In progress...

Background
The 2015 Mars Mining Competition (previously known as Lunabotics) was a competition that NASA held at the Kennedy Space Center in Cape Canaveral. The competition consisted of teams on engineering students from across the United States who designed and built robots capable of functioning on the Martian surface and retrieve regolith samples. 

Team Goals

Our team was tasked with building a remote controlled mining robot that adhered to the strict guidelines of the document "NASA's Fifth Annual Robotic Mining Competition Rules & Rubrics 2014". These guidelines disallowed the use of sensing equipment such as sonic range finders and class 3 lasers. 

Electrical Engineering Tasks

While the Electrical Engineers were tasked to design and implement all of the electrical systems used in the robot, I most closely worked to solve the problem of sensing the environment. Our solution was to use four class 2 laser range finders in the front, back, left, and right of the robot to allow for calculating the x,y position relative to the walls of the competition arena. I also implemented the weight sensor and failsafe switches. The robot carried and delivered the dirt on an actuating arm. The weight sensor kept track of the current weight of the dirt collected to ensure that we did not collect more dirt than the actuating arm could lift. The failsafe switches were in place around the actuating arm to make sure that the actuator would lose power, preventing damage to the arm if it was being overextended or retracted too tightly due to any kind of programming or user error. 

My Contributions

I was given three major tasks throughout the building process. These included programming the laser range finders, programming all switches and internal sensors, and designing a power regulation system for the smaller electrical components. 

• First I was to find a way to connect the laser range finders to an Arduino, since the range finders were commercial products and were not designed to be integrated with other devices. 
• Second I was to program the Arduino to recognize button presses and readings from a pressure sensor. The switches were trivial. one side was set to power, and the other was connected to a digital input pin with a weak pulldown resistor ensuring that 0v was read in the off state. When the button was pressed, the pin would raise to 5v. The pressure sensor was nearly as simple. When powered, the sensor would output a corresponding voltage. This voltage was read in by an Analog In pin on the Arduino. The only difficulty was that the voltage did not have a linear relationship to the weight put on the sensor, so the voltage had to be run through a logarithmic formula to properly calculate the weight. 
• Third I was to design a power regulation system for the Arduino, laser range finders, and all other low power electrical devices. This was necessary because the main voltage source on the robot were a pair of batteries with a combine voltage of 24V, which would destroy these components. My final design used two voltage regulators. One 5v regulator to supply power to the Arduino, and a variable regulator set to 2.7v to power the laser range finders.