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FOBOTFOBOTThe Hexapod Walking The Hexapod Walking

RobotRobot AuthorsAuthors::

Balázs AndrásBalázs AndrásPécskai BalázsPécskai BalázsSupola BalázsSupola BalázsVámossy ZoltánVámossy ZoltánMolnár AndrásMolnár András

Budapest Polytechnic, Budapest Polytechnic, John von Neumann Faculty of John von Neumann Faculty of

Informatics, Informatics, HungaryHungary

23 March 200423 March 2004

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ContentsContents3.3. The main purposes of the robotThe main purposes of the robot4.4. Similar developmentSimilar development5.5. Common featuresCommon features6.6. Particular purposesParticular purposes7.7. Construction of the systemConstruction of the system8.8. Mechanical structureMechanical structure9.9. Electric structureElectric structure10.10. Movement of the legsMovement of the legs11.11. CommunicationCommunication12.12. PC side controlPC side control13.13. Planning of the walking Planning of the walking

strategiesstrategies14.14. Walking strategiesWalking strategies15.15. Global Positioning SystemGlobal Positioning System16.16. Global positioningGlobal positioning17.17. Eye-based navigationEye-based navigation18.18. Processing of the PAL-optic Processing of the PAL-optic

picturepicture19.19. Position determination step by Position determination step by

stepstep20.20. ResultResultss I I21.21. ResultResultss II II22.22. Further informationFurther information

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The main purposes of the robotThe main purposes of the robot

The robot is able to:The robot is able to: Move quickly (apart from the quality of Move quickly (apart from the quality of

the terrain)the terrain) Have duplex communication channel Have duplex communication channel

with the controlling PCwith the controlling PC Have remote control optionHave remote control option Partially explore its environmentPartially explore its environment Avoid obstaclesAvoid obstacles Reach a designated target by self-Reach a designated target by self-

navigationnavigation

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Similar developmentSimilar development

Autonomous hexapod robot Autonomous hexapod robot Only one actuator per leg Only one actuator per leg Speed: 2.25 m/sSpeed: 2.25 m/s 3700 m distance on one set 3700 m distance on one set

of batteriesof batteries Swims, and climbs stairsSwims, and climbs stairs Onboard control of the Onboard control of the

robot and wireless access robot and wireless access to the command interface is to the command interface is supported by RHexLibsupported by RHexLib

RhexRhex

Source: www.rhex.netSource: www.rhex.net

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Common featuresCommon features

Has got six legsHas got six legs

Similar movementSimilar movement

StructureStructure

Six legs can be controlled Six legs can be controlled independently from each independently from each otherother

Curved legsCurved legs

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Particular Particular purposespurposes

Development of the construction (number of the legs)Development of the construction (number of the legs)

Solution of the problem of the motor control:Solution of the problem of the motor control: Turn direction, speed, setting feet optionsTurn direction, speed, setting feet options

Programming of the central process unit:Programming of the central process unit: Duplex communication between CPU and PCDuplex communication between CPU and PC The execution of the various walking strategiesThe execution of the various walking strategies

Joining of the GPS module to CPU:Joining of the GPS module to CPU: Data pre-testing and pass it on to PCData pre-testing and pass it on to PC

Developing the PC-side software:Developing the PC-side software: User interfaceUser interface Communication module and test environment alternativesCommunication module and test environment alternatives Map manager moduleMap manager module Virtual environment building module*Virtual environment building module* Avoiding obstacles, route-planning and navigation module*Avoiding obstacles, route-planning and navigation module*

* optional modules

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Construction of the Construction of the systemsystem

* optional modules

*

*

*

*

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Mechanical structureMechanical structureDimensions:Dimensions:

Length:Length: 420 mm 420 mm Width:Width: 265 mm 265 mm HeightHeight

(standing): 175 mm(standing): 175 mm Leg height: 115 mmLeg height: 115 mm

Evolution of the legs:Evolution of the legs:

EarlyEarly

stage stage Plan-parallelPlan-parallel CurvedCurved

spiralspiralStraightStraight

AluminumAluminum skeletonskeleton

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Electrical structureElectrical structure

Printed electric circuit:Printed electric circuit:

Interfaces on the robot: Interfaces on the robot:

2 pcs. serial port socket 2 pcs. serial port socket

(communication + GPS) (communication + GPS) Programmer interface for PICs Programmer interface for PICs Sockets for GPS and cameraSockets for GPS and camera Interfaces for optional sensor and Interfaces for optional sensor and

structurestructure

Main parts: Main parts:

6 pcs. DC motor (12 Watt)6 pcs. DC motor (12 Watt) 6 pcs. PIC 16F873 microcontroller6 pcs. PIC 16F873 microcontroller 6 pcs. L6203 motor controlling IC6 pcs. L6203 motor controlling IC

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Movement of the legsMovement of the legs

Leg movementLeg movement:: Determination of velocity and direction (automatic Determination of velocity and direction (automatic and/or by PC)and/or by PC)

+ setting to position + setting to position

Speed: Speed: PWM modulation is created by PICPWM modulation is created by PIC

Regulation:Regulation: Speed of the obtaining of the Speed of the obtaining of the desired desired position position is in is in direct proportion to direct proportion to square of square of distance distance

Speed’s derivative is similar to Speed’s derivative is similar to the the aforesaidaforesaid

Advantage: regulation time is Advantage: regulation time is short, short, increased burdenincreased burden is is easier solvedeasier solved

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CommunicationCommunication

FOBOT communicates on the serial port(RS232) with own FOBOT communicates on the serial port(RS232) with own protocol.protocol.

All PICs have different address. All PICs have different address. 1th. byte: address + instruction’s type1th. byte: address + instruction’s type

2nd. byte: desired position or velocity 2nd. byte: desired position or velocity

PICs send back two bytes:PICs send back two bytes: Actual speedActual speed

Actual positionActual position

Advantage of serial communication:Advantage of serial communication: Easy programmableEasy programmable Single transmissionSingle transmission Wireless communication is realizable by two Wireless communication is realizable by two

one-channel transceiver-receiver pairsone-channel transceiver-receiver pairs

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PC side controlPC side control

Control & test:Control & test:The test of the communication and errata The test of the communication and errata continuouslycontinuously

Test of the leg-control:Test of the leg-control: Simple leg-controlSimple leg-control Walking descriptionWalking description

Option of the succession controlOption of the succession control

Simulation: Simulation:

Simulated motion of theSimulated motion of the robot and position-diagram robot and position-diagram of the legsof the legs

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Planning of the walking strategiesPlanning of the walking strategiesPlan:Plan:

Position plottedPosition plotted

against timeagainst time

Items ofItems of

target pointstarget points

SpeedSpeed

Tripod walking:Tripod walking:

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WalkingWalking strategiesstrategies

Tripod:Tripod:

Quattro:Quattro:

Worm:Worm:(the (the slowest)slowest)

Turning:Turning:

the legs move just like at the legs move just like at the tripod strategy, but the the tripod strategy, but the two sides move in different two sides move in different directiondirection

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Global Positioning SystemGlobal Positioning System

Example:Example:$GPGGA,123519,4807.038,N,01131.324,E,1,08,0.9,545.4,M,46.9,M,,*42$GPGGA,123519,4807.038,N,01131.324,E,1,08,0.9,545.4,M,46.9,M,,*42

Measuring controlled by the software:Measuring controlled by the software: Minimum number of the used satellitesMinimum number of the used satellites Applied filters: average, median Applied filters: average, median Displaying the properties of the satellitesDisplaying the properties of the satellites

GPS signals:GPS signals: NMEA sentences (National Marina Electronics NMEA sentences (National Marina Electronics Association)Association)

- GPGGA, GPRMC, GPGSA, GPGSVGPGGA, GPRMC, GPGSA, GPGSV

Degree of latitudeDegree of latitude

Degree of longitudeDegree of longitude

HHeight above sea-eight above sea-level.level.

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Global positioningGlobal positioningPlanning route:Planning route:

Placing sub-targetsPlacing sub-targets

Route following:Route following: Filtering input signalsFiltering input signals

Actual position on the mapActual position on the map

Calculating of the direction of the Calculating of the direction of the sub-sub- targetstargets

Properties of the satellites: Properties of the satellites: Positions Positions

Range of the input signalsRange of the input signals

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Eye-based navigationEye-based navigation

Step of the real-time image Step of the real-time image processing:processing:

Digitalization (Video for Windows)Digitalization (Video for Windows) Modified input image by filters:Modified input image by filters:

DilatationDilatation ErosionErosion Edge detection Edge detection SUSAN algorithmSUSAN algorithm SkeletonSkeleton BinarizationBinarization

Position and orientation Position and orientation

determination based on edge determination based on edge detection detection

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Processing of the PAL-optic pictureProcessing of the PAL-optic picture

PAL = Panoramic Annular Lens (invented by Prof. Pal PAL = Panoramic Annular Lens (invented by Prof. Pal Greguss)Greguss)

Real-time mapping and effect of Real-time mapping and effect of filters:filters:

Centric-minded Centric-minded imagingimaging

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Position determination step by Position determination step by stepstep

Determination of Determination of the vertical the vertical position of position of the FOBOT the FOBOT

Layout Layout of the of the

PAL-imagePAL-image

Determination of Determination of the spatial vectors the spatial vectors from the PAL-imagefrom the PAL-image

EdgeEdgedetectiondetection

Selection of the Selection of the followed points manuallyfollowed points manually

Add Add filtersfilters

3D transformation,3D transformation, mapping the points mapping the points

Here is FOBOT

Schoolyard

PAL-image

2020

Results I.Results I.

Movement:Movement: Speed: 5,8 meters / minSpeed: 5,8 meters / min

Turning around: 36 secTurning around: 36 sec

Simple walking development Simple walking development possibilitypossibility

Several walking strategies are Several walking strategies are developeddeveloped

In progress:In progress: Eye-based Eye-based navigationnavigation

Obstacles Obstacles avoidanceavoidance

Wireless Wireless communication communication and local power-supplyand local power-supply

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Results II.Results II.Tested GPS receiver:Tested GPS receiver: GNV12 (Lowrance), Summit GNV12 (Lowrance), Summit (Garmin),(Garmin), PS1 (µblocks), Navistar (BAE PS1 (µblocks), Navistar (BAE Systems),Systems), Jupiter (Connexant) Jupiter (Connexant)

Test of the navigation on road and the court of the college Test of the navigation on road and the court of the college (football pitch)(football pitch)

Football pitch

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project homepage:project homepage:

Further informationFurther information

fobot.bmfnik.orgfobot.bmfnik.org