These past two weeks have been moving slowly as far as tangible progress goes. Lee and I worked on ordering parts for our final version of the tennis ball cannon project. We needed to order pulleys, belts, shafts, bearings, and couplings, while also making sure that they measured up to size and quality without completely breaking the bank. Some of components are already here, and with just a short wait, the rest will arrive. We also rigged up a crude test for the motors, motor drivers, shaft, and bearings in the meantime.
This week, Denver and I have made some progress on the project – both on software and hardware. A program is almost finished being created on Arduino that will display several coordinates on a Serial Monitor and with those coordinates, we would be able to form a shape using the stepper motor. As for hardware, Denver installed 3D-printed gear to be able to have the actuator turn on a point. Lastly, we tested various grains of sand on a quarter-inch thick of plywood using a steel ball and some neodymium magnets to simulate how it would move during actual operation.
After a long frustrating attempt to get reliable facial detection working, I’ve decided to switch gears and begin working on more hardware based projects (this is a robotics class after all). For the second half of my course, I will be working on Dover International Submarine Races submarine electronics. The electronics will require four stepper motors to control fins on the rear of the submarine, and getting those stepper motors working is my first project. I have never worked with stepper motors or stepper motor drivers before, so this is a learning experience for me.Continue reading Stepper Motor Fun
With the completion of our very own linear actuator arm, I moved on to working with some of the other parts of the project. I left Anthony to handle more of the coding aspect with using the linear actuator, while I began modeling a vital part for our project.
Our project consists of basically two parts, the actuator and then a base which rotates the actuator on a shaft. My job this week was to model a three dimensional part which included a gear, hole to attach to our linear rail, and specifically designed areas for 1/2 in bearings.
At the start of the week I tried to use professional software like Inventor and Solid-works, but the file I was trying to import couldn’t be edited. Mr. Bahn found a nice online software called Tinkercad, where I could edit my imported file and get to working on the various things I needed. After completing one design, we revised it and made a second version.
A week filled with coding and testing, we were able to configure the limit switch and make the motor stop at the midway point of the actuator. To prevent the plate from grinding against the outer end acrylic plate, we had to install and program the limit switch so that once the base plate presses against the switch, it immediately goes the other direction until it reaches 30 cm, the midpoint.
After completeing my research on wind chimes and how they are structured and put together I was able to start putting together a crude setup to let me test a few things I need to know to construct a final project. The first thing i did was cut out a 15.8cm long metal tube with a 1/8” hole 3.54cm down from the top, the position of the hole should be optimal to prevent reduction of the tubes vibrations from attaching other objects to it. Folling this I proceeded by coding a simple program into the Arduino to send a short pulse to a solenoid while I pressed a button. This was helpful in testing how long I should have the delay between the solenoid being powered and being deactivated. I did have some issues coming up with the optimal time because the tube would swing back after being struck and muffle/distort the ringing, however I think the best option is to go with a shorter time with the solenoid (around 10-50ms).
The last few weeks have been tedious, but productive in regards to the cannon’s functionality. Lee and I started with several problems to solve, but have overcome most of them as of 3/6/19. Our small-scale prototype for the launching system has been completed and is fully functional, as well as a model for the barrel and aiming apparatus. To build the flywheel launcher prototype, we used vex robotics as a platform and attached some smaller motors below, connecting them to power supplies and feeding ping pong balls into the wheels. My partner has a video of this attached in his update. In regards to the barrel, we used an accelerometer with a smoothing loop to read the current angle, a potentiometer to set the goal angle, and a linear actuator as a makeshift motor to move the current angle to the desired goal. So far, we have gotten it to be accurate to the nearest half of a degree. Because both models were successful, we have moved on to drafting our final build.
At the start of this week, Anthony and I were in the process of building our linear actuator. The linear actuator is used to move the magnet from side to side. This week including lots of designing in a software so that Mr. Bahn could help and machine our parts.
The Stepper Motor that we are using is the NEMA 17. Last year a student used the same motor and already had a part modeled out. I took the part file that was used last year and adjusted it so that it would work for me. I also had to design out a plate that would be used for the pulley system on the opposite side of the rail from the motor.
After I had these parts in my hands, all it took was assembly. We had our rail, stepper motor, plates, wheels, and screws. We cut our rail to an appropriate size for our project and then got to assembling. I had to make a few adjustments as I went along, such as adding a second idler wheel to get the belting to the appropriate height.
Now with the linear actuator complete, we are moving on towards the lower portion of the project. Working on code as we go along, we now are faced with deciding how we will rotate our actuator.