In engineering we are faced with contradictions all the time when we are tasked to come up with solutions to solve issues. For example aircraft require to be lightweight to keep fuel consumption to a minimal, improve handling and safety but at the same time to be strong enough to not break apart due to the loads experienced during take off and landing. As you improve one characteristic in a design you will negatively impact another. Take it back to our aircraft example in general lighter materials (ignoring heat treatments, post machining processing, composites etc) are generally weaker. This is where TRIZ comes into play as we can look at innovative ways to have a lightweight but strong design. TRIZ was developed by Genrich Atshuller in 1946 who realised that inventive solutions must be identified when problems have unresolved contradictions (1).
Figure 1 TRIZ Framework
The TRIZ framework has 4 stages: Your Specific problem, TRIZ general problem, TRIZ general solution and your specific solution (Figure 1). In our example we are to develop the mechanical layout of each subsystem for a picosatellite such as a 2p pocketqube which is just going to send a signal back to earth. This satellite will have an active ADCS system with sun sensors, radio and antenna. Our ADCS system will consist of reaction wheels and magnetorquers.
Figure 2 Satlla-2 2P pocketqube satellite (Ariel University) Courtesy of Gunter’s Space Page (2)
Your specific problem
This is the 1st phase of the TRIZ framework where you would identify all your requirements of the design. You can use the Ideal final result tool to define an idealistic solution that would fulfil your needs. You will then identify contradictions that you will need to resolve. In our pocketqube example we need to integrate a number of subsystems within a small volume as a 2P pocketqube has a volume requirement of 114mm x 50mm x 50mm plus they have a max mass limit of 500g (3). We will also have to design a satellite that will meet NASA GEVS. To keep things simple, we will just focus on 2 contradictions which are as follows:
- Must fit multiple systems in a small volume.
- Must be lightweight but strong.
TRIZ General Problem
This stage of the TRIZ methodology we try to identify similar problems that has been faced in the past as we can then use them aid in our search for solving our contradictions for our satellite. Our 1st issue is we need to maximise our volume utlisation to ensure our subsystems can fit inside the satellite body. So what will want to improve is the shape of our subsystem while minimising the volume penalties. The 2nd issue is making a design lighter by using lighter materials can make it weaker. To summarise our TRIZ problem are as follows:
- Improve shape minimise volume penalties.
- Improve mass minimise strength penalties.
TRIZ General Solution
TRIZ has a number of tools that will aid us in solving our contradictions such as the TRIZ matrix which contains the features we want to improve while minimising their negative impacts.
Using the TRIZ matrix (4) is very simple as you set the features you identified in the TRIZ general solution you want to improve and match it against the feature we want to preserve. The matrix will then identify which of the 40 TRIZ principles we should use.
Figure 3 Solving shape and volume contradiction
In this case (Figure 3) we want to improve the shape while preserving volume of stationary which. As we can see the matrix proposes 3 principles to solve our contradiction. These are nested doll, taking out and parameter changes. For our mass issue we get the following principles (5): Copying, cheap short living objects, segmentation, and composite materials. The TRIZ matrix can be found in the following link: http://www.triz40.com/TRIZ_GB.php
Your Specific Solution
Some of these principles won’t be applicable to our solution such as cheap short-living objects because we need to ensure that our systems last till the mission ends. But we could investigate composite materials on the structure to reduce the mass while maintaining it’s strength and rigidity. Also we could use nested doll principle to solve our volume issue. We could create a frame that could integrate our reaction wheels and motors into our magnetorquers by having the electromagnets wrapped outside. We could also have an extending mechanism for our antenna that extends outside the chassis as the satellite is deployed but is stowed inside when the satellite is inside a deployer.
If you are stuck with coming up with design ideas you can also browse the 40 TRIZ principles for inspiration.
1. Mind Tools. TRIZ. [Online] Emerald Works Limited , 2022. [Cited: February 12, 2023.] https://www.mindtools.com/amtcc5f/triz.
2. SATLLA 2A, 2B. Krebs, Gunter D. [Online] Gunter’s Space Page. [Cited: February 12, 2023.] https://space.skyrocket.de/doc_sdat/satlla-2.htm.
3. Radu, S., et al. PocketQube Mechanical Interface Standard. dataverse.nl. [Online] July 30, 2020. https://dataverse.nl/dataset.xhtml?persistentId=doi:10.34894/FOBWZU.
4. TRIZ 40. Solid Creativity. [Online] 2014. [Cited: February 12, 2023.] http://www.triz40.com/TRIZ_GB.php.
5. The 40 TRIZ Principles . Solid Creativity . [Online] 2014. [Cited: February 12, 2023.] http://www.triz40.com/aff_Principles_TRIZ.php.