Transcript Deon Blaauw Modular Robot Design

Deon Blaauw
Modular Robot Design
University of Stellenbosch
Department of Electric and Electronic Engineering
Why Design a Robot?

During the Last Decade a Renewed Interest in the Field
of Robotics – Most Research Involving Multi-Robot Teams

Today, Robots are Used to Explore Terrain Dangerous or
Inaccessible to Humans



Aim is to Develop a Modular Embedded Autonomous
Agent (Robot) that can be Upgraded and Expanded as
needed
Primary Goal – First Prototype Must Be Modular Enabling
Different Versions with Different Capabilities to Be
Developed from the Base Model
Secondary Goal - First Prototype Will Demonstrate
Engineering Principles to Prospective Students
Achieving Flexible Design




The Current Robot Exists out of Layers, With Each
Additional Layer Improving Overall Robot Functionality
Layers are Asynchronous Modules Communicating With
Each Other – Each Individual Module Possesses Some
form of Computational Ability
For the Robot to Achieve More Complex Tasks, Higher
Level Modules With Extra Responsibilities can be Added
The Result of the Design is a Very Flexible and
Expandable Robotic Vehicle
Base Prototype Overview



Commands Issued From
Remote Control Station
Drives Forward,
Backwards or Steers
Differentially
Local Obstacle
Detection – A Set of
Proximity Sensors
Prevents Collisions With
Obstacles
Enabling Motion




Four 12V DC Motors
Power to weight
ratio - 213mW/g
Gear ratio – 25:1
Robot Weight – 2kg
Current System
Motor Driver Circuitry

Dual Full-Bridge Driver IC

Bi-directional motor motion

Differential steering


Internal Diagonally
Opposed Switches are Pulsed
10kHz PWM Frequency
Current System
Embedded Motor Driver
Controller





dsPIC30F4011 Microcontroller
20MIPS
Multi-Master CAN useful in Noisy
environments
UART Module
allows PC to
control Robot Motor Drivers Directly
Voltage Feedback
Current System
Embedded Sensor and Radio
Communication Controller




Monitors Cheap Infrared Proximity Sensors – Detects
Reflected Infrared Light from Objects Between 400mm
and 600mm away. Every Sensor Has Unique Operating
Frequency – This Limits Sensor Cross-Talk
Sends Commands to Motor Controller Module via CAN
at 833kbps
Supports 1.25MHz SPI Interface for Radio Link
UART Enabled Allowing Direct Computer Control of
Sensors and Data Link
Radio Frequency Data Link




Operating at
915MHz
Byte Long Data
Length sent From
Monopole Antenna
Re-transmission of
data prevents
information loss
Ready for next
command in 1.81ms
Current System
Remote Control Station




Save Development Time
by Using Same PCB as
the one Monitoring the
sensors
Powered From 9V
battery
Range Confirmed at 10
meters
Serial Communication
with a PC Allows an
alternative
communication Method
Power Supply and Voltage
Levels




Distributed
Voltage
Regulation
Star Grounding
Minimum of 1.6
Hour Battery
Life
7V – 16.5V
Operating
Voltage
Conclusion


Highly Modular Design Approach Using a CAN Interface was
Followed - Simplifies the Addition of Further Functionality
and Allows Expansion of the Current Prototype

The Current Prototype Has Four Full-Bridge Drivers
Controlled By a Dedicated Microcontroller

A Separate Microcontroller Controls Proximity Sensors
Aiding in Collision Avoidance

An External Controller Communicates via Radio Link With
Robot Receiver Sub-System.
Able to Act as Test-Bed for a Variety of New Technologies
and Clearly Illustrates a Broad Array of Applied Engineering
Principles
Conclusion

Some Engineering Principles Employed During
Development:









Power Electronics
Embedded Programming
Digital Circuits
Analog Electronics
Radio Frequency Communication
Power Supply and Grounding Techniques
Physics
Mechanical Design
Prospective Students are Shown that Applied
Engineering Sciences can Lead to Exciting and Very
Rewarding Projects
Demonstration