REV FIRST Global User manual

FIRST Global Building Guide Created by REV Robotics 2019, Licensed Under CC BY-SA
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FIRST Global Building Guide

FIRST Global Building Guide Created by REV Robotics 2019, Licensed Under CC BY-SA
TABLE OF CONTENTS
1INTRODUCTION ...................................................................................................................................................................... 1
1.1 HOW TO USE THIS GUIDE ............................................................................................................................................. 1
1.2 REQUIRED TOOLS .......................................................................................................................................................... 1
2ELECTRICAL COMPONENTS.................................................................................................................................................. 2
2.1 ELECTRONICS................................................................................................................................................................ 2
2.2 SYSTEM WIRING DIAGRAM .......................................................................................................................................... 4
2.3 DC MOTORS ................................................................................................................................................................... 5
2.4 SERVO MOTORS ............................................................................................................................................................ 6
2.5 SENSORS........................................................................................................................................................................ 7
2.6 BATTERY ........................................................................................................................................................................ 8
3MECHANICAL COMPONENTS ............................................................................................................................................... 9
3.1 EXTRUSION .................................................................................................................................................................... 9
3.2 BRACKETS...................................................................................................................................................................... 9
3.3 JOINTS ......................................................................................................................................................................... 12
3.4 BRACKET ASSEMBLY TECHNIQUES .......................................................................................................................... 14
3.5 BEARINGS .................................................................................................................................................................... 16
3.6 LINEAR MOTION V2..................................................................................................................................................... 19
3.7 HINGES......................................................................................................................................................................... 23
3.8 HARDWARE.................................................................................................................................................................. 23
3.9 ADAPTERS ................................................................................................................................................................... 27
3.10 MOTION COMPONENTS ............................................................................................................................................. 28
3.11 WHEELS........................................................................................................................................................................ 29
3.12 SPROCKETS AND CHAIN ............................................................................................................................................ 31
3.13 GEARS .......................................................................................................................................................................... 34
3.14 PULLEYS AND ROUND BELT....................................................................................................................................... 37
4BASIC BUILDING GUIDE ....................................................................................................................................................... 38
4.1 DRIVE TRAIN GUIDE .................................................................................................................................................... 38
4.2 ARM GUIDE .................................................................................................................................................................. 41
4.3 MINI ROBOT EXAMPLE ............................................................................................................................................... 41
ALL COMPONENTS (1:1 Scale) ................................................................................................................................................... 42

FIRST Global Building Guide Created by REV Robotics 2019, Licensed Under CC BY-SA 1
1INTRODUCTION
1.1 HOW TO USE THIS GUIDE
This guide is intended to be an introduction to the REV Robotics Building System that is being used in FIRST Global. The
goal of this document is to give an overview of the parts included in the system and some example building techniques
which will make building your robot easier. The system itself was designed with flexibility in mind, where every bracket
and part can be mounted in infinite locations along the REV Rails, making it easier to tune your design and speed up
iterations.
There are already lots of examples in this document, but we’re committed to continuing to add content to keep making it
more accessible for people to build with REV.
Feel free to pick out specific sections of interest and read those, there is no need to consume this document in any
sequential method.
1.2 REQUIRED TOOLS
The REV Robotics 15mm Building System for FIRST Global only requires a few basic tools. Please see Table 1 for
recommendations.
Table 1: Recommended Tool List
Tool
Required
Use
5.5mm Nut Drive
Yes (Included)
M3 Hardware
5.5mm Combination Wrench
Yes (Included)
M3 Hardware
1.5mm Allen Wrench
Yes (Included)
M3 Shaft Collars
2mm Allen Wrench
Yes
Linear Motion Kit
Small Pliers
Optional
Working with Chain
Chain Breaker
Optional
Working with Chain
Hack Saw
Yes
Cutting Extrusion
Chop Saw
Optional
Cutting Extrusion
Band Saw
Optional
Cutting Extrusion
Diagonal/Flush Cutter
Optional
Trimming Brackets to Customize
File/Sandpaper
Optional
Trimming Brackets to Customize

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2ELECTRICAL COMPONENTS
2.1 ELECTRONICS
2.1.1 Introduction
Robots are made up of mechanical structures and the electrical components that move and control them. Electronics is a
broad category which includes motors, sensors, and programmable controllers or hubs. The REV Robotics Building
System has two kinds of Hubs: Control Hub and the Expansion Hub (Figure 1). The Control Hub has an integrated
computer module running Android and is where the robot code runs, while the Expansion Hub only provides a break out of
additional ports. Please note that every robot must have one Control Hub, but adding an Expansion Hub is optional.
Figure 1: Control Hub and Expansion Hub
2.1.2 Hub Ports
Figure 2: Control Hub and Expansion Hub Rear Ports
Mini USB
This connector is used for firmware updates
USB 1 and 2
Are used for connecting peripheral devices such as a keyboard and mouse. (Control
Hub Only)
Micro USB
Used to download robot code from a computer. (Control Hub Only)
HDMI
Connect an external monitor. (Control Hub Only)
Micro SD
Accepts a standard MicroSD memory storage card which can be used for data
logging. (Control Hub Only)

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Battery
The battery connectors are a pair of male and female XT30 Connectors. Connect the REV
Robotics 12V Slim Battery (REV-31-1302) to either connector. If your robot has both a
Control Hub and an Expansion Hub you can use a battery extension cable to connect power
between the two.
DC Motor Power
Connect motors to the hub’s four built in speed controllers using these ports. The connector
is a 2-pin JST VH connector.
DC Motor Encoder
Each motor has an encoder built-in. Connect the encoder cable to the same port that the
motor is powered from. The connector is a 4-pin JST PH connector.
Servo Motor
Connect up to six Servo motors. The connector is a standard 0.1” Pitch male header. This
connector is not keyed, so be sure to connect it in the correct orientation.
+5V Power
Auxiliary 5V power for robot accessories. The connector is a standard 0.1” Pitch male
header. This connector is not keyed, so be sure to connect it in the correct orientation.
Analog
Analog input for 0-3.3V sensors. The connector is a 4-pin JST PH connector.
Digital
Digital input or output for 3.3V digital devices. The connector is a 4-pin JST PH connector.
I2C
There are four 3.3V compatible I2C buses. Multiple I2C devices can be connected to the
same port, as long as they each have a different address. See the I2C sensor section for
more details. The connector is a 4-pin JST PH connector.
RS485
This port is used to communicate between the Controller Hub and an Expansion Hub. The
connector is a 3-pin JST PH connector.
UART
This port is output only and used for debugging. The connector is a 3-pin JST PH connector.
Status Indicator
LED indicator for robot mode and for debugging
Button
This button is used to pair the Controller Hub with the Robot Driver Station and can also be
programed to have additional functions.

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Most of the connectors on the Control Hub and Expansion Hub are keyed, meaning that the connector is shaped so that it
is not possible to plug the cable in backwards. The Servo Motor ports and the 5V Power ports are not keyed and the pin
out is shown in Figure 3Figure 3
Figure 3: Servo and 5V Power Port Pinouts
2.2 SYSTEM WIRING DIAGRAM
Figure 4: System Wiring Diagram

FIRST Global Building Guide Created by REV Robotics 2019, Licensed Under CC BY-SA 5
2.3 DC MOTORS
DC motors are used to power wheels and control moving robot parts, like arms. The Core Hex DC Motor (Figure 5)
included in the FIRST Global Kit has a 5mm hex socket drive shaft surrounded by six m3 mounting holes on both sides
called the Motion Interface Pattern. The back of the motor has a 2-pin connector for power and a 4-pin connector for an
encoder cable. The normal rotation, the direction of spin when the motor is going “forward,” is marked with an arrow on
the front of the motor.
Figure 5: Core Hex DC Motor
Both sides of the Core Hex motor have a Motion Interface Pattern for bolting to any of our motion brackets (see Table 2).
The Motion Interface Pattern consists of six evenly spaced bolt holes. The bolt hole pattern on both sides of the motor
allow it to be mounted in multiple orientations (Figure 6).
Figure 6: Core Hex Motor Front and Back Mounting Plates
The offset between the front and back mounting plates shown in Figure 6 enables the motor to be mounted at 12 different
motor orientations, including vertical and horizontal when both sides of the motor are used. Figure 7 below shows a
horizontally mounted motor which is flipped from the vertical motor with the front facing out. Note that when the motor is
flipped, the direction that the shaft spins is also flipped.
Figure 7: Core Hex Motor Mounting Options

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The female hex shaft of the Core Hex Motor allows for any length 5mm hex shaft to be inserted through the body of the
motor (Figure 8). The motor can drive wheels or gears on either side of the shaft, or a single shaft can be put through
multiple motors to increase the power. If multiple motors are used on a single shaft, be sure that they are being controlled
in the same direction to prevent damage.
Figure 8: Hex Core Motor Mounted with 5mm Shaft Inserted
2.4 SERVO MOTORS
Servo motors are a specialized kind of motor which can be controlled to move to a specific angle instead of continuously
rotating like a DC motor. Instead of a hex output shaft like the DC motor, servos have an output spline (Figure 9). A spline
is a specific groove pattern cut into the shaft which allows the rotation of the servo motor to be transmitted to the
attached Aluminum Servo Horn or Servo Adapter (see Table 6). Splines are like keys, so only matched types will fit
together. The REV Robotics Servos all use a 25T spline pattern. If the gears or spline of the REV Robotics Smart Robot
Servo become damaged, they are replaceable using a Replacement Gear Set. See the Replacement Gear Guide for
instructions.
Figure 9: Servo Motor
Common servo motors take a programmed input signal range and map that to an angular range. For example, for a servo
with a 180° range, if the input range was from 0 to 1 then a signal input of 0 would cause the servo to turn to point -90°.
For a signal input of 1, the servo would turn to +90° (Figure 10). Inputs between the minimum and maximum have
corresponding angles evenly distributed between the minimum and maximum servo angle.
Figure 10: Servo Motor Angular Mode Output

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The REV Robotics Smart Robot Servo is a programmable servo that can switch between standard servo mode, continuous
rotation, and custom angular modes. To unlock these modes, use the SRS Programmer to configure and test the Smart
Robot Servo. See the SRS Programmer User’s Manual for specific information on how to configure the Smart Robot Servo.
2.5 SENSORS
2.5.1 Analog Sensors
Analog sensors provide measurement data within a continuous range by measuring the voltage output of a sensor.
Analog sensors are good for measuring things like angle of rotation, brightness, and distance because the data they
provide spans a continuous range which would correspond to angle, intensity, and range, respectively.
Sensor
Description
Potentiometer
Potentiometers have a limited measurement range of 0° to 180° and will be damaged if they
are forced to rotate farther. The potentiometer has a 5mm hex socket and a Motion Interface
Pattern. Connect this sensor to a shaft to measure the angle of rotation of the shaft. A typical
example is using a potentiometer to measure the angle of a robot arm.
2.5.2 Digital Sensors
Digital sensors are very simple to use because they only provide one single piece of data, which is either a 0 or 1. A good
example of a digital sensor is a limit switch. The switch is either pressed (1), or not pressed (0).
2.5.3 I2C Sensors
I2C is a common electronic communication standard that allows a master device, the Hubs, to communicate with
multiple devices, slaves, attached to the same port. Each connector on a Hub is a separate I2C bus and many different
sensors can be connected to each of the four I2C busses available on both the Control Hub and Expansion Hub. Every I2C
slave device has an address, a number, which is normally fixed by the manufacturer. All of the devices on an individual I2C
bus must have a unique address so that the master can communicate with one sensor at a time. If two devices have the
same address, such as when using two of the same kind of sensor, they must be used on different I2C busses.
Sensor
Address
Description
9-Axis IMU
0x28
Each Control Hub and Expansion Hub has an 9-axis IMU (inertial measurement unit)
built-in connected to I2C Port 0. An IMU uses built in accelerometers, gyros, and
magnetometer to collect data about how it is being moved around and then
combines all of those measurements to provide more accurate data about the
speed, rotation and heading of the robot.
Color/Distance
0x39
This sensor can be used to detect specific primary colors or measure the distance
to an object that is within 10cm.
2.5.4 Encoders
Encoders convert information about the rotation of the motor shaft into electrical signals that can be read by the Control
Hub. Inside the Control Hub these electrical signals can be used to provide real world data to make better programming
decisions. For example, a programmer can use this information to calculate how far the robot has gone or how fast a
wheel is spinning. Every DC motor from REV Robotics comes with a quadrature encoder already installed. The encoder
cable should be plugged into the same port from which the motor is powered.
The encoder is a relative encoder, which is also referred to as incremental encoder. It provides information about the
motion of the shaft (e.g. forward at 5 RPM) and only provides data while the shaft is rotating. Stated another way, relative
encoders return information on the incremental change of the motor output shaft. and only provide pulses as the motor
turns; interpreting these pulses into useful information must be done externally in the Control or Expansion Hub. A

FIRST Global Building Guide Created by REV Robotics 2019, Licensed Under CC BY-SA 8
relative encoder does not know what position it is in when it is turned on, but it is possible to create a calibration program
that can be run at every start-up to obtain a reference point from which to calculate an angle.
The encoder uses four wires, 3.3V Power, Ground, Channel A and Channel B to communicate data back to the Hub (Figure
11). When the motor is rotating, the Hub can calculate the direction and speed of the motor.
Figure 11: Encoder Connector Pinout
2.6 BATTERY
The Slim Robot Battery for FIRST Global is a 12V 3000mAh NimH battery with inline 20A mini ATX fuse for protection
(Figure 12). The battery has a female XT30 Connector. This connector is polarized so that the battery cannot be plugged
in incorrectly.
Figure 12: Slim Robot Battery
2.6.1 Battery Safety
Batteries store tremendous energy in a small size and it is important to take care of your batteries to keep them in good
working order and to prevent dangerous conditions.
-Batteries should only be charged with approved chargers
-Never leave a charging battery unattended
-Do not leave a battery plugged into a robot when it is not in use and avoid other cases where a battery will be
accidentally over discharged
-Batteries should be fully charged before they are put in storage for extended periods
-Properly dispose of any battery which has been damaged or which shows any signs of excessive heat or melting