Balancing

1. Gravity Balancing

2. Shaking force and shaking moment balancing


1. Gravity Balancing

1.1. Gravity-compensation for the SurgiScope robot

1.2. Gravity-compensation for robot variable payloads


1.1. Gravity-compensation for the SurgiScope robot

There is a large number of gravity balancing techniques that are used in order to reduce, or cancel, the actuator input efforts during a quasi-static mode of operation for mechanical system. Amongst those methods, the most usual ones are:

  • The addition of counterweights: the main issue with such kind of methods is the considerable increase of the robot total mass
  • The use of springs: the main issue is the increase of the spring size when the robot must carry heavy loads

Those methods may be well adapted for some types of industrial applications. However, they are undesirable for the medical operations.

Therefore, the company ISIS was looking for a new balancing system for its manipulator SurgiScope (Fig. 1) and started a partnership with the INSA of Rennes. The SurgiScope is a based on a Delta robot and is designed in order to carry out a microscope system with a weight of 70 kg.

In the case of the SurgiScope typical applications, the displacement speed of the platform is not essential because there is no need for productivity acceleration. However, as a result of the increased mass of the platform (about 70kg), the input torques became important. Thus it became evident that the platform’s mass must be balanced. In this case, the traditional approaches with counterweights and springs mounted on the moving links are not applicable. The Delta robot has a complex structure and after such balancing it becomes either very heavy or a complicated assembly with several complementary articulated dyads. That is why another means for the solution of this problem is proposed.

 

a

Fig. 1. SurgiScope robot sold by the company ISIS.

 

The gravity balancing of the SurgiScope was the topic of the thesis of Cédric Baradat, but I also worked in collaboration with him on the modelling of the balancing system.

It consists in the addition of a secondary mechanism between the manipulator base and moving platform. This mechanism, based on a passivepantograph linkage, can create a supplementary vertical forceon the platform to balance the gravitational forces of the robot (Fig. 2).

 

a

Fig. 2. Balancing system of the SurgiScope

 

Experimental results have shown that it was possible to reduce the input torques up to 80% (Fig. 3).

Moreover, the auxiliary balancing system has a good influence on the robot deformations which can be reduced by 80%.

 

Fig. 3. Experimental measures of input torques for three actuators of the SurgiScope robot in the balanced and unbalanced cases

 

More information can be found in:

C. Baradat, V. Arakelian, S. Briot and S. Guégan, "Design and Prototyping of a New Balancing Mechanism for Spatial Parallel Manipulators," ASME, Journal of Mechanical Design, 2008, Vol. 130, No. 7.

S. Briot, C. Baradat, S. Guégan, and V. Arakelian, "Contribution to the Improvement of the Medical Device SurgiScope®," Proceedings of the 2007 ASME Ine-y out a microscope system with a wei; theg;,&quenter"><1res oc;,&qropdown-tog (DETCrosco). 7.

There i="center">
tybal_payl, the company ISIS we of tdrawbackut a micrurgiSco-d influence proposs heavy ot ha actu ring sass muy e png ite SurgiScope was the i> for ig crnSurgiScop the increasheavy ling ring ythe ( forexayads,e of operaptized inask) the me e is png ite S efforlaoposedThe addi ="center"> .l> g technique robot ino ca ="center"> s.l> rsqu ="center"> align="justifyl, the company ISIAns dcounterwedrawbackniquellaradaein order to ing sizf owi> Weavy loa ing , Vgstem romSay his c1 acta ="center"> his c2,ductivity a , Vgl apppot need medgy> nrobot SurgiS="center">equd actV = g z (m2 − c1) (%.tivig ing size robotcase, therougSt> nrobot SurgiS="center">nal ainput tindusno ca o iable payet ts m a="center">IiS 2 &l200m1, i> ducesqual,g>re tou> ainput t etockn tocen&ness goo medgy> nrcapaeSct in rasett .ravitybal_payl, the company ISI e increasecrnSiiS hder to robot inolta rwrequsppu ="center">of th r-quddraitnoverafa r80%. medgy> nrcapaeSct iased obot tocksm, b app paeSct inasslimib ,ing y medgy> anylladihe pis wh(l oprS="center">nsizf r heat)ut tivoica ing applica paeSct i.ravitybal_payl, the company ISIt th,uellaexsec operndus sgbot variable payloade on tg i> hder Delta rob medgy>effhaielt.l>vitybal_payl, the company ISIInov curabsolyldncrlopp operaare used in order tuellowi> ut ting canuellaradaeidrawbackut

4) a pwets manipulator chemtuellow problem iiable payload i> urgiScopeff i> ng platfo wh ="center">o.n order to ainput tiable payet urgiScopeff i> > effhaielt,i="center">i.e.ry mechap the Medicalts mng platfo wh doeere is="center">requsrput tbf ope medgy> nroborobot Surgi.l>vitybal_payl, the company ISI

569 420">lign="center="images/Torques_D/p> 4 a pwe de SurgiSrndus sare used i syulvit bech his ="center"> creaseP joi 9]>asspoi 9]>Kit beNDeltafix wh%.i> ondus s syulvitre, can cr.l>vitybal_paylI

inl>vitybal_payl, the company ISI which cué

ghres 5 IFToMM Wor> ghres)

AShder Dsibleband ous mizim on m wmut a /p>em mech /p>etoor mechbesibiorlabor,pduput ticaiorimarer such Scop a micior/a> syst, f Spr/b> th h Dsibleband dncob act iDevice SurgiScopior/a>besibior.ravitybal_payl, the company ISIt e/a>

alancing

of a seconapplica fforlaoposed.

diffhat tythe increasimarea>

alancing

le ut ticanalancing ivabrd by 80end, ed mass of ;CMedicallo 70kg) eft: 0; operccuracy.ravitybal_payl, the company ISImoment bng

aboullel Man Deltaappualstem for ilancinas areniqueent gpdow.ravitybal_payl, the company ISIMg y n order to al ap>

alancing

osibleband dncrlopptrial a1 DOF ullel Man the increased sokages g techniquDOF assimarg system e proposs eltamihe he topi duput ticaiorimarer such Scop(e when the robot out aer such Sco, i> his an applicasi-static mod,aappuar appbackon-h duput ticanain iss mounte-rottrong>

alancing

s i> hder ing sus iqueseong>

C. Baradat, yl, the company ISImégibuion to th eechJ.P.suppBa e Improvmoment bFlanciMin mizaoposedAnal the 2007own icon-whifont-sSIallel ManiontrMb> Cabmun

ASME, Journal Dde SuPrMan mechPai the 2007own icon-whifont-sSIgn, 20of iv id=D
g it beJ.-P.ssuppBa e Improvmoment bFlancsiMin mizaoposed,Mo: 0; P ; op the 2007own icon-whifont-sSIME Ine-y out a micr18 SuCISM-IFToMM Sym tubalan S; theg,=D ;Contrl">Anal (ROMANSY 0)
t, 0 U-y e, pIe> e align="justifyl, the company ISIméContribuion to the ImprovC suchyettmoment bFlancit;Desoment bM B was the topeaseP t: 0;-OrieltaoposeS; mouchd PAMcope ME, Journal the 2007own icon-whifont-sSIIEEE/pe system with a wei oseSAdv abotem lthe allel Mcs (AIM 09)
t, 09 StheapnAnal (RoME,Sy> )
t, 08, pTokyo, Japnn.l>vitybal_paylI

Foomes navbar"> > foomes

foomesOut
rea"> FoomesVideos ki
rv . id="contentIn=ign="ss="span12"> media=bookmarks ="center">1.2. m/css://twitter/scripbcute_bzh
    1.2. #
      1.2. #
        1.2. #
="center">
js