Search results for "control theory"
showing 10 items of 1333 documents
Input-Output Feedback Linearization Control with On-line MRAS Based Inductor Resistance Estimation of Linear Induction Motors Including the Dynamic E…
2016
This paper proposes the theoretical framework and the consequent application of the input–output feedback linearization (FL) control technique to linear induction motors (LIMs). LIM, additionally to rotating induction motor, presents other strong nonlinearities caused by the dynamic end effects, leading to a space-vector dynamic model with time-varying inductance and resistance terms and a braking force term. This paper, starting from a recently developed dynamic model of the LIM taking into consideration its end effects, defines a FL technique suited for LIMs, since it inherently considers its dynamic end effects. Additionally, it proposes a technique for the on-line estimation of the indu…
A unified observer for robust sensorless control of DC–DC converters
2017
Abstract Due to the large variety of converters' configurations, many different sensorless controllers are available in the literature, each one suited for a particular converter. The need for different configurations, especially on the same power supply, make it clear the advantage of having a shared control algorithm. This paper presents a unified nonlinear robust current observer for buck, boost and buck–boost converters in synchronous and asynchronous configurations. The unified observer speeds up the design, tuning and the implementation, and requires a memory cheaper code, easier to certify. Simulation and experimental results are presented to validate the approach in different scenar…
Robust Composite Nonlinear Feedback Path-Following Control for Independently Actuated Autonomous Vehicles With Differential Steering
2016
This paper investigates utilizing the front-wheel differential drive-assisted steering (DDAS) to achieve the path-following control for independently actuated (IA) electric autonomous ground vehicles (AGVs), in the case of the complete failure of the active front-wheel steering system. DDAS, which is generated by the differential torque between the left and right wheels of IA electric vehicles, can be utilized to actuate the front wheels as the sole steering power when the regular steering system fails, and thus avoids dangerous consequences for AGVs. As an inherent emergency measure and an active safety control method for the steering system of electric vehicles, DDAS strategy is a valuabl…
Vibration reduction on city buses: Determination of optimal position of engine mounts
2010
International audience; This study is composed of three essential parts. The first part describes an indirect semi-experimental method which is used to reconstruct the excitation force of an operating diesel engine from the acceleration data measured at the mounting points. These internal forces can not be directly measured with force sensors; they have to be derived from the dynamic deformation of the engine support, so a theoretical analysis is carried out to derive the equations for the force re-construction.The second part deals with prevention of low frequency vibration of the powertrain from spreading to the rest of the vehicle. Three uncoupling techniques are used to minimize these v…
Tracking Control of Networked Multi-Agent Systems Under New Characterizations of Impulses and Its Applications in Robotic Systems
2016
This paper examines the problem of tracking control of networked multi-agent systems with multiple delays and impulsive effects, whose results are applied to mechanical robotic systems. Four kinds of impulsive effects are taken into account: 1) both the strengths of impulsive effects and the number of nodes injected with impulses are time dependent; 2) the strengths of impulsive effects occur according to certain probabilities and the number of nodes under impulsive control is time varying; 3) the strengths of impulses are time varying, whereas the number of nodes with impulses takes place according to certain probabilities; 4) both the strengths of impulses and the number of nodes with imp…
Robustness with Respect to Delay Uncertainties of a Predictor-Observer Based Discrete-Time Controller
2006
This paper focuses on the delay-dependent stability problem of a discrete-time prediction scheme to stabilize possible unstable continuous-time systems. The delay-dependent stability condition is expressed in terms of LMIs. The separation principle between the proposed predictor and a state observer is also proved. The closed-loop system is shown to be robust with respect to uncertainties in the knowledge on the plant parameters, the delay and the sampling period. The proposed scheme has been tested in a real-time application to control the roll angle in a prototype of a quad-rotor mini-helicopter.
Integral Control Action in Precise Positioning Systems with Friction
2016
Abstract For high precision positioning systems a fast and accurate settling to the reference state is most significant and, at the same time, challenging from the control point of view. Traditional use of an integral coaction in feedback can attain a desired reference tracking at steady-state motion, but can fail in case of precise positioning. Most crucial is that this is independent on how accurate the integral control part is tuned. This paper addresses the feedback control action in precise positioning systems with friction. Analyzing the closed-loop control dynamics with nonlinear friction in feedback it is shown why the integral action cannot efficiently cope with Coulomb friction wh…
On stability and robustness of Virtual Torsion Sensor (VTS) for flexible joint robots
2016
The so called ‘Virtual Torsion Sensor’ (VTS) has been introduced in pervious works for flexible joint robots without sensing of the joint output states, i.e. link position and velocity. Since VTS is incorporated into the feedback control loop, so as to improve the links' positioning accuracy, the related stability is crucial for the overall control design and robust operation of VTS. In this paper, we analyze the stability of including VTS into the feedback loop while assuming the predicted joint torsion is gained by the proportional term of the underlying motor position feedback control. We start our consideration by an ideal case of the linear joint stiffness, first assuming the measured …
Novel concept for stabilising a hydraulic circuit containing counterbalance valve and pressure compensated flow supply
2016
In this paper, a novel concept for stabilising a hydraulic system containing a counterbalance valve and a pressure compensated flow supply is presented. The concept utilizes a secondary circuit where a low-pass filtered value of the load pressure is generated and fed back to the compensator of the flow supply valve. The novel concept has been investigated theoretically and experimentally. A linear model has been developed to verify the improved stability conditions. The novel concept has been implemented on a single boom actuated by a cylinder. The results show that the pressure oscillations in an otherwise unstable system can be suppressed with the novel concept. This happens without any c…
Identification and control design for path tracking of hydraulic loader crane
2017
The controlled operation of hydraulic machines with multiple degrees of freedom is challenging due to complex nonlinear dynamics of cylinder actuators, in addition to multibody dynamics like in the case of hydraulic manipulators. This paper addresses the system identification and control design for path tracking of a standard hydraulic loader crane. The kinematics of the crane is solved for operation in the vertical plane and generation of trajectories for the tool tip to be followed. A frequency response measurements and analysis have been done for dynamics modeling of both hydraulic cylinders actuating main boom and jib. The static dead-zone type input non-linearity has been identified an…