Servo motion on a RC Hexapod

dennis_de_klerk

Dear Forum members,

I've been playing around with some simple design for a hexapod running on RC Servos. Mostly for fun really:

https://cad.onshape.com/documents/e413edfc2804c36add2b292e/w/b22de048f1c050ba8fd35be2/e/a0b1ad59bab922216a05a056

I've made an assembly with all of the parts and I can move the table in all directions and the servo horns move accordingly. So far so good and pretty awesome to see!

Now I want to built the pod and program my RC radio to actually control the motion. The one for free is the motion in Z-direction, all servos have to move the same amount basically, so simple.

However, the motions in other directions are a lot more difficult. 

I'm wondering if you have an idea to get the angle (of the horn) v.s. motion in X,Y & rotations of the table out of the assembly? My guess would be to try and measure the angles for each delta motion of the table, but perhaps there are easier / less time consuming options?

Thanks!

tom_scarince

Good exercise to get my brain started on a Monday morning.  If this were a 3d printer or industrial robot I'd say you ought to write and solve the equations. Since this is intended for manual joystick input I think a rough approximation will be perfectly fine. 

Draw a table with the a row for each motion input (roll, pitch, yaw, heave, sway & surge) and a column for each of the six servos. For each motion imagine which direction the servo needs to go and write them all out.  Program your mixer accordingly.  For multiple simultaneous motions the outputs for each servo just get added together.  Keep your gain low to start with. 

billy2

@dennis_de_klerk nice model, if you build it, take a video and share how you control it.