Continuing with where we left off last week, we met with Dr. Carter last Friday to get his final input on the device. We were specifically interested in his thoughts on our software with a GUI interface and the hardware specifically with questions about the mobility, comfortability, and flexibility of three of our designs. Our first design was for a finger set up using cable clamps as the predominant fixture point for the potentiometer. The second design utilized goggle straps to secure the potentiometer. The last design we presented was for the wrist using a slide potentiometer fixed onto the wrist with velcro and bungee cords. Dr. Carter suggested that we do what we can to increase processing time and make the interface with the software as intuitive and simple as possible. This week, Chris helped us pivot and adapt to meet this requests by switching our data processing from Matlab to Arduino. Dr. Carter also emphasized making the hardware component as realistic and viable in a clinical setting as possible. He preferred that we focus on developing our finger design with goggle straps over both the more rigid cable clamp design and the wrist set up. Since the priority thoroughly is accurate feedback through a flexible device that suits a patient’s condition, Dr. Carter suggested we just focus on developing the finger components and if need be, ignore the wrist. Earlier this week, we talked with Dr. Yin to clarify aspects in the report such as what he meant by ethical issues and evaluation of meeting our specifications. Dr. Yin confirmed that while the client may be ok with adjusting his requirements for the completed project, we would still be judged at the end of the day whether we met our original design specifications that we covered in our verification and validation report. Currently, the group is working on building the mechanical design and testing the device. In addition, we are preparing the final report and presentation.
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Over the weekend, the team continued to work on different designs using pulley potentiometers, slide potentiometers, and flex/bend sensors. The team then met with Professor Klaesner on Monday morning to get his thoughts on the various designs that were worked on in parallel last week. From this discussion, two major ideas were generated: using a trough-like support structure to mount the potentiometer mechanism onto and ironing out the main outputs our client, Dr. Carter wants. We met with Dr. Carter Monday afternoon and we decided our core priority is to construct any design that we can (we had presented 2 at the meeting) and produce a singular working prototype by Friday. We had asked Dr. Carter if he prefers that we aim to (a) create a mechanical design and software specifically aimed to get accurate angular displacement data or (b) to create solution that collects relative movement data. Solution (a) we believe is better supported by the design where the potentiometer is fixed in the same plane as the joint. Meanwhile solution (b) we believe is better supported with a slide potentiometer design measuring tension in a string based on movement generated along the slide mechanism. This week, we worked to create any prototype that could work. We used a variety of materials over the course of the week (rubber straps from goggles, graduated tubes, 3 oz travel size bottles, velcro, and more) to produce a working support structure. We plan to meet up with Dr. Carter again on Friday. Currently the team is trying multiple solutions in parallel including trying out the flex sensor, slide potentiometer, knob potentiometer, and a pulley potentiometer. Chris and Galen are thinking about using Allen wrenches for each of the joints to measure angle potentially. Chris and Galen went to Gateway Electronics to check out available parts and come up with ideas. After going there, we were able to collect a few slide potentiometers of small size than Professor Widders, and some spring systems. In addition, we were able to find the size of the Allen wrench (5/64”) that fits Professor Widder’s potentiometer. Chris has also been working on the Matlab GUI to use for the device. In its current state, the GUI can set a threshold angle, calibrate to the resting angle, measure the angle of the potentiometer, and deliver visual and auditory feedback. The visual feedback is now changing the color of an RGB LED as opposed to the brightness which should be easier for the patient to distinguish between levels. The audio feedback is a beep that decreases in pause interval until it becomes almost continuous at the threshold angle. Olivia talked with Kristina to hear her thoughts on our Validation and Verification paper, and bought some sensors and LEDs.
This week the team split up the tasks required to finish the project. Galen will be working on the mechanical design and utilizing the index finger design for all the fingers we will be testing. In addition, he is currently thinking about how to create a design the project for use on the wrist. The whole team will be meeting Jake from Objex this Friday at 2:30PM. On the software side, Chris will be working on converting the Arduino code thus far into Matlab in preparation for the additional processing power that will be needed when more sensors and feedback are added to the device. He will also attempt to incorporate audio biofeedback to the device via Matlab as well. Olivia has worked on adjacent tasks such as uploading past weekly reports onto the website and being the team “expert” on Design Safe so we will know exactly how to wrap up this project. Olivia will also work on creating the GUI (graphic user interface) through Matlab that we’ll need to integrate software with end user experience. The team was not able to complete much during Spring Break. The team is currently trying to plan the last 5 weeks to figure out what task are immediate currently to finish the project. Some current plans include emailing Jake Salter again to ask for a time to meet up and discuss our mechanical design. We will also pick up the Verification and Validation report and review the comments to see where we can work on for the coming future.
After just finishing the Verification and Validation report, we are mainly preparing the presentation for Wednesday. In the meantime, Galen is attempting to print out the Single Slider Design, which is our second iteration mechanical design for placing the potentiometer on the finger and wrist joint. We managed to fit in the potentiometer and show the proof that the design could work. At some point we may have to reach out to Jake Salter from Objex Design for assistance for making the design work. We also were able to talk to Dr. Carter on Wednesday (3/7) and show us our Verification and Validation Powerpoint. For some of Yin’s questions such as colocalization surface area and resolution, we were able to get Dr. Carter’s approval that we should not let surface area restrict our design and use an angular resolution higher than 0.2793 degrees. In addition, Dr. Carter said he is find with using higher frequency beeping for feedback and gave us advice with some of mechanical device. We also plan on getting Dr. Carter a drawing of what the final prototype would possibly look like. In the meantime, Dr. Carter has said that he will look into the active range of motion and get back to us.
This week we worked on the proof of concept for our device to ensure that the potentiometer will work to measure angles and would work on a one degree of freedom door hinge joint. Galen helped to create a joint scaffold that could support a sensor without restricting movement. This or another design will be crucial in fixing the potentiometer to the hand in a way that can measure the angular displacement of the fingers and wrist.
Chris met with Dr. Klaesner on Monday morning to gain more guidance. He suggested creating a calibration curve to show that the potentiometer can accurately measure angles. Chris and Olivia were able to successfully develop an accurate and nearly perfectly linear calibration curve to convert the potentiometer reading to an angle. Using that equation, Chris was able to scale the brightness of an LED based on the angle and create an LED intensity vs. angular displacement plot using a photoresistor. Chris and Galen met with Dr. Klaesner again on Wednesday to ask more about the mechanical design of the potentiometer holder. He suggested contacting Jake Salter of Objex Designs for guidance in the mechanical design. We will try to arrange a meeting with him for after spring break. We will also work to collect more data and write the Validation and Verification report as the deadline approaches draws near. We will likely meet with Dr. Carter to show him and double check our progress next week. This week we continued to work on the accelerometers, but found out it was a lot more complicated and had more issues than expected. We initially tried to use a door hinge mechanism to test the angle, but it varied as we moved it around. This was likely due to the fact that the acceleration of the accelerometers around by any movement could change the acceleration reading on the accelerometer. Thus there was an addition of error in the angle. After talking with Dr Klaesner about our problems, we realized that accelerometers would be a challenge to work with, as there were additional technical issues such as finding the constants to integrate from acceleration all the way to position, and dealing with complicated matrix math. Dr Klaesner suggested we use a potentiometer, which would be easier according to him. Chris and Galen are beginning to design a rotational potentiometer to test the angle. Galen will begin working on the CAD drawing in order to make the two rods that will attach the potentiometer at two different points. Chris will begin the coding process. On February 21, we talked with Dr. Yin about the change from accelerometer to potentiometer. He was okay with the change, but expressed concerns regarding stability as the potentiometer might move. The stability will likely decrease with the addition of the glove. This week we continued to work on the project attempting to determine what the issue with the accelerometer was. We also started to write our Verification and Validation report by outlining points for discussion. Galen helped to create a figure illustrating the specification regarding the feedback based on the angular displacement using Matlab and Adobe Illustrator. Olivia helped to work on the timeline and listing the design specifications. Chris worked to get the prototype started by debugging the accelerometer and potentially use Professor Widder’s accelerometers for our initial design. We discovered that the accelerometers we purchased use the SDA and SCL pins on the Arduino, meaning each Arduino can only support one accelerometer since each only has one of each of those types of pins. Chris then attempted to use two of Professor Widder’s accelerometers that use typical analog pins and was able to measure the angle between the two accelerometers with fair accuracy using only the z acceleration for both, but they must both be in the x-y plane for this approach to work. Next, Olivia will try finding the angle between the two accelerometers using all three axis and eliminating the same-plane limitation of a one axis approach. To read all three axis, however, three pins must be used for each Arduino with there only being six analog pins total. We may have to look into interfacing several Arduinos at once in order to use the appropriate number of accelerometers at once. We haven’t scheduled it yet, but we will reach out to Professor Klaesner for feedback on our progress and concerns about the accelerometer accuracy.
At the end of last week, two sensors arrived in the mail, and we were able to begin our first prototyping iteration. We soldered pins into the first pair of accelerometers that we will use for this first prototype. After downloading the test code for our chosen accelerometers, however, we found that they did not work. We suspected there were issues with the soldering, but we weren’t able to find a solution by the end of our team meeting on Friday. We had planned to correct this on Monday of this week.
Yet this week we were not able to go into Widder’s lab on Monday because of a biomechanics lab using the laboratory space. We plan to ask Professor Widder about whether the orientation of the pins is affecting the device. We plan to meet on Friday again to work and diagnose the problems from last week. We as a team also need to determine more times when we can meet during the week to move the building phase along faster. Moving forward, we will try to work more individually and divide up tasks in getting our first prototype running. We will also look to meet again with Dr. Carter to confirm our new specifications and metrics, but hopefully with at least a basic prototype in hand. |
AuthorJust your average engineering students -- solving problems yet to be solved Archives
April 2018
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