Over the course of the spring quarter, I have been working on the transition from understanding the theory behind super coiled polymer actuators to developing the actual manufacturing process for these actuators. This experience has invoked in me a greater appreciation not only for the overall “research process,” but also the larger implications of the research being conducted within the LEMUR Lab.
At the beginning of the year much of my time within the lab was spent working on understanding the basics behind the SCP actuators—primarily their mechanism of operation in the physical sense (i.e. once constructed, how these actuators appeared and could be powered), the science dictating the construction process, and application within the realm of printable robotics. The long term goal of this project was established: to develop a formula for creating SCP actuators, where properties of the actuator, such as string length, and power input, such as the amount of voltage used, could be inputted and the other necessary parameters to create the actuators would be outputted. In order to gain a better understanding of the mechanics behind the printable robot into which the actuators would be implemented, I designed a model of the gripper in Solid Works. Moreover, since the end goal of this project was to create replicable robots with easily available resources, I learned how to use the ESP 8266 and the basics of programming with Arduino. By the end, the goal is to use only the motor shield to both anneal and power the actuators.
The next steps in the research process focused on making concrete progress towards the construction of the actuators, now that the mechanism of operation was fully understood. I created a procedure, which detailed how the actuators would be built, and a table of equations, which consisted of all the equations dictating the behavior of the actuator as a function of various inputs, i.e. temperature, voltage, current, string length, number of coils. Unfortunately, the project suffered a major setback during the winter quarter because I overlooked the importance of the annealing process. In order for the conductive nylon sewing thread to retain the inserted coils, the thread must undergo an annealing process to allow the coils to set and thus, perform as actuators. Past studies and literature mentioned the annealing process but not the specifics, such as the amount of voltage that should be applied for the coils to reach “annealing temperature,” the length of time the voltage should be applied for, the amount of times the coils should undergo this process. Thus, I looked towards my table of equations to decipher this information. At the same time, I attempted to begin construction of the actuators (primarily the insertion of the coils). The length of string to weight ratio became another issue, as was the insertion of the correct amount of coils. I am using a servo motor, which does not account for the number of turns, which made the current procedure not exactly repeatable.
By the end of the spring quarter, I made concrete progress on many of the unknowns that plagued the early stages of the production process. The number of turns inserted into a specific length of string is known, the amount of weight used during the coil insertion process and the annealing process is also known, and the step voltage values can be calculated using the table of equations. Thus, the goals for the summer will be 1.) create reliable actuators (all 10 cm in length) 2.) create different sized actuators 3.) create the actuators using the ESP board instead of a DC power source 4.) work on integration with the RoCo Team to create printable robots
-Pooja