2008 IEEE Inernaional Conference on Roboics and Auomaion Pasadena, CA, USA, May 19-23, 2008 Basic Sysemaic Eperimens and New Type Child Uni of Anchor Climber: Swarm Type Wall Climbing Robo Sysem Masaaka Suzuki, Shinya Kiai, and Shigeo Hirose Deparmen of Mechanical and Aerospace Engineering, Tokyo Insiue of Technology 2-12-1, Ookayama, Meguro-ku, Tokyo, Japan {msuzuki, kiai}@roboics.mes.iech.ac.jp, hirose@mes.iech.ac.jp Absrac High mobiliy and large payload capabiliy are imporan abiliies for wall climbing robos. The auhors have proposed a new robo sysem Anchor Climber ha could achieve boh of hese abiliies. This robo sysem is composed of wo or more child unis and a paren uni. As child unis of Anchor Climber, he auhors have developed hree ypes of special wall climbing robos, Adhering Mobile Unis (AM Unis) Type A, B and C. In his paper, developmens of oher componens of Anchor Climber, configuraion of Anchor Climber wih hese componens, basic sysemaic eperimens wih configured Anchor Climber, and new ype of AM Uni are described. rom resuls of he eperimens, i was confirmed ha Anchor Climber had boh high mobiliy and large payload capabiliy. Inde Terms Wall Climbing, Swarm Type, IB Magne, Anchor Climber, Adhering Mobile Uni I. INTRODUCTION In recen years, many kinds of wall climbing robos have been developed for inspecion, paining, cleaning, ec. Wall climbing robos need wo abiliies: high mobiliy and large payload capabiliy. Unforunaely, convenional single wall climbing robos can achieve only eiher of hese wo abiliies, because a single robo has o weigh own mass and move on he wall by iself. These robos generally use permanen magnes or vacuum suckers as adhering devices [2]-[4], [8]- [10], [13]. To achieve boh of hose wo abiliies a he same ime, a swarm ype wall climbing robo sysem Anchor Climber has been proposed by he auhors [6]. Anchor Climber is composed of wo or more child unis and one paren uni suspended by child unis wih wires. As child unis of Anchor Climber, he auhors have developed hree ypes of special wall climbing robos, Adhering Mobile Unis (AM Unis) Type A, B, and C [6], [11]. The echnique of Inernally-balanced Magneic Uni (IB Magne [1]) was applied o hese robos. In his paper, developmens of Anchor Climber s componens are described: simple ype of paren uni and conrol uni. The simples Anchor Climber wih AM Unis and hese componens was configured, and basic sysemaic eperimens wih configured Anchor Climber were done. rom resuls of hese eperimens, i was confirmed ha Anchor Climber had boh high mobiliy and large payload capabiliy. On he oher hand, Adjus Mechanism which adjused spring force of IB Magne and a new ype of AM Uni wih his Adjus Mechanism (AM Uni Type D) have been proposed by he auhors [12]. The concep of Adjus Mechanism and AM Uni Type D are described in his paper. II. PRIOR WORKS OR ANCHOR CLIMBER In his secion, prior works for Anchor Climber which are described in he papers [6] and [11] are simply eplained. A. Concep of Anchor Climber Anchor Climber can move on a wall by moion sequence of child unis, paren uni, and wires. igure 1 shows an moion sequence eample of Anchor Climber. In his eample, Anchor Climber is composed of a paren uni wih wo adhering devices and hree child unis. All child unis ecep moving unis suspend he paren uni wih each wires, or he paren uni hold iself wih is adhering devices. Wih his sequence, Anchor Climber can carry loads such as baeries, conrollers, and working ools safely and freely. The auhors presumed using Anchor Climber for wall cleaning of a huge anker, as one of he applicaions of his robo sysem. Therefore, only 2D sequence have been considered so far, because ouside walls of ankers were mainly fla, hough i may possible o use Anchor Climber on a curved surface whose curvaure is no so large. B. Concep of Adhering Mobile Uni AM Unis are composed of an adhering device and driving mechanisms, and are used as child unis of Anchor Climber. To realize Anchor Climber, AM Unis mus have wo adhering saes: Sick Sae: robos are firmly aached o a wall wih heir adhering devices, Child Uni 1 Wire Paren Uni Adhering Device Sick Sae Movable Sae ig. 1. 4 Moion Sequence Eample of Anchor Climber. 2 5 3 6 978-1-4244-1647-9/08/$25.00 2008 IEEE. 3034
Movable Sae: robos can move freely on he wall wih heir driving mechanisms, and keep enough adhering force no o fall from he wall. AM Unis also mus be able o shif beween hese wo saes easily. We can choose any kinds of adhering devices and driving mechanisms o enable AM Unis o have hese abiliies. C. IB Magne The echnique of IB Magne [1] was applied o AM Unis, o use small acuaors for heir adhering devices. igure 2 shows a concep image of IB Magne. A permanen magne looked effecive for he adhering device, because seels, ferromagneic maerials, were ofen used for many walls of huge srucures such as ankers. Though big energy is necessary o peel off a permanen magne generally, IB Magne can peel off he permanen magne wih zero force principally, because is nonlinear spring balance wih inernal magneic force. D. Adhering Mobile Unis Using IB Magne Three ypes of AM Unis (ig. 3, TABLE I) have been proposed and developed by he auhors so far. These robos Yoke Magne rame c s (a) m ig. 2. Conrol Rod orce b a a b a Concep of IB Magne. m s (b) b Sroke have a magne uni applied he echnique of IB Magne as adhering devices. 1) Type A: As he firs prooype, AM Uni Type A composed of a magne uni and omni-direcional wheeled mechanisms have been developed. This robo can shif beween Sick Sae and Movable Sae wih one small acuaor in he magne uni. Wheeled mechanisms are equipped wih springs conneced o he magne uni, which was named Deachable Balanced s. 2) Type B: As he second prooype, AM Uni Type B composed of a magne uni and a driving uni using wo acive wheeled mechanisms have been developed. Adhering force of his robo is smaller han AM Uni Type A and Type C, because his robo has smaller magne used for analysis of anoher projec. This robo is suiable for moving on uneven surfaces, because his robo can change he disance beween he robo frame and he magneic surface wih keeping adhering force in Movable Sae, by using anoher acuaor conneced o he driving uni and he magne uni. 3) Type C: As he hird prooype, AM Uni Type C composed of a magne uni and crawler mechanisms have been developed. When we design AM Uni Type A or Type B, comple calculaion is necessary o balance he inernal magneic force wih he nonlinear spring. By conras, comple calculaion is no necessary o design he nonlinear spring of AM Uni Type C as original IB Magne, because crawler mechanisms of AM Uni Type C are conneced direcly o he frame of he magne uni. III. COMPONENTS AND CONIGURATION O ANCHOR CLIMBER A. Simple Type of Paren Uni To make basic sysemaic eperimens wih configured Anchor Climber, a simple ype of paren uni was developed by he auhors (ig. 4). This paren uni is composed of one Type A Type B Type C ig. 3. Three Types of AM Unis. TABLE I SPECIICATIONS O THREE TYPES O AM UNITS. Specificaion Type A Type B Type C Size [mm] φ320 H110 L320 W260 H 110 L245 W190 H87 Mass [kg] 3.5 3.0 2.8 Ma Speed (in Movable Sae) [m/s] 0.15 0.30 0.15 Ma Adhering orce [N] 1100 500 1100 Ma Payload Capabiliy (in Sick Sae) [N] 400 210 400 3035
reel uni, one microcompuer (CPU: SH7047) o conrol he reel uni, four free casers o move on he wall freely, and a permanen magne o keep is posiion near he wall. To configure he simples Anchor Climber, he paren uni only needs one reel uni which can jus reel in and ou he wire, hough he paren uni can also have adhering devices and oher any ools according o he concep of Anchor Climber. 1) Reel Uni: An acuaor uni of anoher robo ( Souki [7]) was used as reel uni o develop a paren uni simply. igure 5 shows he acuaor uni composed of a DC moor (raed oupu: 17W, raed volage: 24V) and hin ype of Harmonic Drive R. TABLE II shows specificaions of he acuaor uni, and TABLE III shows resuls of evaluaion eperimens. By using his acuaor uni, he reel uni can reel in and ou he wire simply. 2) Hyper-Teher: A special eher (Hyper-Teher [5]) was used o connec child unis o he paren uni. This eher is composed of four sranded conducor cables, polyurehane jacke, and so on (ig. 6). TABLE IV shows specificaions of Hyper-Teher. Tensile srengh of Hyper-Teher is very high, and is mass is ligh, because sranded conducor cables are coaed wih Kevlar R, which are used for flak jackes, composie maerials of airplane, ec. Hyper-Teher can be used no only as he wire for payload racion, bu also as elecric cables for power supply and communicaion. B. Conroller Uni To operae Anchor Climber wih one device, a conroller uni was developed by he auhors (ig. 7). This conroller uni has one joysick wih si on/off buons and four aises, one LCD display, hree buons o swich he display, and one microcompuer (CPU: SH7047). C. Configuraion of Anchor Climber Anchor Climber was configured wih hese componens for basic sysemaic eperimens (ig. 8). The requiremen o configure he simples Anchor Climber is having wo child unis and one reel uni. Of course, mobiliy and payload capabiliy can be enlarged, if Anchor Climber has more child unis and reel unis. The auhors however hough even his simples Anchor Climber could realize he concep of Anchor Climber, which was o achieve high mobiliy and large payload capabiliy a he same ime. Thus, he auhors configured Anchor Climber wih he paren uni having one reel uni, he conroller uni conneced o he paren uni wih elecric cables, and wo child unis; AM Uni Type A and AM Uni Type B. In he configured Anchor Climber, AM Uni Type A is called CU-A (Child Uni A) and AM Uni Type B is called CU-B (Child Uni B) hereafer. CU-A is conneced o he reel uni wih a normal seel wire for payload racion and Hyper-Teher jus as elecric cables for power supply and communicaion (hence, Hyper-Teher A). If Hyper-Teher A is used also as racion wire, a slip ring Acuaor Uni Spool Sranded Conducor Cable Polyeser Insulaor SH7047 KEVLAR R Paper Tape Binder Polyurehane Jacke ig. 4. Simple Type of Paren Uni. ig. 6. Hyper-Teher. TABLE IV SPECIICATIONS O HYPER-TETHER. Thin Type Harmonic Drive R ig. 5. Acuaor Uni. DC Moor Diameer φ3.7mm Tensile Srengh 2300N Mass 25g/m Conducor Resisance 0.049Ω/m Raed Volage 30V Raed Curren 6A TABLE II SPECIICATIONS O THE ACTUATOR UNIT. Size Mass Angular Velociy φ70mm L110mm 0.56kg 60deg/s (no-load) Joy Sick Buon TABLE III RESULTS O EVALUATION EXPERIMENTS WITH ACTUATOR UNIT. Curren [A] 0.51 0.75 1.1 1.8 2.4 Torque [Nm] no-load 7.4 15 22 29 ig. 7. Conroller Uni. SH7047 (inside) 3036
is necessary o preven elecric cables in Hyper-Teher from wiss. Therefore, o connec CU-A o he paren uni, he auhors used separaely he normal seel wire and Hyper- Teher A jus as elecric cables. On he oher hand, CU-B is conneced o he paren uni wih Hyper-Teher wihou reel uni (hence, Hyper-Teher B). CU-A, CU-B, he paren uni, and he conroller uni can communicae wih each oher hrough a CAN-bus nework by using heir microcompuers. IV. SYSTEMATIC EXPERIMENTS O ANCHOR CLIMBER In his secion, basic sysemaic eperimens wih configured Anchor Climber (ig. 8), resuls, and discussion are described. A. Eperimens As basic sysemaic eperimens wih configured Anchor Climber, whole Anchor Climber moved wih sequence as shown in ig. 9. Deails of his sequence are as follows: 1) When wo child unis are in Sick Sae, he paren uni can climb up along an arc whose radius is same as lengh of Hyper-Teher B, by operaing he reel uni. Child Uni B Child Uni A 2) Afer he paren uni comes below CU-A, ension of Hyper-Teher B becomes zero, because CU-A weighs all mass of he paren uni wih he seel wire. And hen, he paren uni can move up perpendicularly wih he reel uni. 3) CU-B shifs o Movable Sae, and hen CU-B climb up he wall. 4) CU-B shifs o Sick Sae again, and hen he paren uni climb down along he arc o loosen ension of he seel wire. 5) CU-A shif o Movable Sae, and hen climb up he wall. 6) CU-A shif o Sick Sae again, and hen he paren uni can climb up wih moion 1). Wih repeas of his sequence, he whole Anchor Climber can climb up he wall, and can ranspor a weigh which he child uni can no ranspor by iself. A firs, o confirm payload capabiliy of configured Anchor Climber, he auhors hung 10kg weigh on he paren uni as payload, and operaed wih sequence as shown in ig. 9. Ne, he auhors hung 15kg weigh and operaed wih same sequence. B. Resul igure 10 shows he eperimen wih 10kg weigh. Anchor Climber also could ranspor 15kg weigh wih same moion sequence. Hyper-Teher B Seel Wire Hyper-Teher A (No Tracion) 1 2 3 Paren Uni 4 5 6 ig. 8. Configured Anchor Climber. Child Uni B Child Uni A Hyper-Teher B Seel Wire Paren Uni 2 3 7 8 9 10 11 12 1 5 13 14 15 4 6 16 17 18 ig. 9. Moion Sequence wih Two Child Unis and One Paren Uni Having One Reel Uni. ig. 10. Sysemaic Eperimen wih Configured Anchor Climber. 3037
C. Discussion Compared wih convenional wall climbing robos, Anchor Climber achieved higher mass raio beween whole robo sysem (9.5kg) and payload capabiliy (15kg) wih keeping is high mobiliy. In addiion, if AM Uni Type A or Type C is used insead of AM Uni Type B, Anchor Climber should be able o ranspor heavier weigh han 15kg, because adhering force of AM Uni Type B is weaker han oher wo ypes of AM Unis. Increasing child unis should also enlarge payload capabiliy. Moion efficiency of he moion sequence shown in ig. 9 was no so high, because moion range of he paren uni was limied. However, if anoher reel uni is used o connec CU- B o he paren uni, Anchor Climber can move wih anoher beer sequence, and moion efficiency should become higher. inally, i is safe o say ha boh high mobiliy and large capabiliy of Anchor Climber were confirmed, and poenial abiliies of Anchor Climber was also confirmed. V. NEW TYPE O ADHERING MOBILE UNIT A. IB Magne wih Adjus Mechanism According o he principle of IB Magne, we can conrol he magne wih zero force on a ferromagneic surface such as seel wall, because spring force balance wih inernal magneic force. However, hese walls are ofen pained for prevenion from russ. If IB Magne is used on a pained wall, magneic force will be change, because gap will be rame Holder Magneic Uni Magneic Surface m s (a) c m Conrol Rod s Slide Mechanism (A) Pain c s m m m (b) s made beween conac surface and ferromagneic surface of he wall. As a resul, large energy come o be necessary o conrol he magne of IB Magne, because he nonlinear spring of IB Magne come o be unable o balance magneic force adequaely. To solve his problem, Adjus Mechanism which enable us o adjus balancing force of he nonlinear spring of IB Magne was proposed by he auhors [12]. igure 11 shows concep image of IB Magne wih Adjus Mechanism. In his IB Magne, conrol rod can be moved relaively o spring holder wih operaion from ouside; his is mos imporan difference beween his IB Magne and convenional one. igure 12 shows he adjusmen sequence of balancing force. By using hese mechanism and sequence, we can conrol he magne wih zero force principally, even if magneic force change due o he pain on he wall. Deail of hese concep and sequence is described below. 1) On A Non-pained Wall: When IB Magne is on a wall wihou pain as usual (ig. 11(a)), he magne can be conrolled wih zero force principally, if spring force balance wih magneic force adequaely (ig. 12(a)). 2) On A Pained Wall: When IB Magne is on a pained wall whose hickness of pain is (ig. 11(b)), disance beween conac surface of he magne and ferromagneic surface of he wall is m = m +, hough disance beween conac surface of he magne and he wall is m. Magneic force herefore become weak (ig. 12(b)). On he oher hand, spring force come o be unable o balance magneic force adequaely, because spring force does no change and become sronger han magneic force (ig. 12(c)). In his siuaion, if spring force become weak by sliding of Slide Mechanism A (ig. 11(b)), he characerisic of spring force oward he displacemen will change (ig. 12(d)). And hen, spring force will come o balance wih magneic force compleely on he appropriae posiion (ig. 12(e)). Afer his sequence, magne can be conrolled wihou energy loss again. ig. 11. Concep of IB Magne wih Adjus Mechanism. B. Adhering Mobile Uni Type D By using Adjus Mechanism, a new ype of AM Uni which can be applied o pained wall and can decrease energy loss wih magne operaion. This robo was named AM Uni Type D. igure 13 shows he concep image of AM Uni Type D, which is composed of he magne uni wih Adjus Mechanism and drive mechanisms. This robo can conrol no only a magne wih an acuaor (A1), bu also a spring holder wih anoher acuaor (A2). AM Uni Type D herefore can adjus is spring force o balance magneic force adequaely. On he oher hand, AM Uni Type B can no adjus is spring force o balance magneic force adequaely, because his robo can no conrol he spring holder in he magne uni, hough can conrol is magne uni iself. In he magne uni of AM Uni Type D, if magneic force is smaller, necessary force o adjus spring force is smaller. However, he magne has o keep enough magneic force no o fall from he wall. By seing oher suppor springs (S2) o Magneic orce 0 0 0 orce (a) (b) (c) 0 0 (d) (e) ig. 12. Adjusmen Sequence of Balancing orce. 3038
make spring force which push spring holder, he robo can conrol he spring holder wih small force. The auhors are designing AM Uni Type D by CAD sofware currenly (ig. 14). Afer his robo is developed, he auhors will ry o use his robo as a child uni of Anchor Climber. VI. CONCLUSIONS AND UTURE WORKS A. Conclusions The simples Anchor Climber wih he simple ype of paren uni, he conrol uni, and wo child unis; AM Uni Type A and Type B was configured. Ne, sysemaic eperimens wih he configured Anchor Climber were done. rom resuls of hese eperimens, i was confirmed ha Anchor Climber could achieve boh high mobiliy and large payload capabiliy a he same ime. In addiion, he concep (a) Sick Sae ig. 13. Magne Holder Wheel Mechanism Magne Cover Magne Ineernally Balanced (S1) Magne Holder Acuaor (A1) Acuaor (A2) Holder Suppor (S2) Magneic Surface Pain Concep of AM Uni Type D (b) Movable Sae Gear Train (G1) Timing Bel (B1) of IB Magne wih Adjus Mechanism and AM Uni Type D applied Adjus Mechanism were described. B. uure Works A firs, he auhors will develop AM Uni Type D acually. If developed AM Uni Type D is beer han oher hree ypes of AM Unis, he auhors will re-configure Anchor Climber wih AM Uni Type D as a child uni. Ne, he auhors will develop a special reel uni in order o improve Anchor Climber, because he reel uni need more abiliies han he reel uni which is described in his paper. REERENCES [1] S. Hirose, M. Imazao, Y. Kudo, and Y. Umeani: Inernally-Balanced Magneic Uni, Advanced Roboics, vol. 1, no. 3, pp. 225-242, 1986. [2] B. L. Luk, A. A. Collie, and J. Billingsley: Robug II: An Inelligen Wall Climbing Robo, Proc. IEEE ICRA, pp. 2342-2347, 1991. [3] S. Hirose, A. Nagakubo and R. Toyama: Machine Tha Can Walk and Climb on loors, Walls and Ceilings, Proc. 5h IEEE ICAR, pp. 753-758, 1991. [4] T. ukuda, e al.: A Sudy on Wall Surface Mobile Robos (Developmen of Moving Mechanism for Crawler-Type Wall Surface Mobile Robos wih Vacuum Pads), JSME Inernaional Journal, Series C, Vol. 38, No. 2, pp. 292-299, 1995. [5] E.. ukushima, e al: Developmen of Tehered Auonomous Mobile Robo Sysems for ield Works, Advanced Roboics, Vol. 15, No. 4, pp.481-496, 2001. [6] S. Kiai, K. Tsuru, and S. Hirose: The Proposal of Swarm Type Wall Climbing Robo Sysem Anchor Climber, Proc. IEEE/RSJ IROS, pp. 3999-4004, 2005. [7] K. Moomura, e al: Developmen of Arm-Wheel Hybrid Robo Souki : Trial Model and Basic Eperimen, Proc. ROBOMEC, 2P1- S-016, 2005 (Japanese). [8] Z. Y. Qian, Y. Z. Zhao, and Z. Z. u: Developmen of Wall-Climbing Robos wih Sliding Sucion Cups, Proc. IEEE/RSJ IROS, pp. 3417-3422, 2006. [9] S. Wu, M. Li, S. Xiao, and Y. Li: A Wireless Disribued Wall Climbing Roboic Sysem for Reconnaissance Purpose, Proc. IEEE ICMA, pp. 1308-312, 2006. [10] Y. Oa, T. Kuga, and K. Yoneda: Deformaion Compensaion for Coninuous orce conrol of a Wall Climbing Quadruped wih Reduced- DO, Proc. IEEE ICRA, pp. 468-474, 2006. [11] M. Suzuki, S. Kiai, and S. Hirose: New Types Child Unis of Anchor Climber: Swarm Type Wall Climbing Robo Sysem, Proc. IEEE/RSJ IROS, pp. 1781-1786, 2007. [12] M. Suzuki and S. Hirose: Adjus Mechanism of Balance orce for Inernally-Balanced Magneic Uni Proc. The 25h Annual Conference of he Roboics Sociey of Japan, 1K31, 2007 (Japanese). [13]. Tâche, W. ischer, R. Siegwar, R. Moser, and. Mondada: Compac Magneic Wheeled Robo Wih High Mobiliy for Inspecing Comple Shaped Pipe Srucures, Proc. IEEE/RSJ IROS, pp. 261-266, 2007. (S1) Timing Bel (B2) Gear Train (G2) Crawler ig. 14. CAD Model of AM Uni Type D 3039