromagnetic particles, construct a complex system, by putting ferromagnetic additives into the substance.

A classical Soviet example of this method is:

Liquid acting under pressure brings about hydro-explosions of rock layers.  For controlling the liquid, ferro-magnetic powder is introduced into it.  (S U Author’s Certificate # 754347).

4.4.4. Add ferromagnetic particles to the environment, if they cannot be added to the system.

A classical Soviet example of this method is:

Waves arise when moving a model of a ship through  the water.  In order to study the characteristics of wave formation, ferro-magnetic particles are added to the water.

4.4.5. Measure the effects of natural phenomena associated with magnetism such as the Curie point, hysteresis, quenching of superconductivity, the Hall effect, etc.

Example:

See 2.4.7 for Magnetic Resonance Imaging example

4.5. Direction of Evolution of the Measuring Systems

4.5.1. Transition to bi- and poly-systems. If a single measurement system does not give sufficient accuracy, use two or more measuring systems, or make multiple measurements.

Example:

To measure vision, the optometrist uses a series of instruments to measure overall ability to focus at a distance, ability to focus close up, and consistency of focus across the entire retina compared to focus just at the center.

4.5.2. Instead of a direct measurement of a phenomenon, measure the first and second derivatives in time or in space.  For example, measure velocity and acceleration instead of measuring position.  Measure the rate of frequency change of a sound (Doppler shift) to determine the velocity of the source.

Examples:

Ground-based radar systems for aircraft position and velocity measurement use both direct radar reflection and changes in the radar frequency (measures position, velocity, and acceleration) to calculate an accurate position and velocity for each aircraft.

The “Red Shift” of light from retreating galaxies is used in estimates of acceleration and thus of distance.

## Note of Gratitude

Our thanks go to Zinovy Royzen for sharing his method of Su-field modeling called TOP modeling.  See  “Tool, Object, Product (TOP) Function Analysis” in the September, 1999, issue of The TRIZ Journal, http://www.triz-journal.com.