I'm making a robotic prototype and need some help with writing the control software. It's essentially a 3DOF stewart platform, driven by 3 hobby servos.
You can use arduino or raspi. I have dedicated pololu servo controllers, so the three PWM outputs should be all we need.
Only two movements required, sometimes together:
1. Z axis, up and down
2. Precession (image attached), with the point of rotation in the middle of the platform.
Z is simple. All 3 axes moving together.
Precession will (probably) require a 3 phase sine wave of the PWM signals. We'll need to be able to adjust both frequency and amplitude, and ramp them up or down over time.
Sometimes both movements happen together.
Here’s an example of a sequence that would be performed:
1. Start precession with set frequency, amplitude, and amplitude lower bound.
2. Move z-axis distance over set time, while precession continues.
3. Ramp precession amplitude from x to y and move z-axis together across set time.
4. Stop precession.
5. Move z-axis down and hold (press)
6. Move z axis up and finish
- Will need to do some kinematics of servo rotation so z axis/amplitude relationship is linear. I can send CAD of the device to help with calculations.
- Absolute lower bound of sequence should be easily set by user before starting the sequence. Perhaps with a rotary pot. Should move all PWM values up or down.
- 3 buttons will be needed: Start, all servos to x, all servos to y
- All 3 servos are identical and mounted the same way, so we should be able to skip homing.
That's all I can think of now. I'm sure there's a lot more to cover.
17 freelancere byder i gennemsnit $1065 på dette job
Raspberry or arduino? It's your choice. So, we are using 3dof Stewart platform. And according to the input pwm should be generated to drive, the servo using drivers.... Are you interested to proceed?