Calibration Algorithm of a Spring Static Balancer

This paper proposes a calibration algorithm of a spring static balancer to overcome uncertainties of link parameters or spring constants. The location of the spring attachment is adjusted in this paper considering unbalancing torques. Various algorithms are suggested to determine the location of the spring attachment: 1) an estimation algorithm for static situation is derived from the design equation of the space mapping method; 2) TDE (time delay estimation) is adopted to derive estimation algorithms; 3) an estimation algorithm with no joint torque sensing is derived on the basis of TDE. TDE is adopted to estimate unbalancing static torques. The proposed algorithms are evaluated with the two-dof (degree of freedom) manipulator with the bevel gravity compensator in that two springs are located at the same link. Performances of the proposed algorithms are compared with experimental results. Application to the case of the varying load is discussed and it is showed that the suggested algorithms are applicable to the both cases of uncertainties and varying loads.