Kitty Quan
Quan Nguyen and Kitty Kwan
The Inside-Out Jar
Project team members: Quan Nguyen, Kitty Kwan
The Inside-Out Jar is a device that gives its users changing haptic feedback as it is turned. It features different texture patterns during a course of nine 360 degree rotations of the wheel. This device was inspired by childrens' toys that require a turning crank, such as a Jack-in-the-Box, and the turning propellers on a helicopter. The goal of the project was to create a device that continually gave its users different haptic sensations, similar to a game, as they used the device. The Inside-Out Jar was created through modification of the original Hapkit and the addition of a wheel. We were successful in creating such a device, but fell short of creating the full effect of a game.
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Introduction
The goal of this project was to create a device that produced haptic sensations in the form of a game. This was inspired by common toys and devices that feature a user-controlled wheel. We wanted to use the idea of a game to create a wheel that produced varying degrees of texture, sensations, and forces such as a wall. The actual Inside-Out Jar does not have the wall effect, but does produce changing textures. Rather than functioning as an interactive game as we had planned, the Inside-Out Jar produces the effect of turning different objects, such as the light clicking of a padlock. Due to the devices placement in a mysterious box, it slightly resembles the mystery box we experimented with on the first day of class. The user is not able to directly see the source of the haptic feedback but can feel it as a response to his or her own actions. Haptics is a huge component of this device because the act of turning by the user leads to different haptic feedback on the user's hand.
Background
We originally envisioned The Inside-Out Jar much differently than what it turned out to be. After the initial plan of a game fell through, our idea was very much an extension of the original Hapkit. It is similar to a 360 degree version of the Hapkit with a more intuitive, circular motion. However, unlike the Hapkit, several forces are programmed into the Inside-Out Jar and these forces continuously act on the wheel. The original Hapkit inspired the idea of a haptic feedback device based on the physical motion of user. Many of the textures and forces created by the Inside-Out Jar are programmed and executed in a similar way.
During the Haptics Open House, someone pointed out that the Inside-Out Jar is similar to a Haptic Knob. It is perhaps the most relevant prior work because a haptic knob is designed to represent different haptic feelings. Haptic knobs are simple devices that can recreate the sensation of different objects. Our Inside-Out Box is similar in function and appearance to a basic haptic knob found in Dr. MacLean's Spin Lab. More advanced work on haptic knobs have been done in Immersion Corporations on their iDrive, which is a device used in luxury cars to control functions within the car.
Design
Hardware design
The hardware of our device is an extension of the original Hapkit. Rather than using a handle, a disk/wheel was laser-cut to be used as the "lid" for our jar. The hapkit chassis had to be sawed down to accommodate a smaller radius for the turning component. The modified hapkit is encased in a jigsaw-patterned box that was designed using Adobe Illustrator and also laser cut out of duron (a high-density plywood). Engravings of a smiley face and the Stanford S were added for flavor. The whole device was put together using copious amounts of hot glue, although a more precisely designed box would likely have taken well to wood glue.
(Adobe Illustrator files for the box cut-out can be found in the "Files" section)
Software design
The software for our device was an extended version of the original board. The central feature that was added was a counter – after a certain increment of the "updatedPos" reading from the Arduino board, the counter will increase by one. This counter was used to measure rotations of the wheel. One rotation mapped to approximately twenty-five counts. So, after every twenty-five "counts", a "rotations" counter was increased by one. This rotation counter was used to determine which texture would be rendered.
The texture rendering in a haptic device would usually be based on the velocity of the turns. However, we ran into an error with our Hapkit that led to irregular velocity readings. As a result, we used a constant force output, spaced out across different positions on the circumference of the wheel. An interesting consequence of this is that when the wheel is held in a position where a force would be output, the user feels a vibration coming from the motor. Depending on how many rotations the user has made, the texture rendered will vary – either high frequency/low force, low frequency/higher force, or high frequency/high force texture. After nine rotations, the "rotation" counter will reset, starting the texture loop over again.
(Arduino code for the final project can be found in the "Files" section)
Functionality
The original plan was to create a timed game in which the textures and forces produced by the motor inhibited a user from completing the nine rotations quickly. This would include walls that required specific actions to break down, frequent textures that create a bumpy turning path, and gradients that slow down the speed of turning. However, technical problems and the design of the wheel prevented us from creating the Inside-Out Jar that we had envisioned. Instead, what we have is a wheel that changes its force output as a user turns it. We programmed a series of haptic sensations that the Inside-Out Jar would produce over a series of nine continuous rotations. Because of this, the user would receive unexpected sensations. The user would notice that turning the wheel at different speeds changes the haptic sensations he or she feels. For example, at a certain pre-programmed rotation, if the user held the wheel still, he or she would feel a constant vibration. However, if he turned slowly, he would feel spaced out textures, while if he turned quickly, the textures would be more regular.
The basic functionality of the wheel is what we planned but we fell short of the game effect. The audience of the open house still enjoyed feeling and being surprised about the changes in what they were feeling. Although some had a difficult time understanding the concept of "turning continuously", most were pleasantly surprised by what they felt. Almost everyone was able to identify the light clicking texture of turning a padlock. Much of the audience seemed delighted to physically feel the textures and vibrations on their hands.
The biggest question of the night was, "What does this device do?" Because our original goal was a game, what we created did confuse us a bit. However, we came around to realize that having a device that gave haptic feedback over 360 degrees was a great learning tool. The turning motion, like uncapping a jar, is very natural and intuitive motion. Also, many people felt tired after turning the wheel for the nine rotations. On a light note, the Inside-Out Jar could be adapted into an interesting exercise device. The haptic sensations of this device could stimulate the use of certain muscles through turning of a wheel with different resistances. An audience in the open house pointed out that currently, a similar idea has already been adapted in luxury cars. Those knobs provide driving sensations, such as the feeling of an engine reeving or friction of the wheels, to its driver in the interior of the car while the car remains quiet and considerate to the outside world.
The Inside-Out Jar could definitely improve by adding more levels of textures and forces so that the user would feel more unexpected changes and also by creating more haptic feedback based on the actions of the user. Also, this device would be more interesting for the user if its outputs recreated more realistically the feelings of turning other objects, such as a door handle or a wrench. It could then be a guessing game for the user. Lastly, it would be interesting to see if a game, similar to the original idea, could be produced. For a haptic device, the user experience is the most important aspect.
A video of the device functionality can be found here:
Files
Arduino code file and Adobe Illustrator drawings for box cut-out:
References
https://class.stanford.edu/courses/Engineering/Haptics/Fall2013/about (Lecture slides, videos, etc...)
http://eduhaptics.org/index.php/HapticDevices/HapticKnobs (Haptic knobs)