1kg Motor Module, First Generation P08208 – Mechanical Design P08205 – Electronics, Controls & Support RP1 MSD II 20073

Team Breakdown SubsystemsTeam 205Team 208 Drive--Andrew Matt SteerArtMatt YokeEricJames PlatformArt Eric -- ControlsBrendan Phil -- ElectronicsJonathanBryan

WHAT IS A MOTOR MODULE ? DRIVE MODULAR MOUNTING STEER aka “ MM”

1kg 10kg 100kg OFF THE SHELF MOTOR MODULES

RP100 ( Wired ) RP10 ( Wired ) Sister projects! RP10 ( Redesign ) RP1 ( Wireless )

RP10 Redesign Wireless! Robust! Autonomous! Smaller! Lighter!

FORMAT Overview Project Specifications System Level Subsystem Contributions 208: Drive / Steer / Yoke 205: Support / Electronics / Controls Closing Comments Results Strengths & Weaknesses Future of RP

Steering Drive Train Upper Yoke Lower Yoke MECHANICAL DESIGN OVERVIEW

Computer Wireless Transceivers Microprocessor PWM Motor Controller RP1 Motor Module Circuit Board ELECTRONICS & CONTROLS OVERVIEW

CRITICAL REQUIREMENTS Transport 1kg Payload Robust = Withstand Tabletop Drop Wireless Communication Power Motors with a PWM Signal Open Source & Open Architecture Reflect Design of the RP Family Modular Design for Multiple End Uses

EXPECTATIONS oQuantity 1, Functioning Platform & Motor Module 3, Motor Modules max efficiency 38 in/s oDrop Test Repair Time < 20 min oBattery Life 1 hour + oModular Design

Responsibilities: –Design modular drivetrain system Multiple modes of motor operation –Design and build a robust drivetrain Challenges of MSD II –Drivetrain friction losses –The need for a belt tensioner? –Machining knowledge inadequacy –Failing drop testing –Unforeseen assembly woes –Differences between analytical solutions and testing results Drivetrain Subsystem

Gearbox Selection Process Using the chart to the left a motor gearbox can be selected from velocity requirements that ensures efficient motor operation Similarly a motor gearbox can be selected for max motor power

Final Drivetrain Design IG-32GM 24V Motor 27:1 gearbox reduction Steel couples with setscrews Stainless steel drive axles Steel miter gears Aluminum spacers with thrust bearings 1:2 synchronous drive pulley Aluminum axle with keyway for wheel

Strengths & Weaknesses Strengths –Modular gearbox options –Multiple opportunities to change gear ratios –Belt protects critical drive components –Easy assembly of drive components Weaknesses –Lack of belt tensioner limits modularity –Size of motor increases RP1 size –Limited availability of motor gearboxes

Responsibilities: –Design a steering system capable of infinite rotation –Implement, build and integrate with all RP1 subsystems Challenges of MSD II –Total re-design including custom turntable, starting week #1 Also incorporated re-vamp of tensioning system –Subsystem integration –Belt Sizing –Friction! STEERING SUBSYSTEM

It’s Alive!

Strengths & Weaknesses Strengths: –Robust steer system –Custom turntable is light, smooth, and easy to access/assemble –Infinite rotation –Intuitive and efficient belt tensioning Weaknesses –Side load from belt drive system causing misalignment –Extreme sensitivity to belt length –Tendency of steer system to force rotation of drive shaft, and vice versa –Friction! –Demands tight tolerances     

DRIVE & STEERING Q & A

YOKE SUBSYSTEM

Responsibilities: –Responsible for structural skeleton of RP1 –Design a rigid and robust framework –House all other sub-systems within framing –Provide protection against a drop to the floor Challenges of MSD II: –Maintaining machining tolerances during mass production –Lack of experience with machining equipment early in MSDII –Developing precise and efficient machining techniques YOKE SUBSYSTEM

Drop Test on Side

Drop Test on Wheel

Damage to Axle

Strengths & Weaknesses Strengths –Robust: designed for impact –Concentrates force of impact from drop in lower axle –Easily assembled and disassembled Weaknesses –Size: minimally smaller than RP10 –Lower axle fails in drop test but can be quickly replaced

Responsibilities: –Design a prototype platform Includes area for 1kg payload Includes area for platform electronics Testing the functionality of 1 MM at a time Built-in wheels to allow for platform travel –Design a modular mounting system Must be capable of attachment to platform Must meet design spec for attachment Challenges of MSD II –Use of materials readily available for platform –Having a low center of mass for drivability PLATFORM

PLATFORM EFFORTS Mounting Time: 50 sec

STRENGTHS & WEAKNESSES Strengths –Easy to make prototype platform –Very quick and efficient mounting Weaknesses –Made of plywood and boards –Structural support questionable when using substantial weight –Requires a square-shaped cut-out –MM must mount in the designated forward direction for index to work properly

YOKE & PLATFORM Q & A

Responsibilities –Provide components for motor control H-bridge Boost & Buck PCB Interface PCB Wiring & Connectors –Design and implement power supply Challenges of MSD II –PCB board design –Integration of all electrical components Electronics

Electronics

Electronics

Printed Circuit Boards

PCB Build

Strengths –Capacity for 2 MM’s –Integration of all electrical components –Single connection with platform Weaknesses –Takes time to locate broken components on PCB –PCB Corrections –PCB has no output diode Reflections

Responsibilities: –GUI for user control –Wireless communication between MM and computer –Generate all necessary signals used for controlling motors –Display speed, turning angle, and battery life Challenges of MSD II –Selected wireless components not functioning –Limitations of microprocessor – not enough I/O pins –Out of practice with Java Controls

Wireless Transmission: –Couldn’t download code to MICAZ motes –TelosB motes used instead –Not yet demonstrated to be functional Microprocessor: –Freescale –Handles encoder feedback –Speed up, slow down, turn left and right GUI: –Java, using the Eclipse IDE –New design in consultation with Prof. Hawker Implementation

GUI Screen Shots

Strengths & Weaknesses Strengths –Ability to turn, drive, and stop based on commands issued by the user –GUI supports multiple platform designs –Open-source, Java readily available Weaknesses –One direction communication with the MM –Only set up to work with one MM

CONTROLS & ELECTRONICS Q & A

RESULTS MM attaches in under 1 minute Weighs under 5 pounds Complete disassembly in less than 10 minutes Compact size Infinite rotation Robust Less than $900 Time to repair MM after tabletop drop Package Envelope Size of Individual MM Weight of powered MM Life of primary battery Wireless Range Data transfer rate # of nodes within a network Variability of PWM (duty cycle) Time to access critical components Cost of 2 MM's (w/o S&H) Elapsed time to maintain speed at max efficiency (v = 37.8 in/s) Linear variation from desired path Time to attach each MM Customer Needs WeightEngineering Metrics Robust Design99 Compact9 9 Lightweight9 9 Untethered Power9 9 Wireless Control9 999 Controllable PWM signal to power motors3 3 Consideration for DFMA, easy-to-access critical components3 3 Cost Effective3 3 Smooth Movement3 3 Accurate control of movement3 3 Easy to fix1 1 MM's easily install to platform1 1 Technical Specs Units min (HxWxD) inxinxin lb min ft B/s # % of V min $ (USD) sec in/in min Ideal 20 8x4x4 4 >120 >= to 100 <5 < <1/24 <3 Marginal 25 12x6x6 5 >60 >= to 80 <10 <900 5 <1/12 <

COST ItemCost Motor Module Only (2)$ Platform$ MMs & Platform$ Overall Spending$

THE FUTURE OF RP French Collaboration with INSA DPM Students Senior Design for EE & CE’s Software Engineering Senior Design

COULD RP1 HANDLE 10Kg? Proven robust design Modular mounting Replace drive with 1:71 gearbox motor Resulting 14.5 peak efficiency ANSYS MODELING RESULTS Check: –Design of Machine Element calculations –Effects on batteries

COULD RP1 HANDLE 10Kg? Yes it can! lb Payload! (10.2 kg)

REFLECTIONS Strengths Robust motor module Demonstrated modular design Easy to connect Controllable turn/drive/stop/align Weaknesses Oversized Failed to implement wireless communication Processor can only handle 1 MM of feedback PCB corrections were necessary

THREE SIMPLIFICATIONS 1.Open motor selection & configuration 2.170°or 180° rotation requirement, to replace infinite rotation requirement 3.Emphasize compact design + Establish clear size constraints + Goal of existing design size (ex. 10%)

That’s It Folks! Q & A

Gearbox Selection Process

Gearbox Selection Process

ANSYS Simulation

ANSYS Simulation