book

Robot Building for Beginners

Name: Robot Building for Beginners
Author: David Cook
ISBN: 9781430227489

by David Cook

January 2010

Beginner

488 pages

11h 49m

English

Apress

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Copyright
About the Author
About the Technical Reviewer
Acknowledgments
Introduction
Intended Audience"Where's the stuff about the killer saws?""Houston, we have a problem."Not Ready to Learn How to Solder?Beyond LEGO But Still Not Ready to Solder?Note Regarding Part ListsGetting Updates and Seeing What's New
1. Welcome Robot Inventor!
1.1. Four Disciplines1.2. Anatomy of a Homemade Robot1.2.1. Brains1.2.2. Electrical Power1.2.2.1. Power Source1.2.2.2. Power Regulation1.2.2.3. On/Off Switch1.2.3. Sensors1.2.3.1. Pushbuttons1.2.4. Action and Feedback1.2.4.1. Movement1.2.4.1.1. Motor Controller1.2.4.2. Indicator Lights1.2.5. Miscellaneous Components1.2.6. Body1.2.6.1. Aesthetics1.3. Building Up1.3.1. Taking Small Bites1.3.2. Making Modules1.3.3. Keeping It Fun and Keeping It Light1.3.4. Finding Camaraderie and Support1.4. Onward and Upward
2. Where to Obtain Tools and Parts
2.1. Ordering Free Information2.2. Discovering Hidden Messages2.2.1. Considering Columns2.2.2. Counting Pages2.2.3. Comparing Prices2.3. Saving Money
3. Safety
3.1. Benefiting from Age and Experience3.2. Following Instructions3.3. Reading Chemical Labels3.4. Donning Safety Glasses3.4.1. Hanging Glasses and Placing Them Face Up3.5. Wearing Other Safety Clothes3.6. Insuring Adequate Ventilation3.7. Storing Properly3.7.1. Talking About Your Activities, Materials, and Tools3.8. Washing Before Eating3.9. Avoiding Nasty Elements3.9.1. Lead3.9.2. Mercury3.9.3. Cadmium3.9.4. Purchasing Safer Parts Labeled RoHS3.10. Shocking3.10.1. AC vs. DC3.10.2. Using Rechargeable Batteries and Professional Transformers3.10.3. Connecting Through Circuit Breakers and GFCI Outlets3.10.4. Saving the Ground Prong3.10.5. Disconnecting Power3.11. Steering Clear of Dangerous Robots3.12. Sizing Up Motors3.13. Lighting Up3.14. Staying Rested and Level-Headed
4. Digital Multimeter
4.1. Must-Have Features4.1.1. Digital4.1.2. Digits4.1.3. DC Voltage4.1.4. DC Current4.1.5. Resistance4.1.6. Probes or Leads4.1.7. Overload/Fuse Protection4.2. Nice-To-Have Features4.2.1. Capacitance4.2.2. Diode4.2.3. Continuity4.2.4. Frequency4.2.5. Duty Cycle4.2.6. Autoranging4.2.7. Auto Power Off4.2.8. Transistor4.2.9. Dual Display4.2.10. Maximum4.2.11. Minimum4.2.12. Stand4.3. Optional Features4.3.1. Inductance4.3.2. RS-232/USB Data Interface4.3.3. Scope4.3.4. Backlight4.3.5. Stopwatch/Single Pulse Width4.3.6. Temperature4.3.7. Sound4.3.8. Count4.3.9. Bar Graph4.3.10. Data Hold4.3.11. Data Auto4.3.12. High/Low/Logic4.3.13. Memory4.3.14. Relative4.3.15. Offset4.3.16. Limit Testing/Compare4.3.17. Holster or Rubber Boot4.4. AC Features4.4.1. AC Voltage4.4.2. True RMS4.4.3. AC Current4.5. Obtaining Hook Probe Adaptors4.6. Comparing Actual Multimeters4.6.1. Understanding the Features of a Low-End Multimeter4.6.2. Understanding the Features of a Mid-Range Multimeter4.6.3. Understanding the Features of a Higher-End Multimeter4.6.4. Comparing Prices with Features4.7. Proceeding Without a Meter
5. Numbers and Units
5.1. Choosing the Metric System5.2. Reducing Powers of a Thousand5.2.1. M & m5.2.2. Alternative for Greek Micro5.3. Abbreviating Units5.4. Too Little5.4.1. Guessing Missing Units5.4.2. Expanding from Three Digits5.4.3. Converting Colors to Numbers5.4.4. Determining Component Values with a Multimeter5.5. Base Subjects Covered

6. Robot Line-Following
6.1. Defining the Course Conditions6.1.1. Surface Materials6.1.2. Course Lighting6.1.3. Defining the Line6.1.3.1. Picking Line Marking Material6.1.4. Curving and Crossing Lines6.1.5. Summarizing Course Conditions6.2. Picking the Robot's Size6.3. Seeing Sandwich6.3.1. Examining Sandwich6.3.1.1. Line-Following Switch6.3.1.2. Power Source and Power Switch6.3.1.3. Sensors and Headlights6.3.1.3.1. Placing the Robot on the Center of the Line6.3.1.3.2. Adjusting Sensor Balance6.3.1.4. Brighter-Side Indicators6.3.1.5. The Brains6.3.1.6. The Muscle6.3.1.6.1. Fitting and Changing Wheels6.3.2. Sandwich Body6.3.2.1. Connecting It Together6.3.2.1.1. Physical Connections6.3.2.1.2. Electrical Connections6.4. Obtaining a Kit6.5. Building Up
7. Nine-Volt Batteries
7.1. Testing Battery Voltage7.1.1. Setting Up a Multimeter for Voltage Testing7.1.2. Interpreting Test Results7.2. 9 V Battery Characteristics7.3. 9 V Battery Recommendations7.3.1. Recommended7.3.2. Nickel-Metal Hydride7.3.2.1.7.3.2.1.1. Retaining Charge When Not in Use7.3.3. Lithium-Polymer7.3.4. Alkaline7.3.5. Specialized Use7.3.6. Lithium7.3.7. Not Recommended7.3.7.1. Carbon and Zinc7.3.7.2. Nickel-Cadmium7.3.7.3. e2 Titanium and Ultra7.4. Battery Brand Names7.5. Using 9 V Batteries in Robots7.5.1. Mounting Batteries7.6. Powering Forward
8. Clips and Test Leads
8.1. The Gators Are Hungry Tonight8.2. Obtaining Hook Clips8.3. Testing Jumpers8.3.1. Setting Up a Multimeter for Continuity Testing8.3.2. Testing an Open Connection8.3.3. Testing a Shorted Connection8.3.4. Testing an Alligator Connection (Shorted)8.4. Discovering Unintended Connections8.5. Plumbing with Jumpers
9. Resistors
9.1. Limiting Power with Resistors9.2. Obtaining a Resistor Variety Pack9.3. Understanding Size and Tolerance9.4. Cut It Out9.4.1. Obtaining a Wire Cutter Tool9.5. Resistance and Ohms9.6. Measuring Resistance9.6.1. Interpreting the Resistance Displayed on the Meter9.6.2. Experiencing Resistance Ranges9.7. Looking Up Resistor Values Online9.8. Labeling and Storing9.8.1. Obtaining Storage Cases9.9. Resisting the Temptation to Skip Ahead
10. LEDs
10.1. Learning About LED Attributes10.1.1. LED Sizes10.1.1.1. Using Calipers to Measure LED Diameter10.1.2. LED Shapes10.1.3. LED Lens Clarities10.1.3.1. Water Clear10.1.3.2. White Diffused10.1.3.3. Colored Diffused10.1.4. LED Viewing Angles10.1.5. LED Colors10.1.5.1. Relating Color to a Wavelength10.1.5.2. Indicating Color via the CIE Standard Colorimetric System10.1.6. LED Brightness10.1.6.1. Super Ultra High Brightness to the Max10.1.7. LED Efficiency10.2. Extreme Close Up of an LED10.3. Identifying Multicolor LEDs10.3.1. Bicolor10.3.2. Tricolor or Tri-state10.3.3. Full Color10.4. Testing an LED10.4.1. Setting Up a Multimeter for Diode Testing10.4.2. Interpreting LED Test Results10.4.2.1. Forward Voltage Drop10.5. Variety Pack10.6. Brightening Your Way
11. Power On!
11.1. Introducing the Parts List11.1.1. Testing the Parts Before Assembly11.2. Reading a Schematic11.3. Building the Power Indicator Circuit11.3.1. Do You See The Light?11.3.2. Experimenting with the Power Indicator Circuit11.4. Understanding the Roles of Each Component11.5. Measuring the Power Indicator Circuit11.5.1. Measuring In-Circuit Voltage11.5.1.1. Measuring Voltage "At" a Point11.5.1.2. Measuring Voltage "Drop" or Voltage "Across" a Part11.5.1.3. Summarizing Circuit Voltage11.5.2. Measuring Current Flow11.5.3. Calculating Battery Life11.5.3.1. Extending Battery Life11.5.3.2. Selecting Resistors11.5.3.3. Calculating Current11.5.3.3.1. Minimum Resistor for LED Formula11.5.4. Don't Measure Voltage with Probe in Current Terminal11.6. Circuit Summary
12. Solderless Prototyping
12.1. Needing A Better Way12.2. Solderless Breadboards12.2.1. Connecting with Holes12.2.1.1. 5-Position Group12.2.1.2. Center Gap12.2.1.3. 25-Position Distribution Bus12.2.2. Binding Posts12.2.2.1. Banana Plugs12.2.3. Hungry for Breadboards12.3. Solderless Breadboard Wire12.3.1. Choosing Jumper Wire12.3.1.1. Obtaining Reinforced Jumper Wire12.3.1.2. Obtaining Flat, Ready-Made Jumper Wire12.4. Making Your Own Jumper Wire12.4.1. Stripping the Insulation Off of the End of the Wire12.4.1.1. Choosing Wire Strippers12.4.2. Cutting the Wire to Length12.4.3. Bending the End of the Wire12.4.3.1. Selecting Electrical Pliers12.4.3.1.1. Obtaining Smooth-Jaw Needle-Nose Pliers12.4.3.1.2. Obtaining Serrated-Jaw Long-Nose Pliers12.5. Making The Connection
13. Solderless Breadboard Setup
13.1. Considering Power Sources13.1.1. Obtaining 9 V Battery Snap Connectors13.1.2. Connecting Power to Binding Posts13.2. Choosing a Power Switch13.2.1. Understanding SPDT13.2.2. Adding a Power Switch to the Breadboard13.3. Connecting Power Buses13.3.1. Adapting Multimeter Probes Using Jumper Wire13.3.2. Connecting the Lower Bus13.3.3. Split Down the Middle13.4. Installing a Power Indicator LED13.4.1. Checking Voltages at Certain Points13.4.2. Trimming Leads13.5. Demystifying the Robot's Power Switch13.6. Ready for More
14. Variable Resistors
14.1. Potentiometers14.1.1. Trimpot14.1.2. Turning the Dial14.1.3. Obtaining Assorted Trimpots14.1.4. Testing Potentiometers14.1.4.1. Measuring the Maximum Resistance of a Potentiometer14.1.4.2. Measuring the Variable Resistance of a Potentiometer14.1.4.3. Linear Versus Logarithmic/Exponential14.2. Variable Brightness LED Circuit14.2.1. Building the Variable Brightness LED Circuit14.3. Brightness Balancing Circuit14.3.1. Building the Brightness Balanced LEDs Circuit14.4. Cadmium-Sulfide Photoresistors14.4.1. Obtaining Assorted Photoresistors14.4.2. Experiencing the Variable Resistance of a Photoresistor14.5. Light-Controlled Circuit14.6. Balanced Brightness-Sensing Circuit14.6.1. Part List for Balanced Brightness-Sensing Circuit14.6.2. Brightness-Sensing Pairs14.6.3. Matching Photoresistors14.6.4. Resistance-Balancing Potentiometer14.6.5. Current-Limiting Resistor14.6.6. Test Points14.6.6.1. Calculating the Voltages14.6.6.2. Evaluating Test Point 114.6.7. Converting Resistance to Voltage with a Voltage Divider14.6.8. Building the Balanced Brightness-Sensing Circuit14.6.9. Inability to Balance the Brightness-Sensing Circuit
15. Comparators
15.1. Voltage Comparator15.1.1. Examining the LM39315.1.1.1. Turning to the Datasheet15.1.1.2. Inspecting the Pinouts15.1.1.2.1. Locating the Power Supply Pins15.1.1.2.2. Identifying the Comparators15.1.2. Obtaining Comparators15.2. Brightness Comparator Circuit15.2.1. Comparing a Schematic with a Wiring Diagram15.2.2. Labeling Parts15.2.3. Drawing Connected and Unconnected Wire15.2.4. Understanding the Brightness Comparator Circuit15.2.5. Parts List for the Brightness Comparator Circuit15.2.6. Building the Brightness Comparator Circuit15.2.6.1. Having Fun with the LED Indicators and Light Sensors15.2.6.2. Diagnosing Problems in the Brightness Comparator Circuit15.2.6.2.1. Confirming Power Across the Board15.2.6.2.2. Faking Input to the Comparator15.3. Adding Headlights15.3.1. Understanding the Headlight Circuit's Two LEDs15.3.2. Building the Headlight Circuit15.3.3. Repeating the Multiple LED Trick15.3.3.1. Determining the Number of LEDs that the Battery Voltage Can Support15.3.3.2. Calculating the Maximum Current Draw15.4. Appreciating a Simple Mind
16. Transistor Switches
16.1. Defining Negative Power16.1.1. Focusing on the 2907A Transistor16.1.1.1. Pushing the 2907A's Button16.1.1.2. Checking the Datasheet16.1.1.3. Obtaining 2907A Transistors16.2. Testing Bipolar Transistors with a Multimeter16.2.1. Testing with a Multimeter that Has a Transistor Socket16.2.1.1. Testing a Transistor When You Have the Datasheet16.2.1.1.1. Understanding the Importance of Transistor Gain16.2.1.1.2. Gain Varies from Transistor to Transistor16.2.1.1.3. Switching Off and On Rather Than Amplifying16.2.1.2. Testing a Transistor When You Don't Have the Datasheet16.2.2. Testing with a Multimeter that Has a Diode Test16.3. Bipolar Transistor Test Circuits16.3.1. Examining the Schematic for the PNP Transistor Test Circuit16.3.1.1. Dimming the LED for Reverse Connections16.3.2. Building the PNP Transistor Test Circuit16.3.2.1.16.3.2.1.1. Correcting Problems with the PNP Transistor Test Circuit16.3.2.1.2. Experimenting with the Functioning PNP Transistor Test Circuit16.3.2.1.3. Gathering Data About the PNP Transistor16.3.3. Examining the Schematic for the NPN Transistor Test Circuit16.3.4. Building the NPN Transistor Test Circuit16.4. Brightness Comparator Circuit with Transistors16.4.1. Calculating Current-Limiting Transistors16.4.1.1. Identifying Stresses Beyond Official Limitations16.4.1.1.1. Taking Into Account the LM393's Worst-Case Minimum Limit16.4.1.1.2. Looking Out for Heavy Current Through the Attached Circuit16.4.2. Building the Brightness Comparator Circuit with Transistors16.5. Summarizing PNP and NPN Transistors
17. DC Motors
17.1. How DC Motors Work17.1.1. Looking Inside an Iron-Core Permanent-Magnet DC Brush Motor17.1.1.1. Stator17.1.1.2. Rotor17.1.1.2.1. Rotor Windings17.1.1.2.2. Rotor Shoes17.1.1.2.3. Rotor Commutator17.1.1.2.4. Rotor Brushes17.1.2. Looking Inside an Iron-Core Permanent-Magnet DC Brushless Motor17.1.2.1.17.1.2.1.1. Living Longer Without Brushes17.1.2.1.2. Switching with Brushless Circuitry17.1.2.1.3. Limitations of Brushless Motors17.1.3. Looking Inside a Coreless Permanent-Magnet DC Brush Motor17.1.3.1. Comparing Coreless vs. Iron Core17.2. Simple DC Motor Circuit17.2.1. Selecting a Motor for the Simple DC Motor Circuit17.2.2. Selecting a Battery for the Simple DC Motor Circuit17.2.3. Building the Simple DC Motor Circuit17.3. Primary Characteristics of DC Motors17.3.1. Rotational Speed Characteristic of DC Motors17.3.1.1. Measuring RPM17.3.1.1.1. Mounting Putty Aids Motor Experimentation17.3.1.2. Converting RPM to a Metric Unit17.3.2. Torque Characteristic of DC Motors17.3.2.1. The Significance of Distance in Torque17.3.2.2. Sliding Torque17.3.2.3. Calculating Torque Needed for a Robot17.3.3. Voltage Characteristic of DC Motors17.3.3.1. Understanding the Relationship Between Voltage and Speed17.3.3.1.1. Watching Out for the Relationship Between Voltage and Speed17.3.4. Current Characteristic of DC Motors17.3.4.1. Examining Periods of Widely Changing Current Consumption17.3.4.1.1. Start-Up Current17.3.4.1.2. No-Load Current17.3.4.1.3. Load Current17.3.4.1.4. Stall Current17.3.4.2. Planning for Current Consumption17.3.5. Efficiency Characteristic of DC Motors17.3.6. Audible Noise Characteristic of DC Motors17.3.6.1.17.3.6.1.1. Oiling the Rotor Shaft17.3.7. Electrical Noise Characteristic of DC Motors17.3.8. Mass Characteristic of DC Motors17.3.9. Dimension Characteristic of DC Motors17.3.10. Summarizing the Characteristics of DC Motors17.4. DC Gearhead Motors17.4.1. Looking Inside a Spur Gearhead Motor17.4.1.1. Revealing Pairs of Smaller and Larger Gears17.4.1.2. Gearbox Shaft17.4.2. Describing Gear Ratios17.4.2.1. Absolute Gear Ratio17.4.2.2. Simplified Gear Ratio17.4.2.3. Odd Gear Ratios17.4.2.4. Indicating Both Absolute and Simplified Gear Ratios17.4.2.5. Using a Colon17.4.2.6. Looking at Real Gears17.4.3. Imperfect Speed to Torque Conversion17.4.4. Disadvantages of Gearheads17.4.5. Comparing Planetary Versus Spur Gearhead Motors17.4.6. Choosing a Gearhead Motor17.5. Moving Forward
18. Adding Gearhead Motors
18.1. Selecting Gearhead Motors18.1.1. Obtaining the Gearhead Motors18.1.2. Inspecting the Gearhead Motor18.1.2.1. Current Usage of the Gearhead Motor18.1.2.1.1. Determining the Least Current (Best Case)18.1.2.1.2. Determining the Most Current (Worst Case)18.1.2.1.3. Determining the Actual Current (Average Case)18.2. Adding Motors to the Brightness Comparator Circuit18.2.1. Introducing the Diode18.2.1.1. Protecting the Transistor with a Flyback Diode18.2.1.2. Picking the Schottky Barrier Diode18.2.1.3. Obtaining Schottky Barrier Diodes18.2.2. Building the Motors onto the Brightness Comparator Circuit18.2.2.1. Connecting the Diode in the Proper Orientation18.2.2.2. Connecting the Motor18.2.2.3. Repeating the Setup for the Other Transistor18.2.2.4. Testing the Motors18.3. Completing the Electronics
19. Wheels
19.1. Anatomy of a Wheel19.2. Characteristics of Robot Wheels19.2.1. Creamy Air Filling19.2.1.1. Effects of Air19.2.2. Tire Shapes19.2.3. Tire Width19.2.4. Tread Designs19.2.5. Tire Diameter19.2.5.1. Calculating Linear Speed19.2.6. Selecting Robot Wheels19.2.6.1. Reasons for Choosing LEGO Wheels19.3. Wheel Choice for Sandwich19.3.1. Determining Minimum and Maximum Diameter19.3.2. Determining the Maximum Diameter Based on Speed19.3.3. My Choice of Wheels for Sandwich19.3.4. Alternative Choices of Wheels for Sandwich19.3.4.1. Compensating for Larger Wheels with Lower Voltage Batteries19.3.4.2. Obtaining New Alternative Wheels19.4. Cleaning Tires19.5. Rolling Along
20. Coupler
20.1. Alternatives20.1.1. Making Couplers If You Have Metal-Working Equipment20.2. Tubing20.2.1. Choosing Between Brass and Aluminum Tubing20.2.2. Specifying and Obtaining Tubing Sizes20.2.2.1. Telescoping Tubing Required20.2.2.2. Fitting the LEGO Cross Axle into a Tube20.2.2.3. Fitting the Motor Shaft into a Tube20.3. Measuring and Cutting the Tubing20.3.1. Determining and Marking Tube Lengths20.3.2. Cutting Tubing20.3.2.1. Tube Cutter Tool20.3.2.2. Variable-Speed Rotary Tool20.3.2.2.1. Securing the Tubing in a Vise20.3.2.2.2. Cutting the Tubing with a High-Speed Rotary Tool20.3.3. Finishing the Cut by Sanding20.3.4. Testing the Cut Pieces20.4. LEGO Cross Axles20.4.1. Selecting a LEGO Cross Axle Length20.4.2. Obtaining LEGO Cross Axles20.5. Gluing the Coupler Together20.5.1. Coming Unglued20.5.1.1. Notching the Cross Axle20.5.2. Using Epoxy20.5.2.1. Removing Extraneous Epoxy20.6. Adding a Setscrew to the Coupler20.6.1. Marking a Hole for the Setscrew20.6.2. Drill Press20.6.3. Drill-Press Vise20.6.4. Drilling the Hole for the Setscrew20.6.5. Tapping the Hole for the Setscrew20.6.6. Inserting the Setscrew20.7. Admiring the Coupler
21. Soldering Equipment
21.1. Solder Wire21.2. Flux21.3. Soldering Iron21.4. Soldering Stand21.5. Soldering Sponge21.6. Helping-Hand Tool21.7. Desoldering Vacuum Tools21.8. Steps of a Typical Soldering Session21.9. Get Ready to Solder
22. Soldering and Connecting
22.1. Putting Together the Motors and Switches22.1.1. Putting Together the Motors22.1.1.1. Preparing and Attaching the Motor Wires22.1.1.2. Holding the Motor Firmly and Preparing the Soldering Iron22.1.1.3. Soldering the Motors22.1.1.3.1. In Soldering, Practice Makes Perfect22.1.1.4. Protecting Soldered Joints with Heat-Shrink Tubing22.1.1.4.1. Obtaining Heat-Shrink Tubing22.1.1.4.2. Protecting the Motor Terminals with Heat-Shrink Tubing22.1.1.5. Adding Connectors22.1.1.5.1. Molex KK Connectors22.1.1.5.2. Obtaining Molex KK Equipment22.1.1.5.3. Attaching Molex KK Connectors to the Motors22.1.2. Putting Together the Line-Following Switch22.1.2.1. Obtaining the Line-Following Switch22.1.2.2. Preparing and Attaching the Switch Wires22.1.2.3. Soldering the Line-Following Switch22.1.2.3.1. Reasoning Behind the Diagonal Cross Over22.1.2.3.2. Finishing Soldering the Line-Following Switch22.1.3. Putting Together the Tube LED Circuit22.1.3.1. Examining the Tube LED Circuit Schematic22.1.3.2. Building the Tube LED Circuit22.1.4. Finishing Up22.1.4.1. Obtaining the Power Switch22.2. Soldering Experience
23. The Motherboard
23.1. The Line-Following Circuit23.1.1. Tweaking For Better Performance23.1.2. Point-to-Point Soldering Versus a Printed Circuit Board23.1.3. Point-to-Point Soldering the Line-Following Circuit23.1.3.1. Laying Out the Line-Following Circuit Components23.1.3.1.1. Placing Components with a Helping Hand23.1.3.1.2. Example Layout23.1.3.1.3. Obtaining an IC Socket23.1.3.2. Keeping the Components on the Board During Soldering23.1.3.2.1. Gluing the Molex KK Headers to the Circuit Board23.1.3.2.2. Bending Component Leads23.1.3.3. Creating Power Distribution Buses23.1.3.4. Soldering the Remaining Components23.1.3.4.1. Soldering the Cadmium-Sulfide Photoresistors23.1.3.5. Trimming Leads with Wire Snips23.1.3.6. Cleaning the Board23.2. Testing the Robot's Electronics23.2.1. The Dangers of a Low-Resistance Circuit23.2.2. Checking for Unsoldered Leads23.2.3. Checking All Leads that Connect Directly to Positive Voltage23.2.4. Measuring the Resistance of the Entire Circuit23.2.4.1. Measuring the Power Off Resistance23.2.4.2. Measuring the Power On Resistance23.2.4.3. Measuring the Sensor Resistance23.2.5. Measuring the Voltage Drop23.2.6. Reheating Solder Joints23.3. Holding Your Breath
24. Body Building
24.1. Approaching Robot Bodies24.1.1. Ethereal Drafting—Thinking About the Robot24.1.2. Vision Revision—Accepting Constraints Based on Available Parts24.1.3. Designing Custom Bodies24.1.3.1. Plastic Prototyping—Constructing Models with LEGO Bricks24.1.3.2. Material Substitution—Transitioning Out LEGO Parts24.1.3.3. Origami Helper—Bending Paper Before Bending Metal24.1.4. Embracing Prefabricated Platforms24.1.4.1. Commercially Available Robot Platforms24.1.4.2. Converting and Recycling Everyday Items for Robot Bodies24.2. Transforming the Sandwich Container24.2.1. Creating Motor Holes24.2.1.1. Marking and Determining Space Required By the Circuit Board24.2.1.2. Creating a Template Sticker for the Motor Holes24.2.1.3. Positioning the Template Stickers on the Container's Sides24.2.1.4. Making Pilot Holes and Drilling Screw Holes24.2.1.5. Introducing the Grinding Stone Accessory24.2.2. Mounting the Motors24.2.2.1. Obtaining Metric Screws24.2.2.2. Needing Washers24.2.3. Creating the Motor Tube24.2.3.1. Obtaining the Motor Tube24.2.3.2. Cutting the Motor Tube24.2.3.3. Sanding the Motor Tube24.2.3.4. Removing the Label Residue24.2.3.5. Widening the Motor Diameters24.2.4. Installing the Motors and Tube24.2.5. Adding the Switches and Battery Holder24.2.5.1. Installing the Power Switch24.2.5.2. Installing the Line-Following Switch24.2.5.3. Installing the 9 V Battery Holder24.2.6. Adding the Circuit Board24.2.6.1. Circuit Board Mounting Hardware24.2.6.2. Selecting and Obtaining Spacers24.2.6.3. Installing the Circuit Board24.2.7. Drilling Holes for the Trimpots24.2.8. Carving Out a Window in the Container Lid24.2.9. Finishing Touches24.3. Ready to Roll
25. Launching the Line-Follower
25.1. Correcting and Tweaking25.1.1. Preliminary Examination25.1.1.1. Checking the Power Supply25.1.1.2. Checking the Sensors25.1.1.3. Balancing the Sensors25.1.1.4. Checking the Motors25.1.1.5. Determining the Light and Dark Positions of the Line-Following Switch25.1.2. Trial Run: Following a Straight Line25.1.3. Correcting Common Problems25.1.3.1. Line-Following Switch Toggled to Incorrect Position25.1.3.2. Sensors Placed Too High or Too Low25.1.3.3. Headlights Too Dim or Too Bright25.1.3.4. Objectively Evaluating the Sensors and Headlights25.1.3.4.1. Expected Voltages at the Sensor Test Points25.1.3.4.2. Acceptable Ranges of Voltages at the Sensor Test Points25.1.4. Does This Look Straight to You?25.1.4.1. Following a Dark Line25.1.4.2. Following a Light Line25.2. The Maiden Voyage25.2.1. Solving Steering Problems25.2.1.1. Reducing Battery Voltage25.2.1.2. Reducing Wheel Size25.2.1.3. Modifying the Course25.3. Potential Improvements25.3.1. Protecting Against a Reversed Battery25.3.2. Eliminating Surges with Capacitors25.3.3. Improving Line-Following25.3.3.1. Analyzing Cornering, Frame By Frame25.3.3.1.1. Braking to Pivot25.4. Final Bow
26. Encore
26.1. Robot Components26.1.1. Logic Chips26.1.1.1. Beyond the Golden Age of Logic Chips26.1.2. Microcontrollers26.1.2.1. Capabilities of Microcontrollers26.1.2.2. Microcontroller Costs26.1.2.3. Choosing a Microcontroller26.1.3. Voltage Regulators26.1.3.1. Voltage Regulator Packages26.1.3.2. Voltage Regulator Types26.1.3.3. Selection Criteria26.1.4. Capacitors26.1.4.1. Capacitor Roles26.1.4.2. Capacitor Characteristics26.1.5. Solar Power26.1.5.1. BEAM Robots26.1.6. Resistor Networks26.1.7. Pushbuttons26.1.8. DIP Switches26.1.9. Jumpers and Shorting Blocks26.1.10. Tilt Sensor26.1.11. Temperature Sensors26.1.12. Touch Sensors26.1.13. Object Detection and Infrared Remote Control26.1.14. Distance and Object Sensor26.1.15. Oscillators and Crystals26.1.16. Sound26.1.17. Relays26.1.18. Adding Gears26.1.19. Servos26.1.20. Encoders—Determining Wheel Speed26.1.21. Displays26.1.22. Wireless Data and Control26.2. Everyday Challenges26.2.1. Houseplant-Watering Robot26.2.2. Compost Cart26.2.3. Trash Emptier26.2.4. Window Washer26.2.5. Roof Rat26.2.6. Micro Snowplow26.2.7. Slug Squisher26.2.8. Automatic Street mailbox26.3. Contests26.3.1. Worldwide Robot Sumo26.3.2. Trinity College Fire-Fighting26.3.3. Atlanta Robot Vacuuming26.3.4. Seattle Robotics Society Robothon26.3.5. Dallas Personal Robotics Group Roborama26.3.6. Central Illinois Robotics Club26.3.7. Chicago Area Robotics Group (Chibots)26.4. The Great Wide Open
27. Appendix
27.1. Magical Ohm's Law27.1.1. Ohm's Law is Helpful in Selecting a Current-Limiting Resistor27.1.2. Help in Determining Current from a Voltage27.1.2.1. Multimeter Voltage to Current Trick27.1.3. The Key Point of Ohm's Law27.1.4. The Larger Implication of Ohm's Law27.2. Things I've Accidentally Destroyed While Writing This Book27.2.1. Which Way Does a 9 V Battery Get Installed?27.2.2. Melting Switches27.2.3. Popping Multimeter Fuses27.2.4. Fool Me, Twice27.3. Voltage's Real Name27.3.1. Ground, Not Negative Voltage27.3.2. V Double Letter27.3.2.1. Practical Example

Content preview from Robot Building for Beginners

Chapter 14. Variable Resistors

The brightness sensors and balancing dial at the front of Sandwich are variable resistors. In this chapter, you'll learn about variable resistors and you'll prototype the first portion of the line-following circuit. Along the way, you'll run across techniques for simplifying schematics.

Thus far, the resistors you've experimented with have had fixed values. That is, their resistance stays the same all the time.

For the LED power indicator circuit, the brightness of the LED is based on the value of the resistor installed. To change the brightness, you need to remove the resistor and replace it with a resistor of a different value. It would be nice if the circuit had a resistor that could alter its value so that you ...

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Robot Building for Beginners

by David Cook

Chapter 14. Variable Resistors

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