Introduction
Scamper is an omni-wheel based robot kit designed for students and hobbyist. The kit
comes in a high quality case and includes all parts and tools needed to make a line
following or maze solving robot. No soldering or programming is required.
Features
Pre-programmed ComMotion controller.
Six omni wheels with natural rubber rollers.
Three geared motors with metal gears.
Three hall effect sensors.
Three magnetic encoder discs.
Anodized aluminium chassis.
Battery holder (6x AA) with power switch.
IR sensor PCB.
Can be programmed with the Arduino IDE.
Optional Arduino can be added for more functionality.Ideal for Beginners
This is an ideal kit for beginners who have not learned to program but want to build a robot.
The ComMotion controller has several demonstration programs built in.
When the robot first powers up it will play a tune using the motors as speakers and wait a few seconds for any I2C command from an external controller or serial command from an optional Xbee module.
If no I2C or serial commands are received then it runs the demonstration software and will cause the motors to beep to indicate what mode it is in.
Pressing the reset button while in demonstration mode causes the robot to switch between maze solving and line following modes. The motors will beep to indicate which mode is selected.
Part List
6x Omni wheel with rubber rollers
1x Anodized aluminium chassis
1x Pre-programmed ComMotion controller
1x IR sensor PCB with adjustable sensitivity
1x IR sensor PCB mounting bracket
1x IR sensor cable
1x 6x AA battery holder with 5A power switch
1x Fiberglass battery strap
3X 78:1 geared motor with metal gears
3x magnetic encoder disc with rubber hubs
3x Hall-effect sensor
3x 4mm fiber washer
4x 25mm brass spacer (male to female)
4x 12mm brass spacer (female to female)
2x 17mm brass spacer (female to female)
4x 3x10mm screws
4x 3mm nyloc nut
8x 2.5x8mm screws
15x 3x6mm screws
15x 110mm cable tieComMotion Controller
This controller uses two ATmega8A processors that communicate with each other and any external controller using the I2C protocol.
Although the board is configured as an Arduino R3 shield it can be used with almost any external processor (3.3V or 5V). The I2C pullup resistors are connected to the IO ref pin.
This allows 3.3V or 5V to be selected.
The I2C address of the controller can be selected using 4 dip switches. Advanced users can store additional address data in the EEPROM to access a larger range of addresses if required.
Each ATmega8A processor monitors 2 encoders and 2 current sensors to control the speed and direction of 2 motors as well as providing over current protection.
Arduino Motor Control Shield
As an Arduino shield, the controller does not use any pins except for SDA and SCL. This
leaves all your other pins free for other shields. ComMotion is easy to use and has preprogrammed configurations for 3 omni wheel, 4 omni wheel or 4 mecanum wheel. In these
modes you simply need to send 3 integers over the I2C bus: speed, angle and rotation. A
fourth mode allows each motor to be controlled individually.
Wireless Control
The robot requires a pre-configured Xbee module to be plugged into the provided socket.
The controller will then accept commands from the Xbee module as well as the I2C interface.
Programming
Experienced users can re-program the two ATmega8A processors using an Arduino
running the ISP programmer sample code and the Arduino IDE. A switch on the controller
lets you choose which processor is connected to the ISP socket.
Interfacing
FTDI headers provide access to each processors serial port allowing serial devices such as LCD displays and Bluetooth modules to be connected. 5 spare analog pins are also available along with Vcc and Gnd in a servo style header.
Kit Specifications
Chassis: 2mm thick anodized aluminium
Rollers: Natural rubber
Battery: 6xAA
Motor voltage – nominal: 6V
Motor voltage – maximum: 8.4V
Motor current – no load: 150mA
Motor current – stall: 2.75A @ 6V
Gearbox ratio: 78.125:1
Encoder disc: 8 pole neodymium magnet
Encoder sensor: Open drain hall-effect sensor (3V – 22V)
Encoder resolution: 625 state changes per wheel revolution
ComMotion Specifications
Processors: 2x ATmega8A (16MHz)
Input voltage: 6V – 16V
Logic voltage: 5V @ 500mA
Wireless support: Xbee / WiFly socket with voltage translation
Xbee / WiFly power: 3.3V @ 300mA
Battery monitor range: 0V – 17V
Battery monitor resolution: ≈0.02V
Analog Inputs: 5x 10bit (A3,A6 MCU1 – A3,A6,A7 MCU2)
Motor drivers: 4x FET “H” bridge
Motor current continuous: 2.5A (each motor)
Motor current stall: 4A (each motor)
Current monitor range: 0A – 5A (each motor)
Current monitor resolution: ≈5mA (each motor)
I2C bus speed: 100 kbit/s
I2C addresses: 16 selectable pairs (software configurable)
Serial ports: 2x 5V TTL logic (FTDI sockets)
