Re-definition of the robot motion control problem: Effects of plant dynamics, drive system constraints, and user requirements

A Survey on the Control of Flexible Joint Robots

“…Spong et al have proposed a method to solve this equation approximately to any order of ε by expansion of terms as will be done in Eqs. (8) and (9) [3]. Using the concept of composite control a fast term could be added to the control input to make the fast dynamics asymptotically stable:…”

“…In [9,[16][17][18] it has been shown, theoretically and empirically, that ignoring the flexibility of FJRs in controller design will result in performance degradation and bandwidth limitation. References [19,20] have ignored the coriolis and centrifugal forces, coming up with a linear model and proposing some controllers for that model, but the responses are not perfect for high velocities.…”

“…This also necessitates considering flexibility in manipulators. Out of these necessities have emerged new control strategies, while traditional controllers used directly for FJRs have had limited performance [9,10]. Since the 1980's many attempts have been made to counter this problem, and, now, several methods have been developed.…”

Higher Performance Adaptive Control of a Flexible Joint Robot Manipulators

“…Sweet and Good [9,10] have investigated the problem of robotic manipulation experimentally and identified several problems that limit the performance of a typical robot manipulator. One of the main issues is the unmodeled dynamics, especially the flexibility of the mechanical arm.…”

A Regressor-free Adaptive Control for Flexible-joint Robots based on Function Approximation Technique

“…To achieve high precision tracking performance, the joint flexibility should be carefully considered. 1 However, the modeling of flexible-joint robots is far more complex than that of rigid-joint robots. Besides, the mathematical model of the robot inevitably contains model inaccuracies such as parametric uncertainties, and unmodeled dynamics.…”