Robots

New York State Learning Standards

Mathematics, Science, and Technology

Elementary
M1.1	Use special mathematical notation and symbolism to communicate in mathematics and to compare and describe quantities, express relationships, and relate mathematics to their immediate environment.
M1.1a	Use plus, minus, greater than, less than, equal to, multiplication, and division signs
M1.1b	Select the appropriate operation to solve mathematical problems
M1.1c	Apply mathematical skills to describe the natural world

Intermediate
M1.1	Extend mathematical notation and symbolism to include variables and algebraic expressions in order to describe and compare quantities and express mathematical relationships.
M1.1a	Identify independent and dependent variables
M1.1b	Identify relationships among variables including: direct, indirect, cyclic, constant; identify non-related material
M1.1c	Apply mathematical equations to describe relationships among variables in the natural world

Physics
M1.1	Use algebraic and geometric representations to describe and compare data.
M1.1a	Use scaled diagrams to represent and manipulate vector quantities
M1.1b	Represent physical quantities in graphical form
M1.1c	Construct graphs of real-world data (scatterplots,line or curve of best fit)
M1.1d	Manipulate equations to solve for unknowns
M1.1e	Use dimensional analysis to confirm algebraic solutions

STANDARD 1
Analysis, Inquiry, and Design: MATHEMATICAL ANALYSIS

Key Idea 1: details
Abstraction and symbolic representation are used to communicate mathematically.

Elementary
M3.1	Explore and solve problems generated from school, home, and community situations, using concrete objects or manipulative materials when possible.	√
M3.1a	Use appropriate scientific tools, such as metric rulers, spring scale, pan balance, graph paper, thermometers [Fahrenheit and Celsius], graduated cylinder to solve problems about the natural world	√

Intermediate
M3.1	Apply algebraic and geometric concepts and skills to the solution of problems.
M3.1a	Explain the physical relevance of properties of a graphical representation of real-world data, e.g., slope, intercepts, area under the curve

Physics
M3.1	Apply mathematical knowledge to solve real-world problems and problems that arise from the investigation of mathematical ideas, using representations such as pictures, charts, and tables.
M3.1a	Use appropriate scientific tools to solve problems about the natural world.	√

STANDARD 1
Analysis, Inquiry, and Design: MATHEMATICAL ANALYSIS

Key Idea 3:details
Critical thinking skills are used in the solution of mathematical problems.

STANDARD 1
Analysis, Inquiry, and Design: ENGINEERING DESIGN

Key Idea 1: details
Engineering design is an iterative process involving modeling and optimization (finding the best solution within given constraints); this process is used to develop technological solutions to problems within given constraints. (Note: The design process could apply to activities from simple investigations to long-term projects.)

Elementary
1.1	Describe objects, imaginary or real, that might be modeled or made differently and suggest ways in which the objects can be changed, fixed, or improved
1.2	Investigate prior solutions and ideas from books, magazines, family, friends, neighbors, and community members
1.3	Generate ideas for possible solutions, individually and through group activity; apply age-appropriate mathematics and science skills; evaluate the ideas and determine the best solution; and explain reasons for the choices
1.4	Plan and build, under supervision, a model of the solution using familiar materials, processes, and hand tools
1.5	Discuss how best to test the solution; perform the test under teacher supervision; record and portray results through numerical and graphic means; discuss orally why things worked or didn't work; and summarize results in writing, suggesting ways to make the solution better

Intermediate
T1.1	Identify needs and opportunities for technical solutions from an investigation of situations of general or social interest.
T1.1a	Identify a scientific or human need that is subject to a technological solution which applies scientific principles	√
T1.2	Locate and utilize a range of printed, electronic, and human information resources to obtain ideas.	√
T1.2a	Use all available information systems for a preliminary search that addresses the need.	√
T1.3	Consider constraints and generate several ideas for alternative solutions, using group and individual ideation techniques (group discussion, brainstorming, forced connections, role play); defer judgment until a number of ideas have been generated; evaluate (critique) ideas; and explain why the chosen solution is optimal.	√
T1.3a	Generate ideas for alternative solutions	√
T1.3b	Evaluate alternatives based on the constraints of design	√
T1.4	Develop plans, including drawings with measurements and details of construction, and construct a model of the solution, exhibiting a degree of craftsmanship.	√
T1.4a	Design and construct a model of the product or process	√
T1.4b	Construct a model of the product or process	√
T1.5	In a group setting, test their solution against design specifications, present and evaluate results, describe how the solution might have been modified for different or better results, and discuss trade-offs that might have to be made.	√
T1.5a	Test a design	√
T1.5b	Evaluate a design	√

Commencement
1.1	Initiate and carry out a thorough investigation of an unfamiliar situation and identify needs and opportunities for technological invention or innovation
1.2	identify, locate, and use a wide range of information resources including subject experts, library references, magazines, videotapes, films, electronic data bases and online services, and discuss and document through notes and sketches how findings relate to the problem
1.3	generate creative solution ideas, break ideas into the significant functional elements, and explore possible refinements; predict possible outcomes using mathematical and functional modeling techniques; choose the optimal solution to the problem, clearly documenting ideas against design criteria and constraints; and explain how human values, economics, ergonomics, and environmental considerations have influenced the solution
1.4	develop work schedules and plans which include optimal use and cost of materials, processes, time, and expertise; construct a model of the solution, incorporating developmental modifications while working to a high degree of quality (craftsmanship)
1.5	in a group setting, devise a test of the solution relative to the design criteria and perform the test; record, portray, and logically evaluate performance test results through quanitative, graphic, and verbal means; and use a variety of creative verbal and graphic techniques effectively and persuasively to present conclusions, predict impacts and new problems, and suggest and pursue modifications

STANDARD 2
INFORMATION SYSTEMS

Key Idea 1: details
Information technology is used to retrieve, process, and communicate information as a tool to enhance learning.

Elementary
1.1	Use computer technology,traditional paper-based resources,and interpersonal discussions to learn, do, and share science in the classroom	√
1.2	Select appropriate hardware and software that aids in wordprocessing, creating databases, telecommunications, graphing, data display, and other tasks	√
1.3	Use information technology to link the classroom to world events

Intermediate
1.1	Use a range of equipment and software to integrate several forms of information in order to create good-quality audio, video, graphic, and text-based presentations.
1.2	Use spreadsheets and database software to collect, process, display, and analyze information. Students access needed information from electronic databases and on-line telecommunication services.
1.3	Systematically obtain accurate and relevant information pertaining to a particular topic from a range of sources, including local and national media, libraries, muse- ums, governmental agencies, industries, and individuals.
1.4	Collect data from probes to measure events and phenomena.
1.4a	Collect the data, using the appropriate, available tool
1.4b	Organize the data
1.4c	Use the collected data to communicate a scientific concept	√
1.5	Use simple modeling programs to make predictions.

Physics
1.1	Understand and use the more advanced features of word processing, spreadsheets, and database software.
1.2	Prepare multimedia presentations demonstrating a clear sense of audience and purpose. (Note: Multimedia may include posters, slides, images, presentation software, etc.)	√
1.2a	Extend knowledge of physical phenomena through independent investigation, e.g., literature review, electronic resources, library research
1.2b	Use appropriate technology to gather experimental data, develop models,and present results	√
1.3	Access, select, collate, and analyze information obtained from a wide range of sources such as research databases, foundations, organizations, national libraries, and electronic communication networks, including the Internet.
1.3a	Use knowledge of physics to evaluate articles in the popular press on contemporary scientific topics
1.4	Utilize electronic networks to share information.	√
1.5	Model solutions to a range of problems in mathematics, science, and technology, using computer simulation software.	√
1.5a	Use software to model and extend classroom and laboratory experiences,recognizing the differences between the model used for understanding and real-world behavior	√

Physics
	Measure current and voltage in a circuit	√
	Use measurements to determine the resistance of a circuit element	√
	Interpret graphs of voltage versus current
	Measure and compare the resistance of conductors of various lengths and cross-sectional areas
	Construct simple series and parallel circuits	√
	Draw and interpret circuit diagrams which include voltmeters and ammeters	√
	Predict the behavior of lightbulbs in series and parallel circuits
	Map the magnetic field of a permanent magnet, indicating the direction of the field between the N (north-seeking) and S (south-seeking) poles

STANDARD 4
Process Skills Electricity and Magnetism:
details

STANDARD 5
Technology: Engineering Design
(See Standard 1:ENGINEERING DESIGN)
Key Idea 1:
Engineering design is an iterative process involving modeling and optimization used to develop technological solutions to problems within given constraints.

Elementary
2.1	Explore, use, and process a variety of materials and energy sources to design and construct things.	√
2.2	Understand the importance of safety, cost, ease of use, and availability in selecting tools and resources for a specific purpose.
2.3	Develop basic skill in the use of hand tools
2.4	Use simple manufacturing processes (e.g., assembly, multiple stages of production, quality control) to produce a product	√
2.5	Use appropriate graphic and electronic tools and techniques to process information.	√

Intermediate
2.1	Choose and use resources for a particular purpose based upon an analysis and understanding of their properties, costs, availability, and environmental impact	√
2.2	Use a variety of hand tools and machines to change materials into new forms through forming, separating, and combining processes, and processes which cause internal change to occur	√
2.3	Combine manufacturing processes with other technological processes to produce, market, and distribute a product
2.4	Process energy into other forms and information into more meaningful information.

Commencement
2.1	Test, use, and describe the attributes of a range of material (including synthetic and composite materials), information, and energy resources	√
2.2	Select appropriate tools, instruments, and equipment and use them correctly to process materials, energy, and information	√
2.3	Explain tradeoffs made in selecting alternative resources in terms of safety, cost, properties, availability, ease of processing, and disposability
2.4	Describe and model methods (including computer-based methods) to control system processes and monitor system outputs	√

STANDARD 5
Technology: Engineering Design

Key Idea 2: details
Technological tools, materials, and other resources should be selected on the basis of safety, cost, availability, appropriateness, and environmental impact; technological processes change energy, information, and material resources into more useful forms.

Elementary
3.1	Identify and describe the function of the major components of a computer system.
3.2	Use the computer as a tool for generating and drawing ideas.	√
3.3	Control computerized devices and systems through programming.	√
3.4	Model and simulate the design of a complex environment by giving direct commands.	√

Intermediate
3.1	Assemble a computer system including keyboard, central processing unit and disc drives, mouse, modem, printer, and monitor
3.2	Use a computer system to connect to and access needed information from various Internet sites	√
3.3	Use computer hardware and software to draw and dimension prototypical designs	√
3.4	Use a computer as a modeling tool	√
3.5	Use a computer system to monitor and control external events and/or systems	√

Commencement
3.1	Understand basic computer architecture and describe the function of computer subsystems and peripheral devices
3.2	Select a computer system that meets personal needs
3.3	Attach a modem to a computer system and telephone line, set up and use communications software, connect to various online networks, including the Internet, and access needed information using email, telnet, gopher, ftp, and web searches	√
3.4	Use computer-aided drawing and design (CADD) software to model realistic solutions to design problems	√
3.5	Develop an understanding of computer programming and attain some facility in writing computer programs	√

STANDARD 5
Technology: Computer Technology

Key Idea 3: details
Computers, as tools for design, modeling, information processing, communication, and system control, have greatly increased human productivity and knowledge.

Elementary
4.1	Identify familiar examples of technological systems that are used to satisfy human needs and wants, and select them on the basis of safety, cost, and function.
4.2	Assemble and operate simple technological systems, including those with interconnecting mechanisms to achieve different kinds of movement.
4.3	Understand that larger systems are made up of smaller component subsystems.

Intermediate
4.1	Select appropriate technological systems on the basis of safety, function, cost, ease of operation, and quality of post-purchase support
4.2	Assemble, operate, and explain the operation of simple open- and closed-loop electrical, electronic, mechanical, and pneumatic systems
4.3	Describe how subsystems and system elements (inputs, processes, outputs) interact within systems
4.4	Describe how system control requires sensing information, processing it, and making changes	√

Commencement
4.1	Explain why making tradeoffs among characteristics, such as safety, function, cost, ease of operation, quality of post-purchase support, and environmental impact, is necessary when selecting systems for specific purposes
4.2	Model, explain, and analyze the performance of a feedback control system
4.3	Explain how complex technological systems involve the confluence of numerous other systems

STANDARD 5
Technology: Technological Systems

Key Idea 4: details
Technological systems are designed to achieve specific results and produce outputs, such as products, structures, services, energy, or other systems.

Elementary
1.1	Observe and describe interactions among components of simple systems.	√
1.2	Identify common things that can be considered to be systems (e.g., a plant population, a subway system, human beings).

Intermediate
1.1	Describe the differences between dynamic systems and organizational systems.
1.2	describe the differences and similarities between engineering systems, natural systems, and social systems.
1.3	Describe the differences between open- and closed-loop systems.
1.4	Describe how the output from one part of a system (which can include material, energy, or information) can become the input to other parts.

Commencement
1.1	Explain how positive feedback and negative feedback have opposite effects on system outputs.
1.2	Use an input-process-output-feedback diagram to model and compare the behavior of natural and engineered systems.
1.3	Define boundary conditions when doing systems analysis to determine what influences a system and how it behaves.

STANDARD 6
Interconnectedness: Common Themes SYSTEMS THINKING:

Key Idea 1: details
Through systems thinking, people can recognize the commonalities that exist among all systems and how parts of a system interrelate and combine to perform specific functions.

Elementary
2.1	Analyze,construct,and operate models in order to discover attributes of the real thing	√
2.2	Discover that a model of something is different from the real thing but can be used to study the real thing	√
2.3	Use different types of models, such as graphs,sketches,diagrams,and maps,to represent various aspects of the real world

Intermediate
2.1	Select an appropriate model to begin the search for answers or solutions to a question or problem.
2.2	Use models to study processes that cannot be studied directly (e.g., when the real process is too slow, too fast, or too dangerous for direct observation).	√
2.3	Demonstrate the effectiveness of different models to represent the same thing and the same model to represent different things.

Physics
2.1	Revise a model to create a more complete or improved representation of the system.
2.2	Collect information about the behavior of a system and use modeling tools to represent the operation of the system.	√
2.2a	Use observations of the behavior of a system to develop a model
2.3	Find and use mathematical models that behave in the same manner as the processes under investigation.
2.3a	Represent the behavior of real-world systems,using physical and mathematical models	√
2.4	Compare predictions to actual observations, using test models.	√
2.4a	Validate or reject a model based on collated experimental data	√
2.4b	Predict the behavior of a system,using a model	√

STANDARD 6
Interconnectedness: Common Themes MODELS:

Key Idea 2: details
Models are simplified representations of objects, structures, or systems used in analysis, explanation, interpretation, or design.

Elementary
1.1	Analyze science/technology/society problems and issues that affect their home, school, or community, and carry out a remedial course of action
1.2	Make informed consumer decisions by applying knowledge about the attributes of particular products and making cost/benefit trade-offs to arrive at an optimal choice
1.3	Design solutions to problems involving a familiar and real context, investigate related science concepts to determine the solution, and use mathematics to model, quantify, measure, and compute	√
1.4	Observe phenomena and evaluate them scientifically and mathematically by conducting a fair test of the effect of variables and using mathematical knowledge and technological tools to collect, analyze, and present data and conclusions

Intermediate
1.1	Analyze science/technology/society problems and issues at the local level and plan and carry out a remedial course of action.
1.2	Make informed consumer decisions by seeking answers to appropriate questions about products, services, and systems; determining the cost/benefit and risk/benefit tradeoffs; and applying this knowledge to a potential purchase.
1.3	Design solutions to real-world problems of general social interest related to home, school, or community using scientific experimentation to inform the solution and applying mathematical concepts and reasoning to assist in developing a solution.	√
1.4	Describe and explain phenomena by designing and conducting investigations involving systematic observations, accurate measurements, and the identification and control of variables; by inquiring into relevant mathematical ideas; and by using mathematical and technological tools and procedures to assist in the investigation.
1.5	Analyze science/technology/society problems and issues at the local level and plan and carry out a remedial course of action.

Physics
	Address real-world problems,using scientific methodology

STANDARD 7
Interdisciplinary Problem Solving CONNECTIONS:

Key Idea 1:details
The knowledge and skills of mathematics, science, and technology are used together to make informed decisions and solve problems, especially those relating to issues of sci- ence/technology/society, consumer decision making, design, and inquiry into phenomena.

Physics
2.1	Collect,analyze,interpret,and present data,using appropriate tools	√
2.2	When students participate in an extended,culminating mathematics,science,and technology project, then students should:
	Work effectively—Contributing to the work of a brainstorming group, laboratory partnership, cooperative learning group, or project team; planning procedures; identify and managing responsibilities of team members; and staying on task, whether working alone or as part of a group.	√
	Gather and process information —Accessing information from printed media, electronic data bases, and community resources and using the information to develop a definition of the problem and to research possible solutions.	√
	Generate and analyze ideas — Developing ideas for proposed solutions, investigating ideas, collecting data, and showing relationships and patterns in the data.	√
	Observe common themes—Observing examples of common unifying themes, applying them to the problem, and using them to better understand the dimensions of the problem.	√
	Realize ideas—Constructing components or models, arriving at a solution, and evaluating the result.	√
	Present results—Using a variety of media to present the solution and to communicate the results.	√

STANDARD 7
Interdisciplinary Problem Solving STRATEGIES:

Key Idea 2: details
Solving interdisciplinary problems involves a variety of skills and strategies, including effective work habits; gathering and processing information; generating and analyzing ideas; realizing ideas; making connections among the common themes of mathematics, science, and technology; and presenting results.

CDOS

Elementary
2.1	Identify academic knowledge and skills that are required in specific occupations
2.2	Demonstrate the difference between the knowledge of a skill and the ability to use the skill
2.3	Solve problems that call for applying academic knowledge and skills.	√

Intermediate
2.1	Apply academic knowledge and skills using an interdisciplinary approach to demonstrate the relevance of how these skills are applied in work-related situations in local, state, national, and international communities
2.2	Solve problems that call for applying academic knowledge and skills	√
2.3	Use academic knowledge and skills in an occupational context, and demonstrate the application of these skills by using a variety of communication techniques (e.g., sign language, pictures, videos, reports, and technology).

Commencement
2.1	Demonstrate the integration and application of academic and occupational skills in their school learning, work, and personal lives.	√
2.2	Use academic knowledge and skills in an occupational context, and demonstrate the application of these skills by using a variety of communication techniques (e.g., sign language, pictures, videos, reports, and technology)	√
2.3	Research, interpret, analyze, and evaluate information and experiences as related to academic knowledge and technical skills when completing a career plan.

Standard 2: Integrated Learning
details
Students will demonstrate how academic knowledge and skills are applied in the workplace and other settings.

Integrated learning encourages students to use essential academic concepts, facts, and procedures in applications related to life skills and the world of work. This approach allows students to see the usefulness of the concepts that they are being asked to learn and to understand their potential application in the world of work.

Standard 3a: Universal Foundation Skills
details
Students will demonstrate mastery of the foundation skills and competencies essential for success in the workplace.

Basic skills
Basic skills include the ability to read, write, listen, and speak as well as perform arithmetical and mathematical functions.

Elementary
3.1.1	Listen to and read the ideas of others and express themselves both orally and in writing; they use basic mathematical concepts and computations to solve problems.	√

Intermediate
3.1.1	Listen to and read the ideas of others and analyze what they hear and read; acquire and use information from a variety of sources; and apply a combination of mathematical operations to solve problems in oral or written form.	√

Commencement
3.1.1	Use a combination of techniques to read or listen to complex information and analyze what they hear or read; convey information confidently and coherently in written or oral form; and analyze and solve mathematical problems requiring use of multiple computational skills.	√

Thinking skills
Thinking skills lead to problem solving, experimenting, and focused observation and allow the application of knowledge to new and unfamiliar situations.

Elementary
3.2.1 Use ideas and information to make decisions and solve problems related to accomplishing a task. √

Intermediate
3.2.1 Evaluate facts, solve advanced problems, and make decisions by applying logic and reasoning skills. √

Commencement
3.2.1 Demonstrate the ability to organize and process information and apply skills in new ways. √
Personal Qualities
Personal qualities generally include competence in self-management and the ability to plan, organize, and take independent action.

Elementary
3.3.1 Demonstrate the personal qualities that lead to responsible behavior. √

Intermediate
3.3.1 Demonstrate the ability to work with others, present facts that support arguments, listen to dissenting points of view, and reach a shared decision. √

Commencement
3.3.1 Demonstrate leadership skills in setting goals, monitoring progress, and improving their performance. √
Interpersonal Skills
Positive interpersonal qualities lead to teamwork and cooperation in large and small groups in family, social, and work situations.

Elementary
3.4.1 Relate to people of different ages and from diverse backgrounds.

Intermediate
3.4.1 Demonstrate the ability to work with others, present facts that support arguments, listen to dissenting points of view, and reach a shared decision. √

Commencement
3.4.1 Communicate effectively and help others to learn a new skill. √
Technology
Technology is the process and product of human skill and ingenuity in designing and creating things from available resources to satisfy personal and societal needs and wants.

Elementary
3.5.1 Demonstrate an awareness of the different types of technology available to them and of how technology affects society.

Intermediate
3.5.1 Select and use appropriate technology to complete a task. √

Commencement
3.5.1 Apply their knowledge of technology to identify and solve problems. √
Managing Information
Information management focuses on the ability to access and use information obtained from other people, community resources, and computer networks.
Elementary
3.6.1 Describe the need for data and obtain data to make decisions. √

Intermediate
3.6.1 Select and communicate information in an appropriate format (e.g., oral, written, graphic, pictorial, multimedia). √

Commencement
3.6.1 Use technology to acquire, organize, and communicate information by entering, modifying, retrieving, and storing data. √
Managing Resources
Using resources includes the application of financial and human factors, and the elements of time and materials to successfully carry out a planned activity.
Elementary
3.7.1 Demonstrate an awareness of the knowledge, skills, abilities, and resources needed to complete a task. √

Intermediate
3.7.1 Understand the material, human, and financial resources needed to accomplish tasks and activities. √

Commencement
3.7.1 Allocate resources to complete a task. √
Systems
Systems skills include the understanding of and ability to work within natural and constructed systems.
Elementary
3.8.1 Demonstrate understanding of how a system operates and identify where to obtain information and resources within the system. √

Intermediate
3.8.1 Understand the process of evaluating and modifying systems within an organization. √

Commencement
3.8.1 Demonstrate an understanding of how systems performance relates to the goals, resources, and functions of an organization. √

Elementary
3.2.1	Use ideas and information to make decisions and solve problems related to accomplishing a task.	√

Intermediate
3.2.1	Evaluate facts, solve advanced problems, and make decisions by applying logic and reasoning skills.	√

Commencement
3.2.1	Demonstrate the ability to organize and process information and apply skills in new ways.	√

Elementary
3.3.1	Demonstrate the personal qualities that lead to responsible behavior.	√

Intermediate
3.3.1	Demonstrate the ability to work with others, present facts that support arguments, listen to dissenting points of view, and reach a shared decision.	√

Commencement
3.3.1	Demonstrate leadership skills in setting goals, monitoring progress, and improving their performance.	√

Elementary
3.4.1	Relate to people of different ages and from diverse backgrounds.

Intermediate
3.4.1	Demonstrate the ability to work with others, present facts that support arguments, listen to dissenting points of view, and reach a shared decision.	√

Commencement
3.4.1	Communicate effectively and help others to learn a new skill.	√

Elementary
3.5.1	Demonstrate an awareness of the different types of technology available to them and of how technology affects society.

Intermediate
3.5.1	Select and use appropriate technology to complete a task.	√

Commencement
3.5.1	Apply their knowledge of technology to identify and solve problems.	√

Standard 3b: Career Majors
details
Students who choose a career major will acquire the career-specific technical knowledge/skills necessary to progress toward gainful employment, career advancement, and success in postsecondary programs.

Prodos

Objectives

Create an open source 3D printed dynamically balancing walking robot
Demonstrate how to coordinate simple limb chain actuation using a microcontroller
Develop 8 degrees of freedom (joints) to perform a simple walking action.
Follow a set of instructions, evaluate and amend designs to ensure they work.

Prodos is a self contained bipedal robot that can walk. In the original project, the servos were not powerful enough to make Prodos move under its own weight, and the robot had to be suspended in the air to move.

Project Link

Parts

Arduino
Proto Shield
39 Printed Plastic Parts
327cc of plastic
manifest of parts, source and cost

Instructions

Considerations

How could you modify this bot so that it was self-supporting?
What is a robot?
How does the robot move? Can you do anything to improve it?

Simple Flip Flop

This simple bot is inspired by a tutorial from David Cook's http://www.robotroom.com

A common theme in robot contests is to have a robot drive straight forward to a wall, detect the barrier, and reverse straight back to the starting point. I previously posted a basic robot that accomplishes this goal uses two chips; with the direction remembered by a flip-flop. A couple of people wrote me to ask:

Can you make the robot even simpler?
My motor needs a voltage above 6V, which is the limit for the logic chip. Can you make a back-and-forth robot that permits higher voltages?

Yes! Let's build a forward-reverse robot with a single motor and only a single 8-pin off-the-shelf chip!

The robot is built on a 170 tie-point mini solderless breadboard (SparkFun PRT-08801), to make it that much easier for readers to reproduce themselves.

Back And Forth robot on solderless breadboard

Back-And-Forth robot on a solderless breadboard.

Because my robot is fairly small (35 mm x 60 mm or about 1.5" by 2.25") with a high-efficiency Swiss motor, I chose to power it from a pair of lithium CR1/3N cells for a total of 6 V. But, if you have a larger platform or more power-hungry motors, you can use a 9 V battery instead. (Note: Lithium cells such as CR1/3N, DL1/3N, and 2L76 cannot put out more than 60 mA of current, which is too little to drive most motors.)

The heart of the robot is a Clare Semiconductor IXDI604PI dual inverting 4A MOSFET driver (IC1). (The IXYS IXDI404PI can be substituted if you have some lying around, like I did.) This chip is designed to drive MOSFET transistors, but I use the chip all over the place for driving light gearmotors.

As you'll see on the schematic pages that follow, a pair of resistors (R2 & R3) feed the outputs of the motor driver chip back into the inputs, so that the chip can remember the current state.

The robot has a snap-action switch on the back (SW2) and the front (SW3) to detect collisions with walls or other obstacles. However, the circuit will work with ordinary pushbuttons or even spring whiskers passing through loops of wire.

Underside of robot with a single escap motor.

Since the robot doesn't spin or turn, only a single motor (M1) is required to provide motion. Additional wheels ① allow the robot to roll smoothly, but are not powered.

A pair of 1/8-inch holes ② permits the wires to pass up the stack from the bottom to the breadboard.

Side view of simple back and forth robot.

From top to bottom, the layers are:

Electronic components
Blue solderless breadboard
Double-sided sticky tape (unused) that electrically insulates the metal strips underneath the breadboard
Custom machined plate of blue UHMW plastic where everything screws together
Motor, wheels, and switches

Now let's look at the schematic to see how this robot works...

As you saw in the video of the robot driving backwards and forwards on the previous page, this is a fairly simple design.

Back-And-Forth robot schematic.

B1: A direct current (DC) power source with a voltage between 4.5 V and 18 V. This range was chosen from the minimum power supply requirement of the chip (IC1) to the upper limit of the input pins. You should choose a battery within this voltage range that provides the desired speed based on your motor (M1).

SW1: Power switch. When switched off, the battery is electrically disconnected. This means no current flows and the robot does nothing.

M1: A gearmotor (not a plain motor) with sufficient horsepower to push and pull your robot platform at a moderate speed. If the robot moves too quickly, it will smash into obstacles due to momentum, before it has time to change direction based on the switch press.

escap M915 L61 flat rectangular gearmotor.

Be sure your motor doesn't consume more than 400 mA of current, or else IC1 will not be able to provide enough power to get the motor to turn. I chose a nice little compact escap motor, which I obtained, used, from eBay. (Before you write to me -- no, sadly, I don't know where to obtain some more.)

IC1: IXDI604 (or obsolete IXDI404) dual inverting driver. Make sure the chip name starts with "IXDI" -- NOT "IXDN", NOT "IXDF" and NOT "IXDD". It is absolutely essential for the outputs to generate signals that are the opposite (inverting) of the inputs for this circuit to work.

This chip is officially intended for driving MOSFET transistors. As long as your motor doesn't need more than 400 mA continuously, then the chip will be fine. But, if your motor refuses to turn or the chip gets hot, then your motor or robot is too large for this circuit.

R2 and R3: 22 kilohm resistors. These resistors return signals from the outputs into the opposite inputs (described in detail over the next several pages). The relatively high resistance allows signals coming from the bumper switches (R2 and R3) to override the output values. If you're familiar with pull-up or pull-down resistors, then you can think of these resistors as performing the same function. The resistors provide default values to the input pins when the switches aren't pressed.

SW2 and SW3: Normally open (disconnected) switches. I picked snap-action switches because they have a large actuator and require very little force to activate. Any switches will do, so long as the robot has enough strength to push them when contact is made with an obstacle. You can even wire additional switches in parallel, to provide greater obstacle detection coverage.

How Does The Robot Work?

When the power switch (SW1) is turned on, the battery connects to the power supply pin (Vcc) of the motor driver chip (IC1). As the chip powers up, the output voltages are fed back into the input pins to provide a default starting state. (Technically, the initial state is random. You could add a 220 kilohm resistor from pin 6 to pin 7 to ensure the forward state is always chosen at startup.)

It helps to look at a simplified wiring diagram, where extraneous text and parts do not appear.

1. Forward state. No bumpers pressed.

To make the example concrete, let's assume the power supply is 6 V. On IC1:

Input A (pin 2) is low (0 V). The chip inverts that to set Output A (pin 7) to high (6 V).
Output A (pin 7) is high (6 V). That signal passes through R3 into Input B (pin 4) and sets it high (6 V).
Input B (pin 4) is high (6 V). The chip inverts that to set Output B (pin 5) to low (0 V).
Output B (pin 5) is low (0 V). That signal passes through R2 into Input A (pin 2), which is already low. Nothing changes. Everything is stable.

Output A and B also provide power to the motor (M1). The motor spins forward because it receives high (6 V) on one terminal and low (0 V) on the other terminal. The robot will continue to drive forward, because the output pins continue to provide the same values to the input pins.

Neither switch (SW2, SW3) is pressed. So, they have no affect on the circuit. Let's see what happens when a switch is pressed.

On the previous page, you saw the schematic for a robot that drives forwards and backwards. You also saw the starting state of moving forward.

When the robot hits its front bumper switch on an obstacle, the circuit reverses almost instantaneously. By almost, I mean about 100 nanoseconds, which is the time it takes for the signals to race through the chip (called "propagation delay) twice.

I've broken the changes down into three steps to make it easier to illustrate.

2. Front bumper pressed. Reversing step one.

When the bumper is pressed, SW3 connects Input B (IC1 pin 4) to the battery's low (0 V) terminal, which is represented by the three little horizontal lines underneath SW3. If resistor R3 wasn't included, there would be a conflict between Output A at 6 V and SW3 at 0 V. This would result in a short circuit that could damage the battery, chip, switch, or board, or just cause the robot to stop. Thankfully, we have a resistor that not only reduces the current, but drops the conflicting voltage as a little bit of heat.

The 0 V signal dominates the voltage at Input B. This is because SW3 is connected directly to the battery ground (no resistance), whereas the 6 V signal is comparatively weak due to passing through R3.

3. Front bumper pressed. Reversing step two.

Now that Input B (pin 4) is low (0 V), the chip sets Output B (pin 5) to the opposite (inverted), which is high (6 V). Everything connected to Output B must also be high. Notice the high signal passes through R2 and controls Input A (pin 2) because SW2 is open and therefore does not provide a conflicting signal.

4. Front bumper pressed. Reversing step three.

Since Input A (pin 2) is set to high (6 V), the chip sets Output A (pin 7) to the opposite (inverted), which is low (0 V). Everything connected to Output A must also be low.

And now, there is no conflict between Output A and SW3. They both agree that Input B (pin 4) should be low. No power is wasted on R3 as heat anymore.

Check out the motor (M1). The terminals are now the opposite of what they were before the switch was pressed. The motor now drives in reverse.

5. Reverse. No buttons pressed.

The robot is now backing away from the wall or obstacle. The front switch is no longer pressed. But, the robot remembers its state.

Previously, we saw how the Back-And-Forth Robot backs up. It will continue to back up until the rear switch (SW2) is pressed.

As before, the change to a forward state happens almost immediately. But, I've broken it down into three steps to help the understanding. In fact, these are the same three steps as before, just on the opposite side of the circuit.

6. Back button pressed. Forward step one.

The back button (SW2) is pressed -- perhaps because the robot backed into a wall, pet, or small child. The switch sets Input A (pin 2 of IC1) to low (0 V). This overrides the signal coming from Output B (pin 5) due to the constraining effects of resistor R2.

7. Back button pressed. Forward step two.

The chip inverts the low signal from Input A (pin 2) to set Output A (pin 7) to high. Everything connected to Output A is also set high. SW3 isn't pressed, so it doesn't matter.

8. Back button pressed. Forward step three.

Lastly, Output B is made to be the opposite of Input B. The motor terminals are set to the forward direction again. The robot drives forward.

1. Forward No bumpers pressed.

The robot drives away from the wall or obstacle, releasing SW2. We've come full circle back to the forward state again!

On previous pages, we've stepped through the changes that the Back-And-Forth robot's circuit goes through when the robot's bumper switches are pressed. If you have a browser that supports animated GIFs, then you'll see each of those changes in the animation below.

Back-And-Forth robot schematic animation.

This is pretty amazing. The motor driver chip not only supplies power to the motor, but uses those same signals to remember its state even when the switches are released.

Well, it isn't that amazing. The motor driver chip consists of two logical transistors. We add two resistors to the circuit and two input switches, and voilà, we have recreated a flip-flop. No kidding. Look up flip-flops on Wikipedia. Okay, we've created a "power" flip-flop, but it is a flip-flop none-the-less.

So, really, this is nothing more than the Flip-Flop Robot boiled to its essence.

Pressing Both Buttons

Sooner or later, either through the robot getting trapped in a corner, through an inquisitive mind, or a malevolent heart, both bumper switches (SW2, SW3) are going to become pressed at the same time. Will the robot go forward, go reverse, or keep the same state?

The answer is none of the above. The robot will safely enter a stopped state.

9. Stopped. Both bumpers pressed.

Switch SW2 forces Input A (pin 2) low, and switch SW3 forces Input B (pin 4) low. The signals from Output A and Output B are ignored at the inputs, because the signals are relatively weak after going through R2 and R3. A tiny amount of energy is wasted dropping the voltage in the resistors; but it is harmless.

Both outputs are set to the opposite of the inputs. Therefore, both outputs are high.

The motor terminals are both set to the same voltage (high), so no current flows. The motor stops.

The robot remains peacefully at rest until at least one switch is released. At that point, the robot will go whatever direction based on whichever switch is released last.

The next two pages discuss the machining of the robot's body.

The Back And Forth robot drives forward and reverse based on switch presses to a motor driver circuit. The circuit provides power to a tiny gearmotor. I need to attach a tiny wheel to the tiny gearmotor to move the robot.

It was fun for me to create a small robot. But, counter-intuitively, small robots are much more difficult to make than lunch-box size robots. If you aren't comfortable machining, then I recommend using the circuit from this robot combined with the no-machining body of the original Flip-Flop robot.

Okay. Back to the issue of attaching wheels to gearmotors. Lego makes some wonderful wheels in small sizes. Unfortunately, the wheel hubs have shaft slots designed to mate with Lego plates, not commercial gearmotors.

When experimenting with ShapeLock, I realized I could fill in Lego pieces with plastic. The plastic melts at low temperatures, so it is safe to use. And, the plastic bonds nicely to ABS, which is the type of thermoplastic of which most Lego pieces are made.

Original Lego wheel hub partially filled over filled drilled with opposite side fill

Left-to-right: Original Lego wheel hub, partially filled, overfilled, and the finished piece drilled (showing completeness of the fill on the opposite side).

I began by pulling off the black rubber tire from a small Lego wheel. Using wire snips, ShapeLock beads were cut into itty-bitty pieces and melted on a silicone cooking tray at 170 °F in a home oven. When the plastic bits turned clear, I dropped them into the center of the Lego hub, and jammed them into the crevices with a stainless steel rod and tip of a push-pin.

At first, I was going to use the hub as-is with the layers of melted plastic. But, I was concerned that the tiny layers didn't seem fused together, as they had cooled independently as I dropped in each bit. Hesitantly, I placed the Lego hub itself (with the inserted plastic) into the oven to melt everything together. Surprisingly, the Lego plastic didn't melt at that temperature, and the ShapeLock plastic congealed and flowed as desired.

Eventually, I ended up with a fully-filled Lego hub with a slight overflow.

Facing off excess plastic in a lathe.

Using a lathe, the excess plastic can be removed with a facing operation.

The ShapeLock plastic is slippery, stringy, and has such a low melting point that it can deform due to the heat caused by friction during machining. In other words, it isn't easy to machine accurately and cleanly.

Milling hole in ShapeLock plastic rather than drilling.

Rather than use a long flexible 2 mm diameter drill, which has a high likelihood of walking and bending, I switched to a stubby 2 mm diameter end mill for drilling the relatively short motor shaft hole. It works okay.

Despite my complaints about trying to machine ShapeLock, the plastic expands enough after being cut that it grabs tightly to the motor shaft. As such, I didn't even need to add a set screw to hold the wheel to the motor. (Of course, this is acceptable only because the forces are so weak on such a small robot that the wheel won't get pulled off.)

Cutting the Free Wheels

Although the Back-And-Forth robot needs only one motor for driving forward and backward, it still needs some glide pads or additional wheels to stay upright. For good looks and smooth driving, I decided to attach a pair of Lego wheels to the opposite side of the robot.

Lego produces a nice plate piece that connects to a pair of wheels. This makes it convenient to build the front or rear axles of small cars. But, I wanted the wheels individually on the same side of the robot, at the back and the front.

Free rolling wheels ① on one side.

Since I couldn't locate a one-sided axle plate, I decided to split a dual-sided plate in half.

Lego wheel plate with studs drilled for #2-56 screws.

Before splitting the piece, I drilled holes in the studs for #2-56 size screws. The plate rests on a standard 2x2 red square piece during drilling because:

The friction fit between pieces helps hold the plate during relatively low-force drilling operations.
The thin plate would have been awkward to hold with a vise, potentially tilting during drilling. The block starts it flat and keeps it steady.
Unless I control the depth exactly, the drill is going to plunge slightly deeper than necessary, which will make contact with whatever is underneath. No harm is done if the red brick gets partially drilled.

Cutting in Half

My smallest end mill is a delicate 1 mm. If I cut the plate in half, then 1 mm of middle material will be lost. If that much material compromised the integrity of the plate, I could cut up two plates, with each having a "good half" that is retained and a "bad half" that is discarded.

My thinnest miniature table saw blade is 0.02 inches, which is about half a millimeter. I figured that's a small enough loss of material to avoid destroying a second plate from my sons' Lego car collection.

Table saw Lego jig cutting a slit in a Lego wheel plate.

To cut a straight line with my fingers out of the way, I built a small jig out of Lego pieces. The long Lego brick slides against the rip fence.

Split plate well centered but a bit deeper than necessary.

The wheel-plate divided beautifully. A nice straight line down the center, without critical loss of material. And, it sure took a lot less time than machining my own shaft and bearing.

Finally, to end the article, let's look at the machining of the base plate and solderless breadboard.

The Back-And-Forth robot is slightly more complicated to put together than meets the eye. For example, one wouldn't initially suspect that ShapeLock plastic and a table saw were needed to attach the Lego wheels.

Drilling holes in small blue solderless breadboard.

Starting at the top, the attractive blue solderless breadboard needs screw holes to hold it onto the base plate, as well as holes going straight through the entire body for the motor and switch wires.

At this point, my mistake was choosing a base plate material based on the color matching the breadboard. I selected blue "premium" UHMW. It cuts almost as badly as the low-temperature prototype plastic, without the benefits.

Screw holes drilled in blue UHMW plastic need razor blade scraping.

The base plate has approximately a dozen holes; most of them threaded for screws. Each hole required delicate scraping to remove residual material.

Rough machining wheel slots in base plate.

The wheel-well slots turned out almost as ugly. Lots of "stringy burrs".

Final machining of wheel slots in base plate.

Flipping the piece upright to finish and square the slots cleaned it up a lot.

Nearly finished base plate made from premium UHMW plastic.

Ugh. You can just sense how uncooperative this plastic is from the messy and uneven base plate in the above photo. The sides of the motor slot (in the middle) were already cleaned up with my wife's best sewing scissors. Seriously, when your finest semi-professional machining skills and equipment give way to domestic tailoring tools, it is time to switch materials.

Despite these complaints, after drilling a couple of additional holes to mount the motor, the base plate really brings the robot together.

Completed one-chip back and forth robot.

The electronics snap into the solderless breadboard. The solderless breadboard screws onto the base plate. The motor, wheels, and switches also screw onto the base plate.

One of the most satisfying aspects of learning to machine your own parts is that you don't need to rely on glue, tape, or anything flimsy to connect your robot. Sure, I used a little bit of transparent tape to hold the motor wires in place, but that's an appropriate use. When the robot runs, I don't have to worry about it falling apart, even if the robot runs into walls. When the robot isn't running for some reason, I can disassemble it by unscrewing parts, and reassemble it quickly after maintenance.

However, if you're a beginner, don't let the machining dissuade you. This is an easy circuit to build on a solderless breadboard. If the remainder of your robot is cardboard, tape, and bubblegum, it will still be that much better and enjoyable than never having built anything. Go for it!

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'a'	Set pin 5 HIGH
'q'	Set pin 5 LOW
's'	Set pin 6 HIGH
'w'	Set pin 6 LOW
'd'	Set pin 7 HIGH
'e'	Set pin 7 LOW

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