Robot Arm for Romi

Robotics and electronics discussion Electronics
1

I was interested in purchasing the robot arm kit for romi. However, I am trying to use it for a different application than for the Romi. I was wondering would this kit still work for my application? Also if it does is there a 3D CAD model of the entire arm? Also is there a different robot arm I could purchase in case this doesn’t work?

Thanks

2

For reference, we are using a Raspberry Pi.

3

Hello.

Without additional information about your application, it is hard to say if it would work or not. Here is some information that could be useful for making that decision:

  • The robot arm can function separately from the Romi; you just need some way to power and control the 3 servos.
  • The arm can articulate up and down and the gripper can pivot up and down, but it relies on the robot to move side-to-side.
  • There are a variety of holes on the mounting plate that you can use to mount the arm to something other than the Romi chassis (i.e. you aren’t required to use the ones that are designed to work with the chassis).
  • We do not make a 3D model of the entire arm assembly available, but we do have a model and dimension diagram of the gripper available under the “Resources” tab of the Robot Arm Kit for Romi product page. Similarly, you can find a model, dimension diagram, and DXF file of the expansion plate that the arm mounts to under the “Resources” tab of its product page.

If you have any specific concerns, I would be happy to try to help further.

Brandon

4

Thank you!
For reference, we were looking at designing a mobile robot that picks up various objects. We plan on designing our own robot instead of using the Romi. We were just looking at using this arm specifically, to avoid designing our own arm. Also, would we be able to program this arm using a Raspberry Pi?

5

There is nothing on the robot arm that you need to program (i.e. it does not come with a control board); as I mentioned previously, you will just need to be able to power and control the 3 servos. You can find more information about this in the “Using the Robot Arm for Romi” section of the user’s guide.

It is possible to control servos from a Raspberry Pi; however, we do not have any specific examples for doing so, and it is generally not great at handling time-sensitive tasks like generating servo signals, so you might get some noticeable jitter. You can probably find many helpful resources with an Internet search. A brief search I did lead me to this video, which seems like a good starting point. Please note that you should power the servos separately from the Raspberry Pi (the setup in the video powers the servos from the Raspberry Pi’s 5V pin, but notes that in typical applications you should power it separately).

If you want to avoid the potential jitter or want more accurate control, you might consider adding a separate controller for the servos that the Raspberry Pi can communicate with, such as a Maestro servo controller or even a small Arduino-compatible controller such as one of our A-Star programable controllers (although the Maestro will generally generate cleaner more precise signals).

Brandon