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Autonomous Sensor and Control

Platform Rover

Tae Lee

Josh Reitsema Scott Zhong

Mike Chao

Mark Winter

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Detailed Subassembly

Scott Main control and Processing

Tae Motor Control Hardware

Mark

Sensor interfaces Mike Wireless Communications

Josh Video and High Level Control

Software

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System Overview

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Mainboard

68HC11K1

XCS10

EPROM and SRAM Bus Drivers

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Motor Controls

What we have: Two Pittman GM8000 series DC GearMotors

HEDS-9000 series optical encoder

The plan:

Use two LMD18200T H-Bridges to control the motors PWM is used to control speed (Duty Cycle)

High/Low logic for direction

Brake feature

HEDS 9000 series optical encoder These will give rotational/direction information of each motor

HCTL 2020 Decoder 16-bit Decodes quadrature signal from the HEDS-9000

Outputs a count (rotational speed) and direction signal

Provides interface to MPU

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Motor Current Delivery

H-Bridge

Use two LMD18200T H-Bridges to control the motors Duty Cycle of PWM determines current sent to motors (Speed) Direction pin determines which way the motor spins

Brake Pin Thermal sensor

Note: Optical Isolation between MPU and H-bridge

FROM THE MOTORS

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HEDS-9000 Encoder/HCTL 2020 Decoder

HEDS-9000 Optical Incremental Encoder Module Used with a code wheel, detects rotary position (Shaft Encoder) Fairy accurate 500 CPR (counts per revolution) Produces two signals which need to be decoded

HCTL 2020 Decoder Decodes two signals into a count signal and direction signal The decoded signals are available on external Pins (5 & 16) Provides bus interface between encoder and MPU/FPGA Operates well in noisy environments (Motors)

Note: Optical Isolation Between Decoder and FPGA

To the MPU/FPGA

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MPU / FPGA

FPGA Create latches in FPGA, work as registers

Registers hold decoded position information

The registers are updated continually with new position

information (we can control how often it latches the new signal)

HC11K1 When needed, goes out to FPGA and grabs contents of register

HC11 will use information and compute PWM adjustments

PWM is sent out from HC11

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Recent Discovery

LMD18200T with a LM629 Motion Control Device

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The Sensor Subsystem andInterface

Polling logic in the FPGA requests datafrom a sensor address on the sensoraddress bus.

The sensor addressed is enabled and getsdata, which it outputs to the sensor databus.

The data is taken off the sensor data businto a memory mapped latch and thepolling logic continues to the next address.

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Advantages

This interface should allow for the additionof several more sensors without anyhardware changes as long as they have a

unique address

This interface could be modified to use theI2C bus interface, thereby reducing the

sensor interface footprint.

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Schematic for Polling Logic

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IR Sensors/Driver

Upon enable, begin outputting a clocksignal of ~38kHz to IR LEDs.

Wait a few clock cycles. Then enableoutput from all 6 of the IR sensors andplace it on the data bus.

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Schematic for IR Sensor/Driver

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Ultrasonic Sensor/Driver

Once enabled send a single pulse of widthperiod ~25.3us to selected transducer unit.Begin counting time units.

Blank input from transducer for a shortperiod in order to avoid hearing the soundas it leaves.

Once input is received stop counter andoutput its value to the data bus.

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Simplifications

In order to get the sensor interface up andrunning, we will put all of the logic into theFPGA, which means that the interface will

be internal to the FPGA for now.

One of the possible extensions would beto use a second FPGA or discrete logic so

that other sensor could indeed be addedon at a later date.

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WiFi communication

Lantronix WiPort

Communicates with HC11 usingRS232

Wireless gateway for RS232transmission

Advertised indoor range of 300 ft.

Bandwidth limited by serial clock

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RS232

HC11 uses a UART with the standardnon-return-to-zero format

Same format as RS232

Selectable bit rate up to 20 kbps

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SCI (Port D) Pinouts

RXD receive data pin 2

TXD transmit data pin 3

GND ground pin 5

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Sample Transmission

Received interrupt from RDRF (received data register full

Read from input buffer SCDR

Decode the character received

Change the duty cycle of the PWM output.

Write toPWDTY1/2

DecodeTransmission

Read FromSCDR

Interrupt FromData Register

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Web Based Control

The wi-fi creates an IP-address for a web pagewhich is where the user interface will be located.

The web-page will utilize Java applets as a GUI

for the user to send information to the robotsuch as turn, or speed up, run presetautonomous programs, etc. and also to receiveinformation such as video and positioningmeasurements in a user friendly manner.

The web-control basically will call basic subfunctions that are preset into the ROM or RAMwhich will then send instructions to the motorcontroller.

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Video System

The video camera will be mounted into thefront of the robot

The data will not be sent through the wi-fidue to bandwidth concerns

A button on the webpage will access thedirect feed through an applet

No significant processing of the video willbe done

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Example Webpage

Autonomous Control and Sensor Platform Rover

F

R

B

L

KILL SWITCH

Open Video Applet

Velocity

Incoming Data:

X: 1.8 M

Y: 25 M

Speed : 3 m/sec

...

Wall Follow

Search Area

Avoid Objects

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Parts List

Rover (Pebbles III) $0

H-Bridge and Control Circuit $100

Lantronix WiPort $300

Mainboard and FPGA Charge it to Tom

IR and Sonar Included

Baby Monitor w/Video Capture $400

Quality hours spent in Capstone Priceless

Total $800

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Schedule

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Thanks