Robotics chp 1 to chp 5
What type of fi re extinguisher should be used to put out a fi re that involves fl ammable liquids?
A class B fi re extinguisher that contains carbon dioxide should be use to put our fi res of fl ammable liquids
Servo robots are considered closed-loop systems. Sketch a diagram of a closed-loop system and explain how it works.
Evaluate student sketches individually. In a closed-loop system, the feedback signal sent to the servo amplifier affects the output of the system. A servo amplifier translates signals from the controller into motor voltage and current signals. Servo amplifiers are used in motion control systems where precise control of position or velocity is necessary. Errors in positioning and movement are detected and corrected.
What are four popular storage devices used for organizing tools?
Popular storage devices for tools include tool belts, mobile storage boxes, tool chests, and rolling storage cabinets.
Servo robots can be classified as intelligent or highly intelligent. Explain the difference between these two classifications.
The primary difference between an intelligent and highly intelligent robot is the level at which sensors provide information about the surrounding environment.
What factors influence the dynamic performance of a robot?
The two most important factors that influence dynamic performance (operational speed) are the desired accuracy and the payload. The robot configuration and location of the tool in the work envelope also influence operational speed.
What are some negative aspects and some positive aspects of having robots as part of the workforce?
A negative aspect of having robots in the workplace is that robots perform some jobs that were done by people in the past. Workers and members of labor unions often see robots as a threat, thinking that robots may displace human workers. Some positive aspects of having robots in the workplace include: • Robots are more productive at some tasks than humans. • Robots can perform work less expensively for some jobs. • Robots perform work that relieves men and women from repetitive operations that are monotonous. • Robots do jobs that are unpleasant or dangerous for people
What is a common definition of the term robot?
A robot is commonly defi ned as a machine or device that automatically performs tasks or activities that are typically completed by a person using skill and intelligence.
What is the purpose of a safety fence, and what are some materials that can be used to construct a safety fence
A safety fence prevents unauthorized entry and provides containment of flying objects. A safety fence is typically 6 feet high and constructed of wire mesh, safety glass, or rigid plastic sheets.
Why should a three-wire conductor be used with power tools and electrical equipment?
A three-prong plug connects to the equipment or safety ground of the electrical outlet to assure safe operation. Equipment grounds reduce the possibility of shock due to electrical shorts or leakage.
What are three topics related to robots found in the OSHA Technical Manual?
Three topics related to robots found in the OSHA Technical Manual include robot classifications, typical hazards, and safeguarding personnel.
What is the purpose of a fi rst aid kit, and what are some examples of items that a fi rst aid kit could contain?
A first aid kit consists of supplies and equipment used to treat a person in the event of an accident or injury. A kit could contain standard supplies, such as bandages, latex gloves, antiseptic ointment, and eye drops. A kit may be created or a standard kit may be supplemented to contain items needed to treat injuries likely to occur in a particular type of work setting.
How does a light curtain function as a safety barrier?
A light curtain consists of an array of photoelectric sensing devices. If a worker enters the work envelope, the light beam between two sensors is broken. The sensors send a signal to cut the power to the robot. An infrared light curtain is programmable, which allows certain areas to be excluded from the sensing devices. This permits access to equipment that is not within the reach of the end effector of the robot.
. Briefly explain the difference between accuracy and repeatability
Accuracy expresses how precisely the end effector of the robot is programmed to reach a predetermined point. The value associated with accuracy is expressed as half of the spatial resolution. Repeatability expresses the variation in movements that occurs when an action is performed several times, such as when the end effector of a robot moves to a designated position each time it performs a task.
What is an automaton? What is one example of an early automaton?
An automaton is an object made by a person that moves automatically. The first useful automatons were clockwork devices introduced during the Middle Ages to keep track of time automatically. As these clocks became more complex, systems of gears and pulleys enabled the workings and figures attached to the clocks to move in lifelike ways.
What is an electrical shock? How can work surfaces and fl oors in a work area be treated to help avoid electrical shocks?
An electrical shock is an injury that occurs when a person comes into contact with electric current. Work surfaces in a laboratory should be covered with a material that does not conduct electrical current to avoid potential problems. The fl oor of a laboratory should also be made of or covered with nonconducting materials. Concrete fl oors should be covered with rubber tile or vinyl.
What is an interlock
An interlock is a safety device that is designed to prevent unauthorized access to hazardous areas by requiring a key for entry
What is the difference between command resolution and spatial resolution?
Command resolution is the closest distance between movements of a robot. It is calculated by dividing the travel distance of each joint by the number of control increments. Spatial resolution describes the accuracy of movement of the robot tool tip. Spatial resolution takes into account command resolution and mechanical inaccuracy
Some robots are considered anthropomorphic. What does this term mean?
Anthropomorphic is a term that describes an object that is humanlike in form or has human attributes.
What is the defi nition of the term robot that was published by the Robot Institute of America? Discuss the key factors in that defi nition.
As defi ned by the Robot Institute of America, a robot is a reprogrammable, multifunctional manipulator designed to move material, parts, tools, or specialized devices through various programmed motions for the performance of a variety of tasks. Key factors of this defi nition include: • The robot is a machine. The robot is reprogrammable, meaning that it can be given new instructions that allow it to meet changed requirements and perform new tasks. • The robot has a multifunction manipulator, which means it may be used in different ways, even within the same program. • The robot is flexible and can perform a variety of operations to meet special needs.
What are four examples of personal protective equipment (PPE) that may be used by workers?
Boots with steel toes, safety glasses or goggles, earplugs, gloves, respirators, and hard hats are examples of PPE.
What is the purpose of a circuit breaker or fuse in an electrical system?
Circuit breakers and fuses are important safety devices. Both devices stop fl ow of electric current when a short circuit or power surge occurs, thus providing overload protection.
What is flexible automation and what are some advantages of using flexible automation?
Flexible automation refers to machinery that is capable of performing a variety of tasks. Robots belong in this category. As new products or new models are needed, flexible machines can be reprogrammed to make the parts required. This flexibility can save money because equipment does not have to be discarded or rebuilt. In addition, it takes much less time to reprogram an existing machine than to build and install a new one.
How can you avoid accidents or injuries that are the result of taking shortcuts or working with too much haste?
Following correct work procedures will help you avoid accidents or injuries that may result from taking shortcuts. Do not operate equipment or systems unless you have been fully trained in their use.
What are some characteristics of high-level programming languages used for robots?
Even though robot programming languages have been developed by different groups, many are similar to others. The main difference among the languages is in the choice of key words and commands. Each language also has its own syntax, or structure. Instructions are given in the form of subroutines. Each language defines the number of characters allowed for a program name and use of special characters. Comments may also be included within the program code.
What are four companies that were involved in early robot development for commercial use?
Four manufacturers that were involved in early robot development for commercial use were Prab Robots Inc., DeVilbiss, Asea, and Cincinnati Milacron.
What are fi ve guidelines that product engineers should consider when a robot will be used for assembling a product?
Guidelines that product engineers should consider when a robot will be used for assembling a product are listed below. Students should list fi ve of the guidelines. • Minimize the number of parts to reduce complexity. • Reduce the directions of approach required to assemble a product. This allows a less sophisticated robot to be used. • Minimize the number of obstructions in the environment so that the robot can work in a straight line. • Whenever possible, use subassemblies with components that stack on top of each other or that can be assembled in sequence using downward motion. • Add chamfers, guide pins, ridges, and other physical characteristics that allow the robot to lock the part into its proper location. The cost of these guides is far less than the cost of robot vision systems. • Simplify fastening by using tabs, snaps, or other methods that allow parts to be joined in one motion. • Eliminate screws, springs, and adjustments. • Avoid parts that compress or deform easily, such as wires, foils, or foams, which robots do not handle well. • Give parts common features. For example, all parts might have the same size hole or post in the center. This allows the same end effector to pick up any of the parts. • Make parts as close to symmetrical as possible to ensure correct assembly no matter how the robot picks them up. If a part must be asymmetrical, use the asymmetrical features to assist in orientation
What is hard automation and in what situation is the use of hard automation justified?
Hard automation refers to machinery that has been specifically designed and built to perform particular tasks within an assembly line. To justify the use of a hard automation system, the product built must be produced at a very high volume and have the potential of being in use for a long period of time.
7. What method is used to convert high-level programming languages to machine code that a computer can understand?
High-level languages are translated into machine code that computers can understand by means of a program called a compiler.
Companies will often design parts for robotic assembly. Are there any advantages to this practice, even if robots are not actually used to assemble the parts?
Many companies have discovered that when they design for manufacturability, the process becomes so simplifi ed that it is faster and more productive to use human workers or dedicated machines than to incorporate robots
Which robot application has the greatest potential for growth in the future?
Many robotics experts agree that in the decades ahead service will be the fastest-growing robot application.
What type of robots are considered open-loop systems? Explain what open-loop means
Non-servo robots are open-loop systems. In an open-loop system, no feedback mechanism is used to compare programmed positions to actual positions.
What are the two types of control systems used to classify robots? What is the main difference between the two types of control systems?
Robots may use one of two control systems: non-servo and servo. Non-servo robots use an openloop system in which no feedback mechanism is used to compare programmed positions to actual positions. Servo robots use a closed-loop system that allows feedback to affect the output of the robot.
What are some factors to consider when designing a work station that allows the robot and operator to work safely?
Several factors can be considered to allow the robot and operator to work safely. Omit places where space may be too limited by being aware of fixed objects within the work area, such as vertical poles. Keep the end effector in mind when designing the space. The relationship of the end effector to work fixtures and other equipment must be taken into account. Outline the full range of motion for the end effector on the floor using paint or colored tape. This provides a constant, highly visible perimeter of the work area for the robot. The work station should also include barriers that cannot be passed through or over. The design should place control panels outside the work envelope and provide interlocks (safety devices that are designed to prevent unauthorized access to hazardous areas).
What are some advantages of task-level programming?
Task-level programming is a highly efficient method that replaces hundreds, even thousands, of lines of programming code with a small number of statements selected from menus. The need for programming knowledge is reduced. The operator can focus attention on the task instead of on writing programming code. Programming software has become so user-friendly that even inexperienced programmers can program a robot
What is one example of a robot configuration that offers fairly constant spatial resolution throughout the work envelope
The Cartesian configuration offers fairly constant spatial resolution
What is the technical name for the device that acts as a "hand" for a robot?
The device that acts as a "hand" for a robot is called the end effector
In what year was the fi rst industrial robot patented?
The first industrial robot was patented in 1954
In terms of degrees of freedom, explain why the human hand is able to accomplish movements that are more fluid and complex than those produced by a robot.
The movements of the human hand are controlled by 35 muscles. Fifteen of these muscles are located in the forearm. The arrangement of muscles in the hand provides great strength to the fingers and thumb for grasping objects. Each finger can act alone or together with the thumb. This enables the hand to do many intricate and delicate tasks. In addition, the human hand has 27 bones. This bone, joint, and muscle arrangement gives the hand its dexterity.
List and explain the six degrees of freedom used for robots
The six degrees of freedom used for robots are: • The rotational traverse is movement on a vertical axis. This is the side-to-side movement of the robot arm on the base. • The radial traverse is the extension and retraction of the arm, creating in-and-out motion relative to the base. • The vertical traverse provides up-and-down motion of the arm. • The pitch, or bend, is the up-and-down movement of the wrist. • The yaw is the side-to-side movement of the wrist. • The roll, or swivel, involves wrist rotation.
The evolution of programming for robots consists of three periods. List these periods and discuss the developments in each period.
The three periods are: • First generation: Late 1950s through the mid-1970s. First-generation robots performed purely repetitive tasks and did not respond to changing conditions. These robots often had only two or three degrees of freedom. These robots used pneumatic or hydraulic actuators for moving objects. Programming involved adjusting mechanical stops and limit switches. Pneumatic or electric relay logic circuits were also commonly used. Robots that used computer-controlled manipulators were introduced. Microprocessors provided increased processing power at reasonable cost. • Second generation: Mid-1970s through the mid-1980s. Manufacturers introduced robots that could be controlled by means of programming languages. Robots were equipped with internal sensors and closed-loop control systems. Sensors gave them a limited amount of feedback about their environment and condition. • Third generation: Mid-1980s to present. Third-generation robots evolved through the use of artifi cial intelligence. These robots are capable of sensing their environment and can make intelligent decisions about performing tasks more effi ciently
What determines the shape of the work envelope for a robot?
The type of coordinate system, the arrangement of joints, and the length of the manipulator segments determine the shape of the work envelope. To identify the maximum work area, a point on the robot wrist is used rather than the tip of the gripper or the end of the tool bit. Therefore, the work envelope is slightly larger when the tip of the tool is considered.
What are two types of work for which robots are not suited?
There are two types of tasks for which robots are not suited. One such task is extended, high-speed production of many identical items. Robots also are not suited for short, complex tasks that require a high degree of hand-eye coordination.
. Describe three devices that are used to provide overload protection for the end effectors on industrial robots.
Three overload protection devices used with industrial robots are: • Mechanical fuses are pins or tubes that break or buckle under extreme stress. Mechanical fuses must be replaced after they perform their function, but they are not as expensive as other overload protective devices. • Detents are two or more elements held in position by spring-loaded mechanisms. They move from their original position when placed under excessive stress. When detents move from their original position, power is removed from the machine, providing overload protection. • Preloaded springs may also be used to prevent overload conditions. Excess stress causes the spring to release, and the end effector breaks away from the work area. These devices reset automatically when the overload is removed.
What are the three types of actuator drives used to classify robots? What are three types of motors commonly used for electric actuator drives?
Three types of actuator drives used to classify robots include electrical, pneumatic, and hydraulic drive systems. Three types of motors are commonly used for electric actuator drives: ac servo motors, dc servo motors, and stepper motors.
What are two examples of ways voice recognition can be used with robots?
Voice recognition is a system that uses recognizable words or phrases as a form of audio data entry, rather than using a keyboard for data entry. Robots have been developed that understand basic phrases in multiple languages and can respond in the appropriate language. Manufacturers are considering placing voice recognition systems in items for use by physically handicapped people. For example, robots equipped with two-way communication can help meet the needs of a person who is completely paralyzed. Voice communication from a robot may also serve to diagnose and warn of possible problems in a manufacturing operation
Why should you be concerned about the work envelope shape when installing a robot for a particular application?
Work envelopes vary from one manufacturer to another, depending on the exact design of the robot arm. Combining different configurations in a single robot can result in another set of possible work envelopes. Before choosing a particular robot configuration, the application must be studied carefully to determine the precise work envelope requirements.
. What are some advantages of using a computer to create programs for controlling robots?
Computer programming provides greater flexibility than other programming methods. It is not necessary to take a robot out of operation while the program is being written and debugged, so productivity is not affected. Using programming languages makes creating complex operations easier. Using these languages reduces programming time, which increases productivity
What are three advantages of using continuous-path motion control?
Continuous-path motion offers several advantages, including: • Movement is smooth and continuous. • Programming is simple, and no prior knowledge of programming is required. • Velocity and acceleration of the end effector can often be controlled. • The operator must simply understand the operation he or she is trying to teach the robot to be successful in programming it.
How were George Devol and Joseph Engelberger involved in the early development of industrial robots?
George Devol patented the fi rst industrial robot in 1954. Joseph Engelberger was the president of Unimation Inc., a company formed to develop Devol's invention.
What are the main differences between hierarchical control programming and task-level programming?
Hierarchical control programming is a method of creating instructions for a robot in which the commands are structured in levels. Each level accepts commands from the level above and responds by generating simplified commands for the level below. This system uses sensory feedback (input from the environment) to affect how the robot responds. Task-level programming is a method of creating instructions for a robot in which the user specifies the goals of each task rather than the motions required to achieve those goals. Instructions are entered using simple English-like terms. Many activities are programmed automatically by the computer.
What distinguishes high-level languages for programming, and why is this distinction important?
High-level languages are programming languages that more closely resemble standard English than other programming languages. This distinction is important because it makes them easier for people to use.
What are some important considerations when selecting a robot to perform an industrial task?
In addition to environmental conditions and coordination with associated equipment, other important considerations when selecting a robot include the work envelope, degrees of freedom, and other measures of performance, such as resolution, accuracy, repeatability, operational speed, and load capacity.
How did Isaac Asimov's writings infl uence the way people think about robots?
Isaac Asimov wrote science fi ction stories in which robots were machines that could be built with safety measures that would prevent them from harming people. Although Asimov's three laws of robotics are part of a work of fi ction, they have been taken seriously by some. His term robotics, which means the engineering and use of robots, has become an established part of our language. Asimov's portrayal of robots as useful machines is now generally accepted.
Who was the dramatist that introduced the word robot in his writing? What is the meaning of the Czech word robota?
Karel Capek is the dramatist that introduced the word robot in his play titled R.U.R. (Rossum's Universal Robots). Robota means forced labor.
4. Identify four methods used to program robots and briefly describe each method
Manual programming: An operator adjusts the necessary end stops, switches, cams, electric wires, or hoses to set up the sequence. • Teach pendant programming: The operator leads the robot through the various positions involved in an operation. As the end effector reaches a desired point, that point is recorded into memory by pushing buttons on the teach pendant. The recorded points are used to generate a point-to-point path. • Walk-through programming: An operator physically moves the end effector through the desired motions, while the robot records as many as several thousand points into memory. • Computer programming: A person programs the movements and operations of a robot from a computer using high-level computer languages. On-line programming is creating the instructions for a robot on a computer that is connected to the robot console. Off-line programming is creating the instructions for a robot on a computer that is not connected to the robot. Final testing of the program is done at the job site
Identify the fi ve major components of a robot and explain the purpose of each.
Robots consist of fi ve major components, which include the controller, the manipulator, an end effector, a power supply, and a means for programming. The controller is a microprocessor linked to input/output and monitoring devices. It coordinates all movements of the mechanical system. It also receives input from the immediate environment through various monitoring devices. A manipulator is the arm of the robot that is used to move materials, parts, tools, or special devices through various motions to provide useful work. An end effector is a device attached to the wrist of the manipulator for the purpose of grasping, lifting, transporting, maneuvering, or performing operations on a workpiece. The power supply is a mechanism that provides the energy to drive the controller and actuators. The means for programming is used to record instructions that are saved to the controller. A robot may be programmed using any of several different methods, one of which is by using a teach pendant
. What are four safety rules related to tools that you should follow?
Safety rules related to tools are listed here. Students should list four safety rules. • Always be safety aware. Use caution when operating any type of tool or equipment. • Clean tools after using them to keep them in good working order. • Check lubrication on tools and equipment and lubricate as needed. • Inspect electrical cords on tools and other devices to be sure they are in good condition. • Always use the right tool for the job, and use it correctly. • Repair or replace damaged tools immediately. Do not use broken or malfunctioning tools and equipment. • Do not place tools where they may fall and create a potential hazard. • When repairing electrical tools or equipment, be sure that the power is turned off. Take steps to ensure that no one else can turn on the power while you are working. Use lockout/tagout procedures, which are practices used to disable machinery and prevent injury to workers from hazardous energy releases. • Follow recommendations regarding electrical voltages and maintain an awareness of safe practices for electrical tools and equipment.
How does a pressure sensitive safety mat function as a safety barrier?
Sensors embedded in the mat send a signal to the controller when weight is placed anywhere on the mat. The controller then sends a signal that shuts down the connected equipment. Pressure sensitive safety mats can be easily placed in dangerous areas within a facility and will automatically turn off dangerous machinery when a worker steps on the mat.
. List seven major production applications for robots
Seven major production applications for robots include pick-and-place operations, machine loading and unloading, die casting, welding, spraying operations, machining processes, assembly operations, inspection operations, material handling, and service operations.
What are the four basic configurations for robots? List some advantages and disadvantages of each.
The common work configurations used by robots are: • Revolute configuration or jointed-arm: Various joints mimic the action of the wrist, elbow, and shoulder. A joint called the sweep represents the waist. The robot performs in an irregularly shaped work envelope and has a long, flexible reach. This configuration requires a very sophisticated controller, and the programming is more complex than for the other configurations. Different locations in the work envelope can affect accuracy, load-carrying capacity, dynamics, and the ability to repeat a movement accurately. This configuration also becomes less stable as the arm approaches its maximum reach. • Cartesian configuration: Movement can start and stop simultaneously along all three axes, resulting in smoother motion of the tool tip. The robot can move directly to its designated point instead of following trajectories parallel to each axis. This configuration has simpler controls and a high degree of mechanical rigidity, accuracy, and repeatability. The robot can carry heavy loads, but it is generally limited in movement to a small, rectangular work space. • Cylindrical configuration: This configuration produces a larger work envelope than a Cartesian configuration. Overall mechanical rigidity is reduced. Repeatability and accuracy are also reduced in the direction of rotary movement. This configuration requires a more sophisticated control system than the Cartesian configuration. • Spherical configuration: This configuration provides a larger work envelope than the Cartesian or cylindrical configurations. The design is simple and provides good weight lifting capabilities. This layout has reduced mechanical rigidity and needs a more sophisticated control system than either the Cartesian or cylindrical configurations. Vertical movement is limited
What are five questions related to the characteristics of a robot that should be answered when planning safety considerations?
The following questions should be answered: • What is the size and shape of the robot's work envelope? • What methods of motion control are used? • What are the limits for a safe payload (the amount of weight the robot can lift)? • What is the range of operating speeds? • What other features are provided by the manufacturer?
0. List and define the six Japanese classifications of robots.
The six Japanese classifications of robots are: • Manual manipulator: A manipulator worked by a human operator. • Fixed-sequence robot: A manipulator that repetitively performs successive steps of a given operation according to a predetermined order, condition, and position. Its instructions cannot be easily changed. • Variable-sequence robot: A manipulator that repetitively performs successive steps of a given operation according to a predetermined order, condition, and position. The order of movement it follows can be easily changed. • Playback robot: A manipulator that can reproduce operations originally executed under human control. An operator initially feeds in the instructions relating to a sequence of movements, conditions, and positions. These instructions are stored in memory. • Numerically controlled (NC) robot: A manipulator that can perform the sequence of movements, conditions, and positions of a given task which are communicated by means of numerical data. • Intelligent robot: A robot that can, by itself, detect changes in the work environment by means of sensors (visual and/or tactile). Using its decision-making capabilities, the robot can then proceed with the appropriate operations
. What is the spatial resolution of a robot that has a command resolution of 0.006″ (0.0152 cm) and a mechanical inaccuracy of 0.004″ (0.0102 cm
The spatial resolution is 0.010″ (.0254 cm). This is calculated as 0.006″ (0.0152 cm) + 0.004″ (0.0102cm) = 0.010″ (.0254 cm)
Name the three types of power supplies used to power robots. List the advantages and disadvantages of each.
The three basic types of power supplies are electrical, hydraulic, and pneumatic. • Electrical power supplies are quiet, simple, and can be used in clean-air environments. They use a readily available energy source. They can cause problems of backlash, friction, compliance, and wear. They have poor output power compared to their weight. • Hydraulic power supplies provide both linear and rotary motion using a much simpler arrangement than for conventional electric-drive systems. The storage tank supplies a large amount of instant power. They allow precise motion control over a wide range of speeds. They can handle heavy loads on the end of the manipulator arm, can be used around highly explosive materials, and are not easily damaged when quickly stopped while carrying a heavy load. They are expensive to purchase and maintain and are not energy effi cient. Hydraulic actuator drivers are also noisier than electric-drive actuators and are not recommended for clean-room environments due to the possibility of hydraulic fl uid leaks. • Pneumatic power supplies use air, an economical and readily available energy source. Pneumatic actuator drives work at high speeds and are most useful for small or medium loads. They are economical to operate and maintain and can be used in explosive atmospheres. Since air is compressible, precise placement and positioning require additional components to achieve the smooth control possible with a hydraulic system. It is also diffi cult to keep the air as clean and dry as the control system requires. Robots that use pneumatic actuator drives are noisy and vibrate as the air cylinders and motors stop.
List three classifi cations of robots according to the pattern of motion they use and briefl y describe the three patterns of motion.
The three classifi cations for robotic motion control include: • Pick-and-place motion: Programming this pattern of motion is done by manually setting mechanical end stops or limit switches for each designated point. Because of the laborious programming, the number of points the robot can move through is comparatively low. • Point-to-point motion: Programming involves moving the robot through a number of points in space. The programmer uses a combination of manipulator axes to position the end effector at a desired spot. The path of motion is a series of straight lines between the points. • Continuous-path motion: This method is an extension of point-to-point motion. The continuouspath motion can involve several thousand points, resulting in movement that is smooth and continuous. With continuous-path motion, control of the end effector's path is more important than end point positioning.
Wiring in a laboratory should conform to the specifi cations of what code?
Wiring in a laboratory should conform to specifi cations of the National Electrical Code (NEC).
