In this paper we present results of systematic and comprehensive simulation analysis of the Tsao & Safonov unfalsified controller for complex robot manipulators. In particular, we show that the controller falsification procedure yields the closedloop unfalsified controller, which accomplishes the control objective, within a finite and relatively short time interval with the number of invocations of linear programming based unfalsified controller selection procedure being relatively small. We also present some conclusions resulting from the investigation of the effect of such elements as manipulator structure complexity, prior knowledge about disturbances, reference trajectory and assigned closed-loop spectrum on unfalsified controller performance and computational complexity.

Characters with split personalities in Nessuno torna indietro by Alba de Céspedes and the German-Polish history of the novel – This paper focuses on the Polish reception of Nessuno torna indietro, a novel by Alba de Céspedes. In Italy the novel was a bestseller between 1938 and the eighties, however it was impossible to publish it in Poland due to the fact that negotiations failed. Nevertheless, the book was translated into Polish on the basis of the German version and published in a newspaper in 1947. The presentation of the Polish history of this novel will be based on archival materials.

This paper presents a mechanical positioning system for a measuring microphone designed for acoustic studies in anechoic and reverberation chambers at the Department of Mechanics and Vibroacoustics, AGH. The results are discussed in the context of mechanical positioning and its impact on the outcome of the execution of individual measurement procedures. Moreover, areas for research were identified and solution concepts shown for further development of the automation of acoustic measurements in different research rooms in order to reduce the human involvement in them.

The paper addresses optimal control problem of mobile manipulators. Dynamic equations of those mechanisms are assumed herein to be uncertain. Moreover, unbounded disturbances act on the mobile manipulator whose end-effector tracks a desired (reference) trajectory given in a task (Cartesian) space. A computationally efficient class of two-stage cascaded (hierarchical) control algorithms based on both the transpose Jacobian matrix and transpose actuation matrix, has been proposed. The offered control laws involve two kinds of non-singular terminal sliding mode (TSM) manifolds, which were also introduced in the paper. The proposed class of cooperating sub-controllers is shown to be finite time stable by fulfilment of practically reasonable assumptions. The performance of the proposed control strategies is illustrated on an exemplary mobile manipulator whose end-effector tracks desired trajectory.

This paper deals with two control algorithms which utilize learning of their models’ parameters. An adaptive and artificial neural network control techniques are described and compared. Both control algorithms are implemented in MATLAB and Simulink environment, and they are used in the simulation of a postion control of the LWR 4+ manipulator subjected to unknown disturbances. The results, showing the better performance of the artificial neural network controller, are shown. Advantages and disadvantages of both controllers are discussed. The usefulness of the learning algorithms for the control of LWR 4+ robots is discussed. Preliminary experiments dealing with dynamic properties of the two LWR 4+ robots are reported.

The primary importance of the paper is the application of the efficient formulation for the simulation of open-loop lightweight robotic manipulator. The framework employed in the paper makes use of the spatial operator algebra and the associated equations are expressed in joint space. This compact representation of the manipulator dynamics makes it possible to solve the robot forward and inverse dynamics problems in a recursive and fast manner. In the current form, the presented algorithm can be applied for the dynamics simulation of an open-loop chain system possessing any number of joints. Specifically, the formulation has been successfully applied for the analysis of the 7DOF KUKA LWR robot. Results from a number of test cases for the robot demonstrate the verification of the calculations.

This paper presents a vibration analysis of a multi-link surgical micromanipulator joint, based on its detailed mathematical model. The manipulator’s prototype contains 6 links with the diameter of 8-10 [mm] and with the length of the modules of about 130 [mm]. It is driven by brushless servomotors with worm and planetary gears, for which the total transmission ratio is above 1/10000. Regarding the low efficiency of micro-robot drive systems and its vibrations, a reliable joint model and its performance is crucial for the development of a high-precision control system. To achieve the required accuracy, modelling framework has been enriched with an advanced model of friction. Simulation results are presented and discussed.

Main topic of the paper is a problem of designing the input-output decoupling controllers for nonholonomic mobile manipulators. We propose a selection of output functions in much more general form than in [1,2]. Regularity conditions guaranteeing the existence of the input-output decoupling control law are presented. Theoretical considerations are illustrated with simulations for mobile manipulator consisting of RTR robotic arm mounted atop of a unicycle which moves in 3D-space.

A method of planning collision-free trajectory for a mobile manipulator tracking a line section path is presented. The reference trajectory of a mobile platform is not needed, mechanical and control constraints are taken into account. The method is based on a penalty function approach and a redundancy resolution at the acceleration level. Nonholonomic constraints in a Pfaffian form are explicitly incorporated to the control algorithm. The problem is shown to be equivalent to some point-to-point control problem whose solution may be easier determined. The motion of the mobile manipulator is planned in order to maximise the manipulability measure, thus to avoid manipulator singularities. A computer example involving a mobile manipulator consisting of a nonholonomic platform (2,0) class and a 3 DOF RPR type holonomic manipulator operating in a three-dimensional task space is also presented.

Iterative Learning Control (ILC) is a well-known method for control of systems performing repetitive jobs with high precision. This paper presents Constrained Output ILC (COILC) for non-linear state space constrained systems. In the existing literature there is no general solution for applying ILC to such systems. This novel method is based on the Bounded Error Algorithm (BEA) and resolves the transient growth error problem, which is a major obstacle in applying ILC to non-linear systems. Another advantage of COILC is that this method can be applied to constrained output systems. Unlike other ILC methods the COILC method employs an algorithm that stops the iteration before the occurrence of a violation in any of the state space constraints. This way COILC resolves both the hard constraints in the non-linear state space and the transient growth problem. The convergence of the proposed numerical procedure is proved in this paper. The performance of the method is evaluated through a computer simulation and the obtained results are compared to the BEA method for controlling non-linear systems. The numerical experiments demonstrate that COILC is more computationally effective and provides better overall performance. The robustness and convergence of the method make it suitable for solving constrained state space problems of non-linear systems in robotics.

The process of designing control systems for devices operating in microgravity, on-orbit environment, requires testing to verify the effectiveness and characteristics of the algorithms. The key issue is to design a relevant environment in terrestrial conditions that affects both the linear and angular three-dimensional motion of a rigid body. This paper contains a description of the mechanical aspects of two test beds used to evaluate control algorithms planned for use in a space manipulator. Two solutions are presented: (i) a planar manipulator with a free base placed on an air-bearing table; and (ii) a test bed with a 7-DOF manipulator fixed through a force-torque measurement system to the base.