Adjustment of Home Posture of Biped Humanoid Robot Using Sensory Feedback Control

Humanoid robot dynamic walking is seriously affected by the initial home posture (walking ready posture). If the initial home posture is not accurate, the robot may fall down during walking despite using robust walking control algorithm. Moreover, the initial home posture of a real physical robot is slightly different at every setting because the zero position of the joint is not exactly the same. Therefore, an accurate and consistent initial home posture is essential when we compare and analyze walking control algorithms. In order to find a zero position, an incremental encoder with a limit switch or an absolute encoder such as a potentiometer can generally be used. However, the initial calibration of this method for a multi-axis humanoid robot that enables the desired initial sensor signal is difficult and time-consuming. Furthermore, it has the disadvantage that additional limit switches or absolute encoders can interfere with the design objective of compactness. Therefore, this paper describes a novel adjustment method of the home posture for a biped humanoid robot utilizing incremental encoders, an inertial sensor and force torque sensors. Four kinds of controllers are proposed for the adjustment of the home posture and adjusted offsets are measured when the outputs of the controllers have converged. Experimental results from KHR-2 show the effectiveness of the proposed adjustment algorithm.     

室外移动机器人TYIRV-I的定位系统的设计与实现

定位系统是保证准确避障和导航的必要条件,只有准确稳定的定位才能够准确避障和导航,所以定位系统在室外移动机器人中是不可缺少的组成部分。本文介绍室外移动机器人TYIRV-I的组合定位系统,即GPS、磁罗盘和光码盘组合定位,其中,GPS虽然能够提供较精确的位置信息,但是会由于遮挡等原因导致数据无效。磁罗盘和光码盘通过航位推算得到位置信息,短距离定位效果较好,但存在严重的累计误差。对以上两种定位方法进行信息融合形成GPS、磁罗盘和光码盘组合定位,取长补短,取得较好的效果。实践证明,该定位系统具有较高的准确性和稳定性,能够满足移动机器人的定位和导航需要。     

BiSS接口的光电编码器数据读出研究

高精度的光电编码器作为位置传感器广泛应用于伺服系统中,双向同步串行接口(Bidirectional Synchronous Serial Interface,简称BiSS)由于速度快,抗干扰能力强,越来越广泛地用于连接编码器和控制器;为了实现BiSS接口传感器数据的读取,提出了两种读取数据的方式:微控制器方式和CPLD方式,两种方式都是用端口产生时钟,通过差分器件把时钟发送给光电编码器,同步接收光电编码器返回的差分n位位置数据、2位状态数据和6位CRC校验码;微控制器或CPLD利用位置和状态数据运算产生CRC校验码,如果运算产生的CRC和接收到的CRC不一致,说明传输过程出错;实验结果表明,两种方式都具有高可靠性,CPLD方式的快速性更高,通用性更强。     

一种基于视觉的移动机器人定位系统

具有自主的全局定位能力是自主式稳定机器人传感器系统的一项重要功能,为了实现这个目的,国内外均在不断地研究发展各种定位传感器系统,这里介绍了一种采用光学蝗全方位位置传感器系统,该传感器系统由主动式路标、视觉传感器、图象采集与数据处理系统组成,其视觉传感器和数据处理系统可安装在移动机器人上,然后可通过观测路标物「视角定位的方法,计算出机器人在世界坐标系中的位置和方向,实验证明,该系统可以只的在线定位,     

迈克尔逊干涉仪条纹采集和波长测量装置设计

设计了一套基于单片机的迈克尔逊干涉仪条纹的采集和波长自动测量装置。该装置通过光敏传感模块、旋转编码器和单片机处理显示模块实现,滤除了电路噪声,同时可以适应不同的背景光强,具有精确度高、操作简便且可靠等优点。     

A visual integrated navigation for precise position estimation

In this article, we propose a visual integrated navigation method which is composed of a relative position estimation and an absolute position estimation. The aim is to estimate precise position and overcome accumulative position errors for long-distance and long-time visual navigation. The relative position estimation measures relative displacement and position by a simple optical flow method, but its accumulative position errors would increase with time. The absolute position estimation aids the relative position estimation for correcting these accumulative errors timely. The absolute position estimation employs a Kalman filter based on image entropy, which can continuously correct accumulative errors according to the actual and predicted image entropy. As a result, the proposed navigation method can supply precise position information all along the navigational path, which has been proven by some experiments in the paper.     

Swing-up and LQR stabilization of a rotary inverted pendulum

In this article, we consider the swing-up and linear quadratic regulator (LQR) stabilization of a rotary inverted pendulum. A DC motor rotates a rigid arm. At the end of the rigid arm is a joint with a pendulum suspended from it. Two encoders check the degree of the rigid arm and the pendulum every 0.5 ms. This article describes a modified bang-bang control which swings the pendulum up safely and fast. In order to solve the stabilization problem, we used a linear quadratic regulator. When the user gives a large disturbance to the pendulum so that it loses its position, it quickly recovers to the upright position. Experimental results showed that the proposed bang-bang and LQR controllers can stabilize a rotary inverted pendulum system within 3.0 s from any starting point. The system also showed robustness to a large disturbance.     

Encoder based online motion planning and feedback control of redundant manipulators

This paper proposes and investigates an online motion planning and feedback control (OMPFC) scheme for redundant manipulators via techniques of quadratic programming and rotary encoder. The proposed OMPFC scheme is performed on a planar six degrees-of-freedom (DOF) manipulator. This robotic scheme incorporates the feedback of task-space position error. The joint state is obtained in real time via rotary encoders equipped on the physical manipulator. The original scheme is finally reformulated as a unified quadratic program (QP). The QP is solved online during the joint motion by employing an efficient numerical algorithm. Simulation and experimental results validate the physical realizability, online property, and efficacy of the proposed OMPFC scheme (including the employed numerical algorithm).     

激光与视觉融合的透视平面检测与深度预测研究

针对单一的激光传感器或视觉传感器无法检测到透视三维平面的问题,提出一种基于激光传感器与视觉传感器融合的透视平面检测与深度预测算法;首先采用透视平面检测网络,在二维彩色图像中对透视平面进行图像分割;其次应用单一图像反射去除算法,在分割得到的透视平面区域分离背景信息,并使用MegaDepth算法进行深度预测,得到相对深度图;最后结合激光传感器的深度数据,采用抽样一致性算法,计算深度标尺,并使用对透视平面进行深度赋值,将相对深度图转化为绝对深度图,进而完成对透视平面的深度预测;实验结果表明该算法能成功检测并分割透视平面,且能得到正确的透视平面绝对深度信息.     

移动机器人THMR-V的组合定位系统

定位系统是室外移动机器人中不可缺少的组成部分,是车辆定位与导航的基础。文章介绍了清华移动机器人THMR－V的定位系统,它是由GPS、磁罗盘、光码盘组成的。GPS能够提供比较精确的绝对位置,但是采集数据较慢,而且可能由于遮挡等原因而失效或跳变。磁罗盘－光码盘系统（CEPS）通过航位推算计算车体位置,在短期内定位效果较好,但是存在积累误差。通过GPS／CEPS组合定位,取长补短,从而整体上达到良好的性能。在THMR－V上经过一年多试验证明,该系统具有较高的准确性和稳定性,满足移动机器人的定位与导航的需要。     

一种基于视觉的图书馆室内定位方法

提出一种可用于图书馆内图书运载车的车辆室内自动定位定向方法。借鉴二维条形码思想,设计了一种简单方便、易于识别、内含绝对位置坐标、具有一定纠错能力的路标,可将路标放置在图书馆天花板上,由安装于图书运载车上且光轴和天花板垂直的摄像机进行拍摄。通过图像分割、连通域寻找、轮廓特征曲线匹配以及路标特征识别步骤定位路标,解析路标中所包含的坐标信息以及偏转角度,进而计算出车辆当前所处的绝对位置和航向角。通过实验,验证了所提出方法的有效性,能够满足图书馆内图书运载车室内定位的要求。     

Stereo perception and dead reckoning for a prototype lunar rover

This paper describes practical, effective approaches to stereo perception and dead reckoning, and presents results from systems implemented for a prototype lunar rover operating in natural, outdoor environments.The stereo perception hardware includes a binocular head mounted on a motion-averaging mast. This head provides images to a normalized correlation matcher, that intelligently selects what part of the image to process (saving time), and subsamples the images (again saving time) without subsampling disparities (which would reduce accuracy). The implementation has operated successfully during long-duration field exercises, processing streams of thousands of images.The dead reckoning approach employs encoders, inclinometers, a compass, and a turn-rate sensor to maintain the position and orientation of the rover as it traverses. The approach integrates classical odometry with inertial guidance. The implementation succeeds in the face of significant sensor noise by virtue of sensor modelling, plus extensive filtering.The stereo and dead reckoning components are used by an obstacle avoidance planner that projects a finite number of arcs through the terrain map, and evaluates the traversability of each arc to choose a travel direction that is safe and effective. With these components integrated into a complete navigation system, a prototype rover has traversed over 1 km in lunar-like environments.     

Low-resolution implementation of high-resolution position control

Digital implementation of position or path control using high-resolution encoders may require high resolution for control algorithm computations too if the controller state variables carry high-precision absolute position information. If the control algorithm is reformulated in a form in which the controller state is continuously offset according to the possibly nonconstant setpoint, then much less arithmetic wordlength may be sufficient     

印染错花在线智能监测系统的研究

针对目前圆网印花机对花技术的现状,提出了一种基于机器视觉技术的新型圆网印花机自动对花系统。该系统采用图像传感器实时采集印花过程中的花位标记图像,利用数字图像处理算法对采集到的图像进行处理分析,实时获取对花误差,并根据误差信号转化输出为控制信号,通过控制器控制、调节各印花网筒和整纬器的运行状态或参数,实现了印花精度的智能式检测与控制,提高了对花精度,进而提高了产品质量和工作效率。     

A Method for Estimating Angular Separation in Mobile Wireless Sensor Networks

Resource-constrained mobile sensors require periodic position measurements for navigation around the sensing region. Such information is often obtained using GPS or onboard sensors such as optical encoders. However, GPS is not reliable in all environments, and odometry accrues error over time. Although several localization techniques exist for wireless sensor networks, they are typically time consuming, resource intensive, and/or require expensive hardware, all of which are undesirable for lightweight mobile devices. In this paper, we describe a technique for determining spatial relationships that is suitable for resource-constrained mobile sensors. Angular separation between multiple pairs of stationary sensor nodes is derived using wheel encoder data in conjunction with the measured Doppler shift of an RF interference signal. Our experimental results demonstrate that using this technique, a robot is able to determine the angular separation between four pairs of sensors in a 45 × 35 m sensing region with an average error of 0.28 rad. in 0.68 s.     

Positioning of a mobile robot based on odometry and a new ultrasonic LPS

Odometry is a method that calculates the position and heading angle of a mobile robot using encoders attached to the wheels of the robot. Errors in the position and heading angle in odometry continuously increase as the operating time and moving distance increase. The solution to overcome these accumulated errors is to periodically compensate with the external absolute position information. An ultrasonic local positioning system (LPS) consists of multiple ultrasonic transmitters located in the environment and an ultrasonic receiver. In this study, ultrasonic transmitters are in a line at one side, and four transmitters are grouped for a coverage area. In order to measure the time of flights (TOFs) for an ultrasonic signal, the receiver predicted the transmitted time from each transmitter using a hyperbolic model. Four transmitters emit ultrasonic signals sequentially, and then the receiver calculates the position using the present measured distance and the pre-measured distance. In order to extend the distance that is measured, the receiver collects the ultrasonic signal and executes cross correlation with a sinusoidal signal. The measured distance data of the previous step causes the position error. This error is compensated for by the predicted distance data using a bilinear interpolation method. An extended Kalman filter is designed to combine odometry, a compass sensor, and an ultrasonic LPS. The proposed system provides reliable and accurate position and heading information, regardless of the operating time and moving distance.     

基于图像处理的太阳光矢量倾角测量方法

为了提高在轨太阳光谱辐射的绝对定标精度,提出了太阳光矢量和太阳光谱仪主光轴夹角的测量方法。以图像处理技术为基础,构造了太阳光矢量和太阳光谱仪主光轴夹角的测量系统。入射的太阳光经在成像器件上成像,然后经过图像处理,获取了太阳光像点中心的位置,进而计算了太阳光矢量和与太阳光谱仪主光轴的倾角。实验表明测量方法是有效的,测量系统工作可靠稳定,测量精度约为0.05°。     

Electroless plating Co–P films for high performance magnetic rotary encoders

The recording media is of crucial importance for magnetic rotary encoders of high resolution and accuracy. In the present study, the potential use of electroless plating Co–P films as the recording media for magnetic encoders was investigated. The microstructure and chemical states were analyzed by field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The results indicated that Co and P co-existed as elementary substances in the as-deposited Co–P films, where Co grains had an hexagonal closed-packed structure with c-axis in the plane. The read and write characteristics revealed that the Co–P films could be recorded 2048 original magnetic poles while the amplitudes of the output square and sinusoidal waves were uniform. It is suggested that the Co–P films can be a promising candidate as recording media for high performance magnetic rotary encoders, which may greatly improve the resolution and accuracy of rotational speed or displacement measurements in industrial and automotive applications.     

Real Time Relative and Absolute Dynamic Localization of Air–Ground Wireless Sensor Networks

A novel approach for relative and absolute localization of wireless sensor nodes using a potential field method is presented. The main idea of our work is to develop relative and absolute localization algorithms for the position estimate of stationary unattended ground sensor (UGS) nodes using a potential field method. A dynamical model is derived for each sensor node to estimate the relative and absolute position estimates under the influence of a certain fictitious virtual force. In the algorithm the sensor nodes do not move physically, but a virtual motion is carried out to generate optimal position estimates. The convergence of the estimator system to a least squares solution is guaranteed using Lyapunov theory. Separate control algorithms for relative and absolute localization are developed which guarantee the convergence of the position estimates. The relative localization algorithm assumes that distance (i.e. range) measurements between UGS nodes are available and for absolute localization algorithm, uninhabited aerial vehicles (UAV) are available with on board GPS such that they have absolute position information together with range measurement information. In the relative localization algorithm the UGS nodes are localized with respect to an internal co-ordinate frame. In absolute localization the UGS nodes are localized with respect to the known absolute position of UAV in the air–ground network. The effectiveness of the control algorithm is highlighted by the real time implementation results.     

一种新的光学遥感器优化设计方法

针对高分辨率空间光学遥感器,既要实现轻小型化,又要获得高品质遥感图像的要求,本文提出一种基于成像链路仿真的遥感器优化设计方法。文章以MTF和噪声模型为基础分析成像链路中的各个环节对成像质量的影响,同时考虑末端图像复原处理,构建成像链路仿真模型,通过遥感器指标评价和仿真图像质量评价来优化遥感器的总体指标,从而在保证成像质量的同时降低遥感器研制难度。实验验证了优化设计方法的可行性和优势。