Design: New Wrist

We have designed a new wrist for the LittleArm. This can only be used in place of the actuated gripper. Therefore the end effectors that can be used are currently the hook and clamp for markers.

This wrist does allow for better implementation of drawing programs since it is now possible to keep the pen vertical.

STL files for the wrist can be downloaded here.

Design: Gripper Attachment Dimensions

For all of those out there that are making their own LittleArm and want to create a custom gripper, here are the dimensions of the adapter slot and gripper fitting.

Wiring Diagram: Arduino 3DOF Arm

Here is a basic wiring diagram for the 3DOF arduino robot arm. All the parts for the diagram can be found on the Project Links Page

Testing 3D Printed Gripper

We are trying out a few different 3d printed gripper designs.

For this one, each finger has a gear printed at the joint so that when 1 moves the other does also. This can be tougher to print but it is a nice mechanism.

The print went bad about 3/4 of the way through, but we were able to get a proof-of-concept test finished.

We are also making a rigid gripper that can hold a Sharpie, and one that is just a small hook.

The servo-actuated finger of the 3D printed gripper

Design Specs: Goals of the Arm

This is the list of goals and design specifications that will be met in the 3D printed arm part of this project. There will be two phases on the mechanical design. A very simple low cost arm and a more capable but expensive arm

Low Cost Arm

1. Aside from screws all structural components must be 3-D printed (using makerbot)
2. Excluding the microcontroller, component cost must be <$25
3. Arm must lift 1.5 oz at maximum extension
4. May only use a single type of servo
5. Controlled from keyboard (no more than 6 keys)
6. <5 3D printed parts

Higher Cost Arm

1. Modular gripper that can hold writing utensil
2. Excluding the microcontroller, component cost must be <$40
3. May only use a single type of servo
4. Controlled by mouse
5. <8 3D printed parts

Future Expansions

1. Trainer Pendant Arm
2. Sense and Follow
3. Implement with webcam to collect objects and draw picture
4. More grippers

Arm Demo: Prototype Videos

An initial prototype for the arm was completed recently. Here are a couple of videos.

Operated from Keyboard

Servo Sequence