Poke Yoke (also known as mistake-proofing) is a Japanese method (1) in avoiding human errors in the design, manufacturing, assembly or usage of equipment. The main goal is to avoid these errors from occurring in the first place by implementing features or systems. These errors can result in costly rework, time delays due to having to disassemble and reassemble components, damage to products.

There are many different examples of Poke Yoke used in our everyday life for example power cables in PCs ensure the cable is in the correct orientation. Sensors in petrol pumps to prevent petrol or diesel to be sprayed when not plugged into the filling nozzle of the tank. Another automotive example is the nozzles for petrol and diesel pumps are different therefore the user can’t accidently add the wrong fuel to their car. 

Figure 1Cubesat with Poke Yoke hole placements

In our example of poke yoke we want to ensure our optical module is in the correct orientation (Figure 1) of our cubesat. If our laser module was mounted incorrectly, we could face mission failure as the payload within our module will be unable to perform properly. To avoid this, we have one of our tapped holes outside of the hole array therefore it can only be mounted in one orientation.

Figure 2 Bolts with different lengths 10mm, 8mm & 6mm

Figure 3 Bolts with same lengths

Another Poke Yoke example is replacing different lengths of bolts to assemble multiple components (Figure 2) with the same length (Figure 3) as this will prevent the likelihood for using the incorrect bolts which will lead to a delay in the assembly of multiple components. Another benefit in uniform bolt lengths is a smaller Bill of Materials (BOM) which can reduce costs as you can just have a larger order of a single bolt.

When it comes to implementing Poke Yoke in your design you want to make the mistake easy to detect and eliminate from happening in the first place. This is especially important for your space mission as satellites are complex mechatronic projects therefore it will be inevitable for mistakes to happen. In fact, there have been multiple missions fail due to human made errors. Poke Yoke can aid designers in “Keeping It Simple Stupid” as the examples highlighted earlier are simple fixes.  

Poke Yoke can help improve the efficiency of assembly and help reduce cost. A design with good Poke Yoke principles can make a design intuitive that requires little to no training for it to be used, manufacture or assemble which can improve the accessibility of your product.

The earlier Poke Yoke is adopted in a design the better as it can help eliminate issues caused by human error. Like a lot of other engineering management tooling mentioned in earlier posts Poke Yoke can be used alongside FMEA.

References

1. Poka-Yoke Explained. Reliable PLant. [Online] [Cited: July 31, 2023.] https://www.reliableplant.com/poka-yoke-31862.