Mentors

Austin Russell

Ricardo Ortiz

James Corcoran

Austin

• Network & Cyber Security Engineer
  • Groton Utilities
• Student on the team for 2013 & 2014 season, now mentor for the past year
• New England Institute for Technology, September 2017
  • Associate of Science, Network Engineering
  • Bachelor of Science, Network Engineering & Cyber Security
• Other than just electrical, I manage the IT and computer systems for the team, as well as anything else that needs to be done

Ricardo

• TODO

James

• Software Engineer at Electric Boat
  • Move air, water, and metal with electrons and dinosaurs
• Electrical/Programming mentor on FRC2168 since 2008
• BS Computer Engineering from Rochester Institute of Technology
• I like to learn about new & random stuff:
  • Space, 3D Printing, Computer Vision, Flat Earth Society
  • Micro controllers, Artificial Organs, Information Security
  • CNC, Lego, Cheap stuff from China, Linux, Pyrotechnics,
  • Test Automation, Wood working, primitive technologies
  • Robotics!, Web Design, Statistics, Photo editing, ...

Overview

Topics to cover

• Team role
• Interfacing with other disciplines
• Build season role
  • Prototype support
  • Final wiring
  • Criticality of our work
  • Aware of design decisions for seamless autos
• Hardware overview

Team Role / Discipline Interaction

• Electrical
  • Mechanical
    • Aid prototype development
  • Programming
    • Determine the right sensors for the job
  • CAD
    • Plan component placement
  • Drive Team
    • Custom controls & Automation

Build Season Role

• Week 1 - 3
  • Test which sensors work for detecting game elements
  • Source components for games specific features
  • Support prototype wiring
• Week 4 - 6
  • Plan out electrical layout for comp bot
  • Wire practice & comp bot
• Week 6+
  • Keep the robot running at events
    • Fix broken wires, sensors, etc
  • Wire up new mechanisms & design revisions
  • Figure out what doesn't work, find solutions

Hardware Overview

Battery

The brains of the operation.

• 12V Sealed Lead Acid Battery
• Like what you'd find on a motorcycle or lawnmower
• All power for robot operation must come from ONE battery.
• Can supply 100s of Amps
  • Respect the batteries and don't get hurt!

Main Breaker

High current (120A) circuit breaker.

• Main robot power switch
  • OFF - Depress red button
  • ON - Close black lever 
• Open circuits when high current drawn for long duration of time
• Prevents fires, causes tears
  • Design bot to never pop

Power Distribution Panel (PDP)

Distributes power from the battery to all components on the robot.

• Up to 8 40A circuts
• Up to 8 30A circuits
• Special 10A & 20A circuits for peripherals 

Auto-Resetting Circuit Breaker

Different sizes (40A, 30A, 20A)

• Protect hardware from blowing
• 40A breakers for powerful motors
• 30/20A breakers for 
• After heating up (high current), these open circuit
• Once cool they will automatically close and send power back to downstream componet

Pneumatics Control Module (PCM)

Allows control of pneumatics components over CAN bus

• Control up to 8 solenoid channels
•  Turn compressor on/off compressor

Voltage Regulator Module (VRM)

Provides regulated supply voltages

• 12V 2A
  • 500mA section counts towards 2A limit
• 5V 2A
  • 500mA section counts towards 2A limit

RoboRIO

The brains of the operation.

• Runs our code
• Controls all outputs
• Reads all inputs
• Talks back to driver station laptop 
• Interfaces
  • PWM
  • Digital Inputs/Outpus
  • Relay Channels
  • Analog inputs
  • MXP expansion header

Motor Controllers

Control speed and direction of motors

• Many different kinds
  • SPARK, Victor 888, Talon, Victor SP, Talon SRX
• Controlled by roboRIO over
  • PWM
  • CAN
• Don't plug in backwards
  • Expensive learning experience

Robot Radio

Standard WIFI Radio (802.11)

• Can be configured as Access Point
  • For use at home
• Wireless Client 
  • For use at competitions

SPIKE Relay module

Contains two relays (switches)

• Not terribly common
• Can be used to control anything that just needs to be turned on/off (12V).
  • Compressor
  • LEDs
  • Low power motor with no speed control
• Contains its own 20A fuse

Cameras

Ethernet / USB

• Used for:
  • Operator feedback
  • Object detection
• Camera feed can be fed back to driver station or processed locally on the roboRIO

Motors

Topics to cover

• Intro on voltage, current, resistance

• Review FRC parts

  • Battery

  • PD board

  • Breakers

  • Motor controllers

• DC Motors

• Servo Motors

Voltage/Current/Resistatnce

FRC Parts - Refresher

Find them:

• Battery
• PD Board
• Breakers
• Motor Controllers
• RoboRIO
• Radio
• VRM
• PCM

 A                B                   C

                                           D

                        E

                        F

  G                                       H

MOTOR CONTROLLERS

Motor Controllers

• Allow motors to be... controlled by the roboRIO
• Varying degrees of features
  • Some are very simple just speed/direction control
  • Some are complex and can interface directly to sensors and have internal position/speed controllers

• Brake/Coast setting
  • High RPM >> Use COAST!

Brushed DC MOTORS

DC MOTORS

• Magnets mounted around the exterior
  • "stator"
• Coil of wire at center
  • "rotor"
• When current flows through the coil it creates a magnetic field that reacts against the field created by the magnets and causes rotary motion

Brushed DC Motors: the most common type of motors used on our robots.

Brushed DC Motors

Lab

Materials Needed

• Motor tester board with PWM generator

Procedure:

• Wire up motor tester board to DC Motor
• Hook up multimeter across input and output of motor controller.
• Monitor voltage output as motor speed is changed

How does the Brake/Coast jumper affect operation?

​What happens when the load is applied to the motor?

SERVO MOTORS

Rotary Position Servos

Command motor to specific angle

• Can be used for controlling mechanism to specific position
• Need to take external forces into consideration when choosing part to prevent stripped gears and backdriving

Same as position servos but, control circuitry is modified.

• Instead of controlling position...
  input controls speed and direction (sound familiar?)
• These aren't the solution to all out problems though, remember there's still a very small DC motor inside the servo. 

Linear Servo Motors

Command motor to extension

Similar to rotary servo, but extends and retracts

• Gear boxes in some of them can provide a large toque multiplier.
• Surprisingly strong
• Easy to break when side loaded

Lab

Materials Needed

• Motor tester board with PWM generator

Procedure:

• Wire up motor tester board to servo (directly to PWM generator)
• Monitor position of servo as the PWM generator moved.

What will happen when an external force is applied?

Topics to cover

• Discrete Sensors
  • Switches, Hall effect, 
• Analog Sensors
  • Potentiometer, SHARP IR, Pressure Sensor
• Position Sensors
  • Encoders, Gyros, IMUs
• Cameras

Discrete Sensors

• Report a Boolean status to the control system
  • On/Off, True/False
• Examples:
  • Limit switch (Mechanical contact)
  • Hall Effect Sensor (Magnetic field)
  • Proximity Sensor (Metal presence)
  • Photo Detector/Emitter (Light)

Analog Sensors

• Voltage varies over sensed range
• Can be used to measure
  • distance, pressure, current, position, etc
• Analog sensors can be turned into Boolean statuses with logic in robot code:
  • e.g. If voltage >= 2.5 true; else false;

Analog Sensors (cont)

• Examples:
  • SHARP IR
  • Pressure Sensor
  • Potentiometer
  • Ultrasonic

Encoders

• Incremental or absolute indication of position
• Produce a train of pulses
• Number of pulses can be counted to determine position or speed of component

Gyros

• Gyro
  • A gyro can be used to measure the robots heading (which way it's facing), usually relative to a calibrated zero
  • Value reported as a rotation rate which is integrated to determine heading
  • Interface can be serial (ADXRS450) or analog (ADW22307)

IMUs

• Inertial Measurement Unit (IMU)
• Combine multiple sensors for multi-axis position indication
  • Typically at least a Gyro and Accelerometer
  • Can also include Magnetometers, temperature sensors, etc.
• Typically provides roll/pitch/heading
• Some can also provide translation/offset relative to starting position (field oriented).

Camera

• Used for drive team situational awareness and Autonomous robot navigation
• Connect to robot over Ethernet or USB
• Important performance characteristics
  • Resolution (more is not nesc. better)
  • Exposure (calibratable)
  • Image latency

Pneumatic Systems

Topics to cover

• Pneumatic components
• Pneumatic controls

Air Compressor

• Convert electric energy into compressed air
• VIAR 90C
  • Runs off 12VDC, ~10A
  • Rated at 9% duty cycle!!!

Air Tanks

• Clippard tanks store 574ml of air ea.
• Max 125 PSI

Pressure relief vlave

• Releases pressure out of system when above "safe" set point

Pneumatic Actuator (Cylinder)

• Linear actuator
  • Two "ports", one at each end
  • Rod down the middle
  • Tail end of rod seals against inner wall of cylinder
  • Pressure difference across the seal causes rod to extend/retract

Pneumatic Actuator (Cylinder)

• Extend cylinder
  • Apply pressure to the left of the seal
  • Vent pressure from the right of the seal

• Retract cylinder
  • Apply pressure to the right of the seal
  • Vent pressure from the left of the seal

Solenoid Valve

Electrically control air flow.

• Solenoids in FRC are either 12 or 24V
• We typically use "5/3" double solenoid valves
  • 5 physical ports (holes) on it
  • 3 positions the valve can be in
• Called "double" solenoids because each valve has two solenoids.
• The solenoids are coils of wire
• When electricity flows through them it creates a magnetic field.
• The magnetic field causes the valve to port air in different directions

Solenoid Valve

What do these symbols mean?!@#

Solenoid Valve Positions

Pneumatics Control Module (PCM)

Allows control of pneumatics components over CAN bus

• Turn compressor on/off compressor
• Control up to 8 solenoid channels
  • 8 single acting solenoids
  • 4 Double solenoids

Lab

Topics to cover

• Personal Safety
• Robot Safety
  • Yes, Robots have feelings too

Personal Safety

• Safety is always a number one priority
• We want to keep ourselves safe at all times

• Cutting tools 
  • Flush cutters
  • Scissors
  • Strippers

• Heating tools 
  • Soldering Iron
  • Heat gun

• Crushing/Impact tools 
  • Crimpers

• Common shop tools
  • Screw drivers
  • Wrenches
  • Pliers
  • etc.

• Machinery
  • Band Saw
  • Drill Press
  • Drills