Research an Online Monitoring Method of Propulsion Shafting Alignment Adapting to Hull Deformation

Hull deformations are caused by factors such as loading status, wave load, diving depth of underwater vehicles, etc. This causes a change in the shafting alignment state of the ship's propulsion shafting.This affects the alignment state of the ship propulsion shafting. It is very important for engineering significance to research an online monitoring method of propulsion shafting alignment that adapts to the influence of hull deformation. Based on Euler's rigid body attitude theory, this paper constructs a spatial attitude relationship model of the main and driven shafts of the ship's propulsion shafting. By converting to a fixed earth coordinate system, their absolute position-posture can be obtained. Using laser displacement sensor measurement technology, an online monitoring method of propulsion shafting alignment that adapts to the influence of hull deformation is established, which was verified by experiments. This method is suitable for situations where both the main shaft and the driven shaft may have rigid body posture changes. It can provide shafting alignment control compensation for the influence of hull deformation under different working conditions. This will greatly reduce the operating noise of the shaft system and the mechanical operation failure caused by the misalignment of the ship's propulsion shafting.

Vehicle attitude compensation control of magneto-rheological semi-active suspension based on state observer

This paper presents a vehicle attitude compensation algorithm based on state observer for vehicle semi-active suspension system equipped with four magneto-rheological dampers (MR dampers). The proposed algorithm including magneto-rheological damper control algorithm, attitude compensation control algorithm, and design method of state observer is to effectively improve ride comfort and control vehicle body attitude. First, the actual equivalent damping of magneto-rheological damper is introduced into state observer, and the parameter matrix of suspension system is updated in real time via precise discretization method to enhance the estimation accuracy of state observer. Then, the velocity signal estimated by state observer is employed as the evidence to realize attitude compensation control for vehicle body. Finally, relevant co-simulations and hardware-in-the-loop test are conducted to verify the validity of the proposed control algorithm. Results of simulations and tests demonstrate that the application of the control algorithm proposed in this paper can significantly improve ride comfort of magneto-rheological suspension and optimize vehicle body attitude.

Global Attitude Stabilization of a Rigid Body on SO(3) via Observer-based Hybrid Feedback Under Constraints

This paper studies the global stabilization of a rigid body attitude, a task that is subject to topological obstacles. Theseobstructions preclude the existence of a globally stable equilibrium point. Consequently, the rigid body attitude cannotbe globally stabilized by continuous feedback control laws. In order to resolve this challenge, this paper presents anobserver-based hybrid feedback control law. Thereafter, in order to derive the proposed feedback law, a new kind ofsynergistic potential functions is presented which induces a gradient vector eld to globally stabilize a given set. Moreover, the gradient of the proposed synergistic potential functions is utilized to derive a hybrid angular velocityobserver. The outputs of the proposed observer are employed to produce the necessary damping from the noisy measurements of the attitude. Furthermore, this paper considers two types of constraints: angular velocity constraints, and input torque constraints. Afterward, these constraints are formulated in terms of the Linear Matrix Inequalities (LMI) optimization problem to perform constraints satisfaction at all times. Moreover, this paper introduces a novel hybrid quantizer to deal with the problem of the low-price wireless network. This paper analyzes the global asymptotic stability of the reference set via the Lyapunov's method. Finally, a comparative study in simulations is provided to assess the performance of the proposed control technique.

An attitude updating algorithm using Picard iteration and higher degree polynomial

To accurately track body attitude under high dynamic environments, a new attitude updating algorithm for the strapdown inertial navigation system is proposed after further applying higher degree polynomial to the quaternion Picard iteration (QPI) algorithm. With QPI, calculation error introduced by Picard approximation can be eliminated, but the angular rate fitting error introduced by substituting polynomial for angular rate of body will still affect the accuracy of the attitude updating algorithms which are designed based on polynomial model. Hence, a five- rather three-degree polynomial constructing method using four samples of gyro outputs with coning motion constrain is designed and tested. Simulation results indicate the proposed method owns more accuracy than QPI, optimal coning algorithm, and Fourth4Rot under both low and high dynamic environments.

A Imagem corporal e autoestima em homens estudantes universitários

Objetivo: O presente estudo, pretende avaliar diferenças e possíveis relações entre o grau de (in)satisfação com a imagem corporal, índice de massa corporal, autoestima, classificação académica, prática de exercício físico e grau de satisfação com a vida académica numa amostra de estudantes do sexo masculino que frequentam o ensino superior. Método: Participaram 100 estudantes universitários do sexo masculino. Responderam às escalas da versão portuguesa, Rosenberg Self-Estime Scale (RSES), Male Body Attitude Scale Revised (MBAS-R) e Índice de Massa Corporal (IMC). Resultados: Os instrumentos apresentam bons índices de consistência interna. Quase todos os participantes apresentam baixos graus de insatisfação com a imagem corporal e elevada autoestima. Somente se verificaram diferenças estatisticamente significativas entre a variável prática de exercício físico com a classificação académica e os variáveis graus de insatisfação com a imagem corporal e autoestima com a classificação do IMC. Conclusões: Existe uma relação moderada entre o grau de (in)satisfação com a imagem corporal com o IMC e a autoestima. Os participantes que praticam exercício físico apresentam maior classificação académica.