hello everyone my name is hongnan lin i'm a phd student at georgia tech
and on behalf of myself and my co-authors i'm presenting our paper called FlexHaptics
a design method for passive haptic inputs using planar compliant structures
researchers have proposed many methods leveraging magnetic materials flexible materials and flexible
structures to create a set of passive mechanisms that support certain movement practice and haptic
effects here are two recent developments that we are focusing on first designing haptic profiles
by configuring haptic effects and movement constraints for instance Mechamagnets showed 6
haptic effects by arranging magnets and 5 spatial constraints by applying 3d printed widgets
second using computer-aided design and fabrication and single ordinary material
to generate predictable haptic profiles for instance kirigami haptic swatches leverage
cutting plastic sheets and various cut-and-fold structures and Ondule employs 3d printing pla
and coil spring structures they also provide computer-aided design tools assisting users to
design the structures with desired haptic profiles based on mathematical models of the structures
inspired by these developments in flex haptics we aim to combine these advantages of expanding
the design space and computational design and fabrication and bridge beam structures that
enable simple geometries and predictable haptic properties with this study we present the design
of eight haptic modules they support resistance detent and bounce haptic effects within linear and
rotary practice they can work alone or combine for compound movement paths and haptic effects
they come with mathematical models connecting haptic properties and geometric parameters
of the modules also we developed a design editor that transforms haptic properties into module
geometries finally we demonstrate a broad spectrum of use cases applying the proposed method and tool
now we'd like to introduce eight primitive modules including linear resistance linear detent linear
bounce rotary resistance rotary detent and rotary bounce modules and two ortho planar
linear bounce modules in square and round shapes we introduce two mixing strategies
parallel mixing is applicable to two or more modules with the same movement path it fixes
the mobile parts to mobile parts base parts to base parts producing a compound input with
multiple haptic effects along the single path mixing in series fixes the base of one module
to the mobile part of another so on and so forth resulting inputs have a complex movement path
and maintain the component haptic effects along each component path
the force displacement curve of a module can be fine-tuned by adjusting its geometry based on a
mathematical model quantifying relationships between its haptic profiles and geometries
taking a linear resistance module as an example
the resistance force equals two times the friction constant times the reaction force
and the reaction force can be calculated with the provided equation which constitutes a
compound explanatory variable containing multiple geometric parameters coefficient A and constant B
the explanatory variable is adapted from Euler Bernoulli's beam theory whereas the theory
requires material properties such as Young's modulus which are hard to know in fabricated parts
since they are affected by laser cutting or 3d printing fabrication
our model uses coefficients A and B to accommodate material effects
as well as flexibility due to the rest part of a module rather than the beam
we calculated A and B and evaluated how well the mathematical modules predict modules
using linear regression still using linear resistance module as an example we generate
a series of geometries by varying l b and h and measured the reaction forces from the geometries
we conducted linear regression using b times h cubed divided by l cubed to predict F in order
to obtain A and B to complete the equation and R squared to measure the percentage of the variance
in the reaction force that can be predicted with the geometric variable using such method
we calculate equations for linear resistance modules made of 3d printing pla laser cutting pom
and laser cutting acylics as well as equations for the rest modules made from the three materials
we encoded our study into a design editor to support designers it's developed as a plugin
for rhino and grasshopper to generate a module in flex haptics editor designers simply choose
a module type select a fabrication method and material and set desired haptic values
then the editor generates a geometry in rhino viewport and calculates its haptic
profiles designers also have chances to explore other possible geometries
that produce the same haptic profiles finally the geometries can be exported
in two dimension or three dimension format for fabrication by later cutting or 3d printing to
validate the proposed method and demonstrate the use cases we developed six example applications
the haptic control panel for a painting application is proposed to reduce divided
attention caused between canvas and toolbar it employs a linear resistance module
for changing brush size and a linear detend module notched at preferred values for adjusting opacity
the piano keyboard interface used on a touch screen music app is to improve user performance
it's made by shaping and collocating square shape ortho planar linear bounce modules
made with laser cutting acrylic modules and copper tapes it adds haptic sensations to on--touchscreen
interaction without blocking the graphics we demonstrate the modules are suitable as
haptic proxies in vr the vr controller attachment consisting of a linear bounce module simulates
increasing resistance while opening a bow and retracting effects while releasing an arrow
the wearable device provides haptic feedback to different gesture interactions in vr it comprises
multiple stackable string retracting units each leverages a rotary bounce module for retracting
and another rotary module for additional haptic effects with the compact form factors enabled by
the FlexHaptics modules we can make a stack of three units as small as a smart watch
we can connect FlexHaptics interfaces with embedded circuits to microcontrollers
for instance with this example we demonstrate a tactile timer input interface
for low varying people each dial consists of a rotary resistance module and a detent module the
hour minute and second dials present dinimishing resistances and different detent distributions
starting and cancelling buttons are made with ootho planar modules the joystick allows rotation
in horizontal and vertical planes by serial mixing two mutually perpendicular rotary balance modules
the button on the handle can activate single or scattering shooting mode under light or
hard press by serial mixing two outer final bounce modules with different bounce constants
thank you very much for your attention and do reach out to me if you have any
questions and comments and you can find all of our open-source resources on github