Stanford Hapkit
ME327: Design & Control of Haptic Systems
Stanford University - Spring 2020
During the spring quarter of 2020, I enrolled in Prof. Allison Okamura’s course for haptic devices. A key component of the course was using personal haptic devices designed by Allison and her lab called “Hapkit”. These are small 1 degree-of-freedom personal assemblies featuring 3-D printable components, an Arduino, one DC motor, a capstan, and a magnetic position sensing mechanism.
Here are two haptic feedback force profiles that I coded for the course. The first virtual object is an inelastic wall at a position of x = 0. The second virtual object is a mass attached to a spring and damper in parallel that can move freely in the x dimension.
The location of the blue outlined ball corresponds to the position of the white tip of the handle.
When the user tries to push the handle past x = 0, where the virtual wall is located, a large torque is applied via the motor at the base of the handle as a reaction.
The result is a very rigid surface that you can “bounce” the virtual ball on.
Here, the red outlined ball corresponds to the tip of the white handle, and the blue outlined ball represents a mass that is part of a mass-spring-damper system.
The user can freely move until they encounter the blue outlined ball. Pushing quickly on the mass results in a very strong damping force and slows the user down. Letting go of the handle allows the elastic force from the spring to bounce the user’s ball away from the mass spring damper.
