On an adaptive control system for angular motion of a communication satellite

Synthesis of adaptive control system with adjustable model of the communication satellite without using data on angular velocity is considered. Information on deflection angles from the local vertical sensor and tachometers measuring angular velocities of rotation of rotors of three flywheels, and on angular mismatch about the local vertical is used in the control block. The information on the angle of rotation of the satellite about the local vertical is formed on the Earth based on the variation of the polarization plane of the radio signal transmitted from the satellite. The convergence of estimates of the parameters of angular motion to their actual values and the stability of the feedback control with respect to these estimates are studied. This algorithm can be applied as a reserve algorithm in case of failure of angular velocity sensors for prolonging the resource of the communication satellite.     

Studying the Possibility of Ensuring the Stabilization Accuracy Characteristics of an Advanced Spacecraft for Remote Sensing of the Earth

The possibilities of using of single-gimbal control momentum gyros (gyrodynes) in the control system of an advanced remote sensing satellite of the Earth are studied. The main difficulty arising in the phase of designing a composition of the motion control system for this satellite is that the gyrodynes currently produced in the Russian Federation have an angular momentum magnitude, considerably exceeding the value required for this satellite. The second circumstance is the limited range of the selected angular rate sensor, which hampers performing attitude maneuvers at high rates. Ways of solving these problems are considered and the possibility to ensure the required accuracies of stabilization in surveying the Earth’s surface is shown. The capability of this satellite to conduct areal and corridor surveys is demonstrated by the results of mathematical simulation.     

Attitude determination and stabilization of a spherically symmetric rigid body in a magnetic field

Observation and stabilization problems for a rigid body rotating about its mass centre in a time-periodic magnetic field is considered. The moment of the applied forces about the mass centre is a vector product of the field and the vector of control. The only measurement is of the field and its time derivatives in the body co-ordinates. The model describes the angular motion of a satellite in the geomagnetic field with the control carried out by a magnetic moment of current coils (magnetorquers) mounted on the satellite body. It is shown that generically the knowledge of the field and its derivatives is sufficient for the attitude determination. A problem of stabilization along one direction is considered. The stabilizer constructed in this work drives the system to a given motion from all initial points that do not belong to an unstable manifold. It is shown that all stabilizers have such a manifold of initial conditions.     

欠驱动刚体航天器姿态运动规划的遗传算法

研究欠驱动刚体航天器姿态的非完整运动规划问题．航天器利用3个动量飞轮可以控制其姿态和任意定位,当其中一轮失效,航天器姿态通常表现为不可控．在系统角动量为零的情况下,系统的姿态控制问题可转化为无漂移系统的运动规划问题．基于优化控制理论,提出了求解欠驱动刚体航天器的姿态运动控制遗传算法,并且数值仿真表明：该方法对欠驱动航天器姿态运动的控制是有效的．     

偏置动量卫星阻尼力矩作用下的姿态运动特性分析及控制方法

针对偏置动量卫星阻尼阶段的姿态运动特性进行分析,并基于时域分析方法提出弱偏置角动量的选取方法,改善阻尼过程中滚动-偏航角收敛的动态性能.以实际应用为背景,考虑一箭多星发射模式下,安装约束的限制导致星箭分离后偏置角动量方向严重偏离轨道面法线方向的情况,提出一种基于弱偏置角动量的姿态控制方法,在无需三轴姿态信息的情况下,可以避免由于偏置角动量的定轴性导致滚动-偏航角收敛时间很长的问题.仿真结果表明,所提出的方法能够有效减少姿态捕获时间,且易于实现,具有较高的工程实用价值.     

带有两个动量飞轮刚体航天器的姿态非完整运动规划问题

航天器利用三个动量飞轮可以控制其姿态和任意定位.当其中一个动量飞轮失效,在某些特定的情况下,如何控制航天器的姿态问题还没有有效的方法.利用最优控制方法研究了带有两个动量飞轮的刚体航天器姿态优化控制问题.为此考虑系统角动量为零的情况下,将航天器姿态运动方程化为非完整形式约束方程,系统的控制问题可转化为无漂移系统的非完整运动规划问题.通过Ritz近似理论得到求解带有两个动量飞轮航天器姿态的运动规划控制算法.通过数值仿真,表明该方法对航天器姿态运动规划控制是有效的.     

基于PXI的多功能卡在卫星测试系统中的研究

在卫星技术及应用方面,卫星的姿态确定和控制是很重要的。由于各种干扰,卫星在空间的姿态角和姿态角速度往往会偏离设定值,这时就要进行控制和调整。主要介绍了卫星姿态控制系统的工作原理。并设计了一款测量卫星动量轮转速的多功能卡。设计中采用了DSP芯片TMS320C6713作为控制器,以及一款编程灵活、采集速率快的FPGA器件XC3S700A进行对动量轮转速的测量分析及控制输出,通过PXI接口将控制信号和数据传送给主CPU,然后与星体进行动量交换,进而控制卫星姿态,使其满足特定任务的需要。     

Arm path planning of a space robot with angular momentum

Arm path planning of a space robot with angular momentum is considered in this paper. A space robot changes its attitude by the arm motion and angular momentum of the space robot has the possibility to reduce the attitude change. A path planning method of the arm where the final satellite attitude becomes the same as the initial one is proposed. The method derives an approximate path first based on the attitude change when the arm moves along an infinitely small closed curve and then modifies the path by the Newton method. The amplitude of the arm motion decreases with the magnitude of the angular momentum, which shows that the proposed method utilizes the angular momentum effectively.     

卫星姿态的状态转移控制

本文面向卫星的应用需求,对卫星姿态的运动学和动力学进行了分析与建模.利用反馈线性化,将姿态运动的高阶非线性项包含在姿态控制中,通过局部动态线性化,将动力学系统近似为定常系统.通过幂级数法对系统进行了状态转移过程的求解.采用模型预测的方法获得姿态角和姿态角速度的预期偏差.通过广义逆变换构造关于偏差的最小范数、最小二乘控制器.提出了一种基于状态转移的卫星姿态机动、跟踪与稳定控制的新方法.控制器的参数具有根据系统采样周期和当前状态时变自适应的特点.考虑帆板挠性及多种偏差和噪声影响,仿真验证了方法的可行性和有效性.     

Stabilization of a wheels carrying communication satellite without angle and angular velocity sensors

An algorithm of maintaining three-axis orbital orientation using limited angular motions of the gyrostat satellite is proposed. The algorithm uses measured angular velocity of rotation of the flywheel rotors and measured angular mismatches formed on the Earth using data of radio measurements from ground stations as the initial data. This algorithm can be applied as the reserve algorithm at failures of angle and angular velocity sensors for extending the resource of the satellite retransmitter.     

空间机器人连续运动轨迹控制建模和仿真研究

基于地面机器人常用的D-H 建模方法和空间机器人（SR）满足的动量守恒和角动量守恒原理,提出 了SR 连续运动轨迹控制建模算法．首先基于地面机器人雅可比矩阵的思想和D-H 法,建立了适用于空间机器人 的运动学模型;其次研究了空间机器人的广义雅可比矩阵计算及其连续运动轨迹控制的有效算法;最后通过计算 机仿真验证了所提出算法的有效性．本文基于D-H 方法的SR 概念模型和运动学模型可推广到包含旋转关节和平 移关节的树型结构链杆的任何SR．     

Analytic Controlling Reorientation of a Spacecraft Using a Combined Criterion of Optimality

We consider the problem of optimally controlling the reorientation of a spacecraft (SC) from an arbitrary initial angular state into a given final angular position. We study the case when the minimized functional joins, in the given proportion, the time spent and the integral of the squared modulus of the angular momentum on the reorientation of a SC. The problem is solved in a kinematic setting. We consider two versions of the problem of the optimal rotation of a SC, with bounded and unbounded control. Using the necessary optimality conditions in the form of the Pontryagin maximum principle and the quaternion method for solving control problems on the motion of spacecrafts, we obtain an analytical solution of the posed problem. The solution of the problem is based on the quaternionic differential equation relating the angular momentum vector of a SC with the orientation quaternion of the related coordinate system. We present formalized equations and give computational expressions for constructing the optimal control program. We state the control law as an explicit dependence of the control variables on the phase coordinates. Using the transversality condition as a necessary optimality condition, we determine the maximal value of the modulus of the angular momentum for the optimal motion. For a dynamically symmetric SC, the problem of reorientation in space is solved completely: we obtain the dependences for the optimal law of the change of the angular momentum vector as explicit time functions. We give the results of the mathematical modeling of the motion for optimal control which demonstrate the practical realizability of designed algorithm for controlling the spatial orientation of a SC.     

雷达稳定平台模糊PID串级控制设计与仿真

机载雷达稳定平台是根据陀螺仪采集到载机角速度信息,驱动直流伺服电机采用反向运动补偿原理工作,以保证机载雷达成像稳定,清晰。为了提高机载雷达稳定平台的响应性能和抗干扰能力,提出一种模糊PID串级控制方案,根据陀螺仪所采集的角速度信息和编码器反馈的角度位置信息,采用速度模糊PID控制和位置模糊PID控制串联的形式对直流伺服电机进行控制。经MATLAB仿真实验证明,模糊PID串级控制比传统单级PID控制以及传统PID串级控制具有更优秀的响应性能以及抗干扰能力,更加适合复杂环境下机载雷达稳定平台的稳定要求。     

Estimating nonmeasurable coordinates of elastic oscillations for large space constructions with a gyroforce engine

We develop a mathematical model for the angular motion dynamics of a large-scale space construction with a gyroforce engine, in which coordinates of the construction’s elastic oscillations are fully observable. This lets us design a joint estimation algorithm for angular motion coordinates and elastic oscillations for orientation control and angular stabilization of the construction in question. We show mathematical modeling results for the synthesized estimation algorithm that support its high accuracy, convergence, and stability.     

Terminal synthesis of orbital orientation for a spacecraft

This paper presents an algorithm for the terminal synthesis of the orbital orientation for a spacecraft. The algorithm is based on solving the following problems: the analytical determination of the program values for the angular velocity vector components in an orbital coordinate system and the stabilization of the program values for the turn rate vector components and the desired terminal angular position of a spacecraft. The program values of the angular velocity vector components are determined analytically using the method previously proposed by the authors for solving a boundary value problem based on the parameter identification of a discrete model with the use of modal control. The simulation results demonstrating the effectiveness of the proposed algorithm, as well as the high accuracy level of the steady-state control, are presented.     

Digital stabilization of motion of precision controlled base platforms with inertial sensitive elements. I. Application of float angular velocity sensor

The problem of synthesis of a complex digital controller for a control system of a new generation precision calibration testbed is considered; the specific feature is the application of inertial float angular velocity sensor as the sensitive element of the system. The problem is connected with finding two algorithms of digital control realized in one processor; one of these algorithms determines the controller of the angular velocity sensor and the second one, the controller of the main loop (stabilization loop) providing stabilization of the given motion of the controlled base platform. Solution of this problem underlying the method of synthesis of such systems is given; obtained solution is analyzed in the time and frequency domains.     

Dynamics of spacecraft with elastic and dissipative elements in the attitude control mode

Rotational motion of a spacecraft with elastic and dissipative elements as a whole about its center of mass taking into account the control elements designed as single-axis gyrostabilizers in the attitude control mode is studied. Oscillatory processes related to the spacecraft attitude control when the terms emerging due to the elastic oscillations of the structure are comparable with gyroscopic terms. A model problem of spacecraft reorientation is considered. Conditions under which the elastic oscillations do not affect the flat slew of the satellite and assumptions under which no flat slew is possible are obtained. Analytical expressions for estimating the spacecraft deviations from the programmed motion (drift of the angular velocity) are found.     

Rotational motion-damper for the capture of an uncontrolled floating satellite

This paper discusses a method for damping the angular momentum of an uncontrolled target satellite in order to make it easy to capture using a chaser-satellite-mounted robotic arm. During the capture operation of an uncontrolled floating target, it may be difficult for the arm to grapple it directly because of the target’s nutation or tumbling. In this paper, the authors propose a contact/push-based control method using a cushion-type damper in order to absorb the rotational motion. The scenario is as follows: (1) a cushion-type damper is attached to the end-effector of the arm, (2) the arm softly pushes the damper on a selected point on the target, and (3) the contact force between the damper and the target causes the angular momentum of the target to decrease. The validity and feasibility of the proposed method are verified through numerical simulations.     

基于机器人运动模型的EKF-SLAM算法改进

针对两轮驱动机器人运动模型定向误差的累积问题,提出改进的三轮驱动机器人运动模型,对EKF-SLAM算法的一致性进行改进;该模型通过对机器人车轮线速度的解耦运算,将机器人运动过程中的旋转角速度提取出来并作为系统的控制输入之一,从而可以直接得到各个控制时间间隔内的机器人姿态角变化,很好地避免了机器人定向误差的累积;最后,基于归一化估计方差的检验标准进行实验,验证了三轮驱动机器人运动模型有效提高了EKF-SLAM算法的一致性。     

Tracking Control for a Cushion Robot Based on Fuzzy Path Planning With Safe Angular Velocity

This study proposes a new nonlinear tracking control method with safe angular velocity constraints for a cushion robot. A fuzzy path planning algorithm is investigated and a realtime desired motion path of obstacle avoidance is obtained. The angular velocity is constrained by the controller, so the planned path guarantees the safety of users. According to Lyapunov theory, the controller is designed to maintain stability in terms of solutions of linear matrix inequalities and the controller's performance with safe angular velocity constraints is derived. The simulation and experiment results confirm the effectiveness of the proposed method and verify that the angular velocity of the cushion robot provided safe motion with obstacle avoidance.