By Michael S. Slocum

Ideality, an important tool within the Theory of Inventive Problem Solving (TRIZ)is a philosophical construct that can be used to identify the perfect resolution of the problem solving process. It also can include a role in developing future generations of existing products and services. Ideality is the summation of useful functions divided by harmful functions in a system. A problem solver’s objective is to increase the useful functions (numerator) at a rate greater than any consequential increase in the harmful functions (denominator) – this forces a system’s evolution that also increases a system’s ideality.

It is possible that a small, localized reduction in ideality could still be part of a multi-generational product plan (MGPP) in which the total system continues to approach an ideal final result. Additional functionality can create some initial complexity with, for example, the introduction of control systems or micro-electronics; holistic system dynamics should be analyzed during the development of product or service generational planning.

Ideality Objectives

It is key to remember the objectives of developing the ideality for an existing system:

1. Removes original disadvantage(s)
2. Preserves original advantage(s)
3. Does not introduce new disadvantage(s)
4. Minimizes (any) increase(s) in complexity

These objectives may be suspended for a particular generation, but not for the system model in its entirety over the total life cycle.

Case Study: Solar Panel Deployment

Satellite systems are deployed to low-Earth orbits as a payload (what the space shuttle or rocket [launch vehicle] carries to put in orbit) in the nose cone of a launch vehicle or in the cargo bay of a space shuttle. Whatever the system of deployment, a satellite’s external envelope (the outside volume of the satellite) has to match the available volume of the carrier system. One feature of satellites that violates this requirement is the deployed span of the solar panel system. To counter this, the solar panels are designed for a pre-deployment launch configuration to meet payload volume specifications.

Failure Potential

After the satellite is put into orbit, the solar panels need to be deployed to their operational configuration in order to perform their main function: convert solar energy into electrical energy. The existing system uses a design that allows one large panel to separate and fold in order to reduce the satellite’s launch configuration volume. The panel is stored with a pre-loaded tension that allows for full-panel deployment when the panel end is released from a catch mechanism. After deployment, a small explosive device (squib) located at the catch is detonated; the catch is destroyed and the panel end is released. This system is mostly reliable; however, there is the potential for failure in three key ways (harmful functions):

B1: Squib does not detonate
B2: Squib does not destroy catch and panel end is not released
B3: Squib detonation damages the solar panel

Customer Requirements

The squib is the common element in the modes of failure (B1-B3). An ideality objective – eliminate harmful function(s) to identify a future need state of this system – helps identify the following customer requirements (CR):

CR1: Squib detonates when desired
CR2: The catch is destroyed by the squib allowing panel release
CR3: Squib detonation does not cause solar panel damage

Non-optimized Ideality

The creation of a design concept to satisfy CR1-CR3 would be an improvement and can be considered a legitimate member of the system’s MGPP. Analysis of the squib as a component in the system design, however, reveals a local non-optimization of its ideality, shown in the following useful functions (F_u):

A1: Hold panel in launch configuration
A2: Allow panel release to deployed configuration after orbit insertion

A simple analysis shows that it would be ideal to eliminate the use of the squib in the system. The problem is:

• We want to eliminate the squib so that failure modes (and harmful functions) B1-B3 are eliminated; however,
• We need to preserve useful functions A1 and A2 in the system.

There are two options for this useful function conservation:

1. Transfer useful functions A1 and A2 to a remaining element in the system or
2. Introduce a new element to the system that can provide useful functions A1 and A2 (or a competing function that accomplishes the goals).

Redesign Options

There are now three concept descriptions for the solar panel release MGPP:

Option 1: Optimize the performance of the current design enhancing the reliability of the squib system. This could include:

1. Optimization of squib detonation performance.
2. Redesign of the catch mechanism that will ensure release on squib detonation.
3. Redesign of squib housing and/or the panel housing to preclude panel damage during detonation.

Option 2: Eliminate the squib and transfer the useful functions (hold panel in launch configuration and allow panel release to deployed configuration after orbit insertion) to another element in the system.

Option 3: Create a new concept to deliver the useful functions that does not leverage an existing element in the system.

All three options could (and probably should) be addressed. This helps to produce a comprehensive MGPP. Each approach can be protected from the intellectual property perspective as required.

The resolution of Option 1 would yield a system much like the current, with a lower frequency of failure for the observed modes. The resolution of Option 2 may yield additional system complexity, where another element in the system has its useful functionality increased with the addition of A1 and A2. Options 1 and 2 provide opportunities for incremental improvement; from a tactical perspective this is important. Resolving Option 3, however, may create a discontinuous response to the problem and allow a large increase in system ideality. From a strategic perspective, this approach is the most interesting.

Option 3 Explored

A simplified substance-field model of the existing squib release system will yield:

Trigger—(F_electrical)—Squib—(F_mechanical)—Catch—(F_{mechanical: hold/release/damage})—Panel end

(Note: The “mechanical: hold and release” interactions between the catch and the panel are useful; the “mechanical: damage” interaction between the catch and the panel is harmful. The catch, therefore, is a bi-polarity that makes it a physical contradiction. The same is true of the squib. These two physical contradictions also yield several technical contradictions.)

The development of a competing system for the squib would allow for the elimination of the trigger, the squib, the intermittent activation of the squib by the trigger and damage caused to the panel by the squib or the catch:

Trigger—(F_electrical)—Squib—(F_mechanical)—Catch—(F_{mechanical: hold/release/damage})—Panel end

The simplified system looks like:

Catch—(F_{mechanical: hold/release})—Panel end

The catch will need an initiating signal in order for the release to be as needed. An unknown element, S_x, represents an element in the system that needs to be introduced; this results in field, F_x:

S_x—(F_x)—Catch—(F_{mechanical: hold/release})—Panel end

By introducing S_x and Fx, the ideality Objectives 1-4 need to be achieved.

Other Possible Modifications

In theory, the catch material is also subject to change. Consider the system by substituting C_x in place of the catch, where C_x is a catch manufactured from a possible alternative material. F_mechanical also needs to be substituted, as it is not known what type of force C_x will introduce to the system:

S_x—(F_x)—C_x—(F_{x: hold/release})—Panel end

Delving further into TRIZ, other opportunities to modify the existing system arise. For example, combine system using the mono-bi-poly pattern of evolution. This pattern states that functions in a system are integrated over time yielding composite multi-function systems. In this example, S_x and C_x could be integrated into a single ideal element that would provide the useful function(s) of S_x and C_x – a heterogeneous bi-system, SC_x:

SC_x—(F_{x: hold/release})—Panel end

The Ideal State

The simple substance-field model has been manipulated to identify an ideal state based on Option 3. The next step is to investigate and research to identify candidates for SC_x. In this case, the functions that this element must perform are:

A3: Hold panel in closed position
A4: Release panel as required
A5: Cause no damage to the panel
A6: Perform reliably

Ideality constraints are also integrated:

A7: Introduce no new disadvantages
A8: Minimal increase in system complexity (if any)

The ideality of the system needs to increase with the identification and implementation of SC_x. Alternatively, a local ideality increase in the system is permissible if, over time, the system evolves according to the increase in ideality law.

To increase the ideality of the solar panel, a shape memory alloy (SMA) could serve as an alternative catch material. The SMA has the following impact on the identified characteristics SC_x must possess:

A3: Hold panel in closed position – a catch can be formed from a SMA, whose geometry will hold the panel in the closed position
A4: Release panel as required – the SMA can be heated by the introduction of a current, which will cause the SMA geometry to return to a “memory” position, thereby releasing the panel
A5: Cause no damage to the panel – the SMA geometry changes are due to heat changes over time and do not release energy or particulates
A6: Perform reliably – the SMA temperature response is guaranteed

Ideality constraints are also integrated:

A7: Introduce no new disadvantages – no new disadvantages are introduced
A8: Minimal increase in system complexity (if any) – the current introduction system for the SMA is no more complex than the trigger in the existing system; machining the SMA is no more complex than machining the existing catch material

Therefore, the introduction of the SMA as SC_x is ideal and provides a significant discontinuous improvement to the system:

Trigger—(F_{thermoelectrical})—SMA catch—(F_{mechanical: hold/release})—Panel end

Compare this system to the initial system, in which the squib performed intermittently:

Trigger—(F_electrical)—Squib—(F_mechanical)—Catch—(F_{mechanical: hold/release/damage})—Panel end

Conclusion

This system has proven extremely reliable since its introduction and is a considerable advancement for solar panel deployment systems.

Ideality is a powerful driver for next generation system evolution. All tactical and strategic implications of this technique should be considered when developing new products, processes and services.

About the Author:

Michael S. Slocum, Ph.D., is the principal and chief executive officer of The Inventioneering Company. Contact Michael S. Slocum at michael (at) inventioneeringco.com or visit http://www.inventioneeringco.com.