Compatibility with Shelves
Now that initial testing of the main radio shuttle systems had been completed, the assembly of the prototype was finalised before testing the compatibility of the model with the shelves already constructed. This initially involved placing the shuttle on to the shelves without any connections to a power supply and performing some common movements that the prototype would have to perform in order to determine how successful the design had been.
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Movement along the length of the shelves by the shuttle both with and without a pallet(s) resting above was undertaken along with the lifting mechanism raised and lowered. Some improvements to the radio shuttle design were required.
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Firstly, when attempting to move the shuttle along the shelves, at one point the wheels on the drive shaft were obstructed by one of the middle shelf supports. It appeared that during the manufacture of the shelves, the width had been altered slightly to the point where the drive wheels were not able to transport the prototype to the end. Our design included enough space between the wheels and the shaft supports to reduce the length of the drive shaft so the wheels would remain on the track along the entire shelf. Therefore, the drive shaft was reduced from 550mm to 530mm and new "cut" sections were created to re-place the wheels. With the shortening of the drive shaft, the radio shuttle was able to move along the entire length of the shelf and with all four wheels positioned on the surface.
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However, we discovered a particular design flaw regarding the stability of the radio shuttle on the shelves. There was no component or system in place to prevent the wheels sliding off the side of the shelf surface should the direction of travel of the prototype not be perfectly straight. If a wheel were to fall off, this would prove catastrophic in a real working warehouse environment.
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The client had provided "tracking wheels" in order to stabilise the radio shuttle horizontally as it drove across the shelf structure. While discussing a solution to implement these wheels, it was discovered that due to the profile of the shelf, fixing the tracking wheels to the shaft supports would prevent any excessive movement horizontally to the point where the wheels would fall off the edge. If the sides of the base plate were removed, this solution would prove fruitful. So, the sides of the base plate were sawed off and a tracking wheel was screwed to each of the four shaft supports. In doing so, the tracking wheels extruded outwards to the underside of the shelf where a strip of metal was present for the wheel to run along and correct the course the shuttle was on. Performing the movement of the prototype again displayed how much more secure the model was now on the shelves with the inclusion of the tracking wheels.
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The only other issue regarding the compatibility of the radio shuttle and the shelves centred around the lifting plates. Despite the linkages being in the "fallen" position, when the radio shuttle attempted to move under a pallet, one lifting plate in particular was catching on the pallet above and even dragging it at times.
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To correct this, initially the problematic plate was filed down at the edge which was catching on the pallet. While this did improve the situation it was not a permanent solution. Alternate material was sourced for the lifting plates which was thinner than previously. After manufacturing the new lifting plates, they were implemented to the prototype and the reduction in thickness did indeed prevent the plates from catching the pallet above.
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However, the client provided aluminium plates to be included as lifting plates instead as they were more aesthetically pleasing and were not as wide as the previous so more of the internal components of the shuttle could be viewed during operation. Although slightly thicker than the lifting plates which were proven to work, when the aluminium plates were fitted minimal contact was observed between the plate and pallet and was deemed acceptable for demonstration purposes.
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