机器人学导论分析解析

1、教材 ： John J. Craig. Introduction to Robotics: Mechanics and Control (3rd ed). Pearson Prentice Hall. 2005. 参考资料： 美Saeed B.Niku著, 孙福春等译. 机器人学导论分析、系统及应用(第2版) (原书: Introduction to Robotics: Analysis, Systems, Applications). 电子工业出版社. 2013. 蔡自兴, 谢斌. 机器人学(第3版). 清华大学出版社. 2015. 谭民, 徐德等. 先进机器人控制. 高等教育出版社. 20

2、07. 比较知名的刊登机器人方面研究成果的期刊：Advanced Robotics，Autonomous Robots, Journal of Robotic System，机器人，自动化学报，机器人技术与应用，控制理论与应用。 MATLAB的Robotics工具箱(by Peter I. Corke)： 上课形式（全日制硕士-全英；在职工硕-双语）： 讲授20学时、实验12学时。 考核（全日制硕士-全英；在职工硕-双语）： 仿真作业，实验报告，课程论文（综述）。,Chapter 1 Introduction,A rudiment of manipulator,What does a robo

3、t look like in your mind？,Definitions of robots: Definition 1: A robot is a mechanical or virtual artificial agent, usually an electro-mechanical machine that is guided by a computer program or electronic circuitry. (from Wikipedia) Definition 2: An automatically controlled, reprogrammable, multipur

4、pose manipulator, which may be either fixed in place or mobile for use in industrial automation applications. (from International Organization for Standardization (ISO) ) Definition 3: A reprogrammable, multifunctional manipulator designed to move material, parts, tools, or specialized devices throu

5、gh various programmed motions for the performance of a variety of tasks. (from Robot Institute of America (RIA),Summary: There is no consensus on which machines qualify as robots but there is general agreement among experts, and the public, that robots tend to do some or all of the following: accept

6、 electronic programming, process data or physical perceptions electronically, operate autonomously to some degree, move around, operate physical parts of itself or physical processes, sense and manipulate their environment, and exhibit intelligent behavior especially behavior which mimics humans or

7、other animals. (from Wikipedia),1.1 BACKGROUND,Yearly installations of multipurpose industrial robots for 1995-2000 and forecasts for 2001-2004,Robot prices compared with human labor costs in the 1990s,Categories of robot:,According to actuator types: Electrical actuators Hydraulic actuators Pneumat

8、ic actuators Others: piezo actuators, shape memory alloy (SMA), magnetostrictive actuators According to intelligence levels: Normal robots: only programmable Intelligent robots: some kind of artificial intelligence According to moveability： Fixed robots: the base is fixed, while the joints are movea

9、ble Mobile robots: wheel, pedrail, legged (single, double, four, six, eight),accord to application fields:,The robot type of our course: industrial robots (robotic arms, manipulators),robots,Industrial robots,Specialized robots,Service robots,Underwater robots,Military robots,Agricultural robots,Rob

10、otized machine,Humanoid robots,Entertainment robots,Aerospace robots,Micro robots,Medical robots,According to designs of the first three joints:,Cartesian,Spherical,Cylindrical,Articulated,SCARA,(Manipulator structure: Positioning structure + orienting structure or wrist),Topics： Lectures: Descripti

11、on of position and orientation (Chapter 2) Forward kinematics of manipulators (Chapter 3) Inverse kinematics of manipulators (Chapter 4) Velocities, static forces, singularities (Chapter 5) Dynamics (Chapter 6) Trajectory generation (Chapter 7) Manipulator design and sensors (Chapter 8) Linear posit

12、ion control (Chapter 9) Nonlinear position control (Chapter 10) Experiments: Programming robots and Off-line programming and simulation (Chapter 12 & 13),Description of position and orientation (Chapter 2) In order to describe the position and orientation of a body in space, we will always attach a

13、coordinate system, or frame, rigidly to the object. We then proceed to describe the position and orientation of this frame with respect to some reference coordinate system. Any frame can serve as a reference system, so we often think of transforming or changing this description from one frame to ano

14、ther.,Forward kinematics of manipulators (Chapter 3) Kinematics is the science of motion that treats motion without regard to the forces which cause it. e.g. position, velocity, acceleration and all higher order derivatives of the position variables. Structure of a manipulator parts: nearly rigid li

15、nks connection: by joints (rotary or revolute joints, sliding or prismatic joints) joint variables: joint angles (revolute joints) joint offset (prismatic joints),Forward kinematics of manipulators: Given a set of joint variables, to compute the position and orientation of the tool frame relative to

16、 the base frame. in other words, to change the representation of manipulator position from a joint space description into a Cartesian space description.,Attached to the end-effector,Attached to the base,Degree Of Freedom (DOF): In many scientific fields, the degrees of freedom of a system is the num

17、ber of parameters of the system that may vary independently. (from Wikipedia) For example: A point in the plane has two DOF for translation: its two coordinates. A rigid body on the plane has three DOF: its two coordinates and its orientation. A rigid body in space has six DOF: three translation and

18、 three revolution.,The number of DOF that a manipulator processes is the number of independent position variables that would have to be specified in order to locate all parts of the mechanism. Key word: independent For example, four-bar linkage has only one DOF (even though there are three moving me

19、mbers),A typical industrial robot is usually an open kinematic chain, and each joint position is defined with a single variable, so the number of joints equals the number of DOF.,5个自由度（2个冗余自由度）,4个自由度，若要空间内在任何方向上定向，需另外2个自由度,Inverse kinematics of manipulators (Chapter 4) Problem: given the position an

20、d orientation of the end-effector of the manipulator, calculate all possible sets of joint angles that could be used to attain this given position and orientation. Could be thought as a mapping of “locations” in 3-D Cartesian space to “locations in the robots internal joint space.,Difficulties: The

21、kinematic equations are nonlinear, their solution is not always easy (or even possible) in a closed form Existence of a solution Multiple solutions,Velocities, static forces, singularities (Chapter 5) To analyze manipulators in motion. Jacobian: a matrix specifies a mapping from velocities in joint

22、space to velocities in Cartesian space. This mapping changes as the configuration of the manipulator varies.,At certain points, called singularities, this mapping is not invertible. Example of singularity: The gun must follow the enemy plane. Two DOF: Azimuth, Elevation A=15，E=25, Its easy to follow

23、. A=15，E=70 and become bigger, soon the plane is passing overhead. The gunner is no longer able to track the plane. He must change his azimuth rate at a very high rate.,Singularity of the mechanism: with the stream of bullets directed straight up, their direction aligns with the axis of rotation of

24、the azimuth rotation. i.e. the azimuth rotation does not cause a change in the direction of the stream of bullets. At this point, we have lost the effective use of one of the joints. The mechanism has become locally degenerate . Singularity conditions do not prevent a robot arm from positioning anyw

25、here within its workspace, but cause problems with motions of the arm in their neighborhood.,Dynamics (Chapter 6) In order to accelerate a manipulator from rest, glide, and decelerate to a stop, a complex set of torque functions must be applied by the joint actuators. The exact form of the required

26、functions of actuator torque depend on the spatial and temporal attributes of the path taken by the end-effector and on the mass properties of the links and payload, friction in the joints, and so on. Dynamic equations of motion usage 1: control - to calculate actuator torque functions to control a

27、manipulator to follow a desired path. usage 2: simulation - simulate how a manipulator would move under application of a set of actuator torques.,Trajectory generation (Chapter 7) to cause a manipulator to move from here to there in a smooth, controlled fashion, we need: to cause each joint to move

28、as specified by a smooth function of time. each joint starts and ends its motion at the same time. Trajectory generation: to compute these motion functions.,Manipulator design and sensors (Chapter 8) considerations: size, speed, load capability, number of joints, geometric arrangement. These conside

29、rations affect the manipulators workspace size and quality, the stiffness of the manipulator structure, and other attributes. For example: to determine the number of joints: specialized robot：for specific task. careful thinking of the task, e.g. to place electronic components on a flat circuit board, 3 joints for positioning, the 4th for rotation about a vertical axis. universal robot: for a wide variety of tasks. six joints,Linear position control (Chapter 9) Position control: In order to cause the manipulator to follow the desired trajectory, a position-control sy