l1b_mitset - MITSET MITSET System Overview Climber Specs...

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Unformatted text preview: MITSET MITSET System Overview Climber Specs Climber ► ► ► ► ► ► ► ► ► The scoring equation for last year’s competition was mpayload * Vavg/ mstructural The climber had to be able to ascend a 50m ribbon at an average speed of 1m/s . Maximum beamed power of 100KVA. No previously stored energy. Maximum energy storage of 25% at any time. 10kg < mstructural < 25 kg Fully autonomous Safety regulations must be met Power Transmission belt ribbon Early Goals Early ► Based on the competition rules, the team delineated some goals concerning the climber, that were believed to maximize performance on competition day based on the scoring equation It should travel at an average speed of 1m/s. It It should weigh about 25kg without payload It It should be able to carry 25kg of payload while It maintaining its average speed. First Recursion First Lessons from First Recursion Lessons ► 1st recursion was a crash course in climber design recursion in which the team mostly experimented brainstormed ideas. brainstormed ► Construction and machining mandated that several aspects of the initial design be modified. ► After testing the first recursion, the team discovered that the roller configuration was flawed for it could not generate enough torque. ► The team also discovered that the climber was too heavy and flimsy. CURRENT DESIGN CURRENT Modifications Modifications ► ► ► ► ► The team applied the lessons from the first recursion to create a better climber. The team decided to switch to a two motor configuration with 50:1 gear ratio which provides substantially greater torque and weighs as much as the earlier recursion. Polycarbonate is the primary material instead of aluminium. Changed overall design layout to increase stiffness. Included additional design for a more complete climber setup that included mount points for failsafe brakes, guide rollers, belay hooks, payload and electronics. Current Design Current Components ► Motor-roller module ► Payload module ► Electronics module ► Power module ► All modules except electronics module have been modified Motor-Roller Module Motor ► Powered by 2 DeWalt power drill motors. ► Structure made of polycarbonate (including the roller) which provides greater strength compared to aluminum. ► Motors are geared to generate necessary torque. Payload and Power Modules Payload ► Solar panels have been replaced by rectanna array so the payload bucket’s status is currently unknown. ► Rectanna array will be attached to bottom of climber via kevlar or wood attachment. Current Design Current Current Design Current Power System Power ► Climber powered by beam source ► Beam source must direct most of its energy at climber ► Turn on/off at a command ► Only a quarter of the total energy can be stored Microwave System Microwave ► Microwave Efficient Efficient Need magnetron, rectennas Need Developing field Developing ► 800 W Magnetron 5.81 GHz 5.81 Diode Vacuum Tube-Oscillates to create Diode Oscillates microwave microwave Microwave System Microwave Microwave System Microwave ► Waveguide ► Directs the extracted RF energy to the antenna ► Antenna Circularly polarized Circularly Helical Antenna Helical Out-of-phase microwaves Out Microwave System Microwave ► Dish/Reflector 14 foot satellite dish 14 Collimates beam Collimates ► Rectennas Rectifiers and Antennas Rectifiers Receives microwaves energy and converts Receives oscillating current to DC Control & Logic Control ► Controlled by Bitsy Single Board Computer Single Runs Linux Runs 802.11 802.11 Runs logic Runs ► Stop/Start ► Reverse ► Speed Regulation Power Transmission Power Design a better, more efficient transmission Design system. Fixed Input - 750W, 5.801GHz signal via waveguide or Fixed coax Fixed Output - circularly polarized microwaves at same Fixed frequency Current design uses waveguides to transmit signal up to Current a hemispherical reflector and back to a parabolic dish, before traveling in a beam up to the rectenna array. Goal - to transmit 400W of power to the rectenna array Goal Rectenna Design Rectenna Design - based on a Texas A&M based design which transmitted power on small scales (10W) scales ► Patch Antennas and rectifying circuitry ► Primary Goals - cheaper and more efficient cheaper (60-65%) (60 ► Secondary Goals - Lighter and stronger (self Lighter supporting) supporting) ► Current Control System Design Control ► Current control system is an analog control system supported by an onboard computer ► Requires finding many optimal parameters within the circuit. ► Many of the issues involved are pretty complicated and require us to find a delicate balance Varying-voltage power supply Varying voltage 15kF of capacitors that are restricted to 2.5V 15kF Motors that can act with or against our power circuitry Motors depending on operating levels Gear Ratios Gear ► Current design - Two DeWalt drill motors Two DeWalt drill .667 N/m of torque @ 21000 rpm .667 ► Gear Ratio - 46.7:1 46.7:1 1.4 N/m torque @ at rollers 1.4 “Hi Speed” configuration - 10.5:1 10.5:1 gear ratio gear ► Goals - optimize combination of torque and optimize speed supplied the rollers. speed ► Second Weight Minimization Weight ► Allowed weight - 10 to 25kg ► Current Design Polycarbonate is used instead of aluminum or Polycarbonate steel to cut mass Hollowed out gears Hollowed Weight saving roller design Weight ► Goal – Maximize payload to weight ratio without sacrificing performance. ...
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This note was uploaded on 11/08/2011 for the course AERO 16.810 taught by Professor Olivierdeweck during the Winter '07 term at MIT.

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