MANUFACTURE AN AND D DEVELOPMENT OF A A R RC SERVO MOTOR: CHA HALLEN ENGES F FROM T THE HE PERSPECTIVE OF OF A STAR ART UP UP At By TEQIP Pravarthana B. B. Swaroop IIT Kanpur 12-Feb-2016
Application
How a servo works
Principle of Working Basic working of a servo motor Ref. www.digitalnemesis.com
Market • 108 known companies producing servos worldwide – servodatabase.com • Classification – Analog / Digital, Different operating voltages, plastic / metal body and gears, fast / slow, etc • Price range of $1 to $350 • NONE INDIAN • Why not make in India ??
Funds • PRISM – Promoting Innovations in Individuals, Start ups and MSMEs – BY DSIR • With the help of SIDBI, we applied, made presentations, convinced committees and the only group from our Institute to be granted funds under this category Project Manager Lead Designer Mr. Vishnu Prasad Mr. Divyajyoti Guchait
Management Design (Mechanical & Electronics) Electronics Project Electronics Testing manufacture Mechanical Assembly Mechanical Assembly Component manufacture
Drawings
Targets Mechanical Size : 40 x 20 x 45 mm Torque : 12.5 Kg-cm at 8.4V Box material : Aluminium Gear material : Stainless steel & Brass Total weight after assembly: 70gm Electronics PCB Size : 38 x 17.5 x 1.6 mm PCB – multi-layered – glass fiber Chip level components to be procured (all components come from china)
3D - Print • Primary aim - to check dimensional compliances between different parts – Target achieved • Shrinkage • Brittle • Tolerances between different moving parts • Decided on metal covers and gears
Setback • Govt. change • Policy freeze • Funds freeze • Lack of clarity • Changing timelines • We start looking for private investors !!
Metal Gears – Not to scale
Metal manufacturing Gear Hob Cutter
Smallest Gear we need Size is very small Low module, m=0.25 Small hole size
What we saw !!
Manufacturing Challenges • Low volume production for prototypes unsuitable for business • Semi-skilled employees not acquainted with such small dimensions • Lack of seriousness due to small size • Unavailability of the miniature gear hob cutter – Solution – IMPORT….. Probably from China !!
Manufacturing Challenges
Current Status 3D-printed plastic prototype PCB part procurement PCB CAD design Metal gear CAD design Metal box CAD design IN PROGRESS • PCB manufacture • Box manufacture • Gear manufacture TO BE DONE × Assembly × Testing × Iterations
Thank you
Servos • Futaba S3151 • Lateral • Longitudinal • Collective • Throttle • Futaba S9256 • Tail • GY611 gyro • AVCS Controller
Servo Actuators - Specifications Name of S 3151 S 9256 Servo Servo actuators under study Weight 42g 57g Operating Speed at 4.8 0.21 sec/60 0.06 sec/60 S9256 V with no degrees degrees load Torque @ 43.00 oz/in 47.00 oz/in S3151 4.8V (3.1kg.cm) (3.4kg.cm) 40.6 x 20 x 40 x 20 x Dimensions 36mm 36.6mm Source: http://www.futaba-rc.com/
Servo Characterization • Static Calibration Time Response • Basic working of a servo motor Ref. www.digitalnemesis.com • Frequency Response
Servo Calibration - Test Setup National Instruments’ PXI System Potentiometer Protractor Marker SCB 68 used to acquire potentiometer voltage
Servo Characteristics Name of Servo S 3151 S 9256 Response range 0.86 ms to 0.46 ms to (ON time of pulse for which 2.24ms 1.14 ms the servo responds) Time period of signals (ms) 14 - 20 3 Angular range (degrees) 130 117 Angle traversed for every 0.1ms variation in ON time 9 17 (degrees)
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