On the optimal angular velocity control of asymmetrical space vehicles

Inverse problem of optimal control for reducing angular velocities of space vehicle to zer

Robust Model Reference Adaptive Control of Angular Velocity Control Simulation of Brushed DC Motor

Electric motors play an important role in industry as well as our day-to-day life. They are used to generate electrical power in power plants and provide mechanical work in industries. They are also an indispensable part of our daily lives. Electric motors are very important pieces of equipment in our everyday lives. The brushed DC motor is considered to be basic electric motors. The aim of this paper is to introduce students to the modelling of brushed dc motor and to use computer simulation as a tool for conducting transient and control studies. Simulation can be very helpful in gaining insights to the dynamic behaviour and interactions that are often not readily apparent from reading theory. Next to having an actual system to experiment on, simulation is often chosen by engineers to study transient and control performance or to test conceptual designs. Presently, there are many control laws available to control the brushed dc motor. The control law of angular velocity depends on the motor parameters. The motor parameters are time varying, especially load torque, hence adaptive control is one of the best control law. In standard adaptive control, instability may be occur in the presence of unmodeled dynamics. Robust adaptive control is designed so the stability can be guaranteed

Robustness under saturated feedback: Strong iISS for a class of nonlinear systems

International audienceThis note proposes sufficient conditions under which a nonlinear system can be made Strongly iISS in the presence of actuator saturation. This property, recently proposed as a compromise between the strength of ISS and the generality of iISS, ensures boundedness of all solutions provided that the disturbance magnitude is below a certain threshold. We also show that, under a growth rate condition, the bounded feedback law proposed by Lin and Sontag for the stabilization of the disturbance-free system based on the knowledge of a control Lyapunov function, ensures Strong iISS in the presence of perturbations. We illustrate our findings on the angular velocity control of a spacecraft with limited-power thrusters

Intrinsic Reduced Attitude Formation with Ring Inter-Agent Graph

This paper investigates the reduced attitude formation control problem for a group of rigid-body agents using feedback based on relative attitude information. Under both undirected and directed cycle graph topologies, it is shown that reversing the sign of a classic consensus protocol yields asymptotical convergence to formations whose shape depends on the parity of the group size. Specifically, in the case of even parity the reduced attitudes converge asymptotically to a pair of antipodal points and distribute equidistantly on a great circle in the case of odd parity. Moreover, when the inter-agent graph is an undirected ring, the desired formation is shown to be achieved from almost all initial states

Control of VTOL Vehicles with Thrust-direction Tilting

An approach to the control of a VTOL vehicle equipped with complementary thrust-direction tilting capabilities that nominally yield full actuation of the vehicle's position and attitude is developed. The particularity and difficulty of the control problem are epitomized by the existence of a maximal thrust-tilting angle which forbids complete and decoupled control of the vehicle's position and attitude in all situations. This problem is here addressed via the formalism of primary and secondary objectives and by extending a solution previously derived in the fixed thrust-direction case. The proposed control design is also illustrated by simulation results involving a quadrotor UAV with all propellers axes pointing in the same monitored tilted direction

Discontinuous feedback stabilization of the angular velocity of a rigid body with two control torques

There has been much interest over the past decade in the problem of asymptotic stabilization of the angular velocity of a rigid body with only two torque inputs. The smooth feedback laws proposed in the literature provide asymptotic stability with nonexponential convergence rates. This paper proposes discontinuous feedback laws to achieve asymptotic stability with exponential convergence rate

Direction‐cosine‐matrix‐based attitude control subject to actuator saturation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166291/1/cth2bf00839.pd

Wheel–rail contact: experimental study of the creep forces–creepage relationships

The wheel–rail contact problem plays an important role in the simulation methods used to solve railway dynamics problems. As a consequence, many different mathematical models have been developed to calculate wheel–rail contact forces. However, most of them tackle this problem purely from a theoretical point of view and need to be experimentally validated. Such validation could also reveal the influence of certain parameters not taken into account in the mathematical developments. This paper presents the steps followed in building a scaled test-bench to experimentally characterise the wheel–rail contact problem. The results of the longitudinal contact force as a function of the longitudinal creepage are obtained and the divergences with respect to Kalker's simplified theory are analysed. The influence of lateral creepage, angular velocity and certain contaminants such as cutting fluid or high positive friction modifier is also discussed