Obstacle avoidance handling and mixed integer predictive control for space robots

This paper presents a novel obstacle avoidance constraint and a mixed integer predictive control (MIPC) method for space robots avoiding obstacles and satisfying physical limits during performing tasks. Firstly, a novel kind of obstacle avoidance constraint of space robots, which needs the assumption that the manipulator links and the obstacles can be represented by convex bodies, is proposed by limiting the relative velocity between two closest points which are on the manipulator and the obstacle, respectively. Furthermore, the logical variables are introduced into the obstacle avoidance constraint, which have realized the constraint form is automatically changed to satisfy different obstacle avoidance requirements in different distance intervals between the space robot and the obstacle. Afterwards, the obstacle avoidance constraint and other system physical limits, such as joint angle ranges, the amplitude boundaries of joint velocities and joint torques, are described as inequality constraints of a quadratic programming (QP) problem by using the model predictive control (MPC) method. To guarantee the feasibility of the obtained multi-constraint QP problem, the constraints are treated as soft constraints and assigned levels of priority based on the propositional logic theory, which can realize that the constraints with lower priorities are always firstly violated to recover the feasibility of the QP problem. Since the logical variables have been introduced, the optimization problem including obstacle avoidance and system physical limits as prioritized inequality constraints is termed as MIPC method of space robots, and its computational complexity as well as possible strategies for reducing calculation amount are analyzed. Simulations of the space robot unfolding its manipulator and tracking the end-effector’s desired trajectories with the existence of obstacles and physical limits are presented to demonstrate the effectiveness of the proposed obstacle avoidance strategy and MIPC control method of space robots.     

A值及A准则

俄ЦАГИ在地面飞行模拟试验和飞行试验数据的统计分析基础上,提出了一个频域最佳C*响应操纵灵敏度——A值的概念,并找出了驾驶杆特性(pχ)和静态操纵灵敏度(pny、χny)最佳值与A值的表达式,以及它们偏离最佳值时飞行品质评分(PR)与人机耦合振荡(PIO)评分(PIOR)随相对偏离量的关系曲线。 A 将此关系曲线用于预测评估人感系统相关参数对PIO趋势的影响,称之为A准则。本文从应用的角度详细地进行了计算公式的推导,讨论了准则在推导过程中所采用的假设和其适用情况,重新整理和校核了计算步骤和算例,以便于我国航空界使用。     

基于稳定约束的自适应随机共振转子故障检测方法

为解决应用传统遗传算法优化的随机共振(Stochastic resonance, SR)方法易出现的计算发散问题,提出一种基于稳定约束的自适应随机共振方法。对求解随机共振的Langevin方程进行了稳定性分析,得到了考虑输入信号的条件下,使系统输出稳定的频率压缩比R的约束公式。将该稳定性条件应用于遗传算法参数的寻优过程,将原来的无约束最优化问题转化为有约束最优化问题。将改进后的自适应随机共振方法应用于转子早期碰摩故障检测,分析结果表明,该方法确保了系统输出的稳定性,寻优过程中的频率压缩比R的取值均在约束值以下,避免了计算发散现象,实现了在强噪声条件下对微弱故障信号的提取。      

自由漂浮空间机器人多约束混合整数预测控制

针对空间机器人完成任务时需要躲避障碍物的问题,提出一种自由漂浮空间机器人的混合整数预测控制方法。首先,在模型预测控制方法框架下,机械臂关节的物理限制,躲避障碍物的要求被统一描述为最优控制问题下的不等式约束,可以得到自由漂浮空间机器人具有线性二次规划形式的最优控制律。其次,基于命题逻辑建立控制问题中各约束的优先级,保证在最大程度地满足约束的情形下得到控制问题的解,有效弥补了模型预测控制方法用于空间机器人控制时,多约束可能导致最优控制问题不可行的不足。最后,仿真结果校验了所设计控制律的有效性。     

多层CT用数据采集系统的设计与测试

提出了一种多通道、高密度、高精度数据采集系统的设计方案.采用基于现场可编程逻辑门阵列(FPGA, Field Programmable Gate Arrays)内嵌软核的体系结构,实现了多通道数据的缓冲、格式转换、乒乓读写等流水操作,解决了多层CT(Computed Tomography)有限扫描时间内数据量大、时序要求严格和数据传输精确性要求高的问题;同时利用高精度电压源和精密电阻模拟了前端输入,设计了基于PXI(PCI eXtensions for Instrumentation)总线的虚拟仪器,精确测试了设计系统的性能且未额外引入噪声.方案已成功应用于多层CT中,同时也为数据采集提供一种借鉴.      

Influence of shock attenuation on tailored operation in free piston shock tunnels

The free piston shock tunnel is a type of shock tunnel with high performance. For this type of tunnel, the influence mechanism of shock wave attenuation on tailored operation is explored by numerical simulation and theoretical analysis. By introducing the normalized velocity, the simple constraint equation for shock wave under the tailored operation is deduced. Moreover, the real gas effect is also taken into account in this equation. Based on the equation, the tailored operation of shock tunnels can be predicted with very few calculations. The present study shows that the change rate of the thermodynamic state of the gas behind the shock wave is inconsistent with the attenuation rate of the shock wave, which is the fundamental reason why the wind tunnel achieves tailored operation at a lower Mach number of shock waves. This lower Mach number of shock waves differs from the corresponding ideal value by a factor, which is about the square root of shock attenuation rate.     

CGI——一种交互图形设计的通用接口

 CGI(CADEMAS Graphics Interface)是一种通用的与设备独立的高级用户图形接口。我们将说明它与国际图形标准的区别。CGI已在几种图形仪上实现。本文侧重介绍CGI的IBM 5080版本,且说明它的特点。最后是若干工程实例。     

动态测试与数据处理系统在飞行模拟试验中的应用

论述了通用飞行模拟器动态测试与数据处理系统的结构局及各组成部分包括的内容，并与国外同类系统作了比较。从工程飞行模拟应用与试验研究的角度论证了动态测试与数据处理系统在飞行模拟中的必要性，实用性及重要地位。     

柔性空间机械臂动力学模型

本文叙述三种柔性空间机械臂的动力学模型,它们的差异在于用不同的方法描述机械臂的弹性变形,即用有限元法、集中参数法和解析法。     

基于约束满足的多星对区域目标观测活动协同

多星对区域目标观测活动的协同问题是卫星任务规划与调度领域的新问题。讨论了采用多星协同模式观测区域目标的必要性，描述了协同问题的研究内容。基于约束满足理论，建立了多星协同问题的约束优化问题模型，提出了一种禁忌算法与约束传播相结合的求解机制。最后，以仿真算例验证了模型与算法的正确性和优化性能。