huong dan lam robocon

7/16/2019 Huong Dan Lam Robocon

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Hng dnROBOCON 2005 Sample Robots

Ngi dch:[email protected]

www.robocon.vnwww.skynet.com.vn

H ni 2006


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Ni dung

Chng 1: iu khin DC Motor

1.1 Gii thiu hot ng DC motor1.2 iu khin hng chuyn ng dng mch cu H1.3 iu khin DC motor dng nh (1A) dng L293B1.4 iu khin DC motor dng ln (2A) dng L2981.5 iu khin tc DC Motor dng chnh rng xung (Pulse Width Modulation

-PWM)1.6 Phn cng Pulse Width Modulation (PWM)1.7 Phn mm Pulse Width Modulation (PWM)

Chng 2: D ng trng dng Sensor hng ngoi (IR)

2.1 cc c tnh ca IR sensor2.2 IR Sensor iu bin

Chng 3: Lp trnh Robot t ng

3.1 Chy theo ng trng3.2 D v m nhng ng ct


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Chng 1: iu khin DC Motor

1.1 Gii thiu hot ng DC motor cho motor 1 chiu hot ng, chng ta cn t 1 in p 1 chiu vo motor and 1

dng in 1 chiu s chy qua motor, motor s quay theo 1 chiu no .

Nu chng ta i chiu ca in p 1 chiu ny, motor s quay ngc li

Ch : in p V v dng I khng nn vt qu gi tr c ghi trn motor, nukhng motor s b hng. Tuy nhin nu ta t 1 in p thp hn V hoc 1 dng inthp hn I, th tc v chu ti ca motor s gim theo.


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1.2 iu khin hng chuyn ng dng mch cu H iu khin hng quay ca motor 1 chiu, chng ta cn t in p ln motor. C1 mch ph bin dng iu khin motor gi l cu H. N c gi nh vy bi vmch ny trng ging hnh ch H. Mt trong nhng kh nng cc hay ca mch nyl n cho php iu khin motor tin ln hoc li li bt k tc no, ngoi ra ncn c th dng 1 ngun in c lp [1].

Khi u vo Direction trng thi cao th motor s chuyn sang ch hng bnhthng. Nu u vo Direction trng thi thp th motor s quay ngc chiu.

C rt nhiu loi IC dng cho mch cu H. Loi ph thng dng cho motor dng thpl L293B v motor dng cao l L298.

1.3 iu khin DC motor dng nh (1A) dng L293Bng dng in hnh ca L293B c v trn hnh di [2]. Vs l in p t vomotor v c th ln ti 36V. Dng ln nht ca L293B c th ln ti 1A mi knh.Mt IC L293B c th dng iu khin 2 motor. u vo 2 v 7 dng iu khinmotor 1. u 10 v 15 dng iu khin motor 2. Diode D1 v D8 to 1 mch cp.L293B l mt IC ph thng c th mua cc ca hng in t (gi khong 20 ngnng tham kho www.skynet.com.vn)


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Trong cc robot t ng, chng ti s dng con L293B iu khin motor r tri vphi. Mch c v trn hnh di y.

Trong s P1.1 v P1.3 l cc tn hiu iu khin chiu motor t con vi s l87C552. Nhng tn hiu iu khin hng ny c t hp AND vi cc tn hiu iu

bin rng xung PWM0 v PWM1 iu khin tc motor. Chng ti s giithch vic iu khin ny trong mc sau.

Ngun motor c cung cp vo chn 8 ca con L293B. in p thc t ph thucvo thng s ca motor, thng t 9V n 12V. Robot mu ny s dng in p 12V.Chn 16 c ni vo in p 5V logic dng lm ngun IC.

L1 v L2 tch ngun nui L293B ra khi h thng. Chng hot ng ging nhnhng b lc cc tn hiu nhiu c sinh ra bi motor.


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1.4 iu khin DC motor dng ln (2A) dng L298L298 cng tng t nh con L293B nhng n cho php dng ln hn. ng dng inhnh c miu t nh sau [3]. (Gi con ny khong 40 ngn ng tham khowww.skynet.com.vn)


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Cho ng dng dng ln hn, chng ta dng 2 knh nh hnh v trn. Vs l ngunmotor v Vss l ngun logic. in tr Rs c dng hn ch.

Trong robot mu iu khin bng tay, chng ti dng con L298 iu khin 2 motordng ln (2A). Mch c v nh hnh di y.


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1.5 iu khin tc DC Motor dng chnh rng xung (Pulse Width Modulation-PWM)

iu khin rng ca xung c lm bng cch tt bt nhanh ngun in ln

motor. Ngun p 1 chiu DC s chuyn thnh tn hiu xung vung, thay i t 12V

xung 0V, to cho motor mt lot cc c sc in.

Nu tn s bt tt m cao, motor s chy mt tc n nh nhmmen quay

ca bnh xe.

Bng cch thay i chu k hot ng ca tn hiu (thay i rng xung PWM),

tc l khong thi gian Bt, ngun in trung bnh t ln motor s thay i vdn n thay i tc . [4][5]

1.6 Phn cng Pulse Width Modulation (PWM)iu khin rng xung (PMW) c th dng IC thi gian NE555. Mch dng conny c th hin trn hnh v di y. [6]

Trong mch ny rng Bt ca xung ph thuc vo in p t ln u vo chn 5

(RA v C gi nguyn). V chu k ca xung vung ph thuc vo tn hiu Trigger.


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Trong robot mu iu khin tay, 2 con NE555 to thnh phn cng iu khin rng xung nh trn hnh v. Tn hiu iu bin MOD c truyn t bin tr iukhin tc trn bn iu khin. VR1 v VR2 c th c iu chnh thay i chuk ca xung vung. VR3 dng chnh chu k ca sng.

1.7 Phn mm Pulse Width Modulation (PWM)S dng con vi s l c s cc tn hiu PWM, nh 87C552 nh chng ti dng chorobot mu, chng ti c th lp trnh to cc sng PWM.

Con 87C552 cha 2 knh iu bin PWM. Nhng knh ny to cc xung theo rngv khong cch c lp trnh. Tn s lp li c nh ngha bi thanh ghi 8-bittrong tn l b chia PWMP, to nhp ng h cho b m. B chia v b m dngchung cho c 2 knh PWM. B m 8-bit dng m 255, tc l t 0 n 254. Gi trca b m 8-bit c so snh vi ni dung ca 2 thanh ghi: PWM0 v PWM1. Gi


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s ni dung ca nhng thanh ghi ny ln hn gi tr b m, th u ra tng ng/PWM0 hay /PWM1 s l THP. Nu ni dung nhng thanh ghi ny m bng hocnh hn gi tr b m, tn hiu ra s l CAO. Chu k lm vic do c xc nh

bi ni dung ca 2 thanh ghi PWM0 v PWM1. Chu k lm vic nm trong khongt 0% n 100% v c th c lp trnh tnh tin 1/255/

lp li ca tn s fPWM, vi cc tn hiu ra PWMn c xc nh bi:

255)1(2

PWMP

ff OSCPWM

N cho ta tn s lp li t 84.7Hz to 21.7kHz (fOSC=11.0592MHz) trong trng hpca chng ti. Bng cch a vo cc thanh ghi PWM gi tr l 00H hoc FFH, ccknh PWM s cho tn hiu ra mc CAO hoc THP tng ng. V b m 8-bit mmodul 255, n c th khng bao gi t ti gi tr ca cc thanh PWM khi chng tat FFH.

Khi thanh ghi so snh (PWM0 v PWM1) c np gi tr mi, th u ra tng ngs c cp nht ngay lp tc. Vic ny khng cn phi i n ht chu k m. [7]

M ngun C sau y c lp cho cc u ra PWM:

/* PWM for Philips 87c552 */sfr at 0xFC PWM0 ; //Define the registers addressessfr at 0xFD PWM1 ;sfr at 0xFE PWMP ;

PWMP=53; //The period of the pulse (set to around 400Hz)PWM0=127; //Set 50% duty cycle for /PWM0PWM1=63; //Set 25% duty cycle for /PWM1[8][9]


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Chng 2: Dng Sensor hng ngoi (IR) d vch trng

2.1 Cc c tnh ca IR sensor

Trong con robot mu t ng ny, chng ti s dng 2 linh kin hng ngoi (IR): mtlinh kin pht hng ngoi (IR emitter) v mt linh kin nhn (IR receiver) to thnh 1cp cm bin sensor. Linh kin pht s to tia hng ngoi v sau khi phn x s truynti linh kin nhn.

Dng in i qua linh kin nhn s t l vi cng nng lng ca tia hng ngoi

m n nhn c.

Trong robot mu ca chng ti, linh kin pht v nhn c ni mch theo s hnhdi y. Khi TX trng thi thp, dng s i qua linh kin pht v n s pht ra tiahng ngoi. Nu c 1 vt phn x mu trng th nng lng hng ngoi s phn hi liv to mt dng cao hn i qua linh kin nhn, do in p trn IRS0 s h xung.

Nu vt phn x c mu en, hoc mu sm hn th in p trn IRS0 s nng ln.


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c gi tr in p ny chng ta c th phn bit c vch dn ng mu trng trnnn nh mu xanh.

2.2 IR Sensor iu bin

chnh xc ca sensor hng ngoi c miu t trn phn trc bnh hng rtnhiu bi nh sng mi trng. Mc in p trn u ra ca sensor IR khng ch phthuc vo cng nh sng phn x m cn b thay i bi iu kin nh sng mitrng.

gim bt snh hng ca nh sng mi trng, chng ti dng 1 sensor hngngoi iu bin thay v sensor IR thng thng.

Trong h thng sensor IR iu bin ca chng ti, linh kin pht c bt v tt bi 1ng h. Tn hiu nhn c sau i qua 1 mch khuch i 1 chiu DC nh trnhnh v di y. T C2 trong mch s chn dng DC ra khi tn hiu i qua b

khuch i ny. Ch c phn xoay chiu ca tn hiu thay i tng ng vi tia hngngoi phn x pht ra t b pht l c khuch i v tch hp vo mc 1 chiu u ra ca mch. Nh vy mc ra ca mch ch ph thuc vo tia hng ngoi mkhng ph thuc vo nh sng mi trng. [10]


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Chng 3: Lp trnh mt Robot t ng

hon thnh cc cng vic ca 1 robot t ng trong cuc thi Robocon 2005, robotphi c cc tnh nng sau:

1. kh nng ln theo vch trng2. kh nng nhn bit v m cc im giao nhau khi n i qua

3.1 Ln theo vch trng

Trong con robot t ng mu ca chng ti, chng ti t 2 cp sensor IR: bn tri(Left) v bn phi (Right) phn u ca robot. Khi sensor tri ct ng trng, gitr ca sensor s h xung di mc in p ngng t trc v chng ta buc phi cho robot chy sang tri mt vi bc iu chnh hng i ca n. Hoc khisensor phi ct vo vch trng, gi tr ca sensor phi s thp hn gi tr ngng tsn, chng ta phi cho robot chy sang phi mt vi bc iu chnh hng chychnh xc. Nu c hai sensor u khng ct vch trng th chng ta gi nh l ing hng v n chy thng.

Thut ton ln theo vch trng c miu t trong biu sau:

3.2 D v m nhng ng ct

d c nhng im giao nhau ca cc vach khi robot chy qua, chng ti kimtra c sensor tri v phi. Nu c hai sensor u ct vch trng cng lc th chng tac th cho rng robot i qua 1 im giao nhau. Trong trng hp ny, chng ta

phi cho robot i tip vi bc trnh m 2 ln im giao nhau ny.


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Thut ton nhn bit v m im giao nhau c v di y:

Hm C di y l v d cho 1 robot ln theo ng trng v m vch giao nhau khin i qua:

void move_robot(unsigned char step) {

int cnt;

cnt=0;while(cntALIGN_THRESHOLD && read_sensor(2)>ALIGN_THRESHOLD) movet(FORWARD,1,0);else if (read_sensor(1) ALIGN_THRESHOLD) movet(TURN_LE FT,1,80);else if (read_sensor(2) ALIGN_THRESHOLD) movet(TURN_RIGHT,1,80);else if (read_sensor(2)


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References

[1] http://www.robotroom.com/HBridge.html

[2] http://personal.telefonica.terra.es/web/x-robotics/downloads/datasheets/L239B.pdf[3] http://www.learn-c.com/l298.pdf

[4] http://www.cpemma.co.uk/pwm.html

[5] http://www.cse.cuhk.edu.hk/~khwong/ceg3430/mrobot6.ppt[6] http://www.fairchildsemi.com/ds/NE/NE555.pdf

[7] http://www.jjmb.nl/datasheets/microcontroller/8xc5x2_ov.pdf

[8] http://www.cse.cuhk.edu.hk/~khwong/ceg3430/87c552.h

[9] http://www.cse.cuhk.edu.hk/~khwong/ceg3430/demo.c

[10] bottom.pdf

[11] RoboconDemo05.c

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