1,中南大学 蔡自兴，谢 斌 zxcai, xiebinmail.csu.edu.cn 2010,机器人学基础 第六章 机器人传感器,1,Ch.6 Robot Sensors,Fundamentals of Robotics,2,Ch.6 Robot Sensors,2,6.1 Introduction to Robot Sensors 6.2 Internal Sensors（内部传感器） 6.3 External Sensors（外部传感器） 6.4 Robot Sensor Application Considerations 6.5 Summary,Ch.6 Robot Sensors,3,6.1 Introduction to Robot Sensors,Application of multi-sensors in mobile robot,6.1 Introduction to Robot Sensors,4,Robot sensors can be divided into two main categories: Internal state Detect position and orientation in the coordinate of the robot itself, deal with the detection of variables such as arm joint position, velocity, and acceleration. External state Localize the robot to the environment, deal with the detection of variables such range, proximity, and touch.,6.1.1 Classification of Robot Sensors,6.1 Introduction to Robot Sensors,5,Most needed sensory abilities for robot: Simple Touch: detect whether the object is there or not. Compound Touch: detect the size and shape of the object. Simple Force: detect force along one direction. Compound Force: detect forces along multiple directions. Proximity: non-contact detection of objects. Simple Vision: detect feature such as holes, lines, and corners. Compound Vision: recognition of object.,6.1.1 Classification of Robot Sensors,6.1 Introduction to Robot Sensors,6,6,6.1 Introduction to Robot Sensors 6.2 Internal Sensors（内部传感器） 6.3 External Sensors（外部传感器） 6.4 Robot Sensor Application Considerations 6.5 Summary,Ch.6 Robot Sensors,7,6.2.1 Position/Displacement Sensors 位置传感器 A position sensor is any idea that permits position measurement. It can either be an absolute position sensor or a relative one (displacement sensor). Position sensors can be either linear or angular. Inductive Non-Contact Position Sensors, String Potentiometer, Linear variable differential transformer (LVDT) , Potentiometer, Capacitive transducer, Hall effect sensor, Proximity sensor (optical), Grating sensor, Rotary encoder (angular), Photodiode array, etc.,6.2 Internal Sensors,6.2 Internal Sensors,8,1. Linear Potentiometer 线性电位计 Consists of a wirewound resistor (or a thin film resistor), and a sliding contact point.,6.2.1 Displacement/Position Sensors,6.2 Internal Sensors,9,A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position of a shaft or axle to an analog or digital code, making it an angle transducer.,2. Rotary encoder,a) 导电塑料型,b) 线圈型,6.2 Internal Sensors,10,3. Electro-optical Position Sensor,a)光电位置传感器 b) 感光量曲线,6.2 Internal Sensors,Find the relationship between the distance and the received light volume (shows in Fig. b) in advance, we can measure the displacement x of the light source.,11,1Absolute Optical Angle Sensor 光学式绝对型旋转编码器,6.2.2 Angle Sensors,6.2 Internal Sensors,For example, resolution of a 12 bit encoder is 2-12 = 4096, so we have a resolution of 1 / 4096 (for a round of 360 degrees).,12,Absolute rotary encoders can also be used to detect angular velocity. By comparing current value and stored values, we can obtain the corresponding angular velocity.,1Absolute Optical Angle Sensor,6.2 Internal Sensors,13,Counting the number of conversions to calculate relative angle.,Incremental rotary encoder can only measure relative angle from initial value to current one. Therefore, in order to know the exact current angle value, some other methods (such as the absolute encoder) are needed to identify the initial value of angle.,2Relative Angle Sensor 光学式增量型旋转编码器,6.2 Internal Sensors,14,In this approach, no matter the clockwise (CW) rotation, or counter-clockwise (CCW) rotation, output of the sensing light always alternate between H and L, so we can not get the direction of rotation.,2Relative Angle Sensor,6.2 Internal Sensors,15,Adding another sensor (B) 1/4 cycle away from sensor A. Typically, when clockwise (CW) rotation, signal A changes before B, vice versa.,2Relative Angle Sensor,6.2 Internal Sensors,16,Attitude sensors are used to detect the relative relationship between the robot and ground. When the robot is fixed (just as the majority of industrial robot), there is no need to install such sensors. Attitude sensors are essential for mobile robots. Attitude sensors detect moving changes in position and orientation of the robot that can be used to control the robot implement desired instruction.,6.2.3 Attitude Sensors 姿态传感器,6.2 Internal Sensors,17,A gyroscope is a device for measuring or maintaining orientation, based on the principles of conservation of angular momentum.,1电动机2角度传感器3转子4一弹簧,Shown right is a rate gyro.,1Gyro Sensor 陀螺仪,6.2 Internal Sensors,18,gas rate gyroscope 气体速率陀螺仪 optical gyroscope 光陀螺仪 piezoelectric vibratory gyroscope压电振动式陀螺 (shown on the right),2Other Gyros,6.2 Internal Sensors,19,19,6.1 Introduction to Robot Sensors 6.2 Internal Sensors（内部传感器） 6.3 External Sensors（外部传感器） 6.4 Robot Sensor Application Considerations 6.5 Summary,Ch.6 Ro