the material is 3mm Sintra as its ability to glue well with epoxy and superglue,
it can be easily cut, drilled and threaded for screw fasteners.
You can easily shape sintra by immersing it in hot water and bending it to your
desired shape while it cools!
Obviously the final design would have been in Aluminum.
I might return to this project sometime in the future as i said before, so maybe ill introduce this idea.
i think i would start with the programming first if anyone was thinking of taking on tilted a coxa robot.
i under estimated the rotation calculations.
yeah the chassis does allow for the servo to be the other way. i ment to put it the other way but while trying to get a picture done i quickly added it.
the servos will look nicely compact when all installed.
Once my extension for my house is done, and i have got other project out the way i will think about sitting down and try to get my head around the programming. once this is done i might think about constructing it. meanwhile ill experiment with construction ideas.
i would like the chassis to be made from aluminum as before but i done have the means to create a professional finish, im looking at 3mm ally. ill try my best.
Yes, that is an interesting chassis! If you can cut this material, then by using even just a “nibbler” tool, you could cut out the aluminum! Bending aluminum isn’t that hard either. Undoubtedly you have a an inexpensive outlet for tools. In the US, it’s Harbor Freight (and various others). I picked up an 18" sheet metal brake for about $50 USD. but you can also just clamp the stock in a vise, or between plates, and use machinist’s clamps to effect your bends. What rough dimensions did you work out? Maybe I’ll mess around with the design a little…
Apart from the dimensions i drew on the chassis its self (to cut it out) i only did one other drawing that i worked from.
please feel free to mess around. would be nice to work with someone on this.
*i think Jim mentioned awhile back that maybe they would one day work on a Lynxmotion Stalker from my design,
so it will also be nice to work out all the pro’s and con’s for him first. *
one other thing i never thought about… when the servos are turned 180º around i have realized that they will hit each other when in motion. maybe making the dimensions bigger will solve this.
Ah! Thats a good point. I like the 80x80 cm top, a close fit for the SSC32/BB2 or even better : ARC-32 board. Do you know how much larger you must make the body for avoiding the coxas to get in a conflict?
It would be fun to try a new and alot smaller quad one time, but I’ve other future plans/projects in my priority list…
yes the 80x80 (mm) top fit the boards nicely.
looking at my original chassis design (that will allow for the servos to be this way) i would say we would need to have the bottom base at 50mm making the top 96mm. ill draw another one up. maybe later this week.
That gives me a pretty good idea of the dimensions. It would make an interesting build. Even if I couldn’t get it walking! I’ve got the metal part down-pat anyway.
The angle of the “legs” must be about 45 deg. to the body?
I’m currently trying to port a servo control program for the Micromouse I posted on. Continuous rotation R/C servo motors. Wheel encoders for feedback. but that’s a different thread.
The original stalker was very exciting to build that’s mainly why i wish to revisit it. it was very interesting and fun to do. i had loads of support from you guys and that made it great to work on.
im sorry with having time away from here i have missed so much. i see there is a new quad about and 4x4hex and loads more. i must catch up. send me your link for your thread. sounds interesting.
just digging for info here,
iv been thinking about how we should have calculated the tilted coxa.
when using body tilt X/Z “on a normal hexapod” (lets say towards the middle right leg) the coxa is tilted down towards the ground. The leg being leaned against “middle right leg” calculates for this and kinda creating the calculations i was looking for in the project, by arcing its movement.
REF: V1.3 code
Is it possible to take this calculation and implement it into the code for all the legs, so that you can “trick” the robot into thinking all sides are being leaned against at the same time, making all the legs compensate for the “tilt” at the same time…?
when using body tilt X/Z “on a normal hexapod” (lets say towards the middle right leg) the coxa is tilted down towards the ground. shown by the Green line
its then possible to walk like this, so there for it must be calculating the tilt and must be making the tars arc. http://i531.photobucket.com/albums/dd355/innerbreed/Capture1.jpg
No offense but I believe we talked about this in the Stalker thread…
The way the stalker are designed the tilted coxa makes the IK a bit more complicated than just adding an offset angle. Simply because the coxa are tilted in two directions at the same time (both along the X and Z axis, pan and tilt).
Touching old ground here:
Presently im discussing the Stalker chassis with Eric (DialFonZo). he has come up with a very cool, and interesting design for the project.
Iv been looking back over some of the discussions we had about the complex tilted coxa, and since all axis are affected when doing coxa rotations 'and to solve the kinematics we would need to convert all (X,Y,Z) feet coordinates from the original Phoenix code, using a simplified rotation matrix for IKFeetPosX, IKFeetPosY and IKFeetPosZ.
im still working this out on a practical basis and then hopefully develop a snippet to add to the code.
but for now im working on fabricating the external look of the stalker etc. this will come in the main thread.
You could take a little look at the Archer (Phoenix based) code I posted (look for the RotateLeg sub). You can solve it in a similar way by changing the matrix for the two rotations you’ll need to do.
I thought Archer was Arc32 Based. i have plans to use the Arc32 but funding is nil due to unforeseen circumstance. currently im testing ideas with the Atom Pro28. maybe talk more on this in the morning. 00.41am here. :tired: lol im still yet to look at your Archer code. something iv been meaning to do but not got round to it. do you have a link for quicker access.
Do you know how much larger you must make the body for avoiding the coxas to get in a conflict?
