Wojciech Adamski

Control of airship in case of unpredictable environment conditions

The article demonstrates how to generate the trajectory, taking into account the concept of the tunnel of error that ensures route trace with an error no greater than assumed, even in difficult to predict environmental conditions. The mathematical model of kinematics and dynamics using spatial vectors is presented in short. The theoretical assumptions are tested by simulation. The model used in the simulations takes into account the structure of the drives in the form of two engines placed symmetrically on the sides of the object.

A sliding mode control with an adaptation of orientation of an underactuated airship

In this paper new control method for an underactuated airship with a four-engines propulsion structure is presented. The novelty of the method are modified sliding surfaces for orientation, which were derived based on geometrical properties of the movement of an airship. Such approach helps to realize trajectories unsuitable for such underactuated system. The theoretical considerations are validated by a set of simulation tests.

Velocity controller for a class of vehicles

Abstract This paper addresses the problem of velocity tracking control for various fully-actuated robotic vehicles. The presented method, which is based on transformation of equations of motion allows one to use, in the control gain matrix, the dynamical couplings existing in the system. Consequently, the dynamics of the vehicle is incorporated into the control process what leads to fast velocity error convergence. The stability of the system under the controller is derived based on Lyapunov argument. Moreover, the robustness of the proposed controller is shown too. The general approach is valid for 6 DOF models as well as other reduced models of vehicles. Simulation results on a 6 DOF indoor airship validate the described velocity tracking methodology.

A trajectory tracking controller for vehicles moving at low speed

The aim of this work is to provide a control strategy for a class of vehicles that is based on transformation of the velocity vector expressed in the earth-fixed coordinates. The presented trajectory tracking control algorithm can be applied for a class of fully actuated vehicles. To this class belong: underwater vehicles, indoor airships, and hovercrafts that move at low velocity (v < 3 m/s). In the proposed approach the velocity gain matrix is strictly related to the system dynamics which allows one to reduce the kinetic energy quickly. Stability analysis of the system under the control algorithm is done using on the Lyapunovs direct method. Simulation results on a 6 DOF full model of indoor airship illustrates effectiveness of the method.

Nonlinear tracking control for some marine vehicles and airships

This paper presents a trajectory tracking control strategy, based on use of dynamical couplings, which is appropriate for a class of marine vehicles and or indoor airships (blimps) moving at low speed. The strategy consists of two steps: at the beginning the equations of motion are transformed into a velocity space, and next the nonlinear controller expressed in terms of the new variables is designed. The crucial role play here dynamical couplings in the vehicle because the system dynamics is incorporated into the control gain matrix. The control algorithm can be applied for fully actuated vehicles. Because of the assumed limitations the proposed method is suitable for simulation tests. The stability of the system under the designed control algorithm is shown using the Lyapunov theory. Simulation results for an indoor airship model demonstrate successful performance of the proposed approach.

Output-feedback cascaded VFO-ADR tracking controller for autonomous rigid-body vehicles moving in a 3D space

The paper presents a derivation of a cascaded control system for autonomous vehicles moving in a 3D space in the task of tracking a time-parametrized desired trajectory. For a purpose of an outer-loop (kinematic-level) control design one proposes to utilize the Vector Field Orientation (VFO) methodology which has been successfully applied and extensively tested so far in the area of wheeled mobile robots. Geometrical nature of the VFO approach leads to a non-oscillatory and fast-converging system response, and provides simple and intuitive tunning rules for a resultant controller. The inner loop (dynamic level) of a cascade is designed using a principle of Active Disturbance Rejection (ADR) which ensures robustness of the closed-loop system to modeling uncertainties of vehicle dynamics. Implementation of the proposed cascaded control law requires a feedback only from vehicle configuration variables (output-feedback). Performance of the proposed control system has been verified by simulations performed for the fully actuated as well as underactuated torpedo-like vehicles.

Nonlinear trajectory tracking controller for a class of robotic vehicles

Abstract A global state feedback tracking controller for a class of vehicles, namely marine vehicles, hovercrafts and indoor airships is considered in this paper. The control algorithm uses a velocity transformation of the vehicle equations of motion. It is shown that this algorithm is suitable for control of fully actuated systems and leads to fast response. This property arises from the fact that the dynamical couplings in the vehicle are taken into account in the control gain matrix. A Lyapunov-like function is proposed for the stability analysis of the system under the controller. The algorithms robustness issue is considered too. Numerical simulations are given to illustrate effectiveness of the approach.

Investigation of control algorithm for airship before indoor experiment

An application of the set-point controller expressed in generalized velocity components for an airship is presented in this paper. The nonlinear controller was proposed originally for fully actuated underwater vehicles. However, in this work it is shown that the same controller can be used for an airship, thanks the velocity transformation, and it is able to detect risk resulting from lost or reduction gain coefficients. Consequently, the shown approach appears an useful tool for investigation of the control algorithm in case of some flight disturbances of motion. It is worth of notice that the analysis gives further insight into the airship dynamics. The performance of the applied controller is tested by simulation on a 6-DOF model of the airship.

On use of equations of motion for two-rotor airship

In this article, equations of motion for a two-rotor airship are derived. Moreover, the problem of engine applied forces and torques is analysed, and a trajectory generator is described and implemented into a proportional–derivative control scheme. The theoretical considerations are validated by a set of simulation tests. The simulation model takes into account the structure of the drives, namely the two engines placed symmetrically on both sides of the object. The conducted simulations validate the robustness of the controller in the case of unexpected disturbance occurrence.

Comparison of Two- and Four-Engine Propulsion Structures of Airship

The structure of the propulsion system is an important element of every mobile robot. It has a great impact on controllability and possibility to fight against disturbances. In the case of airships, atmospheric conditions can significantly act on them, and are very difficult (sometimes totally impossible) to predict. In this paper two propulsion structures are described and compared to each other in simulations: first, a two-engine structure on one rotating axis, slightly modified by moving drives away from local plane XZ, to make turning by differential control more effective; second, a four-engine structure with two rotating axes, which gives possibility to better control the pitch angle. A mathematical model and a control algorithm of an airship are also described.