Team SpotA Cooperative Robotics Problem

A Robotics Academy Project:Laurel Hesch

Emily Mower

Addie Sutphen

Project Goal

Develop a team of autonomous robots that will, within a fixed boundary:

–Communicate with each other–Locate a spot of light on the Robotable–Follow the spot of light as it moves across table

Last Semester Lego Prototype

• 1 mobile Lego RCX robot

• 2 stationary Lego RCX robot

Stationary RobotMobile Robot

Last SemesterFirst Prototype

• Team of 1 mobile and 2 stationary robots.

• PVC Body

• PIC chip microprocessor

• IR communication

This Semester

• Development Process– Prototype

• Evaluated first semester prototype • Prototyped new robots

– Programming and EE Design• Added complexity to the problem• Developed new and more accurate algorithms• Developed more accurate communication system

– Production• Modified prototype • Final build

Meet the RobotsLucy, Ray and Zoolander

Lucy Ray Zoolander

Completed Robot Team

• Old Elements– PIC chip

microprocessor• Reliable and easy to

use.

– Robot Motors and wheels

• New Elements– Body

• New, robot friendly, body design

• Sleek Lexan Material

– Communication• Long range bluetooth

• More reliable communication

– Programming• New computation

algorithm

Product Research

• Mobile robots, autonomous robots, robot teams

• Robot Body Design

• Communication between robots

• Microprocessors

ElectricalOOPic Chip

• Programming Language: Object Oriented Basic

• 31 I/O pins and additional voltage sources for device interface.

• Voltage source used for Bluetooth communication, the servo motors, and the photo-resistor circuits.

ElectricalMotor Control

• Microprocessors control all servo motors• Due to highly variable torque- constant motion

across motors has not been established• Robot Motion

– Controlled pulses sent to servo motors

– Mobile Robot: Calculated using a set of trig functions (will be discussed later)

– Stationary Robot: Determined through trial and error

ElecticalLight Sensing

• Simple photo-resistor placed in series with a resistor– Output voltage measured at the junction of the

two resistors

• Voltage level inputted to microprocessor using the analog to digital converter

• Accuracy hampered by ambient light spots brighter than the spot being sought.

AlgorithmsFlowchart of Functionality

Stationary robots scan for position of brightest light.

The position of the greatest spot is transmitted via Bluetooth to the mobile robot.

Mobile robot reads in light value

Interprets value using trig functions

Mobile Robot moves to correct position

AlgorithmsStationary Robot Algorithm: 1

• Goal:– Determine location of spot of greatest light

intensity– Convert location into angle measure– Transmit angle measure to mobile robot via

Bluetooth (to be discussed later)

AlgorithmsStationary Robot Algorithm: 2

• Method:– Sweep through 90 degrees– Number of stops depends on strength of battery– Store location of greatest light and covert to the

range accepted by the OOPic sine function

AlgorithmsMobile Robot Algorithm: 1

• Goal:– Given angle measurements from stationary

robots compute location of spot of light– Advance to spot of light– Find new spot of greatest light intensity– Follow new spot

AlgorithmsMobile Robot Algorithm: 2

• Method:– Using sine functions on OOPic chip calculate

location of spot of light– Advance to spot of light using pulses of motor– Once at spot of light, rotate 360 degrees to find

the new spot of greatest light intensity– Follow the new spot by keeping the light

between the three light sensors on front

AlgorithmsMobile Robot Algorithm: 3

CommunicationsThe need for wireless

• Goal:– Send angle measurements serially between

stationary and mobile robots.

• First Semester: Infrared communications

• Second Semester: Bluetooth communications

CommunicationsInfrared

• Serial infrared communication was attempted in the first semester.

• Problems:– The range was too small.

– Significant accuracy problems.

– True serial communications was not established, meaning that pulses representing angle measurements had to be sent.

– This adaptation added an additional level of inaccuracy.

CommunicationsBluetooth

• Bluetooth is a open platform communications protocol for short distance, high throughput, low power communications. 

• Advantages:– Range up to 30 feet.– A master device can potentially connect with up to 8

slave devices at a time.– Each device has a unique 48 bit address, which results

in highly accurate identification.– Bluetooth is also very low power (1mW)

CommunicationsBluetooth Operation

M o bile R o b o t ca lcu la te s p o s it io n a n d m o ve s to d es tina tion

M a s te r # 2 d isco n n ec ts fro m S la ve

T ra n sm its lig h t an g le va lue

M a ste r #2 co n n ec ts to S la ve

M a s te r # 1 d isco n n ec ts fro m S la ve

T ra n sm its lig h t an g le va lue

M a s te r # 1 (s ta tio n a ry ro b o t) con n e cts to s la ve (M o b ile R o b o t)

MechanicalMotors and Gearing

• Hitech HS-422 Motors – Purchased from Lynx Motion

– Modified for continuous rotation

• Gearing – Removed internal gear

– Geared down stationary robot motors

MechanicalBody Design

• Last semesters design large and bulky– Square shape interfered with light sensing

• Developed round design – In scale with Robotable

– Concurrent with light sensors

– Better mobility

MechanicalSecond Prototype – Mobile Robot

Mechanical Stationary Robot Drawings

MechanicalMobile Robot Drawings

MechanicalSecond Prototype

MechanicalSecond Prototype

Mechanical Final Design

Ray Zoolander Lucy

Opportunity for Future Research

• Continuing Bluetooth robotic applications

• Implementation of full Bluetooth functionality

• Algorithms to find multiple spots

• Integration of chemical “nose”

• Expansion of robot team

• Integration of multiple robot teams

Special Thanks

• James the Bluetooth Man

• Warren Gagosian

• Chris Rogers

• Matt Dombach

• Jim Hoffman

• Robotics Academy Professors

• TUFTL lab

DemoCross your fingers