kasubana

results

speed of execution

It takes around 5.4s for the Kasubana to be ready for operation. This time could be shortened, but we chose to let the electrodes be activated for 6 cycles to ensure a more accurate calibration of the base readings. Each electrode is activated every 100ms and the stepper motor also steps 0.9 degrees in the same period of time. Similarly, this speed could be increased, but this particular length of time was chosen to make the flower respond in a lifelike manner. Nitinol speed?

accuracy

The orientation of the flower in response to the position of a human hand is accurate to within 14.28 degrees. This was due to the fact that we used seven field electrodes to cover a total area of 90 degrees. The maximum distance of the human hand from the electrode that could be detected was around 1cm in air.

safety

There is a risk of the overheating the nitinol wire or the current source transistor if the flower is activated (nitinol actuation) for over 3 minutes. Otherwise, the flower can remain in operation without posing danger to users. This issue can be solved easily by adding a security feature in the software to turn off the current source if kept on for 3 minutes and by having a better cooling system.

interference

The Kasubana was not known to interfere with the projects of other students.

usability

The robotic flower is extremely easy to use. One simply needs to turn on the power supply, wait for around 5s and proceed to have fun interacting with the flower.

conclusion

Our goal was to create a robotic flower that would be able to sense human presence and bloom in response, as well as orient itself toward the human. We succeeded in developing Kasubana, a flower that opens its petals when a human hand is placed on the surrounding grassland and slowly moves towards the hand. In our opinion, the Kasubana exceeded our expectations in terms of its life-likeness in blooming. Nevertheless, we could improve on the detection range of the flower. If we could resolve the extremely sensitive nature of the field electrodes to surrounding noise, it would be possible for the flower to detect a human hand hovering above the grass instead of resting upon the grass. Increasing the total number of electrodes would also increase the number of final orientations of our flower.

Apart from the PCB layout, the entire design of Kasubana is novel and belongs to us. While there were no standards to abide to, we wanted to model a real plant as closely as possible in terms of the appearance of the flower and as well as its movements. We believe that there might be patent opportunities for the design of Kasubana.

ethical considerations

Our project adheres to the IEEE Code of Ethics and we list a few of the relevant points:

:: to accept responsibility in making engineering decisions consistent with the safety, health and welfare of the public, and to disclose promptly factors that might endanger the public or the environment
We are fully responsible for a safe user experience with Kasubana. We have advised users regarding safety issues when operating the flower and will seek to improve the safety of our device.

:: to be honest and realistic in stating claims or estimates based on available data
We have been honest in stating our claims and functionality of the Kasubana. All of our claims are based on the results of our testing procedure.

:: to improve the understanding of technology, its appropriate application, and potential consequences
Our personal goals for this project were to understand how nitinol actuation and electric field imaging works as well as develop an appropriate application for both technologies. The design of Kasubana demonstrates the potential of nitinol as an actuator for biomimitic applications and the ability of electric field imaging devices to detect the presence of humans.

:: to maintain and improve our technical competence and to undertake technological tasks for others only if qualified by training or experience, or after full disclosure of pertinent limitations
This project has greatly improved our design skills, both in terms of hardware and software design. Both of us were qualified to work on this project, having had experience in working with microcontrollers in ECE 476. The use of nitinol and electric field imaging devices were also taught in the same class.

:: to seek, accept, and offer honest criticism of technical work, to acknowledge and correct errors, and to credit properly the contributions of others
Professor Bruce Land and many of the teaching assistants, in particular Chethan and John were the people we turned to for advice and criticism of our work. Errors that were pointed out were immediately corrected and we give credit to all the TAs who assisted us, as well as credit the design of the PCB to Catherine Kung.