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  • Author Author: dubbie
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QuadABot #2 : Now With Four Legs (Almost)

dubbie

I have now 3D printed the four shoulder mounts and leg parts (well, 3 legs anyway - somehow I forgot to print the fourth leg) and mounted them altogether. I had overlooked the problem that when the shoulder 3D parts are mounted on the opposite sides that they need to be mirror images rather than being exactly the same. Still, this didn't take long to fix in TinkerCAD as it has a mirror feature and then I just printed two mirror image shoulder parts. The legs do not need a mirror part as they are symmetrical. Below is the fully assembled chassis with four shoulder parts and 4 leg motors but only 3 legs. I'll print out the missing leg soon and then the first version of the assembly will be correct. See video below.

 

 

I have produced an initial programme for the Arduino but it isn't really suitable for controlling the 8 servo motors so I will work on that next. Hopefully in the not too distant future I will have some sort of walking chassis, or at least, some leg movements that look vaguely viable.

 

I have already identified that the flat boy plate needs to be more of a rectangle than a square and is probably too small for the shoulders and legs. My 3D printer can only produce parts slightly larger than the 80 mm original size but it might be enough. Otherwise I might have to try and make the flat body part out of some other material or maybe two or more parts fixed together.

 

Dubbie

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  • Good to see the progress, will be great to see some movement out of it.

     

    Kind regards

  • in reply to three-phase

    Yes, movement will be good. I am thinking of using a lookup table to hold the movements so that I will be able to cycle through the table simultaneously controlling all eight motors. Then I will be able to put the 'gait' into the lookup table and see how different movements work. In my head it sounds easy but I am thinking that getting the optimum values for the lookup table will be tricky. I might need to find some way of visualising the numbers of taking a visual diagram (such as an amended sine wave or similar and then working out the numbers. I can always use an external number for amplification to vary the amplitude of the strides.

     

    Dubbie

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  • in reply to three-phase

    Yes, movement will be good. I am thinking of using a lookup table to hold the movements so that I will be able to cycle through the table simultaneously controlling all eight motors. Then I will be able to put the 'gait' into the lookup table and see how different movements work. In my head it sounds easy but I am thinking that getting the optimum values for the lookup table will be tricky. I might need to find some way of visualising the numbers of taking a visual diagram (such as an amended sine wave or similar and then working out the numbers. I can always use an external number for amplification to vary the amplitude of the strides.

     

    Dubbie

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