Fixed simulation model mass problem
Fixed simulation model mass problem

arocchi/Klampt,hpbader42/Klampt,krishauser/Klampt,arocchi/Klampt,arocchi/Klampt,krishauser/Klampt,arocchi/Klampt,krishauser/Klampt,krishauser/Klampt,krishauser/Klampt,YilunZhou/Klampt,hpbader42/Klampt,YilunZhou/Klampt,YilunZhou/Klampt,krishauser/Klampt,YilunZhou/Klampt,hpbader42/Klampt,hpbader42/Klampt,hpbader42/Klampt