To build this robot, I followed the standard engineering design cycle.
After I identified the problem, I specified the goals I wanted to accomplish with this robot; mechanical and electrical goals. I then evaluated and researched all possible solutions and chose the best solution to accomplish each goal.
Mechanical Goals (best solutions in bold)
Penetration through debris and other small structures
An angled front in combination with ample speed and mass will suffice
Ability to pull a payload of 210 lbs (conscious human)
Tubular Steel frame, eyebolt on back in combination with enough torque to pull 210 lbs
Safe and secure transportation of an object in its enclosed and protected compartment
Accessible compartment using a quick latch system where supplies, equipment, etc. can be stored and transported
Versatility (Pertinent "kits" that can be applied depending on the rescue situations e.g. fire rescue, riot control, medevac, etc.)
Extra space for development must be considered when designing
Ability to traverse obstacles that one would encounter in a rescue situation. Some of these obstacles may include stairs, fallen debris, etc.
Treads will provide the most resilience and will perform the best over obstacles
Electrical Goals (best solutions in bold)
One-way audio communication between the operator and the robot (microphone on robot, speaker on controller
360-degree live video feed
Camera mounted on modified servo for continuous rotation
Ability to operate in the dark/ High powered lighting
Infrared Video (48 IR LEDs) in combination with two ten watt LEDs
LM335a zener diode connected to ADC port on microcontroller
Maximum speed 10 mph along with enough torque to traverse obstacles (stairs, logs, etc.)
High wattage motors (see RMF calculations)
Long range communication (over ½ mile of video feed)
1.3 Ghz frequency, two watts or higher
Simple control that is easy to use
PS2 Controller- lots of documentation and many people are familiar with it
Active battery monitoring
Voltage divider connected ADC port on microcontroller-as battery voltage decreases; the output voltage will proportionally decrease
Remote motor shutoff (safety switch)
Digital signal connected to MOSFET that energizes relay coil when a signal is sent to the MOSFET gate
Battery duration: two hours
Two 12v 55 AH AGM cell batteries in series
Based on the mechanical goals, I constructed a 1:1 scale cardboard model of the frame and a CAD model of the steel frame using CAD.
Based on the electrical goals, I created two schematics: the circuit on the robot and the control circuit.
High resolution imaging of robot schematic can be found here
High resolution imaging of control schematic can be found here
After verifying my designs with my uncle who helped me with the project, and performing the necessary calculations, I began to build my prototype.
Controller Code https://docs.google.com/document/d/1bOuc7qBMk8NQbSVH5AtARbreEkhDFyYMKyuA92uV2qM/pub