Christina Holman | Design Blog

At our team meeting on Sunday after the first spring review, the crew decided to become familiar with the field at hand. We baked and decorated a 9-inch cake for observation. Baking the cake did take a portion of time and for the majority of that time, the team discussed ways in which we could extrude frosting. Emily and Cassie had taken a field trip to a Baking Store and found a Wilton Decorator Pro, which consisted of a plunging mechanism to extrude frosting from the attached storage container. Additionally, the tool allowed for interchangeable tips to create circles, stars, and waves. We took such a luxury into account for our design too. We reversed-engineered the Decorator Pro to understand how we could ensure that the frosting was forced out at a constant pressure. The Mechanics sub-team (Cassie and Emily) discussed how to remove the springs in order to directly integrate the equipment into the CAKEBOT, attaching the plunging arm to a motor for vertical movement. By then, the

At the end of every two weeks, there is a "sprint review" where professors circulate between groups to hear about and give feedback on the progress of each team project. The CAKEBOT team met for a long session the night before to finalize the physical, first iteration of the CakeBot design. We also sketched out the integration of the components for future sprints  to demonstrate that we at least thought about the mechanical, electronic and software pieces. The actual prototype itself focused on the cake rotating platform -- which we knew we would absolutely need for decorations on the side/walls of a cake -- and initial ideas on the icing dispensing system for the face. For the rotating platform, I used a cut-out circle of 9-inch diameter (for standard cake size) and we connected it to a servo motor. I then programmed the Arduino to "sweep" the servo to and fro; the motor itself was pushed into a hole cut out in the foam base. The foam base most likely will be a w

Director Raji Patel, who also invited me to speak at the Regional Meeting, also asked me to speak at the 2014 Massachusetts STEM Summit during the MASGC breakout session with NASA astronaut and icon Sunita Williams. The talk presented a bit of a challenged as I was asked to condense the presentation of my research on "A Multiplexed Digitizer for Dark Matter Detection" to a holistic, non-technical presentation. I had to re-route the order of my presentation and focus on the "big picture" to my audience. I emphasized my own personal development during the summer, explained major decisions on the overall design of the readout circuit, and featured the importance of such research in the physics and current news arena. (See below.) I was ecstatic to be there alongside Sunita Williams and another student presenting her work. As big of an icon she is, Williams was very cordial and eager to share her experience leading up to her record for "longest single space fli

When Professor Battat asked if I would be willing to present for the Massachusetts Space Grant Consortium, there was no hesitation in my reply. I could barely contain my excitement as he replied to the director about my response. Not only was the director Raji Patel asking me to present at their regional meeting but also the MA Stem Summit the following week. In just a two-week time period, I would be in the presence of NASA officials, state consortia directors, the Massachusetts Governor, the MA STEM Council (headed by Congressman Kennedy) and other key stakeholders. As excited as I was, I was also nervous about these events: I knew I had to nail it. This morning, at the regional meeting at MIT -- with less than 4 hours of sleep -- I gave the presentation to floor a nation.... maybe that's a hyperbole but my presentation was no less wonderful. My mother -- my greatest supporter and critic -- flew in for this presentation and Wellesley's Family Weekend to place one more laye

WeLab/WES ( Wellesley Engineering Society ) has gotten off to a great start with almost 100 students and counting . I really want to see the engineering department grow and getting students involved in the seminars, workshops, etc will hopefully retain all those bright-eyed first years interested in engineering. Lookout, World! Wellesley students are ready to show what it means to be An Engineer in Liberal Arts and it's time for people to know about the impact of that tie. As John Maeda says,  STEM + ART = STEAM. Take a look at all the steam these students are building and what's ahead for We-Lab: Can't view infographic? infogr.am/whos-with-me-5283

Using the CoolTerm program to read Arduino serial values to a txt file, we print the serial output values of position, target position, error, and motor output and then used MATLAB to plot these values.We used the PID equation, output = Kp*Error + Ki*Total + Kd*Difference , where Error = target ­ count,  Total = total + error, and Difference = Error_previous - Error_current. With a little experimentation, we found that our control works best when Kp = 14, Ki = .01, and Kd = .1. Yet, we noticed that the accuracy of our plots was not as high as it could be with a 36­resolution encoder, which caused large steps in our plots, as seen in Figures 4 and 5. We tried increasing the accuracy by using different encoders, up to 72­resolution. Challenges: A key challenge in this lab was understanding the dynamics of PID control system and how to translate them into the encoder­motor system we built. Another challenge we had to overcome was dissecting the diagram and data sheets for the

Objectives Use an analog IR reflective sensor to measure the angular position of a motor shaft. Create a closed-loop controller for a brushed DC motor with your DIY shaft encoder. Characterize and visualize the performance of your closed-loop motor controller. In this lab, we used an analog infrared reflective sensor to build an encoder to measure the position of the shaft of a DC motor. With the sensor, the more IR light that is reflected back to the phototransistor, the closer Vout will be to zero (see schematic). We used the position reported by the encoder as a signal around which to design a feedback loop that ensures your motor will go to any position you command it to (even under load). After setting up the sensor circuit with the Arduino, we began to build the encoder. An encoder is a circle with distinct patterns of black and white shapes, usually triangles, that signify on-off or high-low. We placed our 36-resolution*, carboard encoder right on the shaft of

Hello again!  It has been a while since my last descriptive post about my engineering journey though a lot has happened over the past few weeks, from PoE to We-Lab to W.E.S. to research talks. I almost have no time to blog -- almost no time ... So, to get back on track with my documenting the experience, I am submitting a series of posts about all the new developments. Olin's Principles of Engineering (PoE) PoE has kept me extremely busy as the labs have become more and more challenging, moving from simple LED lights to a 3D scanner to Proportional-Integral-Derivative (PID) motor control. PoE is meant to give students a balanced background in both electronics, mechanics and programming -- in preparation for the final project. For the final project, students were allowed to form their own teams and project ideas, which created a frenzy throughout the classroom. People heckled and raced to find a spot on highly-coveted ideas or urge others to join them in an idea with littl

In this lab, we embarked on the journey of creating a 3D­scanner utilizing two Hobbying servo motors, a Sharp Infrared Distance Sensor, and an Arduino Uno. We created a connector that would allow us to secure a reliable connection between our Arduino and IR sensor. We patiently assembled the connector by crimping three JST connectors onto appropriately stripped wires to fit into a 3­pin JST connector. We tested the functionality of the primary parts: the sensor, the Arduino, and the servos. We adjusted and ran the AnalogInput example from the Arduino example library, which caused our sensor to blink at an increased rate whenever an object was nearby. Similarly, we ran AnalogOutSerial from the Arduino library, which allowed us to verify that values were being transmitted and that they consistently changed when an object was nearby. Lastly, we made sure our servos worked and could be controlled, using the "Sweep” example to rotate the servos. After confirming the functionality o