By: Rafi Koutoby (Project Manager)
This is the final blog of team Micro Rover for Electrical Engineering 400D taught by Professor Gary Hill in the spring 2015 semester at California State University, Long Beach. Of all the projects being done this semester, we are the only team with the rover project and have high hopes in producing one that satisfies our mission profile. Our team consisted of Rafi Koutoby (Project Manager), Sherman Xa (Mission, Systems, and Testing Engineer), Eagled’Or Am (Electronics and Control Engineer), and Ahmed Abanumai (Manufacturing Engineer).
Using Mini RoSco’s documentation as a main point of reference and with Professor Gary Hill’s guidance, our team was able of producing a smaller version of the Robot Scout, which we named, Micro Rover. This rover was set to improve upon the design set by Mini RoSco the prior semester, hence the objectives and requirements were very similar.
Micro Rover (and Mini RoSco) was designed to simulate a United States military personnel crawling under barbed wire. Our budget, which was approved by Professor Hill and Vice President Raul Rodriguez, was not to exceed $220. The project had a deadline of Friday, December 15th 2015. Other requirements included 3D printed chassis, wheels, and tracks, a custom printed circuit board (PCB), a vision system that would allow the rover to avoid any obstacles, control via Arxterra, a single power supply, and the primary requirement, which was that the dimensions of the rover were not to exceed those of a Samsung Galaxy S2 Android phone (which would also serve as our remote control and vision provider) plus one inch on the length and width.
One of the biggest challenges was the chassis. With a look that was inspired by World War II tanks, the rover was to have three wheels on each side with a triangular topology and would be tied together via tracks. Halfway through the semester, the primary requirement was altered so the rover could expand in order to carry other Android devices (possibly even tablets). Hence, our base dimensions were those set at the beginning of the project.
One of the main differences between Mini RoSco and Micro Rover was the vision system. Mini RoSco opted for a pan and tilt system, allowing their mirror to move horizontally and vertically to obtain a better picture. Due to our limited space, we were allowed to use just a panning system. This would only require one servo instead of two.
The PCB designed contained connections to our voltage regulator, H-Bridge motor driver, Arduino Micro, and Bluetooth module. The advantages of using a PCB included reducing the size of the internal electronic components and learning EagleCAD.
We utilized the Arxterra App to connect to the phone via Bluetooth. As a result, to create a connection between the Arxterra App and the Arduino Micro, we must create a Bluetooth connection using the HC-06 Bluetooth module, to connect our Android device with the Arduino Micro. The Arxterra Control Panel will act as our user interface to control the Micro Rover’s movements.
Unfortunately, after completing the PCB layout and connection test, we decided to build and assemble all the parts of the chassis. For our motors, we wanted to mount them directly onto the wall of the chassis. We did this by using an R/C hobbyist glue to attach the motors to the wall of the chassis and the wheels to the shaft of our micro motor. However, due to complications in the 3D printing, one of the openings of the wall of the chassis was printed too big and we attempted to use glue to create a tighter fit. Unfortunately, the glue was too heavy and we ended up stripping off one of our motors. Luckily, with the help of a spare motor from team MicroSegbot, we were able to find a solution to this problem. Next, we moved onto the pan mirror system, which gave us trouble on the viewing system. Unfortunately, for our Samsung Galaxy S2 layout, we could not get a full field of vision on our Arxterra Control panel. We were able to get the mirror to display on half of the available screen of the control panel. This could have been resolved if we had more time with the 3D printed chassis and adjusting the pan system’s height. Overall, this was a good learning experience for all of us as we were able to identify the flaws in our design and hopefully, our mistakes will be taken into consideration for future Rover projects.
The final design of our Micro Rover can be seen through our promotional video on YouTube.
Below are the links to the various blog posts that relate to the mentioned topics.
Project Objectives and Requirements: As per the requirements set by Professor Hill, the objective was to build a rover that would run around a chosen test course with parameters similar to Project Mini RoSco from the semester of Fall 2014.
Project Budget: With a budget of $220 that was approved by Professor Hill and Vice President Raul Rodriguez, we set out to build the rover. The final and detailed budget is attached.
System Block Diagram and Interface Definitions: The system block diagram is an overview of the rover design and the interface definitions shows the physical pin connections to our Arduino Micro.
Resource Reports: The power budget ensures that we are within our power limitations of 850 mAh with an input voltage of 8.4 V.
Project Schedule: The project schedule has been broken down based on the stages of completion.
Trade-Off Studies: A number of trade-off studies have been conducted, including choosing a suitable mirror angle, speed requirement, motor drivers, etc.
Verification Testing: Testing on the Bluetooth module, the Arxterra App, the PCB, and other subsystems are detailed in this section.
Project Presentations: Attached are the PDFs of the Preliminary Design Review (PDR) and the Critical Design Review (CDR).
Arduino Code: Attached are the Arduino IDE files for running our rover. This was posted on GitHub by our Electronics and Control Engineer, Eagled’Or Am.
SolidWorks Files: Due to our rover being aesthetically different from Mini RoSco, we drew our design inspiration from World War II tanks. The designs were developed by our Manufacturing Engineer Ahmed Abanumai.
EagleCAD Files: As per the requirement of utilizing a custom PCB, our Electronics and Control Engineer Eagled’Or Am designed the PCB and its layout.