HYBRID DC-AC CONVERTER FOR RELIABLE OFF-GRID SOLAR POWER SUPPLY

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 12 Issue: 12 | Dec 2025 www.irjet.net p-ISSN: 2395-0072

DESIGN AND DEVELOPMENT OF QUADRA LEGGED ROBOT FOR SMART MOBILITY AND OBSTACLE NAVIGATION

Poorna Chandra Reddy S1, Sabha Siddiqua N2 , Vardhan V3

Dr. Mohamed Saleem4

123Student, Dept. of Robotics and Artificial Intelligence, Bangalore Technological Institute, Bangalore, India

4Professor and Head of Department, Dept. of Robotics and Artificial Intelligence, Bangalore Technological Institute, Bangalore, India

Abstract - This project presents thedesignanddevelopment of a quadra legged spider robot designed for smart mobility and obstacle navigation on rough surfaces. The robot uses a stable mechanical body structure and servo based joint for legs and a microcontroller to control the locomotion. Ultrasonic sensor used in this project enables obstacle detection and navigate back to its position while moving and also an Bluetooth camera fixed for live tracking and controlling. The system for this project was built through different stageslikedesigning,prototyping,programming,and testing. Results showed that the robot can walk smoothly on irregular paths and adjust its moments when obstacle appears. This workdemonstrates theusefulnessoffourlegged robots inenvironments where wheeledrobots cannotreachin some environments and this provides a foundation for future improvements.

Key Words: Quadra legged robot, Spider robot, Servo based joints, Ultrasonic sensor, Obstacle detection, Locomotion, Rough surface navigation.

1. INTRODUCTION

This project involves the design and development of a quadra legged spider robot that can walk smoothly and avoidobstaclesonunevensurfaces.Unlikewheeledrobots this legged robots this legged robot can move over rough ground, climb small obstacles and reach places where wheels cannot work. The robot is also integrated with an small Bluetooth camera module that helps to record and sharethelivestreamingtotheoperator.Therobothasfour legs powered by servo motors and microcontroller that helpsincontrollingthemoments.Sensorsareusedtodetect obstaclesallowingtherobottochangeitspathandprevent collisions.

Theprojectincludesdesigningthelegstructurebuildingthe electronic system and programming for different walking patterns and mainly focused on programming the leg momentpartwherethatmustlikearealspider.Therobot canperformbasicactionssuchaswalkingforward,turning left and right and then stopping while the commands are received and when the auto mode is turned ON it automaticallystartsavoidingtheobstaclesandintheoverall

functioning the camera will be kept turned ON for live streamingandrecordingthevideo.

Thisworkshowshowaquadraleggedrobotscanbeuseful forrescuemissions,surveillance,roughterrainexploration andeducationalpurposeswhichhelpsthestudentstolearn andunderstandhowthebasiclegmomentsofarobotwork. Overall, the project highlights how mechanical design, electronics, and programming come together to create a stableandflexiblespiderlikerobot.

2. LITERATURE REVIEW

Previousstudiesonquadraleggedrobotsshowthatlegged systems can move better on uneven surfaces compared to wheeledrobots.Manyresearchershaveusedmotors,basic gaitpatternsandsensorstoimprovewalkingstabilityand obstacledetection.However,mostofthesedesignsareeither expansive or complex for beginners to understand and observedthemainthinginwhichthereisnocameramodule integrated. To address this a simple lost cost models have been developed for education but they often lack smooth momentorsmartsensing.ThisprojectBuildsontheseideas by creating an affordable Quadra legged robot with servo basedlegsandultrasonicsensingtoachievestablewalking andbasicobstacleavoidance.

3. SYSTEM DESIGN

The system design of the quadra legged robot integrates both mechanical and electronic components to achieve efficient movement and control. The mechanical design focusesonlightweight,stablestructurewitha3degreeof freedomlegs for smooth walkingonunevensurfaces.The electronic design includes servo motors, sensors and a control module that enables to control the moment and functions of the robot. Together these designs ensure the robotfunctionswithmaintaininggoodbalance,flexibilityin variousenvironments.

3.1 Mechanical Design

Therobotisdevelopedbyusingalightweightbodystructure forgoodstabilityandmobility.Itsfourlegswitheachlagsof

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 12 Issue: 12 | Dec 2025 www.irjet.net p-ISSN: 2395-0072

3degreeoffreedomwhichoffersagoofbalanceofstrength andreducedweight.Eachleghassimple,welldesignedjoints that enables both forward and backward moment. Fig-3.1 showsthe3D-printedbodyandlegpartsoftherobot The overall structure is designed and developed to be flexible, durablewhilewalkingonunevensurfacesorslightlyrough surfaces making it suitable for both indoor and outdoor exploration.

3.2 Electronics Design

TheelectronicsystemoftherobotisbuiltusingaArduino uno which acts as the central brain responsible for controllingallthelegmomentsandprocessingsensorinput. Each leg is equipped with servo motors that follow a programmed gait pattern allowing the robot to walk smoothly and maintain a good balance. To enable the obstacle detection an ultrasonic sensor is mounted at the frontoftherobotthatcontinuouslymeasuresthedistanceto nearby objects and sends the signals to the controller for avoidance actions. Fig-3.2 shows the entire system is powered by a rechargeable battery that helps to recharge multipletimes.

4. METHODOLOGY

Themethodologyinvolvesthesystematicdesignoftherobot starting from planning the structure, assembling the mechanicalpartsandthenintegratingallelectronicmodules requiredformoment,sensing,communication,andpower management.Eachhardwarecomponenthasaspecificrole inwhichthathelpstherobotforstablelocomotion,wireless controlandefficientoperation.

TheArduinounoactsasthe maincontrollerfor the robot thathelpsinprocessingthesensordatathatreceivesfrom thatBluetoothmodulefromthatoperatorsandthenusing that signals in controls the moment of the robot through programmedinstructions.Fig-3showsithasmanyanalog pins and digital pins mounted to it in which they helps to connecttheexternalcomponents.

4.2

ThePCA9685servodriverboardisusedtocontrolmultiple servosatsingleoperation.Fig-4showsitislikeaexpansion boardthatallowstocontrolmultipleservosbypassingthe powerandthegroundsignalconstantlybyjustfluctuating thesignalaspertheprogram.Ithelpsingeneratingsmooth andaccuratelegmomentsfortherobot.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 12 Issue: 12 | Dec 2025 www.irjet.net p-ISSN: 2395-0072

Itenableswirelesscommunicationbetweentherobotanda mobile controlling device. It allows the user to send movement commands. Fig -5 shows this module has two pinsinwhichonepinhelpstoreceivethecommandfromthe operatorappandotherpintotransferthesignaltotheuno intheprogrammedmethod.

4.4 Ultrasonic sensor

Itdetectsobstaclesinfrontoftherobotthathelpstherobot tostoporchangedirectionstoavoidcollisions. Fig-6The ultrasonicsensorgetsactivatedonlywhenthecommandis received.

4.5 Bluetooth camera module

This module installed in the robot provides live video allowing remote monitoring of the robots path and surroundings that helps the operator to control the robot withoutanycollusions.Fig-7showstheBluetoothcamera selectedforthisprojectbecausethistimeofcameraswork withoutanydelayinstreamingthevideocontinually.

4.6

SG-90 Servo motor

Fig-8theSG-90servomotorprovidesapreciserotational momentforeachlegjointoftherobot.Itallowscontrolled motion for walking, turning. This motor is a plastic gear motorinwhichitconsumelesspowertooperate.

4.7 Power supply

Fig-9showsthelithiumbatteryusedintherobotwhichisa rechargeablebatterythatsuppliespowertoentiresystem includingthecontroller,servomotorsandsensor. Thetsp chargermoduleisusedtochargethebatteriesinwhichthey are safe if connected in series and then charged with a specificvoltagemaintainingacertainchargingtime.

5. WORKING

The robot walks using a designed gait pattern where two legs move forward while the other two stay in the home positiononthegroundtosupportthebody.Thisalternating momentgivestherobotgoodstabilityandsmoothforward motioninwhichtheArduinounocontrolsthetimingofeach step by sending the exact signals to servos as per the programming.ThesignalfromtheHC-05isreceivedfrom the controller app and then as per the signal received the Arduino sends the signals to the servos based on the program uploaded. The PCA 9685 is used to connect the positive and the ground wires to the positive and the negativerailinthePCA9685.

Eachservoliftsthelegswingsitforwardandplacesitdown completing one step cycle. As the robot moves when it receivesthecommandtoactivatetheautomaticmodethe ultrasonicsensorgetsactivatedandtherobotstartsmoving andjustavoidsifanyoftheobstacleisdetectednearbyand navigatesaccordingly.

Table -1: ObservationofObstacleAvoidance

Obstacle Distance Robot Response

15cm Stopped

10cm

25cm

6. RESULTS

Turnedleft/right

Continuedmoving

Therobotwasabletowalksmoothlyonroughsurfacesand small obstacles. It successfully detected objects using the ultrasonicsensorandchangesitsmomentsbyrenavigating toavoidthem.Thewalkingpatternworkedproperlyandthe mechanicaldesignremainedstableduringthefinaltesting. In the beginning I faced a many problems because the

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 12 Issue: 12 | Dec 2025 www.irjet.net p-ISSN: 2395-0072

walkingmomentswearnotproperandnotmatchingaswe plannedandtherobotwasalsonotstandingcorrectlywhen onelegliftsuptomoveforwardandthenslowlyanalyzing theproblembycalibratingeachstepandlegthentherobot worked successfully in which the camera module also workedproperlybystreaminglivevideotorecord.Overall, theprototypeperformedwellintermsofmobility,balance andobstaclenavigation

7. CONCLUSION

Thespiderrobotprojectsuccessfullyshowshowmechanical design, electronics and programming can be integrated to create a remote controlled robot that mimics a spider walkingpattern.Theprojectsuccessfullyperformedallthe operationsasperplannedandperformedthewalkingtasks onroughsurfacesandalsonavigateswhenanobstaclemode isturnedonandthecameramodulesuccessfullyrecordsand Stremslivevideosuccessfully.

8. REFERENCES

[1] B.Geetha,D.Abhishek,K.Abhishek,andB.K.Jagadish, “AI Based Spider Robot for Military Operations,” InternationalJournalofAdvancedResearchinComputer and Communication Engineering, vol. 13, no. 12, Dec. 2024.

[2] D.Gaur,J.Varshney,A.Maryam,andS.Gautam,“Quadra Spider:AFour-LeggedSpiderRobotDesignandControl,” International Research Journal of Engineering and Technology(IRJET),vol.10,no.9,Sep.2023.

[3] S. Kannan, “Spider Bot – A Quadruped Robot for Data Gathering,”ResearchGate,2022.

[4] Y.Nie,D.Zhu,Y.Chen,X.Hu,andL.Wang,“Designofa BionicSpiderRobotwithaTwo-Degrees-of-FreedomLeg StructureandBodyFrame,”AppliedSciences,vol.14,no. 21,p.9809,2024.

[5] Y.Zhu,L.Chen,Q.Liu,R.Qin,andB.Jin,“Omnidirectional Jump of a Legged Robot Based on the Behavior MechanismofaJumpingSpider,”AppliedSciences,vol.8, no.1,2018

Appendix- Photographs of Prototype

Prototype