Vaclav Zada

Predictive control for offset-free motion of industrial articulated robots

This paper deals with the design of model predictive control for the precise motion of industrial articulated robots. The solution is based on specific incremental formulations of equations of predictions. The proposed formulations enable the design to compensate and suppress undesirable positional offsets. The corresponding incremental predictive algorithms incorporating discrete integrators are introduced. The theoretical results are demonstrated by the set of simulation examples with the six-axis multipurpose ABB robot IRB 140 that belongs to the large class of industrial articulated robots.

Development of a robotic arm suitable for demonstration of advanced control methods

Our article deals with the development of a robotic arm with “open control system” (for this particular application — with two degrees of freedom and possibility to add). The open control system allows, together with the known parameters of our robotic arm, to use advanced control methods. The robotic arm is controlled by a PLC and automatically generated code via tools — BR Target for Simulink. This tool allows us to convert Simulink models into an automatically generated code in C/C++ and its direct implementation on PLCs. This method of a design allows an easy implementation for sophisticated simulation models and control structures. The article focuses on the preparation and evaluation of the properties of a robotic arm for implementation possibilities of advanced control methods. At first, we found the physical limitations of the individual actuators. Then we dealt with the problems of generating the trajectory with respect to the physical limitations of the individual actuators. For the dynamics of the robotic arm spline functions for trajectory generation and performed measurements of lag errors are used. In conclusion, we evaluated the advantages and disadvantages of this method of control and outlined possible applications for which we can apply this kind of control.

Application of Hamiltonian mechanics to control design for industrial robotic manipulators

The paper deals with a tracking control for robotic manipulators, where the robot dynamics is described by means of Hamiltonian mechanics. This way leads to different physical descriptive quantities used in control design. In the paper, the model-oriented Lyapunov-based control is considered. It is introduced in the novel formulation using Hamiltonian mechanics and compared with the conventional formulation based on Lagrangian mechanics. The theoretical results, generally applicable to usual articulated industrial robotic manipulators, are demonstrated on one specific robot arm with three degrees of freedom.

Generalized Incremental Small Gain

This paper is directed on a using of Banach fixed-point theorem in the problem of stabilization of nonlinear systems. The theory is developed in Banach spaces with using general operator theory and may be applied both for continuous and for discrete systems. All theorems are proved and may be separated into two classes, global and local contraction operator theorems. It is studied possibility of parameters changes and continuity changes. Moreover there are derived a precision of convergence and a rate of convergence. It is interesting, that although it is almost nothing presupposed about the structure of controlled system and controller, the fact, that the operator of closed loop is k-contractive, allows to prove relatively strong assertions.