The Grabber

The Grabber: Building Using Linkages

Linkages, specifically mechanical linkages, are designed and used to convert some input force or

motion into a different output force or motion and are commonly used in many places. The Grabber

uses a Lazy-Tong style linkage that is used to extend the reach in a direction that is perpendicular to

the direction of the applied force. The applied force can be supplied by hydraulics, electric motors, or

even muscular movement.

This linkage system can also be referred to a scissor linkage due to the elongating cross pattern

mimicking the use of scissors. Common usage of the scissor linkage system can be found in industrial

style scissor lifts or car jacks.

Building with a knowledge of linkages will help you when designing your own robots to solve problems

or become successful in competitions.

Build Instructions

Materials Needed / Setup

VEX IQ Super Kit

Assembly Tips

Make sure there is not too much friction between axes and beams.

Gears are meshed so there is a certain amount of play between them. This is called ‘backlash’.

When gears are not meshed properly you can get too much backlash which can cause the

gears to slip OR too little backlash which causes excessive friction.

When building use VEX IQ Assembly Tips found in the VEX IQ Building Instructions.

Tip 1

Use a 1x Beam for extra leverage when mounting small VEX IQ elements on shafts.

Tip 2

Connector Pins can be smoothly removed from Smart Motors, Sensors, or Robot Brains using a 1x

Beam. Put the 1x Beam onto the pin and twist the Beam while pulling outward.

Tip 3

Quickly remove Connector Pins by pressing a VEX IQ Beam against the back of the Pin and pulling it

out.

Tip 4

Easily remove Corner Connectors by placing a metal shaft through one of the holes and pulling

outward.

Tip 5

Rubber Shaft Collars become softer and easier to install if they are warmed by holding them in your

hand for 15-30 seconds.

Tip 6

The best way to measure an Angle Beam is to compare it against known angles (such as above). To

measure Shaft length, set it alongside a VEX IQ Beam and count the notches.

Tip 7

Standoffs and Standoff Connectors can be separated by pressing a shaft through the Standoff

Connector.

Activity

Guided Investigation

Once you have built the Grabber, operate to see if you can pick up additional pieces at a distance.

What advantage can you gain from use of the Grabber?

Notice that when you operate the grabber how you change a horizontal motion into an outward or

vertical motion that also travels a greater distance.

Three Classes of Levers

A very simple form of a linkage can be lever, which is an arm connected to a fixed point called a

fulcrum that is used to gain mechanical advantage.

By moving the fulcrum, increasing effort, or increasing the length the lever one can gain mechanical

advantage. There are three classes of levers. Below you will learn more about each kind.

First-Class

In a first-class lever, the fulcrum is between the effort and the resistance. A seesaw, scissors, and the

ability to pry objects are examples.

Second-Class

In a second-class lever, the resistance is between the fulcrum and the effort. Wheelbarrows and some

nut crackers are examples.

Third-Class

In a third-class lever, the effort is between the resistance and the fulcrum. Using a shovel or a broom

or even a hockey stick are examples.

Application / Theory

Linkages

A linkage typically consists of a series of levers, connected by freely rotating joints. Typically, one link is

fixed and cannot move, and one link is driven in some input motion. Linkages are a fundamental part of

machine design because of their ability to create such a wide variety of output motions and their ability

to alter the path, velocity, and acceleration of the input. Very precise and somewhat complicated

motions can be designed using a simple linkage design. Linkage motions are extremely repeatable.

Linkages are found in many places throughout the world. Below is an example of a simple linkage

found on a pair of Vice Grips.

The first picture above shows the linkage in one configuration. The link at the bottom is the input link

which is driven, and the link at the top is the fixed link. The second picture shows the linkage at the

other end of its motion. This is a linkage with four links, each link has two joints. This is one of the most

common types of linkage systems.

Types of Linkages

Typical there are four main types of linkages: the Reverse-Motion, Push-Pull, Parallel-Motion, and Bell-

Crank linkages. Combinations and modifications of these four linkage types can form other common

styles or types such as a Slider-Crank Linkage used in locomotives, a Pantograph Linkage used to

manually copy images, or Lazy-Tong Linkage used in the Grabber.

Reverse-Motion

Reverse-Motion Linkage – used to move objects in opposite directions.

Push-Pull

Push-Pull Linkage – used to move objects in the same direction.

Parallel-Motion

Parallel-Motion Linkage – used to move objects in the same direction but at a certain distance.

Bell-Crank

Bell-Crank Linkage – used to change direction of an object, typical at 90 degrees.

Extension Activity

A Pantograph linkage was commonly used in industry with milling machines to make copies of parts,

and by artists to scale images or shapes. With your new knowledge of linkages and time permitting,

create your own pantograph from your remaining parts based on the images below.

By Jlert~commonswiki (Own work) [CC0], via Wikimedia Commons

Once you complete the build, test the pantograph by placing a pencil in the last hole on the right side

and hold the other end of the linkage on the left. Do your best to trace an image and see your scaled-

up result.

Review Questions

Discussion Questions

What other applications to linkages could you see or use in the real world?

How could linkages be used with wheel rotation?

How could you apply linkages to a robot design and gain an advantage?

Scissor lift image:By Smial (Own work) [FAL, GFDL 1.2 (http://www.gnu.org/licenses/old-

licenses/fdl-1.2.html) or CC BY-SA 2.0 de (http://creativecommons.org/licenses/by-

sa/2.0/de/deed.en)], via Wikimedia Commons | Back hoe image: By Staff Sgt. Joshua Garcia

(https://www.dvidshub.net/image/987384) [Public domain], via Wikimedia Commons |

Pantograph image:By Penarc (Own work) [CC BY-SA 3.0

(http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons | Steam locomotive

image:By George Shuklin (Own work) [CC BY-SA 2.5 (http://creativecommons.org/licenses/by-

sa/2.5)], via Wikimedia Commons

Standards

The Grabber: Building Using Linkages

Common Core (CCSS) English

CCSS.ELA-Literacy.RST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts.

CCSS.ELA-Literacy.RST.6-8.2 Determine the central ideas or conclusions of a text; provide an accurate summary of the text distinct from prior knowledge or opinions.

CCSS.ELA-Literacy.RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.

CCSS.ELA-Literacy.RST.6-8.4 Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 6-8 texts and topics.

CCSS.ELA-Literacy.RST.6-8.5 Analyze the structure an author uses to organize a text, including how the major sections contribute to the whole and to an understanding of the topic

CCSS.ELA-Literacy.RST.6-8.6 Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text.

CCSS.ELA-Literacy.RST.6-8.7 Integrate quantitative or technical information expressed in words in a text with a version of that information expressed visually (e.g., in a flowchart, diagram, model, graph, or table)

CCSS.ELA-Literacy.RST.6-8.8Distinguish among facts, reasoned judgment based on research findings, and speculation in a text.

CCSS.ELA-Literacy.RST.6-8.9 Compare and contrast the information gained from experiments, simulations, video, or multimedia sources with that gained from reading a text on the same topic.

Common Core (CCSS) Math

CCSS.Math.Content.6.G.A.3 Draw polygons in the coordinate plane given coordinates for the vertices; use coordinates to find the length of a side joining points with the same first coordinate or the same second coordinate. Apply these techniques in the context of solving real-world and mathematical problems.CCSS.Math.Content.6.SP.A.2 Understand that a set of data collected to answer a statistical question has a distribution which can be described by its center, spread, and overall shape.CCSS.Math.Content.7.RP.A.2.b Identify the constant of proportionality (unit rate) in tables, graphs, equations, diagrams, and verbal descriptions of proportional relationships.

CCSS.Math.Content.7.G.A.1 Solve problems involving scale drawings of geometric figures, including computing actual lengths and areas from a scale drawing and reproducing a scale drawing at a different scale.CCSS.Math.Content.7.EE.B.4 Use variables to represent quantities in a real-world or mathematical problem, and construct simple equations and inequalities to solve problems by reasoning about the quantities.

CCSS.Math.Content.8.G.A.1 Verify experimentally the properties of rotations, reflections, and translations:

CCSS.Math.Content.6.SP.B.5.a Reporting the number of observations.

CCSS.Math.Content.6.SP.B.5.b Describing the nature of the attribute under investigation, including how it was measured and its units of measurement.

Texas (Math Standards 6-8)

Mathematical process standards. The student uses mathematical processes to acquire and demonstrate mathematical understanding. The student is expected to:

(A) apply mathematics to problems arising in everyday life, society, and the workplace;

(B) use a problem-solving model that incorporates analyzing given information, formulating a plan or strategy, determining a solution, justifying the solution, and evaluating the problem-solving process and the reasonableness of the solution;

(C) select tools, including real objects, manipulatives, paper and pencil, and technology as appropriate, and techniques, including mental math, estimation, and number sense as appropriate, to solve problems;

(D) communicate mathematical ideas, reasoning, and their implications using multiple representations, including symbols, diagrams, graphs, and language as appropriate;

Proportionality. The student applies mathematical process standards to develop an understanding of proportional relationships in problem situations. The student is expected to:

(A) compare two rules verbally, numerically, graphically, and symbolically in the form of y = ax or y = x + a in order to differentiate between additive and multiplicative relationships;

(B) apply qualitative and quantitative reasoning to solve prediction and comparison of real-world problems involving ratios and rates;

(C) give examples of ratios as multiplicative comparisons of two quantities describing the same attribute;

(D) give examples of rates as the comparison by division of two quantities having different attributes, including rates as quotients;

(E) represent ratios and percents with concrete models, fractions, and decimals;give examples of ratios as multiplicative comparisons of two quantities describing the same attribute

Expressions, equations, and relationships. The student applies mathematical process standards to use equations and inequalities to represent situations. The student is expected to:

(A) write one-variable, one-step equations and inequalities to represent constraints or conditions within problems;

(B) represent solutions for one-variable, one-step equations and inequalities on number lines; and

(C) write corresponding real-world problems given one-variable, one-step equations or inequalities.

Texas (Science Standards 6-8)

Grade 6

(2) Scientific investigation and reasoning. The student uses scientific inquiry methods during laboratory and field investigations. The student is expected to:

(A) plan and implement comparative and descriptive investigations by making observations, asking well-defined questions, and using appropriate equipment and technology;

(B) design and implement comparative and experimental investigations by making observations, asking well-defined questions, formulating testable hypotheses, and using appropriate equipment and technology;

(C) collect and record data using the International System of Units (SI) and qualitative means such as labeled drawings, writing, and graphic organizers;

(3) Scientific investigation and reasoning. The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions and knows the contributions of relevant scientists. The student is expected to:

(B) Matter and energy. Students recognize that matter is composed of atoms. Students examine information on the Periodic Table to recognize that elements are grouped into families. In addition, students understand the basic concept of conservation of mass. Lab activities will allow students to demonstrate evidence of chemical reactions. They will use chemical formulas and balanced equations to show chemical reactions and the formation of new substances.

(C) Force, motion, and energy. Students experiment with the relationship between forces and motion through the study of Newton's three laws. Students learn how these forces relate to geologic processes and astronomical phenomena. In addition, students recognize that these laws are evident in everyday objects and activities. Mathematics is used to calculate speed using distance and time measurements. (A) in all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student;

(C) identify advantages and limitations of models such as size, scale, properties, and materials;

(4) Scientific investigation and reasoning. The student knows how to use a variety of tools and safety equipment to conduct science inquiry. The student is expected to:

(A) use appropriate tools to collect, record, and analyze information, including journals/notebooks, beakers, Petri dishes, meter sticks, graduated cylinders, hot plates, test tubes, triple beam balances, microscopes, thermometers, calculators, computers, timing devices, and other equipment as needed to teach the curriculum;

(B) use preventative safety equipment, including chemical splash goggles, aprons, and gloves, and be prepared to use emergency safety equipment, including an eye/face wash, a fire blanket, and a fire extinguisher.

(8) Force, motion, and energy. The student knows force and motion are related to potential and kinetic energy. The student is expected to:

(A) compare and contrast potential and kinetic energy;

(B) identify and describe the changes in position, direction, and speed of an object when acted upon by unbalanced forces;

Texas (English Standards 6-8)

Grade 6

(26) Listening and Speaking/Listening. Students will use comprehension skills to listen attentively to others in formal and informal settings. Students will continue to apply earlier standards with greater complexity. Students are expected to:

(A) listen to and interpret a speaker's messages (both verbal and nonverbal) and ask questions to clarify the speaker's purpose and perspective;

(B) follow and give oral instructions that include multiple action steps; and

(C) paraphrase the major ideas and supporting evidence in formal and informal presentations.

(27) Listening and Speaking/Speaking. Students speak clearly and to the point, using the conventions of language. Students will continue to apply earlier standards with greater complexity. Students are expected to give an organized presentation with a specific point of view, employing eye contact, speaking rate, volume, enunciation, natural gestures, and conventions of language to communicate ideas effectively.

(28) Listening and Speaking/Teamwork. Students work productively with others in teams. Students will continue to apply earlier standards with greater complexity. Students are expected to participate in student-led discussions by eliciting and considering suggestions from other group members and by identifying points of agreement and disagreement.

Grade 7

(3) Reading/Comprehension of Literary Text/Theme and Genre. Students analyze, make inferences and draw conclusions about theme and genre in different cultural, historical, and contemporary contexts and provide evidence from the text to support their understanding.

(25) Research/Organizing and Presenting Ideas. Students organize and present their ideas and information according to the purpose of the research and their audience. Students are expected to synthesize the research into a written or an oral presentation that:

(A) draws conclusions and summarizes or paraphrases the findings in a systematic way;

(B) marshals evidence to explain the topic and gives relevant reasons for conclusions;

(C) presents the findings in a meaningful format; and

(D) follows accepted formats for integrating quotations and citations into the written text to maintain a flow of ideas.

(26) Listening and Speaking/Listening. Students will use comprehension skills to listen attentively to others in formal and informal settings. Students will continue to apply earlier standards with greater complexity. Students are expected to:

(A) listen to and interpret a speaker's purpose by explaining the content, evaluating the delivery of the presentation, and asking questions or making comments about the evidence that supports a speaker's claims;

(B) follow and give complex oral instructions to perform specific tasks, answer questions, or solve problems; and

(C) draw conclusions about the speaker's message by considering verbal communication (e.g., word choice, tone) and nonverbal cues (e.g., posture, gestures, facial expressions).

(27) Listening and Speaking/Speaking. Students speak clearly and to the point, using the conventions of language. Students will continue to apply earlier standards with greater complexity. Students are expected to present a critique of a literary work, film, or dramatic production, employing eye contact, speaking rate, volume, enunciation, a variety of natural gestures, and conventions of language to communicate ideas effectively.

(28) Listening and Speaking/Teamwork. Students work productively with others in teams. Students will continue to apply earlier standards with greater complexity. Students are expected to participate productively in discussions, plan agendas with clear goals and deadlines, set time limits for speakers, take notes, and vote on key issues.

Grade 8

Texas (Technology 6-8)

(4) Critical thinking, problem solving, and decision making. The student makes informed decisions by applying critical-thinking and problem-solving skills. The student is expected to:

(A) identify and define relevant problems and significant questions for investigation;

(B) plan and manage activities to develop a solution, design a computer program, or complete a project;

(H) discuss how changes in technology throughout history have impacted various areas of study

Florida State Standards (Technology 6-8)

SC.68.CS-CS.1.3

Evaluate what kinds of real-world problems can be solved using modeling and simulation.

SC.68.CS-CS.2.2

Solve real-life issues in science and engineering (i.e., generalize a solution to open-ended problems) using computational thinking skills.

Florida State Standards (Science 6-8)

SC.68.CS-CS.1.3 Evaluate what kinds of real-world problems can be solved using modeling and simulation.

SC.68.CS-CS.1.4 Interact with content-specific models and simulations to support learning, research and problem solving (e.g., immigration, international trade, invasive species).

Florida State Language Arts (6-8)

LAFS.6.W.3.AP.8a Gather relevant information (e.g., highlight in text, quote or paraphrase from text or discussion) from print and/or digital sources.

LAFS.6.W.3.AP.8b Gather information (e.g., highlight, quote or paraphrase from source) relevant to the topic from print and/or digital sources.

LAFS.7.RL.1.AP.1a

Refer to details and examples in a text when explaining what the text says explicitly.

LAFS.8.W.3.AP.9a Provide evidence from grade-appropriate literary texts to support analysis and reflection.

LAFS.8.W.3.AP.9b Provide evidence from grade-appropriate informational texts to support analysis, reflection and research.

Indiana State Standards (Literacy Science Technical Subjects 6-8)

6-8.LST.1.1: Read and comprehend science and technical texts within a range of complexity appropriate for grades 6-8 independently and proficiently by the end of grade 8.

6-8.LST.2.1: Cite specific textual evidence to support analysis of science and technical texts

6-8.LST.4.2: Distinguish among facts, reasoned judgment based on research findings, and speculation in a text.

6-8.LST.4.3: Compare and contrast the information gained from experiments, simulations, video, or multimedia sources with that gained from reading a text on the same topic.

Indiana State Standards (Language Arts Grade 6-8)

6.RL.2.1 Cite textual evidence to support analysis of what a text says explicitly as well as inferences drawn from the text.

6.RN. 2.2 Determine how a central idea of a text is conveyed through particular details; provide an objective summary of the text.

6.RN. 2.3 Analyze in detail how a key individual, event, or idea is introduced, illustrated, and elaborated in a text (e.g., through examples or anecdotes).

Indiana State Standards (Engineering Grade 6-8)

ETE – 2.2 Apply knowledge and skills learned in science, mathematics, language arts, fine arts, and social studies classes when completing engineering and technology based assignments

ETE – 3.2 Investigate inventions and innovations of products, processes, materials, and tools.

ETE – 5.1 Differentiate between the functions of motors, gears, sensors, wheels and control systems.

Indiana State Standards (Computer Science 6-8)

6-8.NC.2 Exhibit dispositions necessary for collaboration: providing useful feedback, integrating feedback, understanding and accepting multiple perspectives, socialization.

6-8.IC.2 Analyze the positive and negative impacts of technology on one's personal life, society, and our culture.

Indiana State Standards (Engineering and Tech Grade 6-8)

Core Standard 10 Students will identify, select, and use energy and power technology

ETE – 10.1 Analyze a variety of power and energy technology systems. ETE – 10.4 Design and construct simulations, models, and/or prototypes for specific power systems.

ETE – 10.2 Solve a simple power and energy challenge and create an efficient solution.

ETE – 10.3 Utilize appropriate designs, techniques, tools, and processes for energy and/or power systems.

ETE – 10.4 Design and construct simulations, models, and/or prototypes for specific power systems

Core Standard 5 Students will apply the principles of automation and robotics

ETE – 5.1 Differentiate between the functions of motors, gears, sensors, wheels and control systems.

ETE – 5.2 Interpret a technical document to build a working prototype of an automated system.

ETE – 5.3 Design a working prototype or mechanical system to solve a pre-designated task

NGSS (Grade 6-8)

MS-ETS1-3. Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.

MS-PS2-1.Apply Newton’s Third Law to design a solution to a problem involving the motion of two colliding objects.*

MS-PS2-2.Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object.

MS-PS2-3.Ask questions about data to determine the factors that affect the strength of electric and magnetic forces.

MS-PS2-4.Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects.

MS-PS2-5.Conduct an investigation and evaluate the experimental design to provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact.

PS3-1.Construct and interpret graphical displays of data to describe the relationships of kinetic energy to the mass of an object and to the speed of an object.

MS-PS3-2.Develop a model to describe that when the arrangement of objects interacting at a distance changes, different amounts of potential energy are stored in the system.

MS-PS3-3.Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.*

MS-PS3-4.Plan an investigation to determine the relationships among the energy transferred, the type of matter, the mass, and the change in the average kinetic energy of the particles as measured by the temperature of the sample.