Question about controlling 9 motors

[Quazar]

Originally Posted by jgraber

For using two (or more) PICS, you can connect serial ports.

If you want to do this, here is a diagram for the needed cables.

Cheers,
- Dean

[Ali]

Thank you everyone for all your help.

I was afraid you were a middle-schooler in way over your head, but it looks like you are well on your way, and new we have a much better idea of your capabilities. Is this for a senior project or something?

Yes it’s my university’s final year project. My team mate is working on software simulation and I’m working on hardware.

Which joints are motors and which are servos?

The upper two are servos and the lowest is motor. However I might make the lowest servo because with the code I’ve written, I can increase my servo’s speed which can help in a jerk motion of the lowest joint to push the body up, whereas my PID control code of motor might not provide the speed I require.

Any problems with the servos being strong enough?

Since I haven’t fitted a battery to the body, the servo can manage the weight. They waver a bit but their performance will improve after I add the knee joint

An alternate idea is to have the second PIC sensor wires jumpered to the first PIC digital outputs, and run your own protocol.
Some distributed systems that need synchronized movements (eg dynamixel servos) use either a low latency trigger signal to launch a previously-setup command, or run a time-synchronized clock on all distributed systems and schedule the motor commands for future times.

Yes I initially thought of that but then I thought it would be better if my main controller was able to control the movement of every motor instead of just controlling protocols.

Do you use http://en.wikipedia.org/wiki/Inverse_kinematics methodology,
with an internal model of the physical balancing point?
Or emperical recorded movements?
Or force-sensors feet to know when one foot is nearly free?

I intend to use inverse kinematics but if I want my robot to walk on uneven terrain then I might need to have a switch attached to the foot to know when it is on the floor.

MPLAB ( if you want ) and mcc18 v2.40 SE is the version you need....


You might want to investigate my contribution to Vex:

Vex On-Line Controller Code v2.x (Available Source Version 0.80 Beta)

and

Vex Serial Port Reader 0.81ß (VEX On-Line Code Version)

Thanks a lot! I spent a week trying to find a compatible mplab and c18 version. Now my test programming is not giving compiling errors and if mplab works, I’ll translate all my easyc code into mplab code on monday.

If you want to do this, here is a diagram for the needed cables.

I’ll try this in the coming week.