Hi. I am a new enough to robots, I have some knowledge but still building on it. I want to build a hexapod for my Final year project. I have the main components of it drawn up at the moment on solidworks. I now need to start ordering parts. Can you suggest what servos I should use? I was looking at the 645MG and they seem pretty good, would they be fast enough for me? Or do I need better ones?
Also how easy or hard is it to actually get the hexapod walking once assembled? The inverse kinematics code is scaring me!!!
Please help.
Hi mark. might need a bit more info on your hexapod first before these questions can be answered.
the servos you use depend on what Size servo will fit. standard size? secondly the 645s are pretty good all round for a hexapod but again it depends on the weight of the robot.
this says to me you have used the lynxmotion 3d ses components to make your hexapod rather than custom?
if so that answers the first two.
…the 645s would be ok.
getting the hexapod to walk can be as hard or as easy as you like. here you will find lots of hexapod codes that are already to be uploaded to your hex. all you will need to do is change some of the parameters in the code like leg measurements and body measurements… but again this depends on what you are controlling it with. what electronics do you plan on using? lynxmotion botboard, SSC, other?
It is a custom design, I am drawing all the parts from scratch, I never new lynxmotion had 3d ses components on their website until you said it. (those might come in handy now to compare sizes). I will say I have been influenced by designs from others so I will have to give those credit for that. I should have it fully drawn in the next day or two so from SolidWorks I should get a fair estimate of the weight.
I plan on controlling it with a PSP2 controller. The electronics I was hoping to use was the Basic Atom Pro 28, Bot Board II
BASIC Atom Pro 28 and a SSC-32 Servo Controller. I presume this is a good combination as many other hexapods have these components?
The servos and the battery, im still unsure about, ya those Hitec 645MG seem good but many others seem to have a variety of servos in their hexapods, what should I do? should i put these on all around? (18 in total)
Note: These CAD files are provided to aid in building virtual models of robotic
assemblies only. We are not giving permission to anyone to manufacture these components for commercial sale or personal
use. Lynxmotion will make available to anyone who asks the drawings required to make 3D files as long as Lynxmotion, Inc. is
the sole source for distribution of these files.
great, you should have it up and running in no time. here is xans phoenix code if you needed to look over it.
this is version 1.3 lynxmotion.com/images/files/phoen1.3.bas (Note: Requires BASIC Atom Pro IDE v8.0.1.8)
To size the R/C servos, you need to work out the lengths of the leg components, and the overall weight of the 'bot. Compare these lengths and wait to that of the CH3 or maybe the Phoenix, as appropriate. this should give you a rough idea what servos might work. The battery would then be sized to the type and number of servos.
You might also be able to calculate the load on each leg, and the leverage. This would tell you the static torque needed per servo. Coxa servos don’t need to support as much. Tibia and Femur servos get the brunt of the load. The angles that the servos work through (sprawl) also plays into the torque computations.
Sorry about the break, thought i would have this up sooner but it was a long Christmas.
I have my hexapod designed (I won’t take all the credit as I have looked at many others and used ideas and designs from those) I drew it up and assembled it using SolidWorks.
Now I really need to get odrering parts, I know all the electronics I need but i’m having trouble working out the torque of the servos required. The mass of the Hexapod at the moment (structure and servos) is 1.3kg the batteries and pcb’s have not been added yet as I don’t know the weight but I’m guessing when finished it should be 1.5kg approx.
I was going to use the Bot board2, Basic atom pro 28pin and ssc-32 servo controller. What software is required to programme these and is it free?
I have attached some pictures so you can see the design and some measurements of the legs. I know torque is T= Force x distance but how do I work it out for the hexapod legs?
You have the lengths of the lever arms. Start by diving the total weight of the 'bot by the six legs. Then you have the load on each leg. It is actually slightly different then that, as the lower servos and tibia aren’t supported by the femur and coxa servos.
I’d work at maximum “sprawl” expected, that’s when the angles of the lever arms are probably at their longest.
Thanks Alan thats a grt help.
So if I have .260kg per leg multiplied by gravity 9.81 this will give me a force of 2.616Nm.
Now i need to multiply this be the length as shown in the picture below, so 2.616X.169=.4421kg.m
Is this correct? Have I picked the correct length as shown below?
Sorry for all the questions.
