Several readers have requested an inside view of our Spirit II – Mars Rover so that they can see what the electronics look like. We have provided an annotated picture below, along with a couple of external shots.
We would like to introduce Mechatron, our mechatronic tank. When we designed and built Mechatron we wanted him to be tough looking, industrial, and retro-futuristic, with lots of metal, rivets, and gears. He’s built entirely out of aluminum, brass, and steel, but inside, he’s chock-full of high tech electronics. See pictures and more text below. And be sure to watch the video to see Mechatron in action!
Mechatron includes special wheels with rollers slanted at 45 degree angles and driven by dedicated gearboxes, four powerful motors, and a software-controlled drive system that we wrote that operates each of the wheels independently. The result is that he can move in any direction at any time in any orientation. In other words, he can drive forward and backwards or turn like a normal vehicle, but he can also drive perpendicular to the direction he’s facing or at any desired angle. Weighing in at forty five pounds, he is by far our heaviest robot, but he is also our most agile, which makes him tremendous fun to drive.
Mechatron’s gun turret pans 360 degrees, includes 8 range-finding sonars for target detection, a laser, and a high-powered electric automatic weapon that shoots brass or plastic pellets. Ammunition is fed from the base of the robot up through one of the articulated metal tubes attached to the turret (the other tube contains wires). He can fire extremely rapidly while standing still or moving.
Strips of 52 programmable RGB LED lights have been mounted on Mechatron’s underside and within his turret. The turret LEDs indicate the robot’s current mode and whether the weapon system is armed. The LEDs on the underside change color depending on the direction of each of the individual wheels (Blue = Stopped. Green = Forward. Red = Backward), which helps to illuminate how Mechatron’s unique drive system works.
Mechatron is designed to function in a variety of different modes, including both user-controlled Radio Control and/or fully-autonomous. For the RC mode, we built our own controller which matches Mechatron in look-and-feel. The left joystick controls the pan and tilt of the gun turret and includes the firing button on top (which is armed using the missile switch). The right joystick controls the drive system. Forward and Backward motion (Y-axis) moves the robot forward or backward. Twisting the joystick turns the robot in the direction of twist (Z-axis). Moving the joystick left or right (X-axis) causes the robot to strafe left or right while maintaining his current orientation. Combined X-Y-Z joystick motions create unique and agile movements, such as strafing in circles. The robot can move in any direction, while panning and tilting its turret and firing all at the same time.
Overall Design: Beatty Robotics
Arduino Software: Beatty Robotics
Metal armor plates: Beatty Robotics
Main Microcontroller: Arduino Mega 2560
Microcontroller used for controlling LED lights: Arduino Nano
Light Controller Software: Beatty Robotics
Wheels: AndyMark (special thanks to Andy Baker, who was great to work with on these)
Drive Gears: Modulox (special thanks to Dan Richardson at iR3 Creative Engineering & Andy Baker at AndyMark)
Pan-Tilt gears and other parts: RobotZone (special thanks to ServoCity)
Pan-Tilt Servos: Hitec Digital
Sonars: (12) Maxbotix MaxSonar Ultrasonic Sensors
Turret Sensor Head: Beatty Robotics
RGB LED strips: Adafruit (Go Blinky Belt!)
MP3 Sound Board: Sparkfun MP3 Trigger
Servo Controller: Pololu Maestro
Voltage Regulators: Pololu & Dimension Engineering
High-amp Relays: DFRobot
Motor Controllers: (2) Dimension Engineering Sabertooth 2×25
Motors: (4) CIM
Wireless Communication: Xbee Radio with Sparkfun Xbee Explorer Regulated board
Joy Sticks: (2) 3-axis hall-effect joysticks from CH Products
Batteries: (1) 12v 3-cell Lithium-Polymer 20C
Aluminum, hardware, fasteners, wire, tools, and much else: McMaster-Carr
Wire, electronic components, IC boards, and much else: Sparkfun & RobotShop
We have been hard at work on our latest project called Mechatron. To control our Mechatron robot as well as our Mars Rover, we designed and built our own remote control box. We developed our own communication protocol for transmitting commands from the remote control to the robot. On other projects we used iPhones and Playstation remote controllers, but in this case we wanted to build a large, metal box with lots of retro-switches and joysticks.
1. Although it wasn’t cheap, the hall-effect 3-axis joystick was critical for controlling the function of Mechatron’s specialized drive system. We originally tried a traditional analog/resistive/potentiometer-style joystick and it did not work well at all. We thought our whole project was going to fail until we realized that not all joysticks are created equal. The joystick based on the “hall-effect” principle worked perfectly for us.
2. You can’t see it in these photos, but this controller can be charged via banana jacks and re-programmed via a USB jack without having to unscrew and remove the case. The same is true for the Mechatron robot itself.
Security V is a small security robot. It’s equipped with the following capabilities:
Automatic electric gun (Airsoft pellet gun) with ammunition cage
Pan-Tilt Gun Turret
(3) Ping sensors for object avoidance
LED Light Strips
MP3 Sound Player
IR Human Detection Sensor
Two treaded drive wheels and two omni wheels
Arduino Mega Microcontroller
Xbee Radio for remote control
Button panel for selecting the mode
We programmed it with five different modes:
1. Roams autonomously around the house, playing R2-D2 like sounds as it explores & avoids obstacles 2. Remote Control 3. Dance Mode (Plays the song Mr. Roboto and dances around) 4. Guard Mode (enables its infrared human detection sensor and plays a police siren if anyone tries to sneak past it) 5. Shoot (shoots the gun)
When I first saw Roam-bot I thought he was pretty cool. He talked (at this time we had no talking robots) and he had a aluminum box that hides all of his wires. He was neat, and could go by himself using ping sonar.
When you first turned him on he says “Ready, roger, roger, find best direction” in a deep voice then turns his head to each side saying the number of inches until an object. He says “_ inches, _inches, _ inches” Then goes the direction in which there is the most amount of inches. Now that’s pretty awesome!
We ran into a problem when we came to the point were we needed a caster. No sizes fit his front. While waiting for different sizes to be delivered, we temporally put on a furniture felt pad on so we could still play with him. It worked great! Still none of the sizes fit, so it became permanent. He now can only go on wood floors, but thats okay because we have lots of it!