Autodesk's VEX Robotics Curriculum. Unit 12: Object Manipulation

Transcription

1 Autodesk's VEX Robotics Curriculum Unit 12: Object Manipulation 1

2 Overview Object manipulation is one of the primary objectives in most mobile robotic development today. In Unit 12: Object Manipulation, you learn about grippers. You design, build, and test one of your own, as well as evaluate and communicate the attributes of your design. The concepts of mechanical object manipulation have a variety of real-world applications. If we look at nature, we can see numerous examples of object manipulation (e.g., the way a bird will use its beak to pick up and manipulate seeds or nuts). In STEM Connections, we are presented with a series of questions relating to mechanical object manipulation that mimics the movement of a crab's claw. After completing the Think Phase and Build Phase in Unit 12: Object Manipulation, you will see how object manipulation plays out in the real world. Unit Objectives After completing Unit 12: Object Manipulation, you will be able to: List methods used in designing robot object manipulators. Create rendered animations of mechanisms in Autodesk Inventor Professional. Apply your knowledge gained in the Unit 12: Object Manipulation - Think Phase to design and build a gripper to manipulate an object. Prerequisites and Related Resources Related resources for Unit 12: Object Manipulation are: Unit 1: Introduction to VEX and Robotics. Unit 2: Introduction to Autodesk Inventor. Unit 4: Microcontroller and Transmitter Overview. Unit 5: Speed, Power, Torque, and DC Motors. Unit 6: Gears, Chains, and Sprockets. Unit 7: Advanced Gears. Unit 8: Friction and Traction. Key Terms and Definitions The following key terms are used in Unit 12: Object Manipulation. 2 Term Definition Brainstorming A group creativity technique designed to generate a large number of ideas for the solution to a problem. Frames Per Second The measurement of frequency at which Inventor Studio produces unique, consecutive images. Abbreviated as fps. Autodesk's VEX Robotics Unit 12: Object Manipulation

3 Term Definition Friction Grabber (Gripper) An object manipulator that uses friction to grab, hold, and manipulate objects and/or perform tasks. Gripper End of arm tooling (EOAT) that uses a mechanism and actuator to grasp a part with gripping surfaces (claws). Object Manipulator A mechanism specifically designed to interact with objects in the robot s (or other vehicle s) environment. Plow An object manipulator that applies force to the side of an object to push it. Render The process of producing an image or animation based on user-defined parameters, such as fps, lighting style, and scene style. Roller Claw A specific type of friction grabber that rolls the object into its claw by use of a powered wheel or roller. Scoop An object manipulator that uses gravity to lift up an object from underneath. Timeline Specifies the duration in seconds for each of the actions that comprise an animation. Plays the actions in an animation in sequence, or plays actions specified in the timeline. When opened, activates the last animation. Required Supplies and Software The following supplies and software are used in Unit 12: Object Manipulation. Supplies Software VEX Classroom Lab Kit Autodesk Inventor Professional 2010 One assembled gripper built in the Unit 12: Object Manipulation > Build Phase Notebook and pen Work surface Small storage container for loose parts One soda can Overview 3

4 Academic Standards The following national academic standards are supported in Unit 12: Object Manipulation: Phase Standard Think Science (NSES) Unifying Concepts and Processes: Form and Function Physical Science: Motions and Forces Science and Technology: Abilities of Technological Design Technology (ITEA) 5.8: The Attributes of Design Mathematics (NCTM) Measurement: Understand measurable attributes of objects and the units, systems, and processes of measurement. Communication: Communicate mathematical thinking coherently and clearly to peers, teachers, and others. Connections: Recognize and apply mathematics in contexts outside of mathematics. Create Science (NSES) Unifying Concepts and Processes: Form and Function Physical Science: Motions and Forces Science and Technology: Abilities of Technological Design Technology (ITEA) 5.8: The Attributes of Design 5.9: Engineering Design 6.12: Use and Maintain Technological Products and Systems Mathematics (NCTM) Numbers and Operations: Understand numbers, ways of representing numbers, relationships among numbers, and number systems. Algebra Standard: Understand patterns, relations, and functions. Geometry Standard: Use visualization, spatial reasoning, and geometric modeling to solve problems. Measurement Standard: Understand measurable attributes of objects and the units, systems, and processes of measurement. 4 Autodesk's VEX Robotics Unit 12: Object Manipulation

5 Phase Standard Build Science (NSES) Unifying Concepts and Processes: Form and Function Physical Science: Motions and Forces Science and Technology: Abilities of Technological Design Technology (ITEA) 5.8: The Attributes of Design 5.9: Engineering Design 6.11: Apply the Design Process Mathematics (NCTM) Measurement: Understand measurable attributes of objects and the units, systems, and processes of measurement. Connections: Recognize and apply mathematics in contexts outside of mathematics. Amaze Science (NSES) Unifying Concepts and Processes: Form and Function Physical Science: Motions and Forces Science and Technology: Abilities of Technological Design Technology (ITEA) 5.8: The Attributes of Design 6.11: Apply the Design Process Mathematics (NCTM) Measurement: Understand measurable attributes of objects and the units, systems, and processes of measurement. Communication: Communicate mathematical thinking coherently and clearly to peers, teachers, and others. Connections: Recognize and apply mathematics in contexts outside of mathematics. Overview 5

6 Think Phase Overview This phase describes the characteristics of various forms of object manipulators. It also discusses several methods used in the design of object manipulators. Phase Objectives After completing this phase, you will be able to: List methods used in designing robot object manipulators. List the three primary methods for object manipulation. Prerequisites and Related Resources Related phase resources are: Unit 5: Speed, Power, Torque, and DC Motors. Unit 6: Gears, Chains, and Sprockets. Unit 7: Advanced Gears. Unit 8: Friction and Traction. Required Supplies and Software The following supplies are used in this phase: Supplies Notebook and pen Work surface 6 Autodesk's VEX Robotics Unit 12: Object Manipulation

7 Research and Activity A robot interacts with the world around it. All robots are designed with a purpose in mind, and the purposes can vary greatly. Many purposes require a robot to handle and manipulate something. To do this, it must have a mechanism specifically designed to interact with objects in its environment. Object Manipulation The three categories of object manipulators are plow, scoop, and friction grabber. Most manipulator designs fall into one or more of these categories. The plow type of object manipulator does not actually pick up an object; rather, it applies force to the side of the object to push it forward. The scoop type of manipulator lifts an object up from underneath. Examples of scooping manipulators can be seen below. Think Phase 7

8 The third type of object manipulator is a friction grabber. The friction grabber manipulator grips an object in some way and the friction between the gripper and the object holds the object in place. A grabber consists of an actuator that moves the claws or jaws together and apart. This provides a normal force between the claw and the object. This normal force is essential to the operation of the gripper; without a normal force, there would be no friction force to stop the object from sliding from the gripper jaws. The greater the normal force, the greater the friction that will hold the object in place. Of course, if the normal force is too large, the object can be damaged. The most common form of friction grabber manipulator is a claw that pinches an object. Examples are shown here. 8 Autodesk's VEX Robotics Unit 12: Object Manipulation

9 Think Phase 9

10 Another form of this type of manipulator is a roller claw. Using this, an object is rolled into the claw by some sort of wheel or roller. The normal force is provided by the elasticity of the object or some elasticity in the claw. Some examples of a roller claw can be seen below. 10 Autodesk's VEX Robotics Unit 12: Object Manipulation

11 Object Manipulator Design When designing a robot to manipulate an object, it is important to keep the object in mind and size the robot accordingly. Choose the appropriate gripper type or combine some of the types to create an effective geometry. Try to design it so that the motor does not need to be stalled when the gripper is holding the object. It is also important to think of how the gripper will pick up and deposit the object. Consider the following questions: What orientation will the object be in when it is picked up? Does the gripper need to be able to grab the object from multiple orientations? How will the gripper deposit the object? Does it need to deposit the object in multiple orientations? What orientation change does the object need to make between pickup and deposit? The best object manipulators maintain a firm grip on an object. They are able to quickly and efficiently complete their tasks with minimum wasted motion. Effective designs focus on speed and efficiency and, if possible, will not require precise positioning. Think Phase 11

12 Create Phase Technical Overview The following Autodesk Inventor tools are used in this phase. Icon Name Description Animate Constraints Animates linear or angular values for one or more constraints. Go to Start Sets the current time to zero, which is the start of the animation. Play Animation Plays the animation. Changes to Stop Animation during playback. Render Animation Specifies general settings for rendering animations. Required Supplies and Software The following software is used in this phase: Software Autodesk Inventor Professional Autodesk's VEX Robotics Unit 12: Object Manipulation

13 Exercise: Animate a Gripper In this exercise, you animate a gripper assembly using Inventor Studio. Move the Gripper Forward In this section of the exercise, you move the gripper assembly over the soda can. 1. In the browser, right-click Animations. Click New Animation. The completed exercise 2. Open the File 3. You have been asked to show how the gripper assembly can lift a typical soda can Expand Animations. Right-click Animation1. Click Activate. On the Animation Timeline, click Animation Options. Make IFI_Unit12.ipj the active project. Open Gripper_Assembly.iam. On the Tools tab, Begin panel, click Inventor Studio Under Length, for Seconds, enter 10. Click OK. The timeline is set to 10 seconds. On the Animate panel, click Constraints. 7. In the browser, expand Gripper_Assembly_SubAssembly:1. Click Drive Me 1 (6.000 in). Under Action, for End, enter Create Phase 13

14 9. Under Time, click Specify. Complete the Animation of the Gripper In this section of the exercise, you complete the animation of the gripper lifting the can For Start, enter For End, enter Click OK. 13. On the Animate Timeline, click Go to Start. Using the same workflow from the previous steps, use the Animate Constraints tool and the following settings to animate the constraints on Gripper_Assembly_SubAssembly:1. Constraint Action Settings Time Settings Drive Me 2 (6.000 in) End 3 in 4s to 6s Angle:1 (45.00 deg) End 37 deg 6s to 7s Angle:2 (45.00 deg) End 37 deg 6s to 7s Drive Me 2 (3.000 in) End 6 in 7s to 9s 14. On the Animate Timeline, click Play Animation. Complete the Animation of the Can 1. Open the Claws In this section of the exercise, you open the claws over the soda can. 1. On the Animate panel, click Constraints In the browser, click Angle:1 (15.00 deg). Under Action, for End, enter 45. Under Time, click Specify. For Start, enter 3. For End, enter 4. Click OK. On the Animate Timeline, click Go to Start. 9. On the Animate Timeline, click Play Animation. The claw opens. Finally, animate the following constraint on Can:1. Constraint Action Settings Time Settings Drive Me 3 End 3 7s to 9s 10. Repeat this workflow for Angle:2 (15.00 deg). 14 Autodesk's VEX Robotics Unit 12: Object Manipulation

15 Play the Animation 1. On the Animate Timeline, click Go to Start. 2. On the Animate Timeline, click Play Animation. This animation was created using 30 frames per second and took many hours to render. 10. Close the dialog boxes. 11. Save the file. 12. Close the file. The gripper now moves to the soda can and lifts it off the base. Tip: You can edit the animation sequences using the action bars in the expanded Animation Timeline window. To expand the Animation Timeline window, click Expand Action Editor. Create the Animation 1. On the Render panel, click Render Animation From the Lighting Style list, select Four Color. From the Scene Style list, select YZ Reflective GP. On the Output tab, under Time Range, click Entire Animation. Select the Launch Player check box to start the media player when the animation is complete. Specify the folder and output file name Click Render. Click OK to accept the default settings in the ASF Export Properties dialog box. Click OK. The Render Output dialog box is displayed. Depending on the speed of your computer, this animation may take many minutes to render. To view a high quality rendering, navigate to the Video Demonstration folder for this exercise. Create Phase 15

16 Build Phase Overview In this phase, you design and build a gripper to manipulate a soda can. Phase Objectives After completing this phase, you will be able to: Apply your knowledge gained in Unit 12: Object Manipulation > Think Phase to design and build a gripper to manipulate an object. Prerequisites and Related Resources Before starting this phase, you must have completed: Unit 12: Object Manipulation > Think Phase. Related phase resources are: Unit 1: Introduction to VEX and Robotics. Unit 4: Microcontroller and Transmitter Overview. Unit 5: Speed, Power, Torque, and DC Motors. Unit 6: Gears, Chains, and Sprockets. Unit 7: Advanced Gears. Unit 8: Friction and Traction. Required Supplies and Software The following supplies are used in this phase: Supplies VEX Classroom Lab Kit Notebook and pen Work surface Small storage container for loose parts One soda can Optional: Autodesk Inventor Professional Autodesk's VEX Robotics Unit 12: Object Manipulation

17 Activity Design and Build a Gripper In this activity, you design and build your own gripper that will be used to grab a soda can. In later units, you will be required to move soda cans across a room using this gripper. Keep this in mind while designing it. 1. In your notebook, brainstorm different types of grippers that can be used to manipulate a soda can. The following images show some examples of grippers. When choosing a design, among the many factors to consider are: Build Phase 17

18 How tightly will the gripper grab the can? How easy is the can to grab? How easy is the can to release? What orientation does the can need to be in? Work as professionals in the engineering and design fields by leveraging the power of Autodesk Inventor to explore potential solutions through the creation and testing of digital prototypes. Note: Come to class prepared to build and test your best ideas! Team members can download a free version of Autodesk Inventor Professional to use at home by joining the Autodesk Student Engineering and Design Community today at Based on the possible grippers generated during brainstorming, select one and start building! 3. Once your gripper is completed, plug in the motor(s)/servo(s) (if it uses any) to the appropriate ports in a Microcontroller. Test your gripper with a transmitter to make sure the motor(s)/ servo(s) create the desired range of motion. 4. Move on to the Amaze Phase where you will test and evaluate your gripper! Autodesk's VEX Robotics Unit 12: Object Manipulation

19 Amaze Phase Overview In this phase, you test the soda can gripper you built in Unit 12: Object Manipulation > Build Phase. Phase Objectives After completing this phase, you will be able to: Critically evaluate your own design. Prerequisites and Related Resources Before you start this phase, you must have: Completed Unit 12: Object Manipulation > Think Phase. Completed Unit 12: Object Manipulation > Build Phase. An assembled gripper from Unit 12: Object Manipulation > Build Phase. Related phase resources are: Unit 1: Introduction to VEX and Robotics. Unit 4: Microcontroller and Transmitter Overview. Unit 5: Speed, Power, Torque, and DC Motors. Unit 6: Gears, Chains, and Sprockets. Unit 7: Advanced Gears. Unit 8: Friction and Traction. Required Supplies and Software The following supplies are used in this phase: Supplies VEX Classroom Lab Kit The assembled gripper built in the Unit 12: Object Manipulation > Build Phase Notebook and pen Work surface One soda can Amaze Phase 19

20 Evaluation Gripper Challenge In this challenge, you test the gripper you built in Unit 12: Object Manipulation > Build Phase. This prepares you to evaluate your design. Make sure the gripper is hooked up to a Microcontroller to ensure it can be operated via the Transmitter. This involves plugging in a battery and a receiver. For a refresher on how to do this, see the Unit 4: Gears, Chains, and Sprockets > Think Phase or the Inventor's Guide included in your VEX Classroom Lab Kit. To make this test easier to perform, you may want to attach a bar or handle to your gripper so your hands do not interfere with the gripping process. Use your gripper to attempt to grab the soda can. After grabbing the can, use the gripper to release the can. Pay careful attention to the following criteria, making notes where necessary: How tightly does the gripper grab the can? How easy is the can to grab? How easy is the can to release? What orientation does the can need to be in? Is the can secure within the gripper? 20 Autodesk's VEX Robotics Unit 12: Object Manipulation

21 Engineering Notebook In your engineering notebook, rate your design on a scale of 1 to 10 based on the following criteria. The goal here is not to get the highest score, but to assess the strengths and weaknesses of your design, so a low score is not a cause for concern. How tightly does the gripper grab the can? How easy is the can to grab? How easy is the can to release? What orientation does the can need to be in? Is the can secure within the gripper? For each of the criteria, explain why you gave the score you did. If the score was high, explain which feature of the gripper made it so successful. If the score was low, explain the flaw that caused difficulties? Based on your evaluation, what changes would you make if you were to make a revision to this gripper? How would you change this design if you were asked to grab multiple soda cans? Presentation Present your gripper design to the class. What are its main features and flaws? Present the results of your design evaluation. Amaze Phase 21

22 STEM Connections Background Designers and engineers often look to nature for inspiration. A good example of this is Leonardo Da Vinci who closely examined the anatomy of birds to come up with his early ideas for human flight that laid the groundwork for modern aviation. When you think about robotics, you can see similarities between the gripper you built and used in this unit and the claws on a crab. Science Crabs have evolved their specialized claws over millions of years as the result of natural selection. How might a crab with an especially large or dexterous claw gain a competitive advantage over a normal crab? Why do some crab species have especially large claws while other crab species do not? Technology Besides a crab using its claws, can you think of other examples of object manipulation performed by animals in the natural world? How can some of these methods of interaction be adapted to perform a mechanical task? Can you think of any invention that gained its design inspiration from the natural world? 22 Autodesk's VEX Robotics Unit 12: Object Manipulation

23 Engineering Is the crab claw style gripper the most effective way to move most objects? What are the advantages, disadvantages, and limitations of this type of object manipulation? Math Suppose you are watching an animation of a claw-style gripper grabbing a car door. If the animation advances at a rate of five frames per second and the entire animation lasts one minute and 12 seconds, how many frames are there in the whole animation? If you can draw one frame by hand in two minutes, how long will it take you to make the entire animation by hand? How long do you see each frame while the animation plays? STEM Connections 23

24 24 Autodesk's VEX Robotics Unit 12: Object Manipulation