Autodesk's VEX® Robotics Curriculum Unit 12: … › cms › lib › PA01001569 › Centricity...4 Autodesk's VEX Robotics Unit 12: Object Manipulation Term Definition Friction Grabber

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Autodesk's VEX® Robotics Curriculum

Unit 12: Object Manipulation

2 ■ Autodesk's VEX Robotics Unit 12: Object Manipulation

Overview

Object manipulation is one of the primary objectives in most mobile robotic development today. InUnit 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 lookat nature, we can see numerous examples of object manipulation (for example, the way a bird willuse its beak to pick up and manipulate seeds or nuts). In STEM Connections, you are presented with aseries of questions relating to mechanical object manipulation that mimics the movement of a crab'sclaw. After completing the Think Phase and Build Phase in Unit 12: Object Manipulation, you will seehow 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 software.■ |Apply your knowledge gained in the Unit 12: Object Manipulation > Think Phase to design and

build a gripper to manipulate an object.|

Overview ■ 3

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.

Term

Definition

Brainstorming A group creativity technique designed to generate a large number of ideas for thesolution to a problem.

Frames PerSecond

The measurement of frequency at which Inventor Studio produces unique,consecutive images. Abbreviated as fps.


Term

Definition

FrictionGrabber(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 withgripping surfaces (claws).

ObjectManipulator

A mechanism specifically designed to interact with objects in the robot’s (or othervehicle’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-definedparameters, 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 apowered 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 ananimation. Plays the actions in an animation in sequence, or plays actions specifiedin 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 2011

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 ■ 5

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.


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.

Think Phase ■ 7

Think Phase

Overview

This phase describes the characteristics of various forms of object manipulators. It also discussesseveral 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.


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


The following supplies are used in this phase:

Supplies

Notebook and pen

Work surface


Research and Activity

A robot interacts with the world around it. All robots are designed with a purpose in mind, and thepurposes can vary greatly. Many purposes require a robot to handle and manipulate something. To dothis, 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 manipulatordesigns 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 theside of the object to push it forward.

The scoop type of manipulator lifts an object up from underneath. Examples of scooping manipulatorsare shown here.

Think Phase ■ 9

The third type of object manipulator is a friction grabber. The friction grabber manipulator grips anobject 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 anormal force between the claw and the object. This normal force is essential to the operation of thegripper; without a normal force, there would be no friction force to stop the object from sliding fromthe gripper jaws. The greater the normal force, the greater the friction that will hold the object inplace. 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 areshown here.


Think Phase ■ 11

Another form of this type of manipulator is a roller claw. Using this, an object is rolled into the clawby some sort of wheel or roller. The normal force is provided by the elasticity of the object or someelasticity in the claw. Some examples of a roller claw can be seen below.


Object Manipulator Design

When designing a robot to manipulate an object, it is important to keep the object in mind and sizethe robot accordingly. Choose the appropriate gripper type or combine some of the types to create aneffective geometry. Try to design it so that the motor does not need to be stalled when the gripper isholding 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 efficientlycomplete their tasks with minimum wasted motion. Effective designs focus on speed and efficiencyand, if possible, will not require precise positioning.

Create Phase ■ 13

Create Phase

Overview

Objectives

After completing this lesson, you will be able to:

■ Create rendered animations of mechanisms.

Overview

In this phase, you learn how to create an animation of a gripper assembly lifting a soda can.

The completed exercise

Phase Objectives


■ Create rendered animations of mechanisms.

Prerequisites

Before starting this phase, you must have:


■ A working knowledge of the Windows operating system.■ Completed Unit 1: Introduction to VEX and Robotics > Getting Started with Autodesk Inventor.■ Completed Unit 2: Introduction to Autodesk Inventor > Quick Start for Autodesk Inventor.

Technical Overview

The following Autodesk Inventor tools are used in this phase: Icon

Name

Description

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.

PlayAnimation

Plays the animation. Changes to Stop Animation during playback.

RenderAnimation

Specifies general settings for rendering animations.


The following software is used in this phase:

Software

Autodesk Inventor Professional 2011

Create Phase ■ 15

Exercise: Animate a Gripper In this exercise, you animate a gripper assembly using Inventor Studio.

The completed exercise

Open the File You have been asked to show how the gripperassembly can lift a typical soda can. 1. Make IFI_Unit12.ipj the active project. 2.

Open Gripper_Assembly.iam.

3.

On the Tools tab, Begin panel, click InventorStudio.

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. ClickNew Animation.

2. Expand Animations. Right-click Animation1.

Click Activate. 3.

On the Animation Timeline, click AnimationOptions.

4. Under Length, for Seconds, enter 10. 5. Click OK. The timeline is set to 10 seconds. 6.

On the Animate panel, click Constraints.

7. In the browser, expand

Gripper_Assembly_SubAssembly:1. Click DriveMe 1 (6.000 in).

8.

Under Action, for End, enter 1.95.


9.

Under Time, click Specify.

10. For Start, enter 1. 11.

For End, enter 3.

12. Click OK. 13.

On the Animate Timeline, click Go to Start.

14.

On the Animate Timeline, click Play Animation.

Open the Claws In this section of the exercise, you open the clawsover the soda can. 1.

On the Animate panel, click Constraints.

2. In the browser, click Angle:1 (15.00 deg). 3. Under Action, for End, enter 45. 4. Under Time, click Specify. 5. For Start, enter 3. 6. For End, enter 4. 7. Click OK. 8.


9.

On the Animate Timeline, click Play Animation.The claw opens.

10. Repeat this workflow for Angle:2 (15.00 deg).

Complete the Animation of the Gripper In this section of the exercise, you complete theanimation of the gripper lifting the can. 1. Using the same workflow from the previous

steps, use the Animate Constraints tool and thefollowing settings to animate the constraints onGripper_Assembly_SubAssembly:1.

Constraint

Action Settings

Time Settings

Drive Me 2(6.000 in)

End 3 in 4s to 6s

Angle:1 (45.00deg)

End 37 deg 6s to 7s

Angle:2 (45.00deg)

End 37 deg 6s to 7s

Drive Me 2(3.000 in)

End 6 in 7s to 9s

Complete the Animation of the Can 1. Finally, animate the following constraint on

Can:1.

Constraint

Action Settings

Time Settings

Drive Me 3 End 3 7s to 9s

Create Phase ■ 17

Play the Animation 1.


2.

On the Animate Timeline, click Play Animation.

The gripper now moves to the soda can and liftsit off the base. Tip: You can edit the animation sequences usingthe action bars in the expanded AnimationTimeline window. To expand the AnimationTimeline window, click Expand Action Editor.

Create the Animation 1.

On the Render panel, click Render Animation.

2. From the Lighting Style list, select Four Color. 3. From the Scene Style list, select YZ Reflective

GP. 4. On the Output tab, under Time Range, click

Entire Animation. 5. Select the Launch Player check box to start the

media player when the animation is complete. 6.

Specify the folder and output file name.

7. Click Render. 8. Click OK to accept the default settings in the

ASF Export Properties dialog box. 9. Click OK. The Render Output dialog box is

displayed. Depending on the speed of yourcomputer, this animation may take manyminutes to render. To view a high quality rendering, navigate to theVideo Demonstration folder for this exercise.

This animation was created using 30 frames persecond and took many hours to render.

10. Close the dialog boxes. 11. Save the file. 12. Close the file.


Build Phase

Overview

In this phase, you design and build a gripper to manipulate a soda can.

Phase Objectives


■ Apply your knowledge gained in Unit 12: Object Manipulation > Think Phase to design and build agripper to manipulate an object.


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



Supplies

VEX Classroom Lab Kit

Notebook and pen

Work surface

Small storage container for loose parts

One soda can

Optional: Autodesk Inventor Professional 2011

Build Phase ■ 19

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 laterunits, you will be required to move soda cans across a room using this gripper. Keep this in mind whiledesigning 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:


■ 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 ofAutodesk Inventor software to explore potential solutions through the creation and testing ofdigital prototypes. Note: Come to class prepared to build and test your best ideas! Team members can downloada free version of Autodesk Inventor Professional software to use at home by joining theAutodesk Education Community today at www.autodesk.com/edcommunity.

2. 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!

Amaze Phase ■ 21

Amaze Phase

Overview

In this phase, you test the soda can gripper you built in Unit 12: Object Manipulation > Build Phase.

Phase Objectives


■ Critically evaluate your own design.


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



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


Evaluation

Gripper Challenge

In this challenge, you test the gripper you built in Unit 12: Object Manipulation > Build Phase. Thisprepares you to evaluate your design.

1. 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 areceiver. 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 VEXClassroom Lab Kit.

2. 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.

3. Use your gripper to attempt to grab the soda can. 4. After grabbing the can, use the gripper to release the can. 5. 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?

Amaze Phase ■ 23

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 yourdesign, 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 thatcaused difficulties?

■ Based on your evaluation, what changes would you make if you were to make a revision to thisgripper?

■ 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 ofyour design evaluation.


STEM Connections

Background

Designers and engineers often look to nature for inspiration. A good example of this is LeonardoDa Vinci who closely examined the anatomy of birds to come up with his early ideas for humanflight, which laid the groundwork for modern aviation. When you think about robotics, you can seesimilarities 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

Other than a crab using its claws, can you think of examples of object manipulation performed byanimals 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?

STEM Connections ■ 25

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 minuteand twelve 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 entireanimation by hand? How long do you see each frame while the animation plays?

Documents

Autodesk's VEX® Robotics Curriculum Unit 12: … › cms › lib › PA01001569 › Centricity...4 Autodesk's VEX Robotics Unit 12: Object Manipulation Term Definition Friction Grabber