机器人学基础_第6章_机器人传感器.ppt

1、1,中南大学 蔡自兴，谢 斌 zxcai, 2010,机器人学基础第六章 机器人传感器,1,Ch.6 Robot Sensors,Fundamentals of Robotics,Fundamentals of Robotics,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

2、,6.1 Introduction to Robot Sensors,Application of multi-sensors in mobile robot,6.1 Introduction to Robot Sensors,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

3、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,Most needed sensory abilities for robot: Simple Touch:

4、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

5、, and corners. Compound Vision: recognition of object.,6.1.1 Classification of Robot Sensors,6.1 Introduction to Robot Sensors,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,6.2.1

6、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, L

7、inear 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,1. Linear Potentiometer 线性电位计 Consists of a wirewound resi

8、stor (or a thin film resistor), and a sliding contact point.,6.2.1 Displacement/Position Sensors,6.2 Internal Sensors,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

9、transducer.,2. Rotary encoder,a) 导电塑料型,b) 线圈型,6.2 Internal Sensors,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.,

10、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).,Absolute rotary encoders can also be used to detect angular velocity. By comparing current

11、 value and stored values, we can obtain the corresponding angular velocity.,1Absolute Optical Angle Sensor,6.2 Internal Sensors,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

12、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,In this approach, no matter the clockwise (CW) rotation, or counter-clockwise (CCW) rotation, outp

13、ut 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,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 S

14、ensor,6.2 Internal Sensors,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 dete

15、ct 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,A gyroscope is a device for measuring or maintaining orientation, based on the principles of conservation of angular momen

16、tum.,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,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,19,6.1 Introduction to Robot Sensors 6.2 Internal Sensors（内部传感器）

17、6.3 External Sensors（外部传感器） 6.4 Robot Sensor Application Considerations 6.5 Summary,Ch.6 Robot Sensors,6.3.1 Tactile Sensors 触觉传感器 The prototype of robot tactile sensor is an imitation of human tactile sense of touch functions: Tactile sense Pressure sense Slip sense Force sense,6.3 External Sensors

18、 内传感器,6.3 External Sensors,1Touch Sensor 接触觉传感器,Application: Touch sensors are equipped in the palm of the end-effctor in order to grip objects precisely.,6.3 External Sensors,Robot pressure sensor can detect the pressure and its distribution through an array of piezoelectric elements. (Eg. Springs

19、(弹簧) for mechanical detecting).,2Pressure Sensor 压觉传感器,Applications: By smart control of pressure, end-effector can pick up not only fragile objects as glass cups, but also soft object as tofu and eggs.,6.3 External Sensors,Slip sensor is used to detect force and displacement in the vertical directi

20、on of the pressure.,3Slip Sensor 滑觉传感器,6.3 External Sensors,Robot Force sensors can be divided into 3 categories: Joint force sensor, installed in the joint actuator, measure the output force and torque of the actuator itself, is used to control the feedback of the force. Wrist force sensor, mounted

21、 between the end-effector and the last joint, measure forces and torques on the end-effector for all directions. Finger force sensor, installed in the robot finger joints, measure the clamping force of an object.,4Force Sensor 力觉传感器,6.3 External Sensors,Draper实验室研制的 六维腕力传感器,SRI（Stanford Research Ins

22、titute） 研制的六维腕力传感器,林纯一研制的腕力传感器,4Force Sensor,6.3 External Sensors,6.3.2 Distance Sensor 机器人距离传感器,1 Ultrasonic Distance Sensor 超声波距离传感器 Ultrasonic distance sensor is consisting of a transmitter and a receiver, which are both based on piezoelectric effect (压电效应).,6.3 External Sensors,Principles of Ult

23、rasonic Ranging- TOF (Time Of Flight ，时间行程法),超声波测距原理图,1Ultrasonic Distance Sensor,6.3 External Sensors,1Ultrasonic Distance Sensor,6.3 External Sensors,2Proximity Sensors 接近觉传感器,A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sen

24、sor often emits an electromagnetic or electrostatic field, or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensors target.,6.3 External Sensors,Different proximity sens

25、or targets demand different sensors. For example, a capacitive or photoelectric sensor might be suitable for a plastic target; an inductive proximity sensor requires a metal target.,2Proximity Sensors,6.3 External Sensors,Research have shown that the visual perception of information accounts for 80%

26、 of what people perceived from outside world. Cells of human vision have the magnitude of about 108, is 3000 times to auditory cells(听觉), and over 100 times to the sensory cells of the skin（皮肤触觉）.,6.3.3 Vision Sensors 视觉传感器,6.3 External Sensors,Charge-coupled device (CCD) is a major technology for d

27、igital imaging. Although CCDs are not the only technology to allow for light detection, CCDs are widely used in professional, medical, and scientific applications where high-quality image data is required.,CCD (Charge-Coupled Device) Sensors,6.3 External Sensors,A total of 256 gray scale, from the F

28、igure (a) to (f) followed by resolution of 512 512, 256 256,128 128,64 64,32 32,16 16.,The impact of change on the image resolution,6.3 External Sensors,Figure (a) to (f) with resolution of 512 512, followed by 256, 64,16,8,4, and 2 gray levels.,The impact of change on the image gray,6.3 External Sensors,Figure (a) to (f) followed by: 256 256,128-level gray scale; 181 181,64-level gray scale; 128 128,32-level gray scale; 90 90,16-level gray scale; 64 64,8-level gray scale; 45 45,4-level gray scale.,The impact of changes in both resolution and grayscale,6.3 External Sensors,36,6.1 Introdu