hệ thống robot thông minh (1)
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H thng Robot thng minh
Ngc : 1-2-22 Phan: 3-4 Sinh: 5-6 ip: 7-8
Tng lt: 9+15 Tun Anh: 10-11 Chung: 12-13 Hoan:16-17
Tungcl: 18-19 Thy :20-21 Linh 14+15 Hng: 3+23
1 Phn bit robot cng nghip v robot thng minh. Trnh by s phn
nhnh trong pht trin Robot ti nhng thp nin gn y.RBCN l tay my vn nng, hot ng theo chng trnh v c th lp trnh li hon thnh v nng
cao hiu qu hon thnh cc nhim v khc nhau trong cng nghip, nh vn chuyn nguyn vt liu,
chi tit, dng c hoc cc thit b chuyn dng khc.
RBTM l mt loi vt c kh c khnng hot ng mt cch t tr. Ni cch khc n khng phi l 1 c
my ch thc hin nhng nhim v lp i lp li ging nh nhng cmy thng thng.Robot c khnng tng tc vi th gii bn
ngoi (di chuyn, thay i thgii
bn ngoi,) trong khi RBCN
khng c kh nng ny. RBTM c
th hoat ng c lp trong mi
trng m khng cn ngi iu
khin.
S phn nhnh trong pht trin
Robot (Hnh v)
2 nh ngha Robot thng minh?Robot thng minh l mt loi vt c kh c th hot ng mt cch t tr. Mt robot c th s dng
my tnh lm mt khi chc nng bn trong n, tng tnh b no. Robot c khnng tng tc vi
thgii bn ngoi (di chuyn) trong khi my tnh k c khnng ny. Hot ng mt cch t trngha l
robot c th vn hnh c lp trong mi iu kin m khng cn n ngi iu khin, t thch nghi vs
sthay i trong mi trng ca n tip tc t ti mt mc ch no .
T thong minh y ni ln rng robot khng lm vic mt cch n gin, lp i lp li nh cc h
thng tng trong cc nh my. Loi vt c kh ni ln rng cc b phn ca robot lm bng c kh.Tuy nhin, n nay v trong tng lai, cc b phn c thc thay thbng cc cu trc sinh vt hu
c nh cc k thut cy ghp hay sinh sn v tnh. nh ngha nh vy cng nhn mnh rng: robot
khng phi l ci my tnh. Mt robot c th dung mt my tnh lm 1 khi chc nng bn trong n,
tng tnh bno. Nhng robot li c khnng tng tc vi th gii bn ngoi (di chuyn y ,
lm thay i thgii,) trong khi my tnh th khng c khnng ny. Hot ng mt cch t tr ni
ln rng robot c th vn hnh c lp trong mi iu kin m khng cn n ngi iu khin. Khi
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nim t qun trc ngh l robot c th thch nghi vi sthay i ca mi trng ca n tip tc t
ti mt mc tiu no y.
3 Trnh by 3 loi m hnh c thit kcho mt robot thng minh
3.1 M hnh kiu th bc:Robot vn hnh theo cch t trn xung, xem nng vic lp khoch. loi ny, robot cm nhn mi
trng xung quanh, nh khoch cho hnh ng ktip v hnh ng (Sense-Plan-Act). Sau n lp
li qu trnh ny mi bc. Tt c cc thng tin cm nhn c tp hp li vi nhau trong mt m
hnh th gii ton cc. Chng c th c b lp k hoch s dng hay c th c cp ti cc b
hnhd ng
3.2 M hnh kiu phn ng:M hnh ny c sinh ra bi cc nh nghin cu robot thng minh s dng kt qu khm ph v
tm l sinh vt v nhn thc ca chng vi mi trng v do s gim gi nhanh chng ca phn cngmy tnh cng vi s tang cng nng lc tnh ton ca my tnh v cc b x l. Mt m hnh kiu
phn ng c th bi khu lp khoch v tr thnh loi t chc cm nhn-hnh ng (sense-act). Li
vo ca hnh ng lun l li ra trc tip t b cm nhn (sense-act). M hnh ny c thi gian chp
hnh nhanh do khng cn vic lp khoch. Kt qu l m hnh phn ng cung cp nhng c s cho h
thng lai gia cn nhc/ hnh ng.
3.3 M hnh kiu lai:u tin robot lp khoch (cn nhc) phn chia mt cch tt nht nhim v thnh cc nhim v con
(gi l lp khoch nhim v) v cc ng x thch hp thc hin cc nhim vy l g Sau cc
ng x bt u thc hin nh m hnh phn ng.
Cch t chc ny gi l lp khoch - cm nhn- hnh ng (P,S-A) trong du phy ch ra lp k
hoch c thc hin mt bc, sau cm nhn v hnh ng sc thc hin cng nhau. T
chc cm nhn h thng lai cng l s trn ln gia kiu th bc v kiu phn ng. D liu t cc cm
bin c cap ti mi bng x cn chng, nhng cng c sn cp ti b lp khoch xy dng
m hnh mi trng ton cc hng nhim v. B lp khoch c thcng nghe ln trn cc cm
nhn ca mi bng x (tc l bng x nhn ra cc tr ngi m c th cn a vo bn i mi
trng ca b lp khoch). Mi chc nng tin hnh vic tnh ton tc ring ca n, ln khoch
k cng. Th d, cc tnh ton chung thng c cp nht sau mi ln 5s, trong khi bng x phn ng
thng thc hin ch trong khong 1/60s trong cc robot di ng vi tc c 80cm/s.
4 Cc thnh phn c bn ca mt ro bot thng minh t qun tr(Phan)
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5 Trnh by tm tt nguyn tc hot ng v u nhc im ca cc
loi cm bin: lp m trc quay, cm bin chhng, cm bin siu
m pht hin vt th gn, cm bin nh, cm bin o khong cch
bng laser
5.1 Cm bin lp m trc quay:- Cm bin lp m trc quay l loi cm bin ni c s dng ch yu cc robot di ng
do tnh n gin ca n, nht l dung trong cc trng hp iu khin robot di chuyntrong khong cch ngn
- Nguyn l hot ng: l mt a trn xoay quay quanh trc, trn a c cc l (hocrnh). Dng n led chiu ln mt a. Khi quay, ch khng c l(rnh) th n khngth chiu xuyn qua c, ch c l(rnh) th n s chiu xuyn qua. Pha mt bn kiaca a c t mt cm bin thu. Vi cc tn hiu c hoc khng c nh sng chiuqua, ngi ta ghi nhn c n led c chiu qua l hay khng.
Gi strn a c n l, th mi ln cm bin thu nhn c n ln tn hiu n led th cngha l a quay c mt vng.
- u im: n gin, cch ly vi ngun iu khin ng c,- Nhc im: h thng hot ng thi gian di s b sai s tich luy h thng, mt s h
thng encoder tuyt i c gi thnh kh cao(encoder co do phn gii la 10 bit)
5.2 Cm bin chhng:Cc cm bin loi ny cho pht xc nh c gc hng hin ti ca robot so vi mt hngchun no . C 2 li chnh: cm bin la bn hoc cc cm bin nh v qun tnh (INS)
- Nguyn l hot ng:+ Vi loi cm bin la bn: xc nh gc lch ca robot so vi hng bc da vo hintng cm ng tu im : h thng n gin d ch tao,Nhc im: H thng c nhy tng dn theo cng ngh ch to, hay gp phi vn nhiu ttrng.+ Vi cc cm bin nh v INS: h thng INS gm c cc sensor cm bin vn tc gcv gia tc gc, cho php chng ta xc nh c vn tc gc nghing, gc chc, gchngu im: ca h thng ny l: nhy, chnh xc cao, tiu th cng sut nh, kich
thc nh, gi thnh r do s dng cc cm bin MEMS, v gic chnh xc cahng ban u khng ph thuc vo tc nhn bn ngoiNhc im:
Li v tr khi lp t cm bin: gy sai gc nghing, gc chi v gc hng lch (offset) ca cm bin gia tc: Li ra cm bin gia tc s b lch i mt gi tr
khng i. Gi tr ny li thay i mi khi tt / bt thit b.Hin tng lch v tri ca cm bin vn tc gc (do tc ng ca nhit ): Vt th
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khng chuyn ng nhng vn c vn tc gc khng iNhiu ngu nhin: Li ngu nhin trong o lng
5.3 Cm bin siu m pht hin vt th gn- Nguyn l hot ng: h thng gn 2 phn b pht v b thu tn hiu. B pht tn hiu
pht ra sng siu m sau mt thi gian t ta thu c song phn x t vt cn b thu tnhiu. Da vo khong thi gian t lc pht ti lc thu c tn hiu ta c thtnh ckhong cch n vt cn tnh theo nguyn l TOF d=v.t/2. Trong :- d l khong cch t vt cn n h thng- v l vn tc sng siu m trong mi trng truyn sng,
U IM: khong cch m cm bin c th pht hin ln ti 15mSng phn hi ca cm bin khng ph thuc vo bn cht ca b mt i tng hay tnhcht phn x sng ca i tng
Nhc im: cm bin siu m yu cu i tng c mt din tch b mt ti thiu. Sngphn hi cm bin nhn c c th chu nh hng ca sng m thanh tp m. Cm bintim cn siu m yu cu mt khong thi gian sau mi ln sng pht i sn sng nhnsng phn hi.kt qu cm bin tim cn siu m nhn chung chm hn cc cm bin khc
5.4 Cc loi cm bin hnh nh chnh
C hai loi b cm bin hnh nh chnh l b cm bin CCD v CMOS, CCD v CMOS lhai cng ngh khc nhau dng trong cc phn t nhy sng c s dng trong cc lnh vc xl hnh nh nh v tuyn truyn hnh, nhip nh s, cc my mc vn phng (scaners, copyers),thin vn, hng khng v tr, cng nh cc ngnh cng nghip khc.C CCD v CMOS u
thc hin mt nhim v ging nhau: bin cc tn hiu nh sng thnh cc tn hiu in t. Skhc nhau c bn ca chng (v nguyn l hot ng) nm cch chuyn cc tn hiu in t ra khi phn t nhy sng nhm mc ch x l tip v lu tr.
1. Nguyn l hot ng
Nhim v ca chip cm bin l bt nh sng khi ca trp c m v chuyn chng thnh ccin t; sau , cc in t ny c chuyn thnh in p; cui cng in p chuyn sang dngtn hiu s.
CCD gm mt mng li cc im bt sng c ph bng lp bc mu ( red, hoc xanh lcgreen, hoc xanh dng blue), mi im nh ch bt mt mu. Do , khi chp nh (ca trp
m), nh sng qua ng knh v c lu li trn b mt chp cm bin di dng cc im nh. Mi im nh c mt mc in p khc nhau s c chuyn n b phn c gi tr theo tnghng. Gi tr mi im nh s c khuch i v a vo b chuyn i tn hiu tng t sangtn hiu s, cui cng vo b x l ti hin hnh nh chp. Chnh qu trnh c thng tinthc hin theo tng hng lm cho tc x l nh chm, ri thiu hoc tha sng.
Cc nh nghin cu tnh n vic trang b thm b c nh b sung xen k vo cc im btsng c tt c cc thng tin im nh trong mt ln nhng iu ny bt buc phi tng khng
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gian ca chip cm bin, do vy m khng kh thi v mi mt. Chnh ci iu m cc nh nghincu mun b sung cho CCD th CMOS li c sn, bi cnh mi im bt sng c sn mchin b tr d dng tch hp ngay qu trnh x l im nh. Vi cu trc ny, mi im nh sc x l ngay ti ch v ng lot truyn tn hiu s v b x l ti hin hnh nh chpnn tc x l s nhanh hn rt nhiu.
Mt u im na m cu trc ny mang li l c th cung cp chc nng tng tc mt vngim nh (nh phng to mt phn nh) cho ngi s dng, iu m chp cm bin CCD kh lmc. Vi kh nng b tr nhiu nh vy nhng chip cm bin CMOS li tiu th t nng lnghn chip cm bin CCD, cng vi nhiu yu t khc m gi thnh sn xut chip CMOS thp.
th h u ca chp cm bin CMOS, nhiu to ra do vic khuch i im nh l ng k,lm cho nh chp c khng mn. im yu ny c ci thin th h sau bng vicc hai ln im nh (ln 1 c gi tr bt sng, ln 2 c gi tr ca mch b tr; sau thchin php tr) v bng vi thu knh lm nh sng ri vo ng v tr bt sng.
5.4.1
5 u im ca chip cm bin nh sngKhi so snh gia chip cm bin CCD v chip cm bin CMOS, ngi ta thng nu ra ngay 5 uim ca CMOS:
nhy sng cao, phn gii cao. in nng tiu th t, ko di thi gian dng pin. t b nhiu. Tc x l nh chp cc nhanh. Tch hp nhiu chc nng tng tc trn nh chp.
5.5
Cm bin o khong cc bng laserNguyn tc hot ng: o khong cch tmy o n mt vt no , my s pht mtxung laser, tia ny n vt cn s phn x trv, my o trang b b thu s nhn li xung ny.T my kim tra tlc pht n lc nhn mtbao lu v suy ra on ng i v v ca tiasng, sau chia hai xc nh c khong cch tht. Tt nhin my s lp trnh tnh tontt c. Ngi o ch vic bm nt v c kt qu trn mn hnh l bit c khong cch cn o.
- u im: h thng cho kt quc chnh xc cao, thi gian o nhanh,- Nhc im: Sng phn hi ca cm bin ph thuc vo bn cht ca b mt i tng
v tnh cht phn x anh sng ca i tng
Vd: thy tinh cho nh sng truyn thng qua nn h thng khng th pht hin c cc vttrong xut nh thy tinh, cc vt th hp th nh sng hay tn s nh sng.
6 Ti sao li phi s dng phng php tng hp cc cm bin trong dn
ng v nh vRobot di ng.(Cu ny Sinh bo tr li theo cu 5)
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7 nh ngha b chp hnh(actuator)? Ba loi b chp hnh c bn l g?
Cc cch btr cc bnh xe trong robot di ng, mch cu H l g
7.1 nh ngha b chp hnh.1. B chp hnh l mt dng ng c dng cho chuyn ng hoc iu khin mt c cu hoc mt
h thng chp hnh. N c vn hnh bi s dng mt ngun nng lng, thng l mt dng
ca dng in, thy lc, thy kh. Cc ngun nng lng ny sau s c bin i thnh mt
vi dng chuyn ng khc.
2. B chp hnh ging nh c bp ca robot, b phn chuyn i nng lng lu tr thnh
chuyn ng. Cho n by gi, ph bin nht l ng c in (lm quay bnh xe hay bnh rng)
v b chp hnh tuyn tnh m iu khin cc loi robot cng nghip trong nh my. Tuy nhin,
gn y c mt vi tin b i vi cc b chp hnh thay th khc m c cung cp nng lng
bi in, ha hc hay kh nn.
7.2
Ba B chp hnh c bn- Robot dng ngun cp in: Ngun in cp cho robot thng l DC iu khin ng c DC.
H thng dng ngun AC cng c chuyn i sang DC. Cc ng c s dng thng l ng
c bc, ng c DC servo, ng c AC servo. Robot loi ny c thit k gn, chy m, nh v
rt chnh xc.
- Robot dng ngun kh nn: H thng cn c trang b my nn, bnh cha kh v ng c ko
my nn. Robot loi ny thng c s dng trong cc ng dng c ti trng nh c tay my l
cc xy-lanh kh nn thc hin chuyn ng thng v chuyn ng quay. Do kh nn l lu cht
nn c nn robot loi ny thng s dng trong cc thao tc gp t khng cn chnh xc
cao.
- Robot sng ngun thu lc: Ngun thu lc s dng lu cht khng nn c l du p. H
thng cn trang b bm to p lc du. Tay my l cc xy - lanh thu lc chuyn ng thng
v quay ng c du. robot loi ny c s dng trong cc ng dng c ti trng ln.
7.3 Cch btr bnh xe trong robot di ng 3 cch b tr bnh xe
Mch cu
Bng cch s dng cc cng tc in trong mch cu H, ta c th thit lp chiu hot
ng cho ng c.
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B iu khin
8 B iu khin trong robot c nhim v g? Phn bit gia b iu
khin nhng v biu khin dng PCB iu khin s dng d liu t b cm bin tnh ton cc tn hiu iu khin cho b chp hnh v
thng l mt my tnh nhng.
8.1 Nhim v ca biu khin trong robot- ng vai tr nh l b no v c trng cho s thng minh ca robot.
- S dng d liu t b cm bin tnh ton cc tn hiu iu khin cho b chp hnh.
8.2 Phn bit biu khin nhng v biu khin dng PC-
B iu khin nhng l mt h thng my tnh nhng c thit k cho mt s chc nng iunhin c th bn trong mt h thng ln hn m thng c cc rng buc v tnh ton thi gian
thc. B iu khin c nhng nh l mt phn ca thit b hon chnh thng bao gm phn
cng v cc phn c kh. N thng s dng li x l{ l vi iu khin hay khi x l{ l{ tn hiu s
(DSP). Chnh v nhng c im , khi s dng b iu khin nhng, ngi thit k c th ti
u gim gi thnh, tng n nh v hiu nng ca sn phm m vn p ng c v mt
chc nng.
- B iu khin dng my tnh a dng nh l my tnh cc nhn PC th c thit k tr nn linh
hot v p ng c a phn nhu cu ca ngi dng cui.
9 Trnh by 4 khi (block) c bn trong dn ng robot di ng
(robot navigation). Nm r cc khi nim: Navigation, Localization
(hay Positioning), Perception, cognition, motion control, Path-
Planning, Global map. Local map, Map-Building.
Bn khi block dn ng cho robot di ng (Robot Navigation):
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Perception: Robot phi phn tch ccc d liu cn thit nhn c t sensorcm ng.
Localization: Robot phi xc nh c
v tr ca chng trong mi trng
Cognition: Robot phi quyt nh hnhng t c mc tiu.
Motion control: Robot phi iu chnh ng c t c quo nh mong mun.
Cc khi nim:
Navigation: L mt qu trnh gim st v iu khin chuyn ng ca phng tin t
mt hoc nhiu a im. Tt c cc k thut lin quan n nh v dn ng bao gm vtr ca hoa tiu so vi a im hoc m hnh c bit n.
Path planing: c hiu qu trong vic m rng vng hot ng cua robot. Path planing yu cu phi xc nh v tr hin ti ca robot v v tr ca mc tiu, chai uphi trong mt khung tham chiu hoc h ta .
Map building : xy dng bn c thdi hnh thc ca mt bn s liu hoc cck hiu m t v tr trong vng hot ng ca robot.
Map in this context denotes any one-to-one mapping of the world onto an internalrepresentation
10Phn bit gia bi ton ng hoc thun v ng hc ngc cho mt
robot di ng? Phn bit gia cc khi nim: khng gian lm vic
(work space), khng gian cu hnh (configuration space), h thng
Holonomic v Non-holonomic, ng i v quo?Bi ton ng hoc thun l bi ton t thng s ca c cu chp hnh (ng c) ta tnh ton ra
c ta ca robot. Bi ton ng hc ngc l bi ton m ta bit trc c quy lut chuyn
ng ca cc c cu chp hnh (ng c), ta phi tnh ton tt c cc thng siu khin cc ngc a robot t n im ch c ta cho trc.
Khng gian lm vic l tp hp tt c cc v tr m robot c tht ti. Mt cu hnh (bao gm cc thng
s ca robot) s miu t mt tnh trng ca robot. Khng gian cu hnh l tp hp tt c cc cu hnh m
robot c tht c. Khng gian lm vic ph thuc rt nhiu vo khng gian cu hnh.
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- H thng Holonomic l h thng m cc phng trnh ng hc c th biu din ch bng cc
hm hin (explicit function) ca cc gi tr v tr.
- H thng non-holonomic l h thng m cc phng trnh vi phn khng khtch cho n v tr
cui cng, v dnh trong 1 robot di ng non-holonomic cc thng s v khong cch chuyn
ng ca mi bnh khng tnh ton chnh xc v tr cui cng ca robot nh hnh v.
ng i (path) l qutch cc im m robot
di chuyn, n l mt miu t v chuyn
ng mang tnh cht a l thun ty. Cn qu
o (trajectory) l mt ng i m ngoi miu
t v a l, cn c thm miu t v thi gian
c c th ha vi cc bin nh vn tc v gia
tc ti mi im.
11Phn bit gia iu khin vng h (Open-loop Control) v iu khin
vng kn (Closed-loop Control) cho v d?iu khin vng h l iu khin ch s dng cc d liu u vo, h thng khng s dng phn
hi. iu khin vng kn l h thng iu khin ngoi cc d liu u vo m cn s dng phn hi t
iu chnh.
V d: iu khin vng h: ng c bc l mt ng c in 1 chiu m 1 vng quay ca n c chia
lm cc bc bng nhau. ng c bc c th nhn lnh quay hoc gigc quay no vi chnh
xc rt cao m ko cn bt c phn hi no.
Lnh Xung iu khin Dng ng c
iu khin vng kn: ng c servo l mt thit
b truyn ng quay cho php kim sot chnh
xc v tr gc. N bao gm mt ng c cng vi
mt b cm bin thng tin phn hi v tr thng
qua 1 gearbox. N cng i hi mt b iu
khin tng i phc tp, thng l mt mch
iu khin chuyn dng thit kc bit s
dng vi ng c servo. Tn hiu ra ca ng c
c ni vi mt mch iu khin. Khi ng c
Giao din
ngi dng
Ch s Biu
khin
ng c
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quay, vn tc v v tr sc hi tip v mch iu khin ny. Nu c bt kzl{ do no ngn cn chuyn
ng quay ca ng c, c cu hi tip s nhn thy tn hiu ra cha t c v tr mong mun.
Mch iu khin tip tc chnh sai lch cho ng c t c im chnh xc.
12nh v cho robot di ng l g? Vai tr quan trng ca n vi mtrobotdi ng thng minh (t qun tr)?
12.1 - nh vcho robot di ng l g:Khi robot mun i t vtr A n v tr B, robot phi bit mnh ang ng v tr no.
iu l rt quan trng robot c th tiu khin mnh ti c v tr mong mun. nh v
cho robot di ng l xc nh vtr ang ng ca robot, hng , ta , hay v tri so vi mt mc no
thng l im mc ban u.
12.2Vai tr quan trng ca n vi mt robot di ng thng minh (t qun
tr):Vi mt robot di ng thng minh, vic xc
nh v tr ca robot rt quang trng, ging
nh con ngi, nu khng bit mnh ang
ng u, vtr no th chng ta b lc.
robot cng vy. Vi con ngi, vic xc
nh v tr cn ti nhng gic quan, th vi
robot, xc nh c v tr n dng
nhng cm bin, cm bin chhng (con
quay hi chuyn, cm bin la bn, IMU),gii m trc quay hay s dng nh vi ton
cu GPS
Hnh bn l s ca robot xc nh v
tr.
13Cc php o vtr tng i v tuyt i? u nhc im?
13.1Cc php o tngi: ( ni lun uu nhuoc im)+ Gii m trc quang: thng l mt a trn quay quanh trc, trn a c cc rnh v c cn n led v
cc cm bin anh sng thu nhn tn hiu. T tnh ton ra v tri, phng php ny n gin v
khng tn km tuy nhin b sai stch ly.
+ n ng qu tnh: phng php ny s dng con quay hi chuyn v mt strng hp s dng
thm cm bin gia tc k. xc hng. tuy nhin cm bin con quay hi chuyn th b tri theo thi
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gian nn gy ra s khng chnh xc. Tuy nhin vic s dng kt hp vi cc cm bin khc th n s rt
chnh xc tuy nhin gi thnh khng r.
13.2Cc pht o tuyt i:+ Active Beacons: Phng php ny tnh ton v tr tuyt i, da vo 3 v tr mc hoc nhiu hn cc
ct pht tnh hiu (trm thu pht GPS ang { m ko bit dim dt thno),
+ Artificial landmark recongnition( cai nay going ngon hai dang nhe @@) phng php ny s dng cc
ct mc xc nh vtr trn mi trng. N c u im ti u vi nhiu iu khin mi trng v sai
s b gii hn, Ging nh mt hot ng tch cc, n a ra v tr don., Tuy nhin vic nht ra ct
mc v sa li v tr trong thi gian thc khng thlun lun c thc hin.
+ Natural landmark recognition: l mt ct mc c cng nhn, n l mt mc c bit ngoi mi
trn, n l mt mc c sn, n phi ni tri hn so vi mi trng, v tin cy ca phng php ny
khng cao so vi mc c do con ngi to ra. (c ngha l mc ny da vo mt mc c bit ca mi
trng)
+ Model matching (mo hinh kt hp) da vo thng tin thu thp c t cc cm bin v so snh vi
bn hay m hnh ca mi trng, nu cc tnh nng gi tr ca cm bin ph hn vi bn , m
hnh th sau v tr tuyt i ca robot c thc c tnh. inh vthng bao gm cc bn ton
cc da vo cc cm bin quan st trong mi trng,v tch hp thm cc bn bao gm khc v tri
cha c bit n. bn dn ng c chia lm 2 loi chnh: geometric (hinh hoc) maps v
topological maps.
14nh v bng nh x bn (Map-based Positioning)? Hiu v 2 cch
biu din bn (Geometric Map v Topological Map)?nh v bng nh x bn l mt phng php m robot s dng sensor to mt bn ca
mi trng cc b. Sau bn ny c so snh vi bn ton cc m c lu trong b nh.
Nu ging nhau th sau robot tnh vtr v hng. Bn c lu trc c th l mt m hnh
CAD hoc n c thc to nn t d liu ca sensor trc . Cc th tc trong nh b bng nh x
bn c th hin trong hnh v:
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Nhng thun li ca nh v bng phng php nh x bn :
- Phng php ny s dng nhng g xy ra ca mt mi trng bn trong suy ra thng tin v
tr m khng cn thay i mi trng.
- Phng php ny c th dng cp nht bn .
- Phng php ny cho php mt robot lm quen vi mt mi trng mi v nng cao s chnhxc.
Nhng bt li ca phng php nh v bng nh x bn :
- Cn c im chun, nhng c im d phn bit s dng cho so snh.
- Bn cn chnh xc.
- Cn c sn mt khi lng ln nng lng cho cm ng v x l.
14.1Map bulding
14.1.1Map buildingC hai cch c bn trong nh v bng nh x bn l c sn mt bn hoc l robot phi t to
nn bn ca mi trng. Hoppen lit k ra 3 bc chnh ca x l d liu sensor cho vic to bn
l:
- Lc ra nhng im c trng ca d liu t sensor
- S lin kt d liu t nhiu sensor
- T to mt m hnh ca mi trng vi nhng mc tru tng khc nhau.
Mt vn lin quan n xy dng bn l autonomous exploration. to nn bn , robot
phi khm ph mi trng ni cc vng biu . Gi s robot bt u cucj hnh trnh m khng
bit g vmi trng. Khi cn mt phng php chuyn ng ti a slng vng biu trongmt lng thi gian t nht.
14.1.2Xy dng bn v lin kt sensor
Vic kt ni cc d liu t nhng sensor khc nhau l rt cn thit qu trnh ny gi l lin kt sensor.
14.1.3Map Matching
Vic kt ni bn thng tp trung vo vn kt ni mt nh gm vtr v hng vi m
hnh. Thng thng, vic kt ni ny thnh cng bng cch lc ra nhng c im xc nh stng
ng ga nh v c im ca m hnh.
Cc thut ton matching c th chia ra thnh hai cch: icon-based v feature-based.
14.2Geometric and Topological Maps
Trong nh v bng nh x bn c hai cch biu din thng thng l: bn hnh hc v bn
hnh hc topo. Mt bn hnh hc biu din cc vt theo mi quan h hnh hc. N c th l mt
bn k Trong nh v bng nh x bn , nhng bn hnh hc c suy ra t sensor phi
c ni vi bn ton cc ca mt vng rng. Thng vic ny gp kh khn v li v v tr ca robot.
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Mt khc hng tip cn ca hnh hc tp da trn s lin h gia hnh hc v nhng c im c
nhn bit ch khng phi l v tr. Kt qu biu din l biu m cc node biu din nhng c im
nhn bit c v cc cnh biu din mi quan h gia cc c im. Khng ging nh bn hnh hc,
bn topo c thc dng v duy tr m khng cn tnh vtr robot. iu ny c ngha l l i trong
cch biu din nay sc lp vi li trong tnh ton v tr ca robot.
14.2.1Geometric maps for Navigation
C nhiu cch biu din d liu bn hnh hc, c lcch n gin nht l bn hnh .
Thun li ca bn da trn cc trng l:
- Cho php mt ln hn cc bn ni
- t tnh ton v c th to nhanh
- D tch hp cc thng tin t cc sensor khc nhau
- C th s dng biu din d liu mt cch chnh
Bt li:
- C nhng vng bt nh ln.
- Gp kh khn trong vic kt hp vi nhng active sensor
- Cn mt qu trnh nh tnh phc tp cho robot
14.2.2Topological maps for navigation
Nhn nh a im: vi chc nng ny, v tr hin ti ca robot trong mi trng c xc nh.
Thng thng, mt m t ca v tr hay ca node trong bn c lu tr cng vi a im. M t
ny c th abstract hay n c th l mt bn sensor cc b. mi node, matching gia d liu cm
nhn c v m t ca node.
La chn hnh trnh: Vi chc nng ny, mt ng ta im hin ti ti im ch c tm ra.
15nh v da trn cc ct mc (landmarks hay beacons)
15.1Landmarks-based Positioning
Ct mc l nhng vt thng trong mi trng m c thnh v chnh xc khi chng trong
tm nhn ca robot. Robot s dng nhng ct mc nh vthng l nhng ct mc nhn to m
c t sn bi nh thit k. H thng iu khin cho nh v da trn ct mc gm hai bc ri rc.
Khi ct mc trong tm nhn, robot nh v nhanh v chnh xc, nhng khi khng trong vng ct mcrobot nh v khng chc chn n khi gp c ct mc tip theo. Vic chuyn tip t vng ct mc
ny sang vng ct mc khc robot phi lu { ti bn cn thn, vic chuyn i cn ngn, c th
nh v thnh cng khi ti ct mc ktip.
Ct mc l nhng c im d phn bit m robot c th nht bit t li vo sensor. Ct mc c
th l hnh hc hoc bao gm nhng thong tin khc. Thng, ct mc c v tr cnh robot c th
nh v chnh n. Ct mc c chn d xc nhn. Trc khi robot s dng ct mc nh hng
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th nhng c im ca ct mc cn c bit trc v lu trong b nh ca robot. Nhim v quan
trng sau l nhn bit ct mc v tnh ton v tr ca robot. n gin ha, vn thng c gi
s rng v tr hin ti v hng ca robot c bit sn v throbot ch cn tm kim ct mc trong mt
vng gii hn. Quy trnh nh v da trn ct mc nh hnh:
Ct mc t nhin l nhng vt, dc im m c trong mi trng v c chc nng ca n ch khng
phi ch cho robot nh v. Ct mc nhn to l nhng vt c thit kt trong mi trng vs
mc ch cho robot nh v.
im bt tin ca nh v da trn ct mc l n yu cu sthay i mi trng. N cn mt slng
ct mc ln bao ph ht din tch nh my ln hay phng th nghim.
Tm li nhng c im ca vic nh v da trn ct mc:
- Ct mc tnhin a ra s linh hot v khng cn thay i mi trng.
- Ct mc nhn to t, v cn c thm thng tin c m ha.
- Khong cch ln nht gia robot v ct mc (landmark) thng ngn hn trong h thng ct
mc (beacon) tch cc.
- Snh v chnh xc da vo khong cch v gc gia robot v ct mc
- X l nhiu hn trong h thng ct mc tch cc (active beacon system)
- Nhng iu kin bn ngoi nh nh sng cng l mt vn .
- Ct mc cn c sn trong mi trng xung quanh robot
- nh v bng ct mc yu cu robot bit v tr hin ti tm kim ct mc nu khng s mtthm thi gian x l v tm kim.
- Cn c c s d liu v ct mc v v tr.
15.2Beacon based position.
Mt trong nhng gii php cho vn nh v l thit k v dn dng mt h thng ct mc
active cho mi trng. y l phng php c s dng cho c nhng ng dng cng nghip v qun
s vi chnh xc cao. Trong phn ln cc h thng beacon, thit kph thuc u tin vo cc l
thuyt hnh hc nh hng n vic nh v. Trong thng hp ny robot phi bit v tr ca hai active
ultrasonic beacon trong ta global nh v chnh n.
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16Cc thch thc gp phi trong qu trnh nh v (sensor noise and
alising noise, effector noise)?
16.1Nhiu do cm binCm bin l mt u vo c bn trong qu trnh nhn thc ca robot. Tuy nhin, cm bin cng
tn ti mt gii hn nht nh vthang o cng nh cc can nhiu xy ra trong qu trnh o c:
- Khi mi trng c nhng thay i, khng nm trong phm vi v khnng o ca cm bin nn
b cm bin b qua
- nh hng t robot, thit bkhc vo mi trng lm ri lon hot ng ca cm bin
- u o ca cm bin khng cn nhy hoc lm bn, che m mt
C th thy can nhiu do cm bin hu nh khng th trnh khi, tuy nhin ta cng c nhiu cch
khc phc iu ny bng cch xc nh li phm vi o v i tng o i vi tng mi trng quanh
robot hoc s dng nhiu cm bin cng loi gim thiu xc sut sai s so vi vic ch c mt cm
bin lm vic.
16.2Nhiu sai sCc h thng nhn bit ca robot ch lm vic vi cc tn hiu li vo thch hp vi tng loi mi
trng nht nh. V th, khi a robot n mt loi mi trng khc, h thng nh v ca n s tht
bi hon ton do phi nhn nhng thng tin o c sai t mt mi trng l gi ti. Trong robot, nhiu
sai sl hon ton bnh thng v khng th trnh khi. Do vi cc robot ta thng dng nhiu
loi cm bin khc nhau thu thp c nhiu thng tin khc nhau tmi trng, qua xy dng li
bn phc vcho qu trnh nh v.
16.3Nhiu tc ngDo tn ti nhiu cm bin v nhiu sai s nn hnh thnh nhiu tc ng: khi mt hnh ng c
robot thc thi, n c th cho nhiu kt qu khc nhau do chu snh hng t thng s sai lch gy ra
bi nhiu cm bin v nhiu sai s. K ckhi bit trc c v tr ban u ca mnh th v tr tip
theo ca cng s c khc bit so vi tnh ton. S sai lch trong chuyn ng lin quan n s sai
lch trong qu trnh o c hoc khnng tnh ton km ca robot khi khng s dng c cc thng
tin vng hc v ng lc hc; hoc do thay i ca yu tmi trng. Trong qu trnh chuyn ng
v nh v (da v cm bin bnh xe v cm bin heading ch bit dng t g cho thun), v tr ca
robot c thc tnh ton nh vic m ha vng quay bnh xe hoc t s liu o c bi heading
sensor hoc chai. Do , s sai lch tqu trnh o c ny stch ly theo thi gian dn n v tr
robot cng sai lch tch ly theo thi gian. Di y l mt s nguyn nhn ca li odometric:
- Hn chphn gii khi tch hp
- Cc bnh xe khng thng hng
- ng knh bnh xe c sai lch
- Li im tip xc ca bnh xe
- Tng tc vi b mt khng ng u (trt, mt phng g gh)
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Mt s li c thxc nh v loi bc bng cch hiu chnh li h thng. Tuy nhin vn cn c rt
nhiu li bt nh (ngu nhin) kh c th loi bc. Ta c th phn loi nhng li ny da trn quan
im hnh hc thnh ba nhm chnh sau:
- Li phm vi: tch ly khong cch trong qu trnh chuyn ng ca robot (bng tng ca s di
chuyn cc bnh xe)- Li chuyn hng: tng tnh li phm vi, nhng xy ra khi robot chuyn hng (gy ra do
s sai khc tc gia cc bnh xe)
- Li trt: gy ra bi sai khc trong li ca cc bnh xe dn n li ca gc nh hng robot
n mt khong thi gian di, li chuyn hng v li trt vt xa li phm vi, khi tng hp
ng gp li ca chng s tr ln phi tuyn. Hy xem xt mt robot c vtr ban u xc nh ang c {
nh di chuyn thng theo mt trc ta . Tuy nhin, li tt v chuyn hng hnh thnh mt gc
lch . Cng ngy gc lch ny cng ln khin robot di chuyn xa khi khung ban u. y chnh l mt
v d v Nhiu tc ng nh hng n robot khi cc li c tch ly theo thi gian
17Trnh by bi ton xc lp m hnh tnh sai s cho vic c lng v
tr (x,y,0) cho mt robot vi cc bnh xe vi sai, bng phng php
Odometry? Phn bit u l cc thng s h thng? u l cc thng
stc ng vo? Thng so? Cc can nhiu?(Phn ny c qua ton cng thc, vi chm y t cng chng hc hnh ghi chp g, thi th cdch y
nguyn li slide cho cc bn tham kho bn no mun c bn gc th tm slide th2 trang 53-64)
V tr ca mt robot c biu din di dng vector
[
]
Vi mt robot vi sai, vtr c c lng bi qu trnh tch ly chuyn ng bt u t mt v tr xc
nh. Xt mt h thng ri rc vi mt khong cch ly mu t cnh, khong cch dch chuyn ph
tri (x; y; ) l:
Trong :
(x; y; ) = qung ng dch chuyn trong khong ly mu cui cng
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= khong cch dch chuyn ca bnh phi v bnh trib = khong cch gia 2 bnh
T ta c v tr cp nht mi p:
Thay (3.4) (3.5) vo (3.6) ta c:
Phng php odometric c lng mt v tr cp nht rt st vi v tr tht. Tch ly li cc gi tr bt
nh ca p v cc li chuyn ng trong qu trnh tng chuyn ng ( ) khin cho li v tr tch lytng theo thi gian.
Tip theo, chng ta thit lp mt mu li cho vtr tch ly p thu c ma trn hip phng sai ca qu trnh c lng v tr odometric. Ta gi s rng, ti im xut pht, gi trban u ca ma trn
hip phng bit ttrc. Vi gia tng chuyn ng ( ) ta gi s c ma trn hip phng sai sau:
Trong l khong cch dch chuyn bi mi bnh v kr, kl l cc hng s li biu din ccthng skhng xc nh ca motor li v tng tc gia bnh vi sn. Trong cng thc (3.8) chng ta
tha nhn:
Sai lch bnh xe do bnh phi v bnh tri c lp gy ln
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Phng sai ca li (gy bi bnh phi v tri) t l vi gi tr tuyt i ca khong cch dch chuyn
( )Li chuyn ng (motion errors) hnh thnh do sai lch bi bin dng ca bnh xe, trt, bng
phng ca sn, li do encoder,. Gi tr ca hng s li kr v kl ph thuc vo mi trng v robot v
hon ton c th thit lp bng thc thi v phn tch chuyn ng
Nu ta gi s rng p v = ( ) khng tng quan ln nhau v o hm f (phng trnh 3.7)c tnh xp x bng cng thc Taylor bc nht nh sau:
Ma trn hip phng sai lun lun c cho bi ma trn ca ln tnh trc v c thc tnhsau khi xc nh gi trban u
S dng phng trnh (3.7) pht trin 2 Jacobians Fp v F
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Sgia tng tnh bt nh ca
v tr trong qu trnh di
chuyn theo ng thng:
Ch rng tnh bt nh ca
trc tung (y) tng nhanh hn
trc honh (hng cachuyn ng). y l kt
qu ca vic tch ly tnh bt
nh ca nh hng robot.
Cc hnh e-lip v xung quanh
v tr robot th hin tnh bt nh theo trc x,y. S bt nh ca gc khng c biu din trong hnh tuy
nhin ta hon ton c thxc nh mt cch gin tip nh sau:
Ta c phng trnh (3.11)
Stng ca tnh bt nh v tr theo s di
chuyn vng (r l hng s). Ln na, tnh
bt nh ca trc tung li tng nhanh hn
trc honh. Ch rng trc chnh ca cc
e-lip bt nh khng cn vung gc vi
hng ca chuyn ng na.
Tm li:(phn ny l kin ch quan, mong mi ngi gp thm)
Thng s h thng gm: p(x, y, ), direction, speed, b
Thng stc ng vo: kr, kl
Thng so: t
Cc can nhiu: x, y, Sr, Sl,
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18M tbi ton nh v da trn nh x bn bng phng php xc
xut vi b lc Kalman (Probabilistic Map-based localization with
Kalman Filter) trong trng hp c lng tnh (static estimation)?
Phn bit cc khi nim v tr thc, vtr o c, vi vtr c lng
c.Tr li:
5 bc ca phng php nh x bn :
Trong : Prediction (don) da trn estimate (c lng) trc v phng php odometry.
Trong bc u tin, v tr ca robot thi im k+1 sc don bi vtr c ca n(thi im k) v s chuyn ng ca n da theo ma trn iu khin u(k).
Observation (quan st) da trn cc sensor.bc th 2, robot phi quan st v tr mi ca n bng cc sensors gn trn .
Measurement prediction da trn prediction (don) v bn .Bc tip theo, ta s dng v tr c d bo ca robot v bn to ra cc don quan st .
Matching (nh x) cc quan st vo bn .Phn chia cc quan st (h sc gn bi sensors) vo ch (c lu trongbn ).
Estimation (c lng): cp nht v tr.p dng b lc Kalman vi php c lng tnh.
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Phn bit cc khi nim: V tr thc: v tr ca robot trong khng gian.
Vtr o c: vtr c cho l v tr thc qua cc php o s dng sensors.
V tr c lng c: v tr robot c cho l v tr thc sau khi kt hp cc php obng sensors v phng php odometry.
19Hiu th no v bn cht vai tr ca b lc Kalman trong vic tng
hp cc cm bin? Ti sao nh b lc Kalman m c lng v tr ca
robot trnn chnh xc hnRobot da vo cc cm bin xc nh v tr ca mnh. Vi mi cm bin, robot c th
xc nh c mt xc sut v v tr ca n trong khng gian (do cm bin lun c nhiu), B lcKalman l mt thut ton lc nhiu ra khi thng tin. N tng hp cc xc sut v tr ca robot,thu c qua cc cm bin a ra c mt xc sut c lng. Xc sut c lng ny lun
gn vi v tr thc hn xc sut thu c qua tng cm bin n l.Cc cm bin lun tn ti nhiu. Nhiu tng loi cm bin khc nhau l khc nhau.
ng thi, cc cm bin cng c th nhy vi cc vt cn khc nhau. Bng cch tng hp thngtin t cc cm bin, b lc Kalman lun a ra c gi trc lng chnh xc hn so vi gitrthu c ca tng cm bin n l.
20Ti sao li phi dng b lc Kalman m rngB lc Kalman l mt b lc tuyn tnh nn c th p dng cho cc h thng tuyn tnh.
Khng may l trn thc t h thng tuyn tnh khng tn ti, tt c cc h thng u l h thng
phi tuyn. B lc Kalman tuyn tnh ha l gii php cho vn trn. Tuy nhin, p dngc b lc Kalman tuyn tnh ha, chng ta cn phi c nominal trajectory (qu o danh
nh) trc khi c lng. Vi mt s h thng, chng ta c th bit trc c qu o danhnh (v dnh , mt chuyn my bay vi lch trnh nh hay l chuyn ng ca tay mytrong mi trng cng nghip), nhng cho cc h thng khc, chng ta c th khng c cch no bit trc c qu o danh nh. V vy chng ta cn phi dung b lc Kalman mrng chonhng trng hp ny. Cch m b lc Kalman mrng gii quyt vn l s dng chnh gitrc lng x ca chng ta lm qu o danh nh trong b lc Kalman tuyn tnh ha. Ni
cch khc, trong b lc tuyn tnh ha chng ta thay bng y l mt cch kho lo
thc hin vic c lng: chng ta s dng mt qu o danh nh c lng x, sau li sdng gi trc lng ca x nh l qu o danh nh.
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21Phn bit bn cht khc nhau gia cc bi ton vch ng i v
trnh va chmBi ton vch ng i: bn cht l bi ton vch ng ton cc: Mc tiu l tm ra mt
con ng trong khng gian vt l t mt a im ban u ti ch v trnh mi va chm vi
vt c. (tc l bn thn n cng cha bi ton trnh va chm). iu kin gii c bi tonny l chng ta cn phi c mt bn tt vmi trng xung quanh dnh cho vic dndng. C th l bn hnh hc hoc bn metric hoc kt hp c hai.
Bi ton trnh vt cn: bn cht l bi ton vch ng cc b: Mc ch l trnh vachm vi cc vt cn da trn cc thng tin c c t cc sensor thi gian thc. N thngda trn bn cc b. Tuy nhin bi ton trnh vt cn nn c ti u ha vi s ch timc ch chung, tc thc tv ng hc ca robot, cc sensor, nguy c va chm thc t vtrong tng lai.
22Trnh by phng php trng th c bn (khi nim trng th,
xy dng th ht, thy)?Phng php trng thc bn to nn 1 trng th, hoc 1 dc, ngang qua bn ca robot
dn robot ti ch t nhiu vtr khc nhau. Phng php trng thlm robot ging nh 1 qu bng
ln xung 1 qui. ch (1 im nh nht trong khng gian ny) ging nh 1 lc ht v nhng vt cn
th c coi nh nhng nh ni hoc l lc y. Tt c cc lc ny u tc dng ln robot; trong TH ny
robot lun c coi l 1 cht im trong khng gian. Robot si n ch trong khi trnh nhng chng
ngi vt bit trc.
Gi s robot c thnh vc v tr ca n cng vi bn v trng th, n c th lun lun xc
nh c hot ng tip theo da vo mi trng m n ang di chuyn. tng ng sau phng php
trng thny l robot c ht bi ch, trong khi n cng by bi cc chng ngi vt c
bit trc. Nu chng ngi vt mi xut hin trong sut qu trnh dch chuyn ca robot, n c th
update trng th tch hp them nhng thi tin mi ny. Trong TH c bn nht, ta coi robot nh 1
im, v vy, hng c th bqua v trng thc thcoi nh 2D (x,y).
Gi s c hm kh vi U(q), ta c thtm c lc gi F(q), v tr (x,y):
vi,
Trng thtrn robot c thc tnh:
Tng t vi lc thtrn robot:
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Lc ht. Mt lc ht c thc nh ngha n 1 hm parabol:
Trng ht l kh vi, dn ti lc ht Fatt :
Hi t v 0 khi robot vch.\
Tng t vi lc tc ng ln robot c th c 2 thnh phn l lc ht v y:
Trng thy. Trng thny to ra lc y vi robot t nhng vt cn bit trc. Thy cn rt
mnh khi robot gn vi vt th, nhg khng tc ng khi n xa. Mt v d vi lc y:
Lc y:
Kt qu lc F(q)=Fatt(q)+Frep(q) tc ng ln robot gip robot i n ch m ko chm phi vt cn.
23Trnh by phng php tm kim ng i bng th? Trnh by 3cu trc th ph bin (Visibility Graph, Voronoi Diagram v Cell
Decomposition)- Gim gi thnh v mc ti thiu i vi vn tm ng gia hai vtr xc nh trn bn
.
- Cu trc bn l mt hnh dng tng trng.
- Khng gian trng thi nm trong mt khu vc c nh du.
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- Tn ti mt s khu vc cha c nh v trn bn .
23.1Ba cu trc th ph bin
23.1.1Visibility Graph (1/2)( th r rng)Cc nt trn bn l im khi u v im ch n, cc cu hnh vng cung l cc chng ngi vt.
Tt ccc nt c nh vn cc im khc v c kt ni vi nhau thnh cc on, khc c
gi l ng i trn bn (n ging nh mp, g)
Vic s dng th ny ph hp vi khu vc c chng ngi vt gm nhiu cnh.
- di ng i ngn nht
- Trnh vt cn trnh va chm
- S nt v cnh tng tng ng vi s vt c
cnh
- N kh c kh nng hot ng tt trong mitrng ng c, nhiu vt cn.
Cu trc bn loi ny thng c p dng trn cc
robot di ng v vic thc thi kh n gin. Cu trc bn
r rang ny cng c th thc hin vi khng gian lien
tc hoc ri rc. Hai vn quan trng khi thc hin tm
kim trn th r rang ny:
- Th nht, kch thc khng gian v s cnh, s nt tng t l thun vi s vt cn. Phng php
s dng c tht hiu qu tt ty thuc vo mi trng cng nh cng nghc dng
thc hin th.
- Vn th hai l c th thc hin vic d ng cho robot trong hang ng. C th chng minh
phng php thr rang l phng php ti u tm c con ng ngn nht. Gii php
thng thng l pht trin cc vt cn nm ngoi bn knh hot ng cu robot, thay i
phng hng ngay khi xc nh c khong cch trobot n vt cn.
23.1.2Voronoi Diagram (Phng php khi Voronoi)Wiki- l mt cch phn tch mt khng gian mtric
theo khong cch ti mt tp hp ri rc cc vt th cho trctrong khng gian. Tp hp cc vt th c th l tp hp ri rc
ccim.Trong trng hp n gin nht, khi cc vt th lcc im, ta c mt tp hp S gm cc im trn mt phng,c gi l cc im Voronoi. Mi im sng vi mt Voronoi, hay cn gi l Dirichlet, k hiu l V(s), bao gm ttccc im gn shn tt ccc im Voronoi khc. Cc cnhca s Voronoi l tp cc im c khong cch ti hai imVoronoi gn nht l nh nhau. Cc nh ca s Voronoi lcc im c khong cch ti t nht ba im Voronoi gn nht lnh nhau.
http://vi.wikipedia.org/wiki/Kh%C3%B4ng_gian_m%C3%AAtrichttp://vi.wikipedia.org/wiki/Kh%C3%B4ng_gian_m%C3%AAtrichttp://vi.wikipedia.org/wiki/Kho%E1%BA%A3ng_c%C3%A1chhttp://vi.wikipedia.org/wiki/Kho%E1%BA%A3ng_c%C3%A1chhttp://vi.wikipedia.org/wiki/Kho%E1%BA%A3ng_c%C3%A1chhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%83mhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%83mhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%83mhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%83mhttp://vi.wikipedia.org/wiki/Kho%E1%BA%A3ng_c%C3%A1chhttp://vi.wikipedia.org/wiki/Kh%C3%B4ng_gian_m%C3%AAtric -
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Khi Voronoi l tp hp cc ng cha cc im cch u hai (hoc nhiu hn) vt cn. imbt u v im kt thc c xc nhn trn bn , mi ng v di m khong cch t nng bao ca vt cn tng nhanh nht. Khong cch di chuyn trn khi Voronoi cng c chn la khong cch n cc ng bao l ln nht.i vi mi im bt k trn vng khng gian t do, mytnh c thxc nh khong cch tim n vt cn gn nht. Phng php tm ng trong khiVoronoi cng tng tnh phng php xc nh ta chnh xc (Visibility graph) v lun tn ti vng
khng gian robot c th di chuyn gia cc vt cn.
Nhc im ca phng php ny l b gii hn di hot ng ca sesor
23.1.3Cell Decomposition (Phn tch) (slide cui
trang 32)
Bao gm cc vng c th di chuyn n gin, c kt ni
vi nhau thnh cc cell
Cc cell nh kt ni vi nhau thnh s
Cc cell c xy dng da trn cc cnh ca vt cn v lyphn gp khc lm im u im cui mi cnh. Mi
cell c th tip gip vi mt vi cell khc. ng i ni gia
cc cell. Qung ng ngn nht l qung ng tim
bt u n im kt thc m i qua t cell nht
23.2Phng php d ngPhng php d ng gm:
- Breath First: Duyt grapth tnh, xt cacds nh k cng gn cng tt v cho vo danh sch v(dng queue)
- Depth First: Duyt Grapth tnh u, xt cc nh k vi n v cho vo danh sch v (nh du
duyt ri) v mi ln i nh thth cng xa nh u cng tt.(dng stack)
- Dijkstra
- A* and variants: tm kim mt ng i t mt nt khi du cho ti mt nt ch cho trc
(hoc mt nt tha mn mt iu kin din tch). Thut ton ny s dng mt nh gi
heuristic xp loi tng nt theo c lng v tuyn ng tt nht i qua nt . A* lu
tr mt tp cc li gii cha hon chnh, ngha l cc ng i qua th, bt u t nt xut
pht. Tp li gii ny c lu trong mt hng i u tin. Th tu tin gn cho mt ng i x
c quyt nh bi hm: f(x) = g(x) + h(x). trong g(x) l chi ph ca ng i cho n thiim hin ti (tng trng s cc cnh i qua). H(x) l hm nh gi heuristic v chi ph nh
nht n ch t x. Hm f(x) cng thp th u tin x cng cao
- D* and variant: L mt thut ton gii quyt bi ton ng i ngn nht ngun n trong mt
thc hng khng c cnh mang trng s m.
Cho mt thc hng G=(V,E), mt hm trng s w: E-> [0,~) v mt nh ngun s. Cn tnh
ton c ng i ngn nht tnh ngun s n mi nh ca th.
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