Feed-forward torques and reference trajectory for an arm with flexible joints

• Autorzy: Aoustin Y. , Formal'sky A.
• Języki publikacji: EN

Abstrakty

EN

We propose a design method of the feed-forward torques and the reference trajectory for an arm with flexible joints and unknown stiffiness coefficients. The bounds on the control torque are included explicitly. The designed commanded feed-forward torques and the corresponding reference trajectory are close to be time-optimal. The control law for each drive torque is composed with the commanded feed-forward torque and linear angular position and velocity feedback. The torques and the trajectory are used as input signals of PD-controllers. In a case of one-link flexible arm it is proved that so-called 'fluent' control torque enables to reach the desired motion with a small error and without large vibrations in the flexible joint. Designed fluent commanded feed-forward torque is successfully implemented in numerical experiments. The stiffness coefficient is assumed to be unknown so the mathematical model of the flexible arm is not known exactly. In two-link flexible arm the stiffness coefficients are also assumed unknown. Due to discontinuities of the optimal control functions and not acceptable jumps in the optimal control torques a 'trapezoidal' fluent control technique is proposed. Numerical experiments show that the designed control is close to time-opitimal. The approach presented in the paper can be extended to systems with more links and can take the gravity into consideration. however, in this case a time-optimal or a quasi-time-optimal control for the associated rigid system have to be designed.

Słowa kluczowe

EN

one-two-link arm; flexible joint; control torque; torque bount; reference trajectory; feed-forward and feedback control

• Wydawca: Polish Academy of Sciences, Committee of Automatic Control and Robotics
• Czasopismo: Archives of Control Sciences
• Rocznik: 2002
• Tom: Vol. 12, no. 1/2
• Strony: 125--149
• Opis fizyczny: Bibliogr. 31 poz., rys.

Twórcy

autor

Aoustin Y.

• Institut de Recherche en Communications et Cybernetique de Nantes U.M.R., France

autor

Formal'sky A.

• Institut de Recherche en Communications et Cybernetique de Nantes U.M.R., France

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