A team of mechanical engineering students at the University of Pennsylvania has developed a search and rescue robot that overcomes many limitations seen in many modern designs using an ATmega32U4 based Arduino unit. The Hybrid Exploration Robot for Air and Land Deployment (H.E.R.A.L.D.) combines a quadroter and a robotic snake to enable movement both through and over obstacles while also surveying them from the skies.
With guidance from their professor, Dr. Mark Yim, the team set out to build a search and rescue robot that would “be able to traverse uneven and unstable terrain, avoid damaging obstacles and fit through narrow spaces.” All while being able to communicate with the user and be light enough for the average human to carry. Also, with saving lives a major goal, the robot needed to possess the ability to move at a speed that would not hinder the search and rescue process.
The team integrated the two robotic designs to limit the flaws of each individual construct. While quadrotors are known to have short battery life, the team’s system “allows for the quadrotor to be carried by two snakes while not in use, providing increased battery life without sacrificing mobility.” The snake itself would also be limited as to what kind of terrain it could climb, therefore the quadrotor is equipped to carry the snake over large obstacles or debris.
In order achieve this high degree of maneuverability, the snake was designed with seven degrees of freedom: two vertically actuated (pitch) servos, two horizontally actuated (yaw) servos, and three drive motors. As its creators reveal, these motors are incorporated into a mainly 3D-printed design that aims to optimize structural integrity while minimizing weight.
“Integrated treads on the wheel rims prevent excessive slip and provide edge-catching capability for obstacle clearance. The servo coupling arm acts as a bracket between the two steering actuators while providing a docking interface between the snake and quadrotor.”
A custom-made PCB, designed in Eagle, commands the snake via an Arduino Micro (ATmega32U4) and wirelessly communicates to the user over XBee radio. As for software, the team writes, “On each snake robot, we have an Arduino microcontroller running custom-written software in C++.” The team further details, “This low-level embedded software takes motor commands from a serial packet and outputs to the snake’s motors.”
The quadrotor itself runs on ArduPilot, an open-source Arduino-based system for operating DIY flying vehicles. After tweaking a few aspects of the software, the team was able to get their desired flight time of approximately 20 minutes. Using a series of magnets, the quadrotor can also carry the snakes for up to 10 minutes.
The team will continue to further develop the search and rescue implementations for the H.E.R.A.L.D. but this combination proves that we have barely scratched the surface of robotic design possibilities. Interested in learning more? The UPenn students’ entire project breakdown can be found here.