Using GNSS for Robot Positioning

Transcription

1 Using GNSS fr Rbt Psitining Nam Nguyen DEC 2014 Hamburg University. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

2 Intrductin. GNSS GPS, GLONASS, GALILEO OUTLINE Traditinal techniques revisit (prs and cns). Hw it wrks (GPS as example). Why use GNSS fr Rbts. Hw accurate is GNSS (GPS as example). Sme surces f GNSS errr. Techniques t imprve GNSS precisin. Cnclusin. Q&A and Feedback. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

3 Intrductin Glbal Navigatin Satellite System - GNSS Cnstellatin f rbiting satellites. Netwrk r grund statins. Cded signals at precise interval GPS 24 satellites, 24/7 peratin time, 6 rbits planes. Real-time, 3D psitining, Maintained by U.S. D..D. (public sectr funded) Using GNSS fr Rbt Psitining - Nam Nguyen DEC

4 Other GNSS systems GLONASS Russian alternative, 24 satellites, 3 rbit planes. 12 healthy satellites GALILEO Eurpean s next generatin GNSS Funded by bth public and private sectrs. Chargeable services additinal features. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

5 Traditinal psitining techniques revisit TECHNIQUE PROS CONS Odmetry (widely used) Inertial navigatin (IN): gyrscpes Slid-state magnetic cmpasses shrt-term accuracy inexpensive Self-cntained n external references required Lw pwer cnsumptin Tlerant t shck and vibratin Fast acquisitin Drifting (cllisin) Odmeter needs calibratin. Drifting r unsuitable fr lng range missin. Magnetic field can be distrted near pwer lines r metal structures. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

6 Traditinal psitining techniques revisit TECHNIQUE PROS CONS Active beacns Map-mapping Reliable high sampling rate Rbts already have map f the missin, respnsive t the envirnment Require installatin, peratin and maintenance. Scenes changes, mving bjects make it difficult t identify the current lcatin. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

7 Hw GPS system wrks Clcks in the sky Each satellite bradcasts a time signal, plus rbit infrmatin Receivers calculate pseudranges t visible satellites Receivers triangulate their psitin Using GNSS fr Rbt Psitining - Nam Nguyen DEC

8 Hw GPS system wrks Based frequency f0 = Mhz. Tw carrier signals L1 and L2 are generated by integer multiplicatin with f0. L1 and L2 are biphase mdulated by cdes (sequence +1, -1) t prvide clck readings and transmit infrmatin such as rbital params. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

9 Hw GPS system wrks The time r phase measurement perfrmed by the receiver is based n the cmparisn between the received signal at the antenna f the receiver and the generated reference signal by the receiver. Range = velcity * time Using GNSS fr Rbt Psitining - Nam Nguyen DEC

10 Hw GPS system wrks fur equatins fr fur unknwns x, y, z, t c, (x, y, z) are the receiver s crdinates t c is the time crrectin fr the GPS receiver s clck. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

11 Why use GNSS fr Rbt Aerial: In vast space and lng distance missin. FREE: just GPS receiver, 24-hur and all-weather availability. It prvides accurate psitin fr ver-the-hrizn and grunded peratins. MQ1-predatr drne Using GNSS fr Rbt Psitining - Nam Nguyen DEC

12 Why use GNSS fr Rbt Offshre explratin, dangerus envirnment. Enhanced vehicle cntrl User aid-system. Autnmus car It s a cnsistent, glbal crdinate system. Perry XLX Generatin 2 ROVs Using GNSS fr Rbt Psitining - Nam Nguyen DEC

13 Hw accurate is GNSS (GPS as example) Quality f receiver (hw much yu spend). Base GPS receiver: abut 15m Galile: 1m. SBAS in U.S. E.U. and Japan: 3m Surce crrectin and dual frequency (mre than $2,000.0): ~ 10 cm Great crrectin and $10k receiver: < 1cm Number f channels In thery: 3 satellites are enugh In practice: at least 4, the mre the better. Psitin f the GPS satellites Signal travels in space: errr prne (0.001 secnd ~ 300km inaccuracy). GPS satellites are als accurate t abut 10 nan-secnds. (3m at speed f light). Using GNSS fr Rbt Psitining - Nam Nguyen DEC

14 Sme surces f GPS errr Mismatch between insphere mdel and actual cnditins Multi-pathing Dynamic mdel mismatch t real mvement Bugs in cde and standards. Antenna errrs Clck errrs. Orbital errrs. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

15 Differential GPS Generally, t use mre than ne receivers and make differential measurement. Use grund-based reference statins. Grund statins bradcast crrectins via radi links. User device received bth satellite and statin signals. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

16 Differential GPS A: is reference statin; B is mving Rver. Range rate crrectin due t transmissin time between A and B Pseud range at B: Using GNSS fr Rbt Psitining - Nam Nguyen DEC

17 Differential GPS Adding the pseud range at receiver B with PRC crrectin Bth rbital errr and satellite clck errr are eliminated. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

18 Other techniques. GNSS Ambiguity Reslutin. Carrier Phase GNSS. Fast Ambiquity Reslutin Apprach. Wide Area Differential GNSS (WADGNSS) Using GNSS fr Rbt Psitining - Nam Nguyen DEC

19 Cnclusin GNSS are a really prmise apprach t vast space aerial and large grunded rbtics missins. Varius techniques must be apply t btain the precise lcatins. High precisin cme with higher price device, but there are als interesting prject like Lw-cst Differential GPS fr Field Rbtics [2] which is really interesting. Using GNSS fr Rbt Psitining - Nam Nguyen DEC

20 References 1. Vidal AshkenaziDavid ParkMark Dumville, (2000),"Rbt psitining and the glbal navigatin satellite system", Industrial Rbt: An Internatinal Jurnal, Vl. 27 Iss 6 pp Ben Nizette, Andrew Tridgell and Changbin Yu, Lw-cst Differential GPS fr Field Rbtics. 3. P.J.G. Teunissen, GNSS Ambiguity Reslutin fr Attitude Determinatin: Thery and Methd 4. Details f the GPS psitin calculatin details.html 5. Understanding the Glbal Psitining System (GPS) Using GNSS fr Rbt Psitining - Nam Nguyen DEC

21 Thank yu. Yur questins and feedbacks are welcme. Using GNSS fr Rbt Psitining - Nam Nguyen DEC