Yesterday, we added actuators B and C, as well as an optimised intermediary aluminium profile to solve the problem of the secondary arm not being able to rotate sufficiently downwards to pick up/release the pneumatic unit.
We thought that we should maximise the rotation of the intermediary aluminium profile to maximise the angle of rotation of the secondary arm, but Tony said that we should preserve a minimum angle of 15 degrees for safety reasons. This is because the smaller the angle between actuator B and the intermediary profile (i.e. they become more parallel), the large the force actuator B needs to exert onto the intermediary profile to hold it in place. With actuator C and the secondary arm + the pneumatic unit attached, this force will easily multiply and the whole system will become extremely unstable.
Thus, our revised design looks like this, where the angle between actuator B and the intermediary profile is about 15-20 degrees in this photo when actuator B is fully extended. We have also cut the secondary arm to the desired length, so that it will no longer collide into actuator C/the intermediary profile.
Then, we proceeded to test if the desired height of 3m could be reached, with a video of us using a measuring tape to ascertain the height of 3m. Success!
However, we still found that this was not enough for the secondary arm to pick the unit from the ground and bring it to a height of 3m. The angle of rotation was still somewhat limited.
This video shows the motion from the 3m height to this lowest possible height.
Thus, we will have to modify the double-actuator configuration to include a Bell Crank to further extend the range of angles available for the whole arm. However, it was getting late, and we decided to continue this another day.
Here are cool timelapses of us working on all of this:
Also, we have added several reinforcements to the arm. An example is this:
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Its location can be seen here:
Lastly ,we realigned the pillow blocks as they were not exactly aligned (just slightly off). This was necessary to ensure that the secondary arm would be horizontally balanced.
This is how they should be aligned.
We had to hammer the aluminium rod into the pillow block to align them.
The end product looks like this: