It has been a little while since I have made any progress, but with the summer’s vacations and other activities out of the way, I have a chance to buckle down and get some stuff done. This is actually the first time I have gotten motion with the arm with the new electronics. All seems to be working fine, except for a few issues with multistepper (Arduino Library). Next is getting the pen going.
Note – you will notice the steppers are making a bit too much noise, I just haven’t set them up properly, that will change soon.
The 2 degree of freedom arm end effector is nearly complete. Here it is controlling a pen up/down motion. The current design depends on gravity to bring the pen down which is probably ideal for felt tip pens and the like. It uses a micro servo to drive the pen upward. The design is 3D Printed and the files will be uploaded to Github shortly. More coming soon…
In the Hackaday Prize competition on hackaday.io, there has been a lot of robotics activity. This is a pretty clever arm designed to be a 7 DoF (degrees of freedom) arm. What I appreciate about this arm is that the designer, Jonathan Lussier, used steppers and belts at the shoulder and upper arm and used servos at the extremities. Assuming he is using cheaper servos, this would provide low cost, high strength to weight fine motion while the coarse motion could be done accurately with the heavy steppers embedded in the base. The goal of the arm is to be less than $500. Link here
Make put together a pretty good article on drawbots. Given that we are building one, there is lots of room for inspiration here. http://makezine.com/2016/04/06/6-of-our-favorite-drawbot-projects/
For those of you who dont know, this is a great event. I will also be there exhibiting the 2 DoF arm and will have some hypocycloidals kicking around.
For those who didn’t get a chance to see it… Apple’s new “Liam” Robot
While at the Home Brew Robotics Club last week, one of the presentations was on a cool fully open-source brushless motor controller being built by Chris and Cameron Tacklind. What is nice about this is that they have integrated a low cost hall effect position sensor into the controller so that position and phase can be aligned. You can track progress at
The version 2 prototype of 2 DoF arm mechanicals is complete! There are a few changes in the design that can be summed up as fit and finish issues
- switching the direction of Screws and moving the location of screws to make assembly easier
- increasing the length of the shoulder GT2 belt to make it easier to assemble
- moving to higher precision washers.
Items that are still on the to-do list are as follows:
- Finalize the stepper driver and controller (@dhylands is working on this)
- Develop end effector
- Get software running
This design is still in prototype phase and this is a short guide that will walk you through cutting and assembling the parts.
Continue reading 2 DoF arm v2 prototype assembly instructions
Got the prototype of the arm fully running this last week on an Arduino using the Adafruit motor shield. Everything went together pretty smoothly and the steppers are certainly strong enough to move the arm around. however, I did find a few problems:
Continue reading 2 DoF Arm Assembled with Motion