Robotics and Automation Unit 1 part 1 PDF

Robotics and Automation Robotics and Automation By Dr. Pooja P. Gundewar  Professional Elective I Credits: 3+0+1 Course Objectives: 1. Knowledge (i) To know elements of Industrial Robot Systems. 2. Skills (i) To analyze kinematic, inverse...

Robotics and Automation Robotics and Automation By Dr. Pooja P. Gundewar  Professional Elective I Credits: 3+0+1 Course Objectives: 1. Knowledge (i) To know elements of Industrial Robot Systems. 2. Skills (i) To analyze kinematic, inverse kinematics and dynamics modeling of Robot. 3. Attitude (i) To understand & able to solve path planning & control problems. (ii) To illustrate use of robotics. Course Outcomes: After successful completion of this course, the student will be able to 1. Identify key components of Industrial Robot Systems. (CL –II) 2. Solve basic robot forward kinematics/inverse kinematics and dynamics modelling problems (CL-IV) 3. Use various software tools for modelling and simulation. (CL ) 4.Identify and study of the different applications of robots. (CL-VI)  Course Contents Elements of Robotics: Basics of the robot, Robot configurations and their specifications, Robot architecture, Sensors, actuators, and grippers required for robots. Vision system: Image acquisition and image processing techniques. [10 hrs] Kinematics and Dynamics of Robot: Coordinate Transformation, Denavit – Hartenberg parameters, Forward kinematics, Inverse Kinematics, Jacobian Computation ,Need for dynamic analysis, Lagrange’s Equation, Lagrange- Euler formulation for single rotary joint, Lagrange- Euler formulation for 2R manipulator, Equation of motion. [13 hrs] Motion planning & Control: Steps in trajectory planning, Joint space, and Cartesian space trajectory planning, Control of a single link manipulator, Independent Joint PID Control, Robotic Operating System (ROS) [12 hrs] Applications of Robotics: Case studies such as Pick and place, Lane Follower based on RGB, Object detection, Autonomous mobile navigation and Simulation for Robot Arm, Concept and Role of Artificial Intelligence in robotics. [10 hrs]  Learning Resources Text Books: 1.S. K. Saha, Introduction to Robotics, McGraw Hill, 2nd Edition, 2014. 2.J. Craig, Introduction to Robotics: Mechanics and Control, Addison-Wesley New York, 3rd edition, 2006. Reference Books: 1.Robert J. Schilling, Fundamentals of Robotics- Analysis and Control, Prentics Hall India, 1996. 2.M. Thoma & Morari, Robot Motion and control (Recent Developments). 3.Lee, C S G, R C Gonzalez, K S Fu , Robotics , McGraw-Hill, 1987 4. Saeed B.Niku, Introduction To Robotics: Analysis, Control, Applications, 2nd Edition, John Wiley & Sons.  Assessment Scheme Class Continuous Assessment (CCA): 30 marks Mid Term Test Assignments Quiz 15 10 5 Lab Continuous Assessment (LCA): 30 marks Lab Manual Submission and Simulation understanding – 20 Marks PBL– 10 marks Term End Examination : Term end exam of 40 Marks will be based on entire syllabus. Test  Unit 1 Elements of Robotics L1 Introduction  Introduction Dancing Robot Autonomous mobile robot weeding a field (Courtesy of Ecorobotix) Stanford's Stickybot, a Industrial Robot wall-climbing robot that uses gecko-inspired directional adhesives on its feet. Photo: Stanford University  https://youtu.be/SA_1vfH5UIk ABBRobotics at Healthcare Research Hub at the Texas Medical Centre in Houston. Robots can carry out repetitive, processes in laboratories and will leave highly skilled medical and laboratory staff free to undertake more valuable roles and ultimately treat more #patients, #TMC, #Pathology, #MedicalRobot. https://youtu.be/s7gPZT-rDvY Zebro robots work together like a swarm of ants or birds or a school of fish. They can be sent to search difficult terrain and find survivors after earthquakes. https://www.youtube.com/watch?v=QLgZ31NCd0I Harvard University is creating robotic insects to monitor the environment Robot n Robotics From Czech word ‘robota’ meaning slave labour! The Robot Institute of America (1969) defines robot as “.... a re-programmable, multi-functional manipulator designed to move materials, parts, tools or specialized devices through various programmed motions for the performance of a variety of tasks”. Currently the term “robots” are used more broadly as an “intelligent agent, physical or virtual, capable of doing a task autonomously or with guidance”. Robot – An electro-mechanical machine with sensors, electronics and guided by computers. It’s machine that replaces human being for the physical work and decision making- robot and it’s study is robotics. Key concept is re-programmable and the extent of programming — Distinguishes a robot from CNC machine tools.  Laws of Robotics Asimov proposed three “Laws of Robotics” and later added the “zeroth law” Law 0: A robot may not injure humanity or through inaction, allow humanity to come to harm Law 1: A robot may not injure a human being or through inaction, allow a human being to come to harm, unless this would violate a higher order law Law 2: A robot must obey orders given to it by human beings, except where such orders would conflict with a higher order law Law 3: A robot must protect its own existence as long as such protection does not conflict with a higher order law  Introduction Initial robot usage was primarily in industrial application such as part/material handling, welding and painting and few in handling of hazardous material. Most initial robots operated in teach-playback mode, and replaced ‘repetitive’ and ‘back-breaking’ tasks. Growth and usage of robots slowed significantly in late 1980’s and early 1990’s due to “lack of intelligence” and “ability to adapt” to changing environment – Robots were essentially blind, deaf and dumb! Last 15 years or so, sophisticated sensors and programming allow robots to act much more intelligently, autonomously and react to changes in environments faster. Present-day robots Used in cluttered workspaces in homes and factories, Interact safely with humans in close proximity, Operate autonomously in hazardous environments, Used in entertainment and in improving quality of life  Automation The word ‘Automation’ is derived from greek words “Auto”(self) and “Matos” (moving). Automation therefore is the mechanism for systems that “move by itself”. Superior performance than manual systems, in terms of power, precision and speed of operation. Definition: Automation is a set of technologies that results in operation of machines and systems without significant human intervention and achieves performance superior to manual operation A Definition from Encyclopaedia Britannica – The application of machines to tasks once performed by human beings or, increasingly, to tasks that would otherwise be impossible. Automation implies the integration of machines into a self governing system. Role of automation in industry Manufacturing processes, basically, produce finished product from raw/unfinished material using energy, manpower and equipment and infrastructure. Since an industry is essentially a “systematic economic activity”, the fundamental objective of any industry is to make profit. Profit = (Price/unit – Cost/unit) x Production Volume So profit can be maximised by producing good quality products, which may sell at higher price, in larger volumes with less production cost and time.  Applications Robotic Surgery using Da Vinci Robot https://www.youtube.com/watch?v=QksAVT0YMEo Autonomous mobile robots/vehicles: https://mars.nasa.gov/mars2020/mission/overview/ https://mars.nasa.gov/resources/24768/spirit-opportunity-miss ion-to-mars-trailer/ Other miscellaneous robots: Robocup Soccer 2010, https://www.youtube.com/watch?v=4wMSiKHPKX4 and dancing Sony robots https://www.youtube.com/watch?v=9vwZ5FQEUFg, robotic fish, NASA Robonaut humanoid space robot from this website. Japanese humanoid robot capable of feeling pain (shown through facial expressions) Applications… Jobs that are dangerous for humans Decontaminating Robot Cleaning the main circulating pump housing in the nuclear power plant Applications… Repetitive jobs that are boring, stressful, or labor- intensive for humans Welding Robot Menial tasks that human don’t want to do The SCRUBMATE Robot  Applications… Machine loading/ unloading :other machines where the robot supply other machines with parts or remove processed parts from other machines Material Handling or Pick and place operations: This may include palletizing, placement of cartridges, simple assembly( placing tablets into bottle), placing parts in the oven, removing parts from the oven etc. Welding: Due to consistent movement of welding end effector, welds are accurate and uniform. Painting: Automobile Industry Inspection of parts, circuit boards, chips Assembly tasks :fitting, pushing, turning, bending, pressing etc. Manufacturing by robots may include various operations like drilling, de burring, laying glue, cutting, installition of boards into electronic devices (insertion robots) Applications… Medical Applications: To assist the doctor in joint replacement operations: cutting the head of the bone, drilling the hole in the bone’s body, reaming the hole for precise dimensions, installation of the manufactured implant joint- can be performed with better precision by a robot Assisting Disabled Individuals Hazardous Environments: mine-detecting robot, minesweeping robot Underwater, space and inaccessible locations: recovery of crashed airplanes, ships, submarines On Mars, Rovers are landed and explored Robots in Space NASA Space Station Robots in Hazardous Environments TROV in Antarctica HAZBOT operating in atmospheres containing operating under water combustible gases  Medical Robots Robotic Assistant for micro surgery  Robots in Military PREDATOR: unmanned Ariel vehicle ISTAR ((Intelligence, SPLIT STRIKE: used in war against terrorism Surveillance, Target Acquisition Deployed from a and Reconnaissance sub’s hull, Manta could dispatch tiny mine-seeking AUVs or engage in more explosive combat. GLOBAL HAWK: GOLDENEYE high altitude military surveillance  Robots at Home Sony SDR-3X Entertainment Robot Sony Aido AUTOMATION and ROBOTICS Automation as a technology that is concerned with the use of mechanical, electronic, and computer-based systems in the operation and control of production Examples of this technology include transfer lines, Mechanized assembly machines, Feedback control systems (applied to industrial processes), numerically controlled machine tools, and robots. Accordingly, robotics is a form of industrial automation. Types of Automation http://indrobocmr.blogspot.com/2018/12/industrial-robotics-for-iii-ii-mech.html  Fixed Automation It is the automation in which the sequence of processing or assembly operations to be carried out are fixed by the equipment configuration. In fixed automation, the sequence of operations (which are simple) are integrated into a piece of equipment. Therefore, it is difficult to automate changes in the design of the product. It is used where the high volume of production is required Production rate of fixed automation is high. In this automation, no new products are processed for a given sequence of assembly operations. Features: High volume of production rates. Relatively inflexible in product variety (no new products are produced). Ex:- Automobile industries … etc.  Programmable Automation It is the automation in which the equipment is designed to accommodate various product configurations in order to change the sequence of operations or assembly operations by means of a control program. Different types of programs can be loaded into the equipment to produce products with new configurations (i.e., new products). It is employed for the batch production of low and medium volumes. For each new batch of differently configured product, a new control program corresponding to the new product is loaded into the equipment. This automation is relatively economic for small batches of the product. Features: High investment in general purpose, Lower production rates than fixed automation, Flexibility & Changes in products configuration, More suitable for batch production. Ex:- Industrial robot, NC machines tools… etc. Flexible Automation https://www.youtube.com/watch?v=Br2eEpiiwvU A computer integrated manufacturing system which is an extension of programmable automation is referred to as flexible automation. It is developed to minimize the time loss between the changeover of the batch production from one product to another while reloading. The program to produce new products and changing the physical setup i.e., it produces different products with no loss of time. This automation is more flexible in interconnecting workstations with material handling and storage system. Features: High investment for a custom engineering system. Medium Production rates Flexibility to deal with product design variation, Continuous production of variable mixtures of products. Ex:- Flexible manufacturing systems (FMS) FMS Advantages: High Production rates Lead time decreases Storing capacity decreases Human errors are eliminated. Labor cost decreases. Disadvantages: The initial cost of raw material is very high Maintenance cost is high Required high skilled Labour Indirect cost for research development & programming increases. The reasons for the implementation of automated systems in the manufacturing industries are as follows, To Increase the Productivity Rate of Labour To Decrease the Cost of Labour To Minimize the Effect of Shortage of Labour To Obtain High Quality of Products A Non-automation High Cost is Avoided To Decrease the Manufacturing Lead Time To upgrade the Safety of Workers.  Need For using robotics in industries Industrial robot plays a significant role in automated manufacturing to perform different kinds of applications. Robots can be built a performance capability superior to those of human beings. In terms of strength, size, speed, accuracy...etc. Robots are better than humans to perform simple and repetitive tasks with better quality and consistency. Robots do not have the limitations and negative attributes of human works.such as fatigue, need for rest, diversion of attention....etc. Robots are used in industries to save time compared to human beings. Specifications of robotics Axis of motion Workstations Speed Acceleration Payload capacity Accuracy Repeatability etc… V1= 9.1, 9.2, 9.3 9.4,9.5 V2 = 9.119.12,9.13,9.14,9.15 The feature and capabilities of the robots are as follows, Intelligence Sensor capabilities Telepresence Mechanical design Mobility and navigation Universal gripper System integration and networking. Applications of robots: Present Applications of Robots: Material transfer applications Machine loading and unloading Processing operations like, Spot welding Continuous arc welding Spray coating Drilling, routing, machining operations Grinding, polishing debarring wire brushing Laser drilling and cutting etc. Assembly tasks, assembly cell designs, parts mating. Inspection, automation or test equipment. Future Applications of Robots: The profile of the future robot based on the research activities will include the following, Intelligence Sensor capabilities Telepresence Mechanical design Mobility and navigation (walking machines) Universal gripper Systems and integration and networking FMS (Flexible Manufacturing Systems) Hazardous and inaccessible non-manufacturing environments Underground coal mining Firefighting operations Robots in space Security guards Garbage collection and waste disposal operations Household robots Medical care and hospital duties etc. Advantages of Robotics Types of Robots: I Manipulator  Types of Robots: II Legged Robot Wheeled Robot  Types of Robots: III Autonomous Underwater Vehicle Unmanned Aerial Vehicle Robot Anatomy  The manipulator or robotic arm has many similarities to the human body. The mechanical structure of a robot is like a skeleton in the human body. The robot anatomy is, therefore, the study of the skeleton of a robot, that is, the physical construction of the manipulator structure. The mechanical structure of a manipulator consists of rigid bodies which are connected by means of articulations, is segmented into an arm that ensures mobility and reachability. The rigid bodies and their articulations resemble the links and joints of a kinematic chain. A wrist is attached at the end of the arm that confers orientation, and an end-effector that performs the required task is attached to the wrist. Most manipulators are mounted on a base fastened to the floor or on the mobile platform of an Autonomous Guided Degrees of Freedom The number of degrees of freedom that a manipulator possesses is the number of independent position variables that would have to be specified in order to locate all parts of the mechanism Degrees of Freedom Location of an object in 3D space Orientation of an object in 3D space Total degree of freedom for robot = 6 to place and orient the objects in their workspace Robot with 3 degrees of freedom Robot with 5 degrees of freedom Robot with 7 degrees of freedom Two links, two joints: A 2 DOF manipulator Robot Anatomy The base, arm, wrist, and end-effector forming the mechanical structure of a manipulator  Links The mechanical structure of a robotic manipulator is a mechanism, whose members are rigid links or bars. A rigid link that can be connected, at most, with two other links is referred to as a binary link. There are other types of links are being used which have a provision to connect with more than two links each. The connectivity of links can either series or parallel. Two rigid binary links in free space  Joints Two links are connected together by a joint. By putting a pin through holes B and C of links 1 and 2 an open kinematic chain is formed as shown below The joint formed is called a pin joint also known as a revolute or rotary joint. The name was given based on the relative motion provided by that joint which is a rotational motion. Types of Joints A. Ghosal  R&A Lecture 4  1. Prismatic Joint (Linear Motion): Prismatic joints are also called sliders, constituting purely linear motion along the joint axis. The joint may be of two types depending on the construction as shown in the figure a linear joint and an orthogonal joint. This type of motion is common in hydraulic or pneumatic cylinders, there is no rotation. The degree of freedom is one (i.e., translation). 2.Revolute Joint (Revolution Motion): Revolute joints constitute purely revolution motion about the joint axis. Revolute joints are most commonly found in industrial robots. There is no translation motion. Most revolute joints cannot rotate through a full 360 degrees but are mechanically constrained. The degree of freedom is one. (i.e. Revolution) 3. Rotational Joint (Rotational Motion): Rotational joints are often called Pivot joints or Pin joints due to their mechanical construction. In this Joint, the two adjacent links are connected by means of a pin. This joint allows pure rotation motion between the links about the pin joint axis. The degree of freedom is one. (i.e. Rotation 4.Twisting Joint: It is another variant of the rotary joint, where the two adjacent links remain aligned along a straight line but one turns (twists) about other around the link axis. The degree of freedom is one. (i.e. Twisting) 5. Screw Joint (Linear and Rotational Motion): Screw joints are a combination of the first two types of joints. They constitute a simultaneous rotation and linear motion along a joint axis. Screw joints are more often used in tools for a robot end effector rather than a joint of motion for a robot. This joint follows the thread of the axis to move along the axis. The degree of freedom is two. (i.e. Translation and Rotation) 6. Cylindrical Joint: Cylindrical joints are a combination of prismatic and revolute joints. The motion in the joint may be translation, revolution or combined. The degree of freedom is two. (i.e. Translation and Rotation) 7.Spherical Joint: Spherical joints are most utilized joints and just slide causing a revolving movement. The degree of freedom is three. (Three rotations) 8. Planar Joint: In this type of joint one surface freely moves over another surface. The relative motion between them consists of sliding and rotation about the plane normal. The degree of freedom is three as the figure. (i.e., one rotary and two sliding motions) Classification of Robots The robots may be classified in the following two broad categories, Classification by coordinate system and Classification by control system  Classification by Co-ordinate system Industrial robots are available in a wide variety of sizes, shapes, and physical configurations. These configurations majorly depend on the robot arm or End-effectors reachability in the space. The part of the space in which the robot can execute its work is called as a workspace, work volume or work envelope. The vast majority of today’s commercially available robots possess one of the basic configurations: Polar configuration (Sperical) Cylindrical configuration Cartesian coordinate configurable Jointed-arm configuration (Articulated/ Revolute Configuration) Polar configuration: (RRP) (Spherical) It uses a telescoping arm(link) (prismatic joint) that can be raised or lowered about a horizontal pivot. The pivot is mounted on a mounting base. The various joints provide the robot with the capability to move its arm within a spherical space, and hence the name “spherical coordinate robot" is sometimes applied to this type. A number of commercial robots possess the polar configuration. RPR Polar configuration: (RRP) (Spherical) Advantages ▪ Covers a large volume ▪ Can bend down to pick objects up off the floor ▪ Higher reach ability Disadvantages ▪ Complex kinematic model ▪ Difficult to visualize Applications ▪ Palletizing ▪ Handling of heavy loads e.g. casting, forging Cylindrical Configuration: (RPP) Two prismatic joints, one revolute joints The cylindrical configuration, as shown in the figure, uses a vertical column and a slide that can be moved up or down along the column. The robot arm is attached to the slide so that it can be moved radially with respect to the column. By routing the column, the robot is capable of achieving a workspace that approximates a cylinder. Cylindrical Configuration Advantages ▪ Simple kinematic model ▪ Rigid structure & high lift-carrying capacity ▪ Easily visualize ▪ Very powerful when hydraulic drives used Disadvantages ▪ Restricted work space ▪ Lower repeatability and accuracy ▪ Require more sophisticated control Applications ▪ Palletizing, Loading and unloading ▪ Material transfer, foundry and forging  Cartesian Configuration: 3 prismatic joints Cartesian Configuration with box workspace The Cartesian coordinate robot, illustrated in Figure, uses three perpendicular slides, giving only linear motions along three principal axes(x, y, z) directions. Other names are sometimes applied to this configuration, including xyz robot and rectilinear robot. By moving the three slides relative to one another, the robot is capable of operating within a rectangular work envelope.  Cartesian are also called gantry or rectilinear robots. They have the advantage of large work areas and better positioning accuracy. Their three linear joints are operated in line with a Cartesian coordinate system by linear guide rails. Because they work with an X, Y, Z coordinate system, their motion is easier to program. They are also less constrained by floor space. Typical applications include arc welding, assembly operations, pick-and-place applications, sealant application work, and machine tools operations. Cartesian Configuration: Advantages ▪ Linear motion in three dimension ▪ Simple kinematic model ▪ Rigid structure ▪ Higher repeatability and accuracy ▪ High lift-carrying capacity as it doesn’t vary at different locations in work volume ▪ Easily visualize ▪ Can increase work volume easily ▪ Inexpensive pneumatic drive can be used for P&P operation Cartesian Configuration: Disadvantages ▪ requires a large volume to operate in ▪ work space is smaller than robot volume ▪ unable to reach areas under objects ▪ must be covered from dust Applications ▪ Assembly ▪ Palletizing and loading-unloading machine tools, ▪ Handling ▪ Welding Jointed-arm Configuration: (All three R joints) The jointed-arm robot is pictured in Figure. Its configuration is similar to that of the human arm. It is sometimes called as an Articulated arm or anthropomorphic due to the structure. It consists of two straight components. Corresponding to the human forearm and upper arm, mounted on a vertical pedestal. These components are connected by two rotary joints corresponding to the shoulder and elbow. These two links are mounted on a verticle rotating table corresponding to the human waist. Jointed-arm Configuration Advantages ▪ Maximum flexibility ▪ Cover large space relative to work volume objects up off the floor ▪ Suits electric motors ▪ Higher reach ability Disadvantages ▪ Complex kinematic model ▪ Difficult to visualize ▪ Structure not rigid at full reach Applications ▪ Spot welding, Arc welding SCARA Configuration (Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm.) Articulated Configuration + Cylindrical Configuration Most common in assembly robot Arm consists of two horizontal revolute joints at the waist and elbow and a final prismatic joint Can reach at any point within horizontal planar defined by two concentric circles Kinematic designation is RRP Work volume is cylindrical in nature Most assembly operations involve building up assembly by placing parts on top of a partially complete assembly SCARA Configuration.. Advantages Floor area is small compare to work area Compliance Disadvantages Rectilinear motion requires complex control of the revolute joints Applications Assembly operations Inspection and measurements Transfer or components https://www.youtube.com/watch?v=-m1oKuFkSTE  Classification by control system In order to operate, a robot must have a means of controlling its drive system to properly regulate its motions. With respect to robotics, the motion control system used to control the movement of the end-effector or tool. 1. Limited sequence robots (Non-servo) 2. Playback robots with point to point (servo) 3. Playback robots with continuous path control, 4. Intelligent Robots. Limited sequence Robots (Non-servo): Limited sequence robots do not give servo controlled to inclined relative positions of the joints, instead, they are controlled by setting limit switches & are mechanical stops. There is generally no feedback associated with a limited sequence robot to indicate that the desired position, has been achieved. Generally, this type of robots involves simple motion as pick & place operations. Point to point motion (Servo): These type robots are capable of controlling velocity acceleration & path of motion, from the beginning to the end of the path. It uses complex control programs, PLC’s (programmable logic controller’s) computers to control the motion. The point to point control motion robot is capable of performing a motion cycle that consists of a series of desired point location. The robot is tough & recorded, unit. Ex: Soldering, Spot Welding, Drilling etc. Continuous path motion: In this robots are capable of performing motion cycle in which the path followed by the robot is controlled. The robot moves through a series of closely spaced points which describes the desired path. Ex:- Spray painting, arc welding & complicate assembly operations. Intelligent robots: This type of robots have not only programmable motion cycle but can also interact with its environment. It can make logical decisions based on sensor data received from the operation. These robots are usually programmed using an English like symbolic language not like a computer programing language. Wrist Configuration :RPY Types of End- Effectors: End- Effectors are categorized into two types, Grippers Tools 1. Grippers: Grippers would be utilized to grasp an object, usually the work part and hold it during the robot work cycle. The types of material used for grippers depends on the orientation of part & friction between parts & grippers. The applications include material handling, machine loading, unloading, palletizing and other similar operations. The operations performed by grippers are To move the fingers with commanded speeds. To gripper handled part with not more than specified force. To open, move & also the fingers at specified positions. To measure the dimension of a part. Grippers are further classified as, Mechanical grippers Magnetized grippers Suctions or vacuum cups Hooks Scopes or ladles Adhesive grippers  Mechanical grippers: Mechanical gripper in an end effector, that uses mechanical fingers actuated by a mechanism to grasp an object. The fingers are either attached to the mechanism. The function of the gripper mechanism is to translate some form of power input into the grasping action. The power input is supplied from the robot and can be pneumatic, hydraulic, and electrical. The mechanism must be able to open and close the fingers Magnetized grippers: Magnetic grippers are be divided into 2 types: i. Electromagnetic ii. Permanent magnetic. Electromagnetic: Electromagnetic grippers include a controller unit and a DC power for handling the materials. This type of grippers is easy to control and very effective in releasing the part at the end of the operation than the permanent magnets. If the work part gripped is to be released, the polarity level is minimized by the controller unit before the electromagnet is turned off. Permanent magnetic: The permanent magnets do not require any sort of external power as like the electromagnets for handling the materials. After this gripper grasps a workpart, an additional device called as stripper push – off pin will be required to separate the workpart from the magnet. This device is incorporated at the sides of the gripper. This gripper only requires one surface to grasp the materials. The grasping of materials is done very quickly. It does not require separate designs for handling different size of materials. It is capable of grasping materials with holes, which is unfeasible in the vacuum grippers. Suctions or vacuum cups: This type of gripper is typically made of elastic material such as rubber, soft plastic. The shape is round type. The lift capacity of suction cup depends upon the effective area of the cup. The negative air pressure between the cup & the object. F = P * A Where, F = force, P = negative pressure, A = total effective area of the suction cup used to create the vacuum. Hooks gripper: Hooks can be used as end effectors to handle containers of parts to load and unload parts, hanging from, power head conveyors. The items to be handled by a hook must have some soft handle to enable the hook to hold it. Scoopes or ladles: Scoopes or ladles can be used to handle certain materials in liquid or powder form, chemically in liquid or powder form, good materials etc. that can be handled by a robot using method of handling. Specifications of Robots 1. Positioning Accuracy: The robot's program instruct the robot to move to a specified point, it does not actually perform as per specified. The accuracy measures such variance. That is, the distance between the specified position that a robot is trying to achieve (programming point), and the actual X, Y and Z resultant position of the robot end effector. 2. Repeatability : The ability of a robot returns repeatedly to a given position. It is the ability of a robotic system or mechanism to repeat the same motion or achieve the same position. Repeatability is is a measure of the error or variability when repeatedly reaching for a single position.  Degree of Freedom (DOF): Each joint or axis on the robot introduces a degree of freedom. Each DOF can be a slider, rotary, or other type of actuator. The number of DOF that a manipulator possesses thus is the number of independent ways in which a robot arm can move. Industrial robots typically have 5 or 6 degrees of freedom. Resolution: The smallest increment of motion can be detected or controlled by the robotic control system. It is a function of encoder pulses per revolution and drive (e.g. reduction gear) ratio. And it is dependent on the distance between the tool center point and the joint axis.  Axis Movement Specifications: Axes - The individual segments of each robot manipulator are connected with mechanical joints - each serves as an axis of movement. The most common industrial robots have six axes of movement. The number and placement of axes determines the flexibility of each model. Robot Motion Range - Much like the joints between bones, robot axes have limits to each movement. Every axis has a specific scope of motion. On a typical specifications sheet, the degree of movement shows up as positive or negative degree of movement from the center base position of each axis. Robot Motion Speed - Each axis moves at a different speed. They are listed as degrees traveled per second. Focus on this criterion when you need to match certain speed specifications for your application. Robot Specifications for Weight: Payload - The weight capacity of each robot manipulator is its payload. This is a critical specification and includes the tooling weight as well. Robot Mass - Every robot has a specific weight or mass. This number only indicates how much the robot manipulator weighs. It does not include the weight of the robot's controller. Specifications and Work Envelope: Vertical Reach - How high can the robot go? A robot's vertical reach specification refers to the height of the robot when it extends upwards from the base. Horizontal Reach - How far can a robot reach? The horizontal reach measures the distance of the fully extended arm - from the base to the wrist. Structure - Robots are engineered with different structures. The most common by far is the vertical articulated type, sometimes called a vertical jointed-arm robot. Other structure types include SCARA, Cartesian, and parallel kinematic robots. Power Specifications: 1. AC /DC 2. Rated Current rating 3. Power Consumption 4. Power Source 5. Type of power supply: one/three phase Other Specifications: Memory , processor type  Sensor ? Transducer?  Selection Criterion for Transducer Purpose of the measurement: whether measurement or control or both Type of physical quantity to be measured Nature of measurement: static\dynamic Type of principal of operation Requirement of power supply\ excitation Range of measurand Order of accuracy and precision in measurement Static and dynamic response of the transducer Installation consideration of the transducer Loading Effect due to measuring circuit Ambient environmental conditions around transducer Availability Cost Spares required Life span Sensors characteristics/specifications   Response time: It is the time that a sensor’s output requires to reach a certain % of the total change. e.g. 95%, 63.2% - Time constant, 10% to 90% -rise time, 0% to 98% - settling time Frequency Response: The frequency response is the range in which the system’s ability to respond to the input remains relatively high. The larger the range of the frequency response, the better the ability of the system to respond to varying input. Repeatability Reproducibility Repeatability and reproducibility are ways of measuring precision. Repeatability measures the variation in measurements taken by a single instrument or person under the same conditions, while reproducibility measures whether an entire study or experiment can be reproduced in its entirety.  Sensors in Robotics Need: 1. Sensors provide the information about the status of links and joints of the manipulator as well as its work environment 2. Sensors allow robots to understand and measure the geometric and physical properties of objects in their surrounding environment, such as - position, orientation, velocity, acceleration - distance, size - force, moment -temperature, luminance, weight, etc. Internal Sensors Robot sensors can be classified into two groups: Internal sensors and external sensors Internal sensors: Obtain the information about the robot itself. – position sensor, velocity sensor, acceleration sensors, motor torque sensor, etc. External Sensors External sensors: Obtain the information in the surrounding environment. – Cameras for viewing the environment – Range sensors: IR sensor, laser range finder, ultrasonic sensor, etc. – Contact and proximity sensors: Photodiode, IR detector, RFID, touch etc. – Force sensors: measuring the interaction forces with the environment Range Sensor To measure the distance from the sensor to a nearby object Working principles – Triangulation: Use the triangle formed by the traveling path of the signal to calculate the distance – Structured Lighting approach – Time-of-flight: Use the time of flight of the signals to measure the distance Typical range sensors – Infra-red range sensor (triangulation) – Ultrasonic sensors (time-of-flight) – Laser range sensor (triangulation) Triangulation Approach Point Measurement @Fu, Gonzalez, lee Structured Lighting approach Light generated through narrow slit or cylindrical lens Sheet of light Light stripe viewed through TV camera Inflection-change in surface Break-gap between surfaces  IR Range Sensors Principle of operation: triangulation – IR emitter + focusing lens + position-sensitive detector Modulated IR light Location of the spot on the detector corresponds to the distance to the target surface. https://en.wikipedia.org/wiki/Position_sensitive_device  Limitations of Infrared Sensors Poor reflection of IR signals: Certain dark objects cannot reflect the IR signals well. – The absence of reflected IR signals does not mean that no object is present! Background noises: The sensor fails to work if there are similar IR signals sources in the environment. IR sensors measure objects in short range. – typical maximum range is 50 to 100 cm. Echolocation echolocation process—sound waves transmitted, bounced back and received, with the time difference used to calculate the distance of objects Bats and Dolphins https://www.teachengineering.org/lessons/view/umo_sensorswork_lesson06 The time difference between sending and receiving is used to estimate distance.  Ultrasonic sensors emit short, high-frequency sound pulses at regular intervals.... If they strike an object, then they are reflected back as echo signals to the sensor, which itself computes the distance to the target based on the time-span between emitting the signal and receiving the echo.  Ultrasonic sensors are based on the measurement of the properties of acoustic waves with frequencies above the human audible range,” often at roughly 40 kHz 1). They typically operate by generating a high-frequency pulse of sound, and then receiving and evaluating the properties of the echo pulse. Bats can hear upto 200KHz Medical Ultrasound scan: 10MHz Ultrasound is often used in range finding – commonly referred to as SONAR (sound navigation and ranging)  Time of Flight Range Sensors Time of Flight The measured pulses typically come form ultrasonic, RF and optical energy sources. TX/RX Object –D = v * t – D = round-trip distance – v = speed of light/wave propagation – t = elapsed time Sound = 0.3 meters/msec (Ultrasound 340m/sec) RF/light = 0.3 meters / ns (Very difficult to measure short distances 1-100 meters) (IR/LASER 300,000 km/sec)  Ultrasonic Sensors Basic principle of operation: – Emit a quick burst of ultrasound (50kHz), (human hearing 20Hz to 20kHz) – Measure the elapsed time until the receiver indicates that an echo is detected. – Determine how far away the nearest object is from the sensor ▪D = v * t D = round-trip distance v = speed of propagation (340 m/s) t = elapsed time Bat, dolphin, … Ranging is accurate with 30 degree uncertainty. The object can be located anywhere in the arc. Typical ranges are of the order of several centimeters to 30 meters. Another problem is the propagation time. The ultrasonic signal will take 200 msec to travel 60 meters. ( 30 meters roundtrip @ 340 m/s ) Limitations The speed of sound varies with medium temperature and pressure. Cross-talk problem: If a robot has more than one ultrasonic sensors who's measurement ranges intersect, a sensor may receive signals emitted by others Perceptual aliasing Poor surface reflection: Surface materials absorb ultrasonic waves. Surface orientation affect the reflection of ultrasonic signals. LASER range finder The most common form of laser rangefinder operates on the time of flight principle by sending a laser pulse in a narrow beam towards the object and measuring the time taken by the pulse to be reflected off the target and returned to the sender. Due to the high speed of light, this technique is not appropriate for high precision sub-millimeter measurements, where triangulation method is used. Touch and Proximity Sensors To detect whether any object is close to a robot or touches a robot. Proximity sensor does not give distance, but only tells the existence of an object. Non contact type sensor Typical Proximity sensors – IR proximity sensors – Inductive proximity sensor – Capacitive proximity sensor – Magnetic proximity sensor – Photoelectric (optical) proximity sensor – Ultrasonic proximity sensor  Infrared (IR) Detector IR detector: To detect existence of an object. (a) LED is on when there is no obstacle (b) LED is off when there is an obstacle  Inductive proximity sensor An inductive sensor is an electronic proximity sensor, which detects metallic objects without touching them. Common applications of inductive sensors include metal detectors, traffic lights, car washes, and a host of automated industrial processes. Inductive sensors are used for controlling, regulating, automating, positioning and monitoring of work processes. Applications include machine tools, plastics machinery, assembly lines, and anywhere processes need to be automated! 1. Detect ferrous targets, ideally mild steel thicker than one millimeter. 2. They consist of four major components: a ferrite core with coils, an oscillator, a Schmitt trigger, and an output amplifier. 3. The oscillator creates a symmetrical, oscillating magnetic field that radiates from the ferrite core and coil array at the sensing face. 4.When a ferrous target enters this magnetic field, small independent electrical currents called eddy currents are induced on the metal’s surface. 5.This changes the reluctance (natural frequency) of the magnetic circuit, which in turn reduces the oscillation amplitude. As more metal enters the sensing field the oscillation amplitude shrinks, and eventually collapses. (This is the “Eddy Current Killed Oscillator” or ECKO principle.) 6. The Schmitt trigger responds to these amplitude changes, and adjusts sensor output. When the target finally moves from the sensor’s range, the circuit begins to oscillate again, and the Schmitt trigger returns the sensor to its previous output. 7. If the sensor has a normally open configuration, its output is an on signal when the target enters the sensing zone. With normally closed, its output is an off signal with the target present. Capacitive Proximity sensors Capacitive proximity sensors can detect both metallic and non-metallic targets in powder, granulate, liquid, and solid form. They are also used for tank liquid level detection, and hopper powder level recognition. One of the conductive plates, is inside the sensor itself while the other one is the object to be sensed. The internal plate is connected to an oscillator circuit that generates an electric field. The air gap between the internal plate and the external object serves as the insulator or dielectric material. When an object is present, that changes the capacitance value and registers as the presences of the object. Unlike an inductive sensor that produces an electromagnetic field a capacitive sensor produces an electrostatic field. Affected by dirt, humidity, temperature Applications of capacitive proximity sensor Specifications Photoelectric (Optical) Proximity Can detect targets less than 1 mm in diameter, or from 60 m away All photoelectric sensors consist of a few of basic components: ✔ An emitter light source (Light Emitting Diode, Infra-red LED, laser diode), ✔ A photodiode or phototransistor receiver to detect emitted light, and ✔ Supporting electronics designed to amplify the receiver signal. WHY OPTICAL SENSORS? Electromagnetic immunity Electrical isolation Compact and light Both point and distributed configuration Wide dynamic range Amenable to multiplexing 138  Photoelectric proximity Sensors Configurations: 1. Through-beam 2. Retro-reflective 3. Diffuse WHY OPTICAL SENSORS? Electromagnetic immunity Electrical isolation Compact and light Both point and distributed configuration Wide dynamic range Amenable to multiplexing 141 Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Target Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver Optical sensors (Through-beam) Transmitter Receiver  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective Target T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic)  Optical sensors (Retro-reflective) Type : Retro reflective T Transmitter R /Receiver Reflector (prismatic) Sensing distance : 1/2 to 1/3 of through-beam type Not suitable for reflective or transparent targets  Optical sensors (Diffuse) Type : Diffuse Target T Transmitter R /Receiver  Optical sensors (Diffuse) Type : Diffuse T Transmitter R /Receiver  Optical sensors (Diffuse) Type : Diffuse T Transmitter R /Receiver  Optical sensors (Diffuse) Type : Diffuse T Transmitter R /Receiver  Optical sensors (Diffuse) Type : Diffuse T Transmitter R /Receiver  Optical sensors (Diffuse) Type : Diffuse T Transmitter R /Receiver  Optical sensors (Diffuse) Type : Diffuse T Transmitter R /Receiver Sensing distance: much less than reflex type, actual distance depends on colour and reflective nature of the surface Larger targets result in longer sensing distances Not suitable for dirty environments Magnetic proximity sensor Magnetic proximity sensors are used for non-contact position detection beyond the normal limits of inductive sensors. In conjunction with a separate “damping” magnet, magnetic sensors offer very long sensing ranges from a small package size and can detect magnets through walls of non-ferrous metal, stainless steel, aluminum, plastic or wood. Depending on the orientation of the magnetic field the sensor can be damped from the front or from the side. Since magnetic fields penetrate all non-magnetisable materials, these sensors can detect magnets through walls made of non-ferrous metal, stainless steel, aluminum, plastic or wood. Features of magnetic proximity sensor Detection through plastic, wood, and any non-magnetisable metals Small housings with very long sensing ranges up to 70 mm Cylinder and rectangular designs satisfy space-dependent applications High mechanical stability in case of shock or vibration Flush or non-flush installation in non-magnetisable metals No electrical noise effect Operating Principle Magnetic sensors are actuated by the presence of a permanent magnet. Their operating principle is based on the use of reed contacts, which consist of two low reluctance ferro-magnetic reeds enclosed in glass bulbs containing inert gas (Hermetically sealed). The reciprocal attraction of both reeds in the presence of a magnetic field, due to magnetic induction, establishes an electrical contact. Non-contact Proximity sensors Ultrasonic (Sonar) sensors Ultrasonic sensor utilize the reflection of high frequency (20KHz) sound waves to detect parts or distances to the parts. In general, ultrasonic sensors are the best choice for transparent targets. They can detect a sheet of transparent plastic film as easily as a wooden pallet. Different Colors has no effect The most common configurations are the same as in photoelectric sensing: through beam, retro-reflective, and diffuse versions. 175 Thank you