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Aspects Regarding Fly Control of Quadcopter

Endrowednes, Kuantama; Ioan, Tarca; Radu, Tarca; Dan, Craciun

Abstract

Quadcopter is one of Unmanned Aerial Vehicle (UAV) which has two pairs of identical fixed pitched rotor propellers. It can fly autonomously based on pre-programmed flight or manually controlled by a remote, and every movement achieved by varying the speed of each rotor independently. The orientation of quadcopter axes relative to a reference line and its direction of motion are known as attitude. Fly control factors are affected by attitude determination which can be calculated from 3 possible angles using combined measurement. Gyroscope and accelerometer are primary sensors to control quadcopter attitude, but magnetometer sensor and GPS also used to enhance the stability during flight. This paper will focus on details of function and mathematical formula of every factor regarding fly control and comparative data of 2 types of orientation sensor used in this system.

Full text

Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/7. Aspec s Rega ding Fly Con ol o Quadcop e End owednes Kuan ama Enginee ing Doc o al School Uni e si y o O adea 1 Uni e si ăţii S ., O adea, Romania end owedne[email p o ec ed]m Ioan Ta ca1, Radu Ta ca2, Dan C aciun3 Mecha onics Depa men Uni e si y o O adea 1 Uni e si ăţii S ., O adea, Romania 1nelu @uo adea. o, 2 a ca@uo adea. o, 3danc [email protected] Abs ac —Quadcop e is one o Unmanned Ae ial Vehicle (UAV) which has wo pai s o iden ical ixed pi ched o o p opelle s. I can ly au onomously based on p e-p og ammed ligh o manually con olled by a emo e, and e e y mo emen achie ed by a ying he speed o each o o independen ly. The o ien a ion o quadcop e axes ela i e o a e e ence line and i s di ec ion o mo ion a e known as a i ude. Fly con ol ac o s a e a ec ed by a i ude de e mina ion which can be calcula ed om 3 possible angles using combined measu emen . Gy oscope and accele ome e a e p ima y senso s o con ol quadcop e a i ude, bu magne ome e senso and GPS also used o enhance he s abili y du ing ligh . This pape will ocus on de ails o unc ion and ma hema ical o mula o e e y ac o ega ding ly con ol and compa a i e da a o 2 ypes o o ien a ion senso used in his sys em. Keywo ds—quadcop e ; a i ude; gy oscope; ly con ol; o ien a ion senso I. INTRODUCTION Quadcop e is classi ied as Unmanned Ae ial Vehicle which is li ed by 4 o o s, as i s name sugges . I s mo emen can be di ec ed by con olling he angula speed o each o o . The o o s a e connec ed wi h he p opelle s, and he each pai o opposed simila p opelle a e o a ing in he same di ec ion ( wo clockwise and wo coun e clockwise). The mos impo an aspec s needed o be conside ed when designing quadcop e a e ela ed o i s ligh s abili y: wha ac o s a e a ec ing i and how hey in luence he s abili y. Main opics ega ding quadcop e s a e ela ed o hei a i ude; ma hema ical o mulas and ligh con ol aim o con ol hei a i ude. A i ude is a posi ion o he body (ine ial ame) o he o ien a ion o quadcop e axes ela i e o a e e ence line and i s di ec ion o mo ion. Quadcop e a i ude can be measu ed using MEMS (Mic o Elec o Mechanical Sys em) senso . This senso canno accomplish same accu acy as Kalman il e o complemen a y usion algo i hms which a e used o p o ide mo e accu a e and eliable in o ma ion in he MEMS a i ude de e mina ion sys ems [1]. Senso sys em is a undamen al pa o UAV, including quadcop e , ha ing hei ole in calcula ing accu a e a i ude by measu ing h ee angles, using combined measu emen s such as he gy oscope/gy o a e, accele ome e and magne ome e [2]. These senso s measu e h ee-axis angula a es, h ee-axis appa en accele a ion, and Ea h’s magne ic ield wi h espec o he quadcop e ’s body ame. In o de o achie e he bes e alua ion o a i ude angles om hese senso s, i is essen ial o use hese measu emen s in a seamless manne while conside ing he di e ence be ween each senso ’s signal speci ica ions. I is possible o use a a e gy o o ob ain a i udes, by in eg a ing he igid body's kinema ic equa ions, while accele ome e s p o ide g a i y di ec ion. Wi h high quali y gy oscope and app op ia e ini ial alues, hese assessmen s can be e y accu a e o e long pe iods o ime. On he o he hand, accele ome e s signals p esen di ec alues o il angles [3]. When quadcop e shi s om one posi ion o he o he , he wing on espec i e side will slan sligh ly in he mo ing di ec ion as seen on Fig.1. The esul ed angle is an impo an ac o in de e mining he quadcop e s abili y. Each mo emen ’s angle has o be con inuously moni o ed by he o ien a ion senso un il he s abili y is achie ed. Wi h he ligh con ol senso s' help, quadcop e will adjus i s posi ion acco dingly, e en in he case o na u al dis u bances o p opelle ai low. These aspec s e eal he impo ance o quadcop e ligh con ol. Fig. 1. Illus a ion o a i ude quadcop e mo emen II. ATTITUDE PARAMETERIZATION AND REPRESENTATION P ope es ima ion o a i ude angles and posi ion o quadcop e a e he mos impo an ac o in ligh con ol na iga ion. De e mina ion o ligh a i ude also in ol es he compu a ion o quadcop e ’s pi ch angle, oll angle, and heading angle. Bo h pi ch angle and oll angle can be compu ed by measu ing accele a ions and body a es om accele ome e s and a e gy os, while heading angle can be measu ed by calcula ing he magne ic heading. Ha ing known he accele a ion on h ee axes (pi ch, oll, and yaw a e in o ma ion), he pi ch and oll angles can also be de e mined ei he by compu ing he g a i a ional accele a ion componen s Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/7. on he body axes, o by using he Eule qua e nion me hod. The la e me hod, howe e , p o ides low noise con en s and as esponse o changes in he inpu signals, bu ends o d i wi h ime due o gy o bias e o s [4]. The absolu e linea posi ion o he quadcop e is de ined in he ine ial ame x, y, z axes wi h Eule (£). The a i ude is de ined in he ine ial ame wi h h ee Eule angles: Pi ch angle (θ) de e mines he o a ion o he quadcop e a ound he y-axis, while Roll angle (ɸ) a ound he x-axis and Yaw angle (ψ) a ound z-axis. Using concep o kinema ic mo ing ame, quadcop e mo emen om ini ial posi ion o desi ed posi ion can be calcula ed as seen on Fig. 2. Fig. 2. Illus a ion o quadcop e o ien a ion The Eule o mula (1) can be used o calcula e he o a ion o he quadcop e ame h oughou each axis as well as he ma ix mul iplica ion esul o R oll, Rpi ch, Ryaw: (1) Whe e symbol ‘s’ ep esen sine and ‘c’ ep esen cosine. To ge he desi ed quadcop e mo emen (based on each mo emen angle), he angula mo emen o e e y o o mus gene a e app op ia e h us . The h us mo emen in (2) is p oduced by each o o h ough he o que applied by o o which d i en by elec onic speed con olle s. The o o speed is ωi and he li cons an o quadcop e is b ha depends on he ai densi y a ound p opelle . (2) Fly con ol, especially he a i ude measu emen senso , holds an essen ial pa o moni o e e y a i ude and o ien a ion o quadcop e in o de o i o ly s able e en h ough dis u bance. III. QUADCOPTER FLY CONTROL MEASUREMENT In e ms o quadcop e a i ude, o ien a ion and mo emen posi ion ha e o be moni o ed con inuously using o ien a ion measu emen such as accele ome e and gy oscope senso . Accele ome e is used o measu e accele a ion om quadcop e mo emen , whe eas gy oscope is used o measu e he angula a e as seen in diag am block on Fig. 3. Magne ome e and GPS as posi ion senso s a e used o imp o e he accu acy o o a ion and posi ion o quadcop e . By using hese senso s, one can p ecisely e alua e quadcop e speed, posi ion and o ien a ion and help s abilizing quadcop e mo emen . Fig. 3. Quadcop e ligh con ol uni Accele ome e and gy oscope as o ien a ion senso s a e called s ap down sys em in which he ine ial senso s a e di ec ly a ached o he ehicle ame. These senso s unc ion as he ull dynamic mo ion o he ehicle. The ela ionship be ween he body- ixed ame and he na iga ional ame mus be main ained compu a ionally on boa d. A. Quadcop e a i ude es ima ion based on Accele ome e Accele a ion is he a e o eloci y change wi h ime o he a e o change o dis ance wi h squa ed ime. To de e mine speci ic accele a ion, an accele ome e is used. As a measu e senso , accele ome e can calcula e he di e ence be ween ehicle’s accele a ion and g a i y accele a ion. To be able o de e mine h ee-dimensional accele a ion ec o , accele a ion can be calcula ed based on New on’s second law o mo ion which ela es o ce (F), mass (m), and accele a ion (a). Accele ome e is going o be used in ine ial na iga ion; he e o e, accele a ion wi h espec o he ine ial ame is needed. The ou pu o accele ome e is measu emen o he di e ence be ween he ac ual ehicle accele a ion (a) and he g a i a ional accele a ion (g) (3) In (3), F is he speci ic o ce. I is necessa y o know he magni ude and o ien a ion o he g a i y ec o g wi h espec o he accele ome e inpu axis in o de o compu e he accele a ion componen s om he accele ome e ou pu s. The ou pu o accele a ion on a igid body is he e o e gi en by (4). (4) Whe e am is he measu ed accele a ion and Fg is he o ce due o g a i y and F is he ex e nal o ce. One can use (4) o calcula e he g a i a ional e ec when he ex e nal o ces equals o ze o. I is assumed ha he axes o he accele ome e a e aligned wi h he body- ame axes and ha he accele ome e has been p ope ly calib a ed o emo e misalignmen e o s and c oss-axis sensi i i y. Y X ψ X X Y Z Z Z Gy oscope Accele ome e Accele a ion (m/s2) Angula Ra e ( ad/s) Na iga ion Algo i hm A i ude ( ad) Veloci y (m/s) Posi ion (m) Magne ome e & GPS Z’ (c) Pi ch mo emen ψ Y’ X’ (a) Yaw mo emen Y’ ϕ ϕ Z’ X’ θ θ (b) Roll mo emen Y )FF( m 1 ag m  )ga(F  2 i .bT             cccsscssscsc cssssccsccss ssccc R Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/7. In he h ee axis accele ome e , (ax, ay, az) ep esen he accele a ion measu ed in he body ame axes. In he ine ial ame, he o ce o g a i y is in z-axis. Using (4) and he o ce o g a i y, he accele a ion in he body ames is gi en by (5). (5) The symbol Ri ep esen he o a ion ma ix om he ine ial o he body- ixed e e ence ame, which come om calcula ion be ween Pi ch and Roll (Rx, Ry), as in (1). Since he accele a ions in s able ligh egimes a e usually small compa ed o he g a i y accele a ion, neglec ing he linea accele a ion is a classical assump ion [5]. No malizing he ec o o accele a ion measu emen s acili a es o exp ess he oll and pi ch angles as (6). (6) Whe e ϕ is he oll angle and θ is he pi ch angle ela i e o he g ound. Quadcop e s a e di e en om g ound ehicles because o he h us equi ed o keep hem ai bo ne. The accele ome e s in s ap down sys ems measu e he esul an o g a i a ional and o he accele a ions ac ing on he body o which he senso s a e a ached. The idea o his me hod is o ega d he accele ome e s as inclinome e s, which p o ide an absolu e e e ence o he a i ude by ela ing he body o ien a ion o he g a i y ec o . I is assumed ha he body is no mo ing o is mo ing a cons an speed, so ha he accele a ion due o he ea h’s o a ion is negligible and he g a i y is he only sou ce o accele a ion, also known as Co iolis accele a ion [6]. The accele ome e s can p o ide e y accu a e measu emen s o a i ude, bu he accele ome e - based a i ude is sensi i e o ex e nal accele a ion and ib a ion. B. Quadcop e a i ude es ima ion based on gy oscope Gy oscope is he angula a e senso which is used o measu e he a e o o a ion a ound he senso axis in quadcop e . Theo e ically, when in eg a ing he signal om he gy oscope, one can acqui e he angula change o e a pe iod o ime. In Fig. 2 can be seen he illus a ion o quadcop e ’s o ien a ion and posi ion, he e e ence ame X, Y, and Z is aligned wi h he p incipal (main) axis o he body. In s ap down sys ems, gy oscopes measu e he angula a es o h ee axes o he body wi h espec o he ine ial coo dina e ame. Wi h hese measu emen s o angula a es in body coo dina es, he a i ude o he quadcop e can be de i ed by in eg a ing he igid body kinema ic equa ions, s a ing om a known ini ial a i ude a a gi en poin in ime. The a i ude o a body wi h espec o he ine ial coo dina e ame is de ined by Eule o mula. Examina ion o small changes in each Eule angle and he e ec s on he angula ec o a e based on kinema ic mo ing ames heo em. The con inuous ime nonlinea igid body kinema ic equa ion in s a e space ep esen a ion is shown in (7) and (8). (7) (8) Whe e p, q, a e he angula a es measu ed by gy oscopes in he body coo dina e ame. Using his equa ion, he measu emen esul om gy o senso will be compa ed wi h desi ed a i ude o quadcop e . C. Quadcop e a i ude es ima ion based on magne ome e Magne ome e s a e commonly used o measu e Ea h’s local magne ic ield ec o hus de e mine he di ec ion in which magne ic no h lies. A 3 axis magne ome e can measu e magne ic ield in ensi y in 3 dimensions. These poin s a e e e ed o as he magne ic poles. Magne ic ield lines a y bo h in s eng h and di ec ion abou he ace o he ea h. The di ec ion and s eng h o he ea h’s magne ic ield (H) can be ep esen ed by he h ee axis alues Hx, Hy, and Hz. The Hx and Hy in o ma ion can be used o de e mine compass headings in e e ence o he magne ic poles. The a i ude is es ima ed by wo successi e qua e nion o a ions. The i s o a ion is he one be ween magne ic ield ec o measu ed by he magne ome e in i s e e ence sys em and he ea h’s magne ic ield ec o es ima ed by a model. The second o a ion is by sub ac ing he cen ipe al accele a ion om he accele a ion measu ed by he accele ome e [8]. The magne ome e -based a i ude de e mina ion is widely used o spacec a as well as quadcop e [9]. In quadcop e , hese me hods a e based on he qua e nions a i ude ep esen a ion. The in o ma ion abou oll and pi ch angle can be ex ac ed om g a i y poin s which head o he local e ical down di ec ion. The magne ome e is used o measu e quadcop e ’s magne ic ield in ensi y in 3 dimensions. The declina ion (δ) and inclina ion (Ƞ) a e modeled and p o ided by he Wo ld Magne ic Model (WMM) o he Na ional Geophysical Da a Cen e (NGDC). F om his model, he magne ic ec o , which is exp essed in local na iga ion ame, can be known. In addi ion, he yaw, pi ch, and oll angle is de e mined by he magne ome e measu emen s. The g a i y ec o o he ea h is always poin ing o a local e ical down di ec ion. In con as , he di ec ion o he magne ic ec o o he ea h a ies wi h posi ion on he ea h. In yaw mo emen , he di ec ion o he magne ic ec o is exp essed by he declina ion and inclina ion o he local na iga ion ame in Fig. 4.                     coscosg- cossing- sing a a a z y x                               coscos cossinsin R; g 0 0 R a a a ii z y x                                                                           coscossecsin0 cossincos0 sin01 q p 0 0 0 0 R0 0 RR q p xyx                                  q p seccossecsin0 sincos0 ancos ansin1    Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/7. Fig. 4. Magne ic ec o o he ea h on local na iga ion ame The magne ome e -based yaw angle in quadcop e is de e mined wi h he Ea h’s magne ic ield. Ho izon al di ec ion o he Ea h’s magne ic ield is poin ing owa d he magne ic no h o he Ea h. Magne ic no h is de ia ed om ue no h. I s de ia ion is e e ed as a declina ion angle and a ies wi h i s posi ion on he Ea h. The yaw angle de e mina ion om he magne ome e measu emen is conduc ed as shown in (9) and (10): (9) (10) Whe e Hb is he magne ome e measu emen ec o in body ame and δ is he declina ion angle o he ea h’s magne ic ield. The angle ψ can be calcula ed using he equa ion abo e based on illus a ion in Fig. 4. Ob iously, he e o o oll and pi ch angle a ec s he accu acy o he de e mined yaw angle. The e o e, he magne ome e -based yaw aiding me hod should be applied wi h a alid oll and pi ch angle in o ma ion. Example o magne ic oll angle de e mina ion can be seen in Fig. 5. Fig. 5. Magne ic oll angle de e mina ion The heading-down plane and he X, Y, and Z plane a e iden ical, and H ep esen s he p ojec ed magne ic ec o on his plane. Angle ȠT can be calcula ed by ans o ming he magne ic ec o om he magne ic ield model o he heading- down ame. Angle λ is de e mined by he magne ome e measu emen s, which a e ans o med om he body ame o he X’, Y’, and Z’ ame. Likewise, he oll angle can be de e mined by sub ac ing ȠT om λ. This p ocess is gi en by (11): (11) The accu acy o magne ic ec o is limi ed o abou 1o in oo mean squa e by he modeling esolu ion, a ia ion abou ime and ex e nal dis u bances [10]. The magne ic ield is easily dis u bed by he en i onmen , hus he magne ome e -based a i ude me hod should be applied wi h an app op ia e calib a ion and dis u bance de ec ion. The λ and ȠT angle can be calcula ed using igonome y o kinema ic mo ing ame heo em. D. GPS-based a i ude GPS holds an impo an ole in a i ude es ima ion because o i s long- e m accu acy in eading quadcop e ’s posi ion and eloci y. La ge e o s in low-cos ine ial senso s can be coun e balanced by da a upda es acqui ed om GPS. Fo small scaled o a y-wing ai c a , an a i ude es ima ion me hod using he eloci y measu emen s wi h single an enna GPS was p oposed; he ime lag o he es ima ed a i ude was compensa ed wi h he help o measu emen s om gy oscopes by using he complemen a y il e [11]. A GPS ecei e calcula es i s posi ion by using a me hod called T ila e a ion which is shown in Fig. 5. Many ila e a ion algo i hms ha e been p oposed o de e mine loca ion accu a ely. GPS ecei e calcula es he posi ion, eloci y and ime based on he da a om he GPS Sa elli e. Fig. 6. T ila e a ion The 3D mul i-la e a ion uses he ollowing s anda d equa ions: (12) Whe e, (13) F om his heo y o ila e a ion, he syn hesized a i ude is called he pseudo-a i ude. I consis s o an equi alen oll angle abou he eloci y ec o o he quadcop e , an equi alen pi ch angle de ined as he ho izon al ligh pa h angle and an equi alen yaw angle de ined as he e ical ligh pa h angle. S anda d equa ion usage and qua e nion o quadcop e a e wo o he mos popula app oaches which a e used o calcula e pseudo a i ude. The qua e nion and Eule angles a e bo h common ep esen a ions o he a i ude. The qua e nion, which ep esen s a o a ion abou a speci ic axis, is de ined in e ms o ou pa ame e s in a column ec o as seen in (14). (14) One essen ial cons ain o he qua e nion in he applica ion is ha i s no m should be equal o uni y. The qua e nion uni s om q1 o q3 a e called he ec o pa o he qua e nion, while H δ Ƞ X Y ϕ ȠT H λ Y Z Z’ Y’ GPS ecei e (X, Y, Z) D1 D4 D3 D2 (X1, Y1, Z1) (X2, Y2, Z2) (X3, Y3, Z3) (X4, Y4, Z4) X kqjqiqq 310     = ).Z Z- 2(Z + ).YY - 2(Y + X1).X - 2(X = ).Z Z- 2(Z + ).YY - 2(Y + X1).X - 2(X = ).Z Z- 2(Z + ).YY - 2(Y + X1).X - 2(X 14144 13133 12122 )Z-(Z-)Y-(Y-)X-(X - )D - (D )Z-(Z-)Y-(Y-)X-(X - )D - (D )Z-(Z-)Y-(Y-)X-(X - )D - (D 2 4 2 1 2 4 2 1 2 4 2 1 2 4 2 1 2 3 2 1 2 3 2 1 2 3 2 1 2 3 2 1 2 2 2 1 2 2 2 1 2 2 2 1 2 2 2 1     b H cossin0 sincos0 001 cos0sin 010 sin0cos H                               x y H H a c an Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2. DOI: 10.17667/ iim.2016.1-2/7. q0 is he scala pa . The inpu s a e he angula a es measu ed by he gy oscopes and he eloci y wi h espec o g ound in No h-Eas -Down di ec ion coo dina es acqui ed om he GPS ecei e , and he ou pu s a e he es ima ed oll angle, pi ch angle, and yaw angle, compu ed om he qua e nion es ima ed o he Eule angles can be de i ed by using: [12] (15) IV. ATTITUDE AND ORIENTATION SENSOR The o ien a ion senso s compa ed in his esea ch a e he GP9 and UM7 senso . They use hei own a i ude es ima ion in conjunc ion wi h he onboa d accele ome e s, in o de o measu e changes in eloci y. These eloci y es ima es a e hen compa ed o eloci ies epo ed by he GPS and p essu e senso s. Since a i ude inaccu acy is a majo sou ce o eloci y measu emen e o , i is possible o measu e a i ude by compa ing he accele ome e -based eloci y wi h GPS-based eloci y. In Table 1 de ail in o ma ion o GP9 and UM7 AHRS elec onic sys em can be seen. TABLE I. COMPARISON BETWEEN TWO ATTITUDE SENSOR Compa ison GP9 UM7 Powe consump ion < 150mA a 5.0V du ing GPS seek. < 100mA a 5.0V wi h GPS lock 50mA a 5.0V Ope a ing empe a u e -40C o +85C -40 o +85 C Communica ion 3.3V TTL UART 3.3V TTL UART, SPI bus Ra e o measu es o ien a ion, eloci y, and posi ion 500 Hz 500 Hz S a ic pi ch/ oll accu acy +/- 2 deg ee +/- 2 deg ee Dynamic pi ch/ oll accu acy +/- 1 deg ee +/- 4 deg ee S a ic yaw accu acy +/- 5 deg ee +/- 5 deg ee Dynamic yaw accu acy +/- 1 deg ee +/- 8 deg ee Resolu ion < 0.01 deg ees 0.01 deg ee Da a ou pu a e 0 o 255 Hz, selec able da a 0 Hz o 255 Hz (bina y packe s) 1 Hz o 100 Hz (NMEA packe s) I can be concluded ha GP9 has highe le el o sensi i i y o dynamic mo emen wi h less powe consump ion. Da a ou pu a e in he o m o accele a ion, angula a es, magne ic ield, ba ome ic p essu e, GPS al i ude, posi ion, eloci y, a i ude (qua e nion, Eule Angle). Bo h senso and p ocessing yield excellen gy o bias s abili y o e empe a u e. Adjus able low- pass il e and Kalman il e se ings p o ide cus omizable pe o mance o a ious applica ions. S a es and senso da a synch onized o GPS posi ion and eloci y using op ional ex e nal GPS module allows o alignmen calib a ion and hi d-o de bias and scale ac o empe a u e compensa ion o accele ome e s, gy os, and magne ome e . Magne ome e so and ha d-i on calib a ion can be pe o med h ough he se ial in e ace so wa e. V. CONCLUSION Fligh con ol plays an indispensable ole in managing quadcop e ligh s abili y. Gy oscope and accele ome e a e jus enough o moni o quadcop e ’s posi ion and mo emen o ien a ion, bu o coun e he e o ac o and ou side dis u bance, addi ional senso s such as magne ome e and GPS a e needed. While gy oscope compa es he angle be ween he ini ial posi ion and he desi ed posi ion, magne ome e compa es each ini ial and al e ed angle wi h ea h magne ic ield in o de o ge he changes in angle. Wi h his da a, he esul om gy o and magne ic senso can be compa ed o ge be e eading. GPS has accu a e eading on quadcop e posi ioning and mo emen . Senso o ien a ion GP9 has highe p ecision on a i ude changes eading, compa ed o UM7. ACKNOWLEDGMENT This wo k has been unded unde he LEADERS - E asmus Mundus G an (ag eemen numbe 2014-0855/001-001) by Eu opean Commission, h ough he Educa ion, Audio isual and Cul u e Execu i e Agency, in he Ac ion Plan 2 o he yea s 2014-2018. REFERENCES [1] Shiau, J. K., & Wang, I. C. (2013). Unscen ed Kalman Fil e ing o A i ude De e mina ion using MEMS Senso s. Jou nal o Applied Science and Enginee ing Vol.16 No.2, 165-176. [2] M.G.Ea l, & D'And ea. (n.d.). Real Time A i ude Es ima ion Techniques applied o a Fo Ro o Helicop e . IEEE Con e ence on Decision and Con ol Vol.4 (pp. 3956-3961). Alan is-Bahamas: IEEE. [3] Sanca, A., Fe ei a, J., & Ja ie , P. (2012). Real Time A i ude Es ima ion Scheme o Hexa o o Mic o Ae ial Vehicle. 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(2010). The US/UK Wo ld Magne ic Model o 2010- 2015. NOAA Technical Repo NESDIS/NGDC. [11] Tenn HK, J. S. (2009). Pi ch and Roll A i ude Es ima ion o a Small- scaled helicop e using single an enna GPS wi h Gy oscope. GPS Solu ions, 209-220. [12] Bea d, D. B. (2004). Real-Time A i ude and Posi ion Es ima ion o Small UAVs Using Low-Cos Senso s. AIAA 3 d (pp. 1-9). Chicago, Illinois: Ame ican Ins i u e o Ae onau ics and As onau ics.                                                       )qq(21 )qqqq(2 an ))qqqq(2(sin )qq(21 )qqqq(2 an 2 3 2 2 3021 1 2031 1 2 2 2 1 1032 1