UNO In the Making

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UNO In the Making



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As we concluded our last blog with the “under construction” of the tail, and left without revealing our final concept that would allow us to make a fluid motion in order to mimic the tail and successfully integrate it… It is time to reveal what we have been working on.

After much discussion and brainstorming, we initially redesigned our tail to use pneumatics. What this means is the tendons (joins/hinges) in the tail would be controlled by air pressure being generated by a pump that would flow threw a number of pipes and into hydraulic cylinders that would contract or extend the section of the tail. As we prototype it out of technics-Lego we found that this system worked really well. It solved a number of problems that were raised in the previous prototypes such as:

How would we retain tension while the x-axis and y-axis were moving around in order to contract or extend exactly when required? As the pipes can bend and move around, and still pump air regardless of their positioning, this was an optimal solution for the mobility of the arm.

As this was one of our major issues, we unanimously decided this was by far the best option at the time to allow us to further develop our tail.

  • 13th October 2014
  • Phase 3 - Week 4
  • Team Discovery Channel
single project Info
single project Info

However as we began further testing with this new method and once the prototype was built we were still somewhat unhappy with a number of aspects of the tail. Firstly, the pipes would have to be neatly stored within the tail and long enough that they would reach inside the monkey where the housing and extra components such as the pump and control servos would be located. Secondly, as the technics-Lego was optimal for an easy build and fluid motions of the tail and its lightweight, the issue was its strength. Once tested with the 3D pen now at around and potentially over 30cm away from the base hinge, although holding up fine which was a big positive, the plastic support beams were straining under the weight however, which caused the fluidity of the joints to become compromised. This was unacceptable for our overly high standards and we decided to rethink our support material.

Prior to this however we began discussing the issues that arose with using pneumatics. Firstly, how would we control the flow of air through the pumps was our biggest concern. We had already established that one of our 31kg/cm servos would be used to move back and forth to push the air down the spring pump as seen in the pictures. (Replicating some type of generator). However, too much pressure and the pipes would cause them to come unhinged from the hydraulics, and too little would cause the tail motion to be unresponsive to a users immediate input. We decided that we needed an air pressure sensor or air regulator that would connect directly to the Arduino board and regulate the air pressure, directly affecting the servo connected to the pump. The components were available but we were unsure about the PSI being produced in our pumps in relation to what the sensors could incorporate, and so we began researching this.

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single project Info

During our research phase, we all kicked ourselves for being somewhat idiotic when we realized that the pneumatic system we were attempting to create could easily be accomplished by using mini linear actuators directly linked up to Arduino, solving the pump, generator, pipes and regulator issues, as well as the amount of extra coding that would be required to time all of this accurately! Although we are still unsure of the exact mini linear actuators we will require (considering that some are around $90 each) we were still relieved as this allowed us to focus on the structure of the tail once again and not have to worry about the complexity exponentially increasing on us once again.

As we were certain the technics-Lego approach was the most appropriate at the time we searched for a more sturdy material and located the same parts made out of aluminum. This would be ideal for our project as they would not bend and cause the tail to warp and lose fluidity within the joints.

single project Info
single project Info

Finally we had to consider how we would connect the actuators to the support structure in order to cause the hinge to move fluidly (as seen as elastics in the previous images). Using mini springs on either side of the bars and connected into the holes will allow for the bend but also maintain the stability required and produce the correct movement… and so we are now awaiting all of our new components to arrive before putting it all together and testing it…

In the mean time, we are preparing our model for 3D printing and laser-cutting as all our dimensions are finally to scale, we know all of our housing sizes and all that’s left is to test the new 3D filament that is multi-colored, and in a roll rather than individual sections. As well as the tail with the new components and keep iterating until we are satisfied or run out of time for the assignment.

… You know we will be back with more crazy stuff…