<This page is in progress>
Full Prototype Assembly
I designed a fully passive robot arm tool changer that locks through controlled arm motion rather than a powered mechanism. The system is entirely 3D printed, uses off-the-shelf hardware, and can be fabricated onsite for under $10 in purchased parts. Unlike many comparable systems, it does not require an additional rotary axis on the wrist.
During docking, the Wrist Attachment Assembly lowers onto the Gripper Attachment Assembly and slides laterally into place. A dowel pin on the Wrist Attachment engages a wedge feature on the Sled, generating a clamping force that pulls the two assemblies together. Repeatable positioning is achieved with a Maxwell-style coupling, using dowel pins and threaded steel balls as hard contact points.
Cylindrical cutouts on either side of the Sled mate with matching pins on the Dock, while embedded magnets keep the Gripper Attachment Assembly in place when the tool is not in use.
A compliant spring latch provides retention after the sled completes its travel. As the sled moves relative to the Wrist Attachment, it deflects the spring latch, which then snaps into place and prevents the assembly from backing out.
Spring
Displacement graph of Spring from FEA simulation in Fusion360
Assemblies:
Wrist Attachment Assembly, Top View
Wrist Attachment Assembly, Bottom View
Gripper Attachment Assembly
(in locked position)
Gripper Attachment Assembly
(in unlocked position)
Sub-Assemblies:
Wrist Attachment, Top View
Wrist Attachment, Bottom View
Gripper Attachment, Top View
Gripper Attachment, Bottom View
Sled Assembly, Top View
Sled Assembly, Bottom View
Spring Assembly, Top View
The gripper attachment consists of these two pieces that encapsulate the sled:
Gripper Attachment Upper Piece
Gripper Attachment Lower Piece
The Gripper Attachment Lower Piece and Sled are shaped to allow for sliding back and forth:
Better video to come soon... 😅