2.007 Design and Manufacturing I

Transcription

1 MIT OpenCurseWare Design and Manufacturing I Spring 2009 Fr infrmatin abut citing these materials r ur Terms f Use, visit:

2 Supreme Curt Decisins and Rule Clarificatins Impund Questins: Can I pack my machine int the sizing bx nice and tight, then expand it ut nt the table in the full ptential starting area f the zne? NO! Yur machine shuld fit int the sizing bx in its starting cnfiguratin. Yu cannt break yur machine dwn int a bunch f pieces, frce it int the bx, and then expand it back ut n the table. When yu have set up yur machine n the starting zne, it must still fit within the vlume f the sizing bx. Yu have a wide variety f ptins fr where yu lcate this virtual sizing bx, as lng as it remains within the starting zne. The sizing bx may nt bulge and the lid must fit n and clse. Why is the sizing bx 16" by 16" by 25.8"? Check yur lecture ntes fr the glden rectangle... D I need t have a cntrl bx and battery n my machine at impund? The cntrl bx and battery d nt cunt twards the 10lb weight limit. Hwever, yu d need t shw that yur machine will fit int the sizing bx with these items installed. Scring: Hw can I get three blcks int the 80 pint bin? It lks like it can nly

3 fit tw n the web! Als, can I squish mre blcks int a bin? The 80 pint bin is deep enugh t hld three blcks. Nte that blcks that are nt cmpletely within the vertical bundaries f the bin d nt cunt. It is extremely difficult t frce mre blcks int the bin withut damaging smething, s yu cannt frce fur blcks int the space f the bin. Yu may stack as many blcks as yu want n tp f the side bins. All blcks that fit within the cnfines f the walls extended vertically will cunt. Yu may nly receive the multiplier fr the first three blcks in the bin. Des the scring multiplier wrk fr three bricks in the 80 pint bin? Yes, since they are all vertical. Examples are fund n the rules page. D the extra pints fr a marked face cunt in the 80 pint bin? Yes. What happens if my blck is hanging ut f the bin a little bit? Fr the bttm rw valued at 10 pints - A blck nt cmpletely in the bin des nt cunt. A blck will cnsidered in the bin when n part f the brick prtrudes acrss the entrance r exit plane f the bin. The judges will determine "in"-ness by running a straight edge alng the face f the bins. Any blcks that are hit by the straight edge will nt scre. Partial blcks d nt receive a scre. Fr the tp three rws valued greater than 20, 40, and 60 pints - If at least 50% f a blck is within the bin, it will be scred. The referees will measure the blck as necessary t determine the percentage f blck in the bin. The straight edge rule des NOT apply t the tp rws f bins. Fr the side bins, Yu may stack as many blcks as yu want int the side bins. All blcks that fit within the cnfines f the walls extended virtually will cunt. Yu may nly receive the multiplier fr the first three blcks in the bin. What happens if my machine is still tuching a blck in a bin at the end f the rund? If yur machine is still in cntact with the blck at the end f the cntest, the blck still cunts fr scre. If yu machine is still mving after the cntest ends, the judges will have discretin as t

4 whether the blck cunts. Hw will blcks in the side bins be cunted fr the three r fur blck multipliers? A line will be drawn n the 80 pint bins extending ff the bttm edge f the tp rw f bins. Any blck cmpletely abve this line will cunt fr multipliers in the tp rw (60 pint rw). Any blck cmpletely belw the line will cunt fr multipliers in the secnd frm the tp rw (40 pint rw). Any blck that crsses the line will nt be cunted fr either multiplier. This line has n effect n the three blck multiplier fr placing three blcks vertically int the bin and all blcks in the bin still receive 80 pints per blck. Hw much d the blcks weigh? The blcks are made f lightweight fam. The blcks are apprximately 8 inches n a side. Measurements f the weight f the scring items can be made anytime during lab. Can I cme up with a device t remve my ppnent's blcks r blck the bins? Yes, as lng as yu have satisfied the requirements fr crssing the line. Als, make sure that yu read the curt decisins regarding aggressin. If I intentinally r unintentinally mve my blcks t the ppnents side befre scring will I be penalized? S, the rules dn't explicitly prhibit yu frm mving yur blcks nt yur ppnent's side f the table. Feel free t d s and yu dn't have t wrry abut accidentally pushing them ver. Hwever, yu may want t make sure t cmpletely think thrugh the risks f using this mve as a strategy. If yu push yur blcks acrss and the tiniest, little, itsy-bitsy part f yu machine crsses the line, yu will get hit with the penalty. If yu manage t get lts f blcks acrss the line withut crssing it, then yu end up hurting yurself as yu lse thse blcks until yu scre. By the time yu culd mve the blcks acrss the line withut getting dcked pints, the ther persn can prbably scre r get ut f the way already. Lts f ways t lse with little benefit = ptentially risky strategy.

5 What happens if I run ut f blcks? Can I use my ppnent's blcks? Only use yur ppnent's blcks if yu want t scre fr yur ppnent. Each player is limited t the number f blcks n the table at the start f the cntest. What happens if I have three blcks in a segment and my ppnent puts his blck in the furth spt? D either f us get credit fr the fur blcks in a segment? N. Yu may nly receive the scring multiplier if the blcks are all f yur clr. The clred blcks must be cntiguus t cunt (eg. blue - blue - red - blue acrss a rw des nt cunt fr a three r fur blck multiplier). Examples are fund n the rules page. D blcks in the 80 pint bin cunt as being in a segment with the rest f the bins? Yes, but nly if the blck falls within a rw f the main bins. In ther wrds, the first blck in the 80 pint bin wuld cunt as being in the 40 pint rw, while the third blck in the 80 pint bin wuld cunt as being in the 60 pint rw. A secnd blck in the 80 pint bin wuld nt line up t be cmpletely in ne f these rws, s it wuld nt cunt. Examples are fund n the rules page. I have a questin abut the scring multiplier. Is the multiplier nly applied t yur scre at the time when the multiplier is activated, r is the multiplier applied t yur final scre at the end f the rund? The scring system updates cntinually thrughut the duratin f the cntest. S, yur scre will be autmatically updated if yu earn a multiplier. Hwever, if yur ppnent remves a blck frm the multiplier cmb, the multiplier will be remved and the scre will be updated based n the new cnfiguratin f blcks. Aggressin n an Oppnent: May we thrw the ther rbt ut f the playing field? If yu d it nicely and with lve and n malice...yu are just

6 helping them t explre new hrizns... May we flip ur ppnent ver nt its backside? and help them shw the audience their awesme underbelly paint jb? f curse! BUT this is NOT Battlebts...if yu get t vilent abut flipping r yur fcus is disabling yur ppnent while ding nthing t scre.... the judges will disqualify yu. Histry has shwn that actively blcking (pinning them against the wall) is ne f the best strategies (use a Mlestabt, maybe ne that is part f main rbt, and then it detaches and the main rbt ges and des its scring thing). Active scring strategies are encuraged ver negative spiling tactics. Wuld my ppnent be disqualified fr repeatedly ramming int a part f my machine, such as a barricade, until it breaks? N, if yu build a barricade and it is in yur ppnent's way. Yu are respnsible fr building a wimpy barricade... else we will have a nightmare f judging. Beware f barricades that can cause entanglement prblems. If ur ppnent has clamped nt the table and we try t lift them ff and accidentally rip a part f the table ff d we get disqualified? Or d they? It will be the judges discretin, BUT it is nt likely that they will be upset ver this. I am a little uncertain abut the crssing the line rule. If my ppnent meets the requirements by placing blcks in the bins, can I then crss the line? N. If yur ppnent has met the crssing requirements, yu may nt crss until yur ppnent has crssed the line. If yu crss the line withut having met the requirements, yu will be penalized. Hwever, if yur ppnent has met the requirements and crssed the line, yu may als crss the line. If my ppnent crsses the line withut scring. will I get penalized if I then crss the line withut meeting the scring requirements? N. Only the first persn t illegally crss the line will be penalized.

7 Prjectiles: Can an un-tethered part detach frm my rbt t hinder my ppnent r t help me scre (nt a prjectile r a net)? Sure! Be careful abut ffensive tactics - yu must satisfy the criteria fr crssing the line befre ANY part f yur machine can crss the line. Can my machine sht prjectiles? Yes! BUT, remember a few things - 1. The naked phne bth rule always applies. If yu are afraid t have smene pint yur prjectile shter at yu, it prbably is nt a gd idea. Prf. Slcum r yur lab instructrs will give definitive answers n the risk f specific prjectile designs. 2. If yu have a tether attached t yur prjectiles, be sure that it des nt becme entangled in anything. Using tethers as nets r blas is nt allwed. Histrically, judges will re-run a cntest where a machine is accidentally entangled by a tether. The judges view repeated entanglements with extreme unhappiness. Are blas (tw weights tethered tgether with *ne* rpe) allwed? Technically, it's nt a net, which is explicitly disallwed in the rules. Hwever, it can still be used t entangle in a similar fashin. N, yu may nt use a bla r any ther such device!! N weights tethered tgether still cunt as a bla. It is entanglement that we d nt allw!!!! (nt even Battlebts allws them!). May we thrw untethered bjects nt the playing field? The judges have been thinking abut this, and we have decided that we will nt allw anyne t launch a bunch f randm bstacles. It is nt in the spirit f the cmpetitin (great mechanical design and strategy vs. great mechanical design and strategy). Untethered prjectiles are allwed, but nt recmmended. As always, remember that the naked phne bth rule applies. In the rules, it explicitly states that n nets are allwed. Hwever, the Supreme Curt Decisins elabrate t say that it is intentinal entanglement in any frm that is nt allwed. Is it allwable t use a string-mesh net in a case where there is n intent t entangle (i.e., as a

8 cllectin device fr scring mass?) That is a real tugh questin... If yu string a net and smene gets caught in it, even if yu have n intent t entangle them, yu are still liable and will be disqualified under the rules. There therwise wuld be far t many "meshas" that were there fr "gathering with n intent". Autnmus Rbts: Is it allwable t have a cmpletely autnmus rbt? Sure, BUT yu cannt add batteries r ther pwer surces. Yu can nly use the wireless cntrl system and pwer electrnics we prvide. Yu may add any ther electrnics yu wish (micrprcessrs, filters, resistrs, pretty blinking lights, etc), but be mindful f the weight limit! Als be careful f the cmplexity f an autnmus system, as there may be incredibly simple and rbust slutins that are purely mechanical. Always make sure yu have a cuntermeasure fr the risk that the cntrl system desn't wrk. The stuff I've seen n the curse web page abut sub-rbts invlves tethers and what yu can't d with them. D sub-rbts *need* t be tethered? (i.e., an autnmus sub-rbt pwered by the mtrs.) Npe. Yu can have sub-rbts cntrlled separately with a wireless cntrl system n the main rbt. If yur rbt will be using any wireless cmmunicatins, be sure that they dn't interfere with the table cntrl system's radi frequencies. Sme very useful and disruptive strategies can be frmed with an independent machine that desn't require any cmmunicatin. Hwever, yu nly have ne battery t d all this with! May ur rbt have different mdules that can be swapped befre runds depending n the ppnent? Abslutely, that is an excellent example f gd design and strategy! But yu will have t shw at impundment that each cnfiguratin f yur machine meets weight and size limits in their specific starting cnfiguratin.

9 Kit Questins: I've been tld that in past years that handy bards have been permitted. Is this true? Yu are allwed t d yur wn electrnics, s if yu want t, yu can use a handy bard and make an autnmus system...but yu cannt add batteries r ther pwer surces. I'm cnfused abut additins. if peple are allwed t add prgrammable electrnics. What are we allwed t and nt allwed t add as far as materials that are nt in ur kits? We have always allwed peple t use wire and lgic, but n added pwer r mtrs (unless yu build yur wn frm scratch...nt wrth the effrt). Every year sme students ask abut this, and we say "OK" and mst students dn't end up using it. Yu may nt add any ther items r substitute any ther materials, except fr fasteners. Can we exchange r trade kit materials? N, the kit is as is. Yu are allwed t buy yur wn fasteners and adhesives and electrnic bits that s it! See the kit page fr infrmatin n replacements and exchanges and such. Are we allwed t cnstruct ur wn pneumatic pistns? I knw there was sme cnfusin in past years, and I want t be abslutely sure at the beginning f this cntest? The nly prblem is we are nt ffering pneumatic lines, its an all-electric cntest. The table is t big and the hassle f the lines makes it impractical. This als addresses the safety issues f pressurized cntainers. Anything yu culd want t d can be dne with electric mtrs and screws. Yu can cnstruct pistns t be used with the syringes, but that may prve impractical. T what extent may we prcess the kit materials? Fr instance, wuld it be permissible t heat-treat and anneal steel parts t make springs, r t turn the wd int sawdust and make a fiberbard material frm that sawdust and an adhesive?

10 Yu can heat treat t yur hearts delight...yu can als grind and glue. Als, t what extent can cpper wire be used? In past cntests, it was said that nn-kit electrical wire culd be used t bear a lad. What limits are there t the acceptable use f wire? Yu can nly use wire as electrical elements...else we will have peple melting wire and making stuff... Yu have mre stuff in yur kits than yu can imagine. Fcus yur creative energies n using what yu have as it is. Create a strategy and cncepts that kicks butt with it as is. Please nte that yu must have a drawing befre using the large machines (milling machines, lathes, water jet, etc). The shp guys will help yu prcess the parts, but they will nt make the parts fr yu. Drawings are nt necessary, but are highly suggested, befre prcessing materials using machines in the general area (belt sanders, drill presses, etc). Will we be able t use flexible plastic/rubber tubing? It is nt n the kit parts list, prbably because its main purpse was as pneumatic tubing, but it was als the best material with which t make cmpliant mtr shaft cuplings? We will NOT prvide hse as cupling material. Instead, we recmmend that yu cnsider the cheap brass r aluminum cuplings. May we use the syringes as elements f a simple hydraulic system? Yu may NOT create any fluid system (fluids are NOT part f the kit). Yu may create a pneumatic system if yu want t, but nly using elements in the kit. Are Velcr and zip-ties fasteners? Yes, Velcr is a fastener, but yu have t supply yur wn. Zip-ties are prvided fr cable management purpses and may be used t attach mtrs as described in the lecture ntes. Yu may nt use velcr, zip ties, r tape fr any majr structural purpses Culd yu tell me if we're allwed t use Velcr t fasten an bject t the cntest table? Yu can use Velcr hks t stick t the carpet, but yu CANNOT use adhesive backed velcr and stick the adhesive side t the table, because it culd leave a film. Als, yu cannt damage the carpet (velcr will nt) by using ther

11 fasteners, such as screws r pinty bits f metal! Nte that the starting area will be painted and yur velcr may nt stick! May I make creative use f rubber bands? Yes yu may, BUT they can stre n energy (prir t the machines starting) that will be released nce the cntest starts. Why? Because they are ntrius fr breaking and causing premature unintended release, which with sme mechanisms can cause an wie. Can I use a filter capacitr n the battery pack? Als, can I charge the capacitrs befre the rund starts? Yes yu can. But, yu can nly charge the capacitrs frm the batteries yu will use in that cntest. The charging can start nly after yu have placed yur machine n the cntest table. Yu will be respnsible fr discharging them after the cntest is ver (use a lightbulb). Safety: What is the "Naked Phne Bth rule"? DO NOT create any machine yu are nt willing t get int a phne bth with, where yu are naked while yur machine is perating in there with yu (s n spinning spikes, flaming wheels f death, etc). Table and Scring Elements: If I use sandpaper t grip the lexan, the plastic will prbably get a little scratched up. Des this cunt as destrying the table. i.e. fr disqualificatin? Yu shuld be fine. Can yu start with things dug int the carpet, t hld a machine frm lifting ff? Nt if yu hurt ur carpet. In ther wrds, I shuld nt be able t tell the

12 difference befre/after. Nw, if yu have dug in and smene rams yu and little tufts appear, that s OK, we will trim them, BUT yu cannt then cmplain that the carpet is nt letting yu grab a gd hld. It will be what it is. Is the cntest table smehw cated, painted,...? The cntest table is cnstructed as fllws: - The base and sme surfaces are cnstructed f wd. - The tp playing surface is cvered in carpet. Starting znes, blck lcatins, etc may be painted r marked in sme manner that changes the cnsistency f the carpet. - There are plastic walls arund the entire table t prevent things frm running away. The walls are nt painted r cated. Can I grab nt the blcks with a skewer r pitch frk? NO! Yu may nt alter the physical integrity f the blcks in any way. This means that yu may nt use screws, pinty bits f welding rd, sharp bits f metal cut n the band saw, etc. If yu destry the blcks, yu may be disqualified. Als, recall the naked phne bth rule.