Gripper Design

This week our group has begun creating three-dimensional models of our robotic arm's gripper.  The gripper is being designed to have a three finger design where the two outer fingers are the moving fingers connected to a servo while the third finger, or thumb, is stationary and fits between the other two fingers when they are completely closed.  At this time we have not modeled the stationary thumb, so the renderings included in this post are only of the two fingered portion.

 Figure P3.1: Honeybee Robotic's Universal Gripper Anchor

Although its appearance is much different, the three finger design is similar to our current plan.

The third finger, which is stationary in our design, is the middle finger of the three that the other two will close around, similarly to the gripper above.

Click the picture to view Parabolic Arc's article on this project from Honeybee Robotics

Figure P3.2: Two Finger Gripper Rendering, Version 1

This is our current design for the moving portion of the gripper that will clamp objects between it and the stationary 'thumb' that fits between the two 'fingers' of this piece.  This design grew of a standard "C" servo bracket (pictured below).  The ribs added to the back of the two fingers will add strength and rigidity to the fingers as the clamp down on an object.  This part will be printed on Drexel University Engineering Laboratory's 3D printer, and has been designed with a 3mm thickness for greater strength, where an aluminum version of the same gripper could be thinner.

Figure P3.3: Lynxmotion Aluminum "C" Servo Bracket

These are the brackets that will be used in the joints of the robotic arm and also served as a foundation for our gripper design.

Click the picture to see this bracket at RobotShop.com

Figure P3.4: Two Finger Gripper Version 1 Mounted on Servo

This image shows how the two finger gripper will attach to the servo.  The gripper itself is highlighted in blue while the servo has a slightly darker shade of gray than the standard servo bracket to which it is mounted.  As shown in this image, the gripper's upper mount will be directly to the servo, and this will be how the gripper gains its motion.  The lower gripper mount will be a ball bearing that is connected to the standard servo bracket.  The ball bearings used will be the same as those that some with the bracket shown in the previous image.

All parts that have been purchased and mentioned in this posting can be found by following the links included in the Materials Order post.