My Stewart Platform (aka the other kind of hexapod)
Stewart platforms are good for flight simulators, wave motion simulation, earthquake simulation, and 6 axis machining.
I build low cost robotics
- to empower everyone
- to show how easy it can be
- to get attention and (I hope) work building and playing with robots.
This demo will show you how to assemble (but not program) a Stewart platform.
To make this robot you will need:
- an arduino with 6 PWMs
- a 12 pack of ball & sockets joints from DUBRO
- 6 pieces of 4-40 threaded rod of equal length. I use 15cm.
- 6 hobby servos. I recommend metal gear servos. Any brand will do.
- A breadboard.
- A 5v2a power supply.
- A box, cardboard or wood.
- Some wood, plastic, or metal to make the special parts.
- A steady hand
Attach the ball joints to each end of the rods. Line them up and make sure they are all the same length and that the ends are facing the same way. These rods are now the calves of your robot. Measure the distance between the ball holes, you'll need that calf length for later.
Cut a "pocket" (indent) in the wood that matches the side of each servo. A single piece of wood can then be used to clamp or sandwich all the servos onto the top of the box. If that's too complicated, try using zip ties or double sided tape. Make sure the servos face the correct way. (Laces OUT, Dan!)
Use the X shaped gears that come with your servos. This X gear is now the thigh of your robot Measure the distance from the center of the gear to the center of the outermost hole and save it for later.
Cut a triangular hole in the top of the box. Cut an access hole in three sides of the box.
Attach the breadboard to the top of the uncut side. Attach the arduino just under the breadboard. Mount the servos on the top of the box, with the frame on top to sandwich them against the box.
Make the end effector as seen in the video. The important part is that the ball joints go in sideways, are all the same distance from the center, and as close together as possible.
Use the breadboard to wire all the positives and negatives from the servos to the 5v2a power supply. Wire each of the signal lines from the servos to the PWM on the arduino.
Attach the rods to the end effector. Center the servos and attach the rods to the X gears. (tip: attach the gear to the rod, then the gear to the servo.)
You've now built your Stewart platform. Programming it is another story for another day.