機器人學(xué)基礎(chǔ)-第6章-機器人傳感器-蔡自興

1、1中南大學(xué)中南大學(xué)蔡自興，謝蔡自興，謝 斌斌zxcai, 2010機器人學(xué)基礎(chǔ)機器人學(xué)基礎(chǔ)第六章第六章 機器人傳感器機器人傳感器1Ch.6 Robot SensorsFundamentals of Robotics2Ch.6 Robot Sensors26.1 Introduction to Robot Sensors 6.2 Internal Sensors（內(nèi)部傳感器） 6.3 External Sensors（外部傳感器） 6.4 Robot Sensor Application Considerations 6.5 SummaryCh.6 Robot Sensors36.1 Intro

2、duction to Robot SensorsApplication of multi-sensors in mobile robot6.1 Introduction to Robot Sensors4Robot sensors can be divided into two main categories:Internal stateDetect position and orientation in the coordinate of the robot itself, deal with the detection of variables such as arm joint posi

3、tion, velocity, and acceleration.External stateLocalize the robot to the environment, deal with the detection of variables such range, proximity, and touch.6.1.1 Classification of Robot Sensors6.1 Introduction to Robot Sensors5Most needed sensory abilities for robot:Simple Touch: detect whether the

4、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 V

5、ision: recognition of object.6.1.1 Classification of Robot Sensors6.1 Introduction to Robot Sensors6 66.1 Introduction to Robot Sensors 6.2 Internal Sensors（內(nèi)部傳感器）（內(nèi)部傳感器） 6.3 External Sensors（外部傳感器） 6.4 Robot Sensor Application Considerations 6.5 SummaryCh.6 Robot Sensors76.2.1 Position/Displacement

6、 Sensors 位置傳感器位置傳感器 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 di

7、fferential transformer (LVDT) , Potentiometer, Capacitive transducer, Hall effect sensor, Proximity sensor (optical), Grating sensor, Rotary encoder (angular), Photodiode array, etc.6.2 Internal Sensors6.2 Internal Sensors81. Linear Potentiometer 線性電位計線性電位計 Consists of a wirewound resistor (or a thi

8、n film resistor), and a sliding contact point.6.2.1 Displacement/Position Sensors() /() / ()EeeLxLx(2)LeExE6.2 Internal Sensors9A 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

9、 an angle transducer. 2. Rotary encodera) 導(dǎo)電塑料型b) 線圈型6.2 Internal Sensors103. Electro-optical Position Sensora)光電位置傳感器 b) 感光量曲線 6.2 Internal SensorsFind 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 so

10、urce. 111Absolute Optical Angle Sensor 光學(xué)式絕對型旋轉(zhuǎn)編碼器6.2.2 Angle Sensors6.2 Internal SensorsFor 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). 12Absolute rotary encoders can also be used to detect angular velocity. By comparing

11、current value and stored values, we can obtain the corresponding angular velocity. 1Absolute Optical Angle Sensor6.2 Internal Sensors13Counting the number of conversions to calculate relative angle.Incremental rotary encoder can only measure relative angle from initial value to current one. Therefor

12、e, 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 光學(xué)式增量型旋轉(zhuǎn)編碼器6.2 Internal Sensors14In this approach, no matter the clockwise (CW) rotation, or counter-clockwise (CCW) rotation,

13、 output of the sensing light always alternate between H and L, so we can not get the direction of rotation.2Relative Angle Sensor6.2 Internal Sensors15Adding another sensor (B) 1/4 cycle away from sensor A. Typically, when clockwise (CW) rotation, signal A changes before B, vice versa.2Relative Angl

14、e Sensor6.2 Internal Sensors16Attitude 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 de

15、tect 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 姿態(tài)傳感器姿態(tài)傳感器6.2 Internal Sensors17A gyroscope is a device for measuring or maintaining orientation, based on the principles of conservation of angula

16、r momentum. 1電動機2角度傳感器3轉(zhuǎn)子4一彈簧 Shown right is a rate gyro. 1Gyro Sensor 陀螺儀陀螺儀6.2 Internal Sensors18gas rate gyroscope氣體速率陀螺儀氣體速率陀螺儀optical gyroscope光陀螺儀光陀螺儀piezoelectric vibratory gyroscope壓電振動式陀螺壓電振動式陀螺(shown on the right)2Other Gyros6.2 Internal Sensors19196.1 Introduction to Robot Sensors 6.2 Int

17、ernal Sensors（內(nèi)部傳感器） 6.3 External Sensors（外部傳感器）（外部傳感器） 6.4 Robot Sensor Application Considerations 6.5 SummaryCh.6 Robot Sensors206.3.1 Tactile Sensors 觸覺傳感器觸覺傳感器The prototype of robot tactile sensor is an imitation of human tactile sense of touch functions:Tactile sensePressure senseSlip senseForc

18、e sense6.3 External Sensors 內(nèi)傳感器內(nèi)傳感器6.3 External Sensors211Touch Sensor 接觸覺傳感器接觸覺傳感器Application: Touch sensors are equipped in the palm of the end-effctor in order to grip objects precisely. 6.3 External Sensors22Robot pressure sensor can detect the pressure and its distribution through an array of

19、piezoelectric elements. (Eg. Springs (彈簧) for mechanical detecting).2Pressure Sensor 壓覺傳感器壓覺傳感器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 Sensors23Slip sensor is used to detect force

20、and displacement in the vertical direction of the pressure. 3Slip Sensor 滑覺傳感器滑覺傳感器6.3 External Sensors24Robot 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 feedba

21、ck of the force.Wrist force sensor, mounted 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 力覺傳感器力覺傳感器6.3 External Sensors25

22、Draper實驗室研制的六維腕力傳感器SRI（Stanford Research Institute）研制的六維腕力傳感器林純一研制的腕力傳感器4Force Sensor6.3 External Sensors266.3.2 Distance Sensor 機器人距離傳感器機器人距離傳感器 1 Ultrasonic Distance Sensor 超聲波距離傳感器超聲波距離傳感器 Ultrasonic distance sensor is consisting of a transmitter and a receiver, which are both based on piezoelect

23、ric effect (壓電效壓電效應(yīng)應(yīng)).6.3 External Sensors27Principles of Ultrasonic Ranging- TOF (Time Of Flight ，時間行程法)超聲波測距原理圖超聲波測距原理圖1Ultrasonic Distance Sensor6.3 External Sensors281Ultrasonic Distance Sensor 6.3 External Sensors292Proximity Sensors 接近覺傳感器接近覺傳感器 A proximity sensor is a sensor able to detect th

24、e presence of nearby objects without any physical contact. A proximity sensor 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 t

25、he proximity sensors target. 6.3 External Sensors30Different proximity sensor 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 Sensors6.3 External Sensors31Rese

26、arch have shown that the visual perception of information accounts for 80% of what people perceived from outside world.Cells of human vision have the magnitude of about 108, is 3000 times to auditory cells(聽覺), and over 100 times to the sensory cells of the skin（皮膚觸覺）.6.3.3 Vision Sensors 視覺傳感器視覺傳感器

27、6.3 External Sensors32Charge-coupled device (CCD) is a major technology for digital 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-Couple

28、d Device) Sensors6.3 External Sensors33A total of 256 gray scale, from the Figure (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 resolution6.3 External Sensors34Figure (a) to (f) with resolution of 512 512, followed by 256, 64,16,8,4

29、, and 2 gray levels.The impact of change on the image gray 6.3 External Sensors35Figure (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 grayscale6.3 External Sensors36366.1 Introd