bharath ramaswamyembedded and telepresence control of a 3-axis smart wheel demonstrator12-02-2004...

Bharath Ramaswamy Embedded and Telepresence Control of a 3-Axis Smart Wheel Demonstrator 12-02-2004

Embedded and Telepresence Control of a 3-Axis Smart Wheel Assembly

Bharath Ramaswamy

December 2, 2004, MS (Plan-B) Thesis DefenseDecember 2, 2004, MS (Plan-B) Thesis Defense


Presentation Outline

• Smart Wheel Background

• Stand-alone Demonstrator

• Existing System

• Hardware

• Software

• System Limitations

• Future Work

• Videos and Demonstration


Smart Wheel Background

• CSOIS Robotic Vehicles• T1, T2, T3, ODIS

• Smart Wheel Concept

• Omni Directional Vehicle (ODV)

• Enhanced Smart Wheel


Stand-alone Smart Wheel Demonstrator

• Prototype Smart Wheel Assembly

• Stand-mounted• My Goals

• Joystick Control• Telepresence Control

• Outcomes ???


Smart Wheel – Mechanical


Smart Wheel – Existing Vectronics


TT8 Microcontroller

• Tattletale Model 8 (TT8) from Onset Computer Corporation

• Brain of the “Smart” wheel• Processors

• Motorola 68332• PIC 16C64

• Features• RAM 256K• Flash 256K• ADC 8-Channel • TPU I/O Lines 14• RS232 Ports – 2• Hardware RTC

• Programming• ANSI C or TXBASIC


Wheel Node Digital Interface Board

• Interfaces TT8 Controller with the Master Node and Motors.

• Modules• Power supply• TT8 Controller interface• Motor Driver interfaces• Wheel Encoder interfaces• RS232 line drivers• Wheel watchdogs• Optical Isolation


Smart Wheel – Existing Software

• Aztec C cross-compiler• MicroC/OS• Low Level Controllers

• Drive Control• Steering Control• Command Listener• Evaluate Command• Service Watchdog• Miscellaneous


Summary of Modifications

• Z-Axis Control• Telepresence control not possible with all-hardware solution.• Provide interface for z-axis control box with TT8 controller.

• Joystick(s) Interface

• Ethernet-Serial Interface• For telepresence control.• Method to communicate between remote PC and TT8 controller on

wheel node.

• Arbitration• Ensure predictable behavior during simultaneous access attempts by

joystick operator and multiple remote operators.


Hardware Architecture


Joysticks and Interfacing

Fig. Circuit for ADC input protection.

Fig. Selected joysticks: (a) 3-axes joystick (b) single-axis joystick


Modification to Z-Axis Controller

• DAC:• TI TLC5615.• 10-Bit Serial.• QSPI, SPI, Microwire.

• Interface• Using General-purpose

Port pins of TT8.• Analog Output to Vin of

Control Box.

Fig. TLC5615 DAC Package.

Fig. Interfacing the DAC with the TT8 controller and the z-axis circuitry.


Auxiliary Board


Serial Server

• Purpose• Connect wheel node with the

Internet.• Assigns wheel its own IP

Address.• TCP/IP RS232.

• NPort DE-311 Serial Server from Moxa Tech.• 10BaseT and 100BaseT

Ethernet.• Multiple modes.• Multi-OS support.


Internet Camera

• Camera + Computer• Built-in Web server• Configurable IP Address• Direct connection to Hub• DLink DCS 5300

• Video and Audio streaming

• 30 fps at 640x480• Pan, Tilt, Zoom capability• Low-cost


Software Architecture


Wheel Node Development Platform

• TT8 Controller• Aztec C

• Integrated Cross-compiler, Linker, Exe Generator

• TOM8• Mini-monitor on TT8

• Crosscut Terminal Emulator • Downloader


Wheel Node Embedded Software

• Existing Modules• Controller Initialization• Digital I/O Macros• Internal Timer• Time Processor Unit (TPU)• Serial I/O• ADC

• CSOIS Modules• Motor Drivers• Modified Serial I/O• Modified ADC• Wheel Watchdogs

• My Modules• Joystick Routines• DAC Driver• Set-point Conversion• Set-point Controller• Main


DAC Driver

• Used QSPI Standard from Motorola

• Toggle General-purpose port pins owing to lack of SPI/QSPI ports.

• 10-bit data with 2 dummy bits.

• CSBAR held low for entire duration.

• Make data available before Rising edge of SCLK.


Conversion of Joystick Inputs into Drive Set-points


Conversion of Joystick Inputs into Steering Set-points


Conversion of Joystick Inputs into Z-Axis Positions


Control Strategy


Arbitration

• Wheel Node Operating Modes• Idle Mode.• Joystick Mode.• Remote Mode.

• Idle Mode• Wait for either the joystick or any remote operator to begin

controlling the wheel.• Joystick Mode

• Starts when Joystick Operator moves the Joystick(s) along any of the Axes.

• Any requests from remote operator to control the smart wheel are rejected.

• Timeout after 30-second period of inactivity; system goes back into Idle Mode.


Arbitration (contd.)

• Remote Mode• Starts when wheel node received REMOTE_REQ

character.• Commands form Remote Operator will affect Wheel Axes

Set-points. • Any movement of the joystick will have no effect on wheel

set-points. • When Remote Operator is idle for 30 seconds, a timeout

occurs and the system slips into Idle Mode.• The wheel node does not have to arbitrate between multiple

remote operators. This issue is taken care of by the serial server and the remote application software.


Flowchart – Main Module


Flowchart – ‘Idle Mode’ Routine


Flowchart – ‘Joystick Mode’ Routine


Flowchart – ‘Remote Mode’ Routine


Serial Server – NPort DE311

• Modes of Operation• Host Based / Driver Mode• Pair Connection Mode• Socket Modes

• TCP Server• TCP Client• UDP Server/Client

• Ethernet Modem Mode


Serial Server – Host Based/Driver Mode

• Configuration Steps:• Install Virtual COM Driver on Remote PC.• Get PC’s IP address authorized from CSOIS• Link Virtual COM Driver with Smart Wheel Serial Server (using Serial

Server’s IP Address)

• Working on Remote PC:• Intercept data sent to the host’s COM port.• Pack into a TCP/IP packet.• Redirects it through the host’s Ethernet card.

• Working at Wheel Node:• NPort Serial Server accepts Ethernet frame• Unpacks the TCP/IP packet• Sends it transparently to Wheel Node’s RS232 Interface.


Telepresence Control Operator Interface


Communication Protocol – Scenario 1

Fig. Scenario – 1: Remote operator has a successful telepresence control session with the smart wheel.



Fig. Scenario – 2: Session terminates when remote operator sends no new set-points for 30 seconds.



Fig. Scenario – 3: Remote operator is denied access since the wheel is being joystick operated.



Fig. Scenario – 4: Remote operator is denied access since another remote operator is controlling the wheel.



Fig. Scenario – 5: Remote operator is unable to obtain access since the wheel power is turned off.



Fig. Scenario – 6: Remote operator is unable to obtain access since the serial server is turned off.


Control Panel Software Design


Telepresence Control Software- Misscellaenous

• Serial Communication• MSCOMM Control• 9600 BPS, 8 data bits, no

parity bits, 1 stop bit.• Chosen COM Port – COM5

• Video Display• MS Internet Control• Preset URL to Camera’s

webpage• Pan, Tilt, Zoom through

Camera firmware• User Authentication required

• Other Features• CSOIS Information page on

Smart wheel• Videos of T2 and T3 Robot

Motion


Tested Scenarios

• Joystick operation.• Remote access attempt during Joystick operation.• Joystick access attempt during Remote operation.• Attempt to access by second remote operator.• Attempt to access when wheel power OFF.• Attempt to access when serial server OFF.• Video and audio available (up to 20 viewers) without

control access.


Problems and System Limitations

• Occasional non-response to joystick after end of a remote session.

• No visual status indicator for joystick operator.• Telepresence Control not platform independent.• Insecure Communication.• Telepresence control access somewhat

cumbersome.


Future Work

• Panel mounting of Joystick with good status indicators.• Secure and reliable communication protocol with

standardized packet structure and acknowledgement signals.

• Closed loop control of Steering and Drive motors (requires RTOS).

• Implementation of Controller on Remote Location – Networked Control System (NCS).

• Platform independent web-enabled telepresence control solution. (using Java or ASP)


Questions?


Demonstrations…

bharath ramaswamyembedded and telepresence control of a 3-axis smart wheel demonstrator12-02-2004...

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