Stack'em

Project team members: Aaron Li, Caitlin Ramos, Jesus Tejeda, Joanne Low

Give a one-paragraph description/summary of the project, which includes information like the motivation for the project, the goals of the project, and the resulting implementation and success of the project.

Introduction

Explain the motivation for your project in terms of the educational objectives and why your haptic device is an appropriate approach.

Background

Explain the relevant prior work in the field of haptics and provide references. These will likely be different from the references in your project proposal. Make sure to do a thorough literature search on relevant haptic devices/application.

Methods

Provide a detailed description of your project, such that another student from the class could generally re-create your project/experiment from the report if necessary. (You don't need to document every screw, but the design should be clear.) Add images and videos as needed to support the description. You can refer to downloadable drawings and code in the "Files" section (later). You should divide this section into subsections, which can vary depending on your particular project. Here is an example set of subsections:

Hardware Design and Implementation

System Analysis and Control

Demonstration / Application

Results

Describe the results, which may include qualitative responses from users at the open house.

Future Work

Describe how your system could be tested (e.g., through experiments if you have not already done so), how it can be improved, and how it might be applied.

Acknowledgments

Here you can list any individuals or groups who helped you with your project. (e.g., another student in the class, a course assistant, or an especially helpful PRL TA). Optional, so delete this section if you aren't using it.

Files

Code and drawings should be linked here. You should be able to upload these using the Attach command. If you aren't willing to share these data on a public site, please discuss with the instructor. Also, in this section include a link to a file with a list of major components and their approximate costs.

References

List the referenced literature, websites, etc. here.

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Appendix: Project Checkpoints

Checkpoint 1

- starter UI and preliminary rendering on Hapkit

- finished materials list

- rough prototype of mechanical system

- analysis and dynamics and definition of success

Code

For the starting code of our project, our main goal was to have the rendering of a moving platform and blocks stacking to set up the overall framework of our game. Having this setup is crucial for the future integration of block dynamics and force feedback as we continue to develop our mechanical system. The code we developed take in the Hapkit handle position as an input for the position of the moving platform in the virtual environment. A series of blocks are programed to fall at arbitrary locations and stacks successfully as long as it makes contact with the platform or another block. As we developed the framework for this code, we realized that the integration of block dynamics may be more challenging than we initially thought. One of the foreseeable challenges for the next checkpoint will be the successful integration of block dynamics in the virtual environment and accurate force feedback for the physical system.

Materials List

Mechanical System Prototype

Our rough physical prototype consists of a modified Hapkit attached to a linear rail to allow both translational and angular motion. There is a second motor attached to the base of the Hapkit that will be attached to a rack and pinion system to track position in the x direction, while the original motor will track the angular position and provide force feedback to the user. The underside of the platform will contain two ERM motors that will send vibrational feedback when impact is made. Through the creation of this physical prototype, we determined that the optimal platform position should be right above the pivot point, and that the platform should include handles to house the ERM motors for a more transparent sensation.

Preliminary CAD:

Based on our learnings from our rough prototype, we designed the system on CAD which features a modified Hapkit base that can screw directly into the linear rail, and a modified Hapkit sector pulley with the added board. The board features round handles for the user to grip onto, and the ERMs will be embedded in the base of these handles. The linear rail will mount onto an acrylic base to keep it in place. These components will be 3D printed and laser cut within the next week as we begin to integrate the full system.

Analysis and Dynamics

A successful system will provide a convincing feeling of realism in terms of users feeling the dynamics of the block tower and impacts generated by blocks. This translates to users being able to discern, without needing to rely on the GUI, where the tower is located relative to the platform, when falling blocks collide with the platform (or tower of blocks on the board), and how much speed objects had when colliding. The minimum functions the virtual environment should recreate are linear and angular movements of the platform, and should reflect in the blocks motion through the appropriate sliding and colliding dynamics from a penalty based simulation.

In terms of system design, this means finding the highest gain values possible without encountering instability, to create sharp perceivable impacts and object stiffnesses. Alongside this, non-linear effects in the system will have to be accounted for, either by simply being acknowledged and worked around (such as motor saturation), or actively dealt with (ensuring a high sampling time to minimize holds / time-delays).

Checkpoint 2

Here you will write a few paragraphs about what you accomplished in the project so far. Include the checkpoint goals and describe which goals were met (and how), which were not (what were the challenges?), and any change of plans for the project based on what you learned. Include images and/or drawings where appropriate.

Example Video: https://www.youtube.com/watch?v=i_aLBql4Ufo