3DOF Gimbal for Haptic Device

This was my final year Capstone Project. I led my team to build a 3-Degree-Of-Freedom (3DOF) gimbal mechanism to mount onto an existing haptic device. The completed device allows users to interact with virtual objects in all 6DOF in a Unity-powered virtual environment.

The haptic device initially used a passive gimbal (i.e. joint positions not measured) mounted to an R-R-R arm, so only the 3DOF from the arm was represented in the virtual environment. With the addition of the active gimbal, which uses quadrature encoders to read the joint positions, the haptic device can represent all 6DOF in the virtual environment. This allowed for objects in the virtual environment to be both translated and rotated, whereas only translation was possible with the original passive gimbal.

The gimbal was designed to be highly rigid, low-resistance (i.e. low friction, low inertia), ergonomic, and modular. A systems design approach was used to complete the design of the gimbal mechanism.

After analyzing three different 3D printed prototypes, the L-shaped design was settled on. The final design features links machined out of 6061 aluminum and a brass counterweight to reduce the inertia when operating the gimbal. The links were designed to minimize deflection while still being lightweight.

The joint positions were measured using 2048 ppr quadrature encoders, which interfaced with an ESP32 microcontroller. The Unity virtual environment used forward kinematics to display the arm's position, and a force control model to compute the required force feedback.