What is a Robot?

What is a Robot?

• An automatic mechanical device

• Usually an electro-mechanical machine guided by a computer program or electronic circuitry.

Why use Robots?

• To go where people can’t

– To dangerous, expensive, or difficult

– radioactive areas, undersea, space, combat

• To do things people can’t or don’t want to do

– monotonous jobs

• To go where no one has gone before.

– Exploring space, the ocean, volcanoes, glaciers

• To learn engineering

• To have fun!

How do we design & build a robot?

• Designing and building is engineering

• What are goals of engineering?

– To understand human needs or desires

– To design and build tools or technology to meet those needs or desires

– To make life easier, more pleasant, & better

• Just as scientists use scientific methods, engineers follow a design process

Design Process: Relationships

• Don’t start by grabbing parts & building without thinking

• Start with who, what, when, where & how?

– Who is in charge? To whom do you report?

– Who will you work with as a team?

– What is the job? What is your part of it?

– When is the work due? When are deadlines?

– Where will you work?

– How will you document and verify your work?

– How will you deal with challenges that arise?

Design Process: Strategic Design

• What are the “rules of the game”?

– What are the ways to score points?

– How can we stop opponents from scoring points?

– What is the highest possible score?

– What is a reasonable score in a match?

– What are our backup plans if we start losing?

– What are the penalties if we break the rules?

Swept Away video

Design Process: Strategic Design

• What do we want the robot to do?– What are all the possible robot tasks for scoring?

– What are all possible robot tasks to prevent opponent scoring?

– Rank each task (1-10) on benefit toward winning

– Rank each task (1-10) on how difficult the task will be to accomplish

– Calculate benefit to difficulty ratios for each task

– Discuss and determine which tasks will give best odds of success at winning the game

Design Process: Mechanical Design

• What do we have to work with?– What materials, supplies, tools, equipment, hardware,

software, building space and time do we have to work with?

– How is the robot going to move, pick up objects, score, avoid blocking by opponents?

• What are the limitations and parameters to work within?– What are the limits on size, power, number of parts,

software, trial runs, space and time?– What are the penalties for exceeding limits or

breaking rules?

Design Process: Mechanical Design

• What are the subsystems?

– Structure = “skeleton” of the robot

• Chassis, screws, nuts, bolts, spacers, & other hardware

• Tools needed to assemble and disassemble the robot

• Concepts: center of gravity, support polygon, stability

– Motion = “muscles” of the robot

• Square shafts, gears, motors, servos

• Concepts: motors vs. servos, gear ratios, torque, speed

Design Process: Mechanical Design

• What are the subsystems?– Power = “heart and blood” pumps electric current

• Battery pack, battery box, chargers, wires

• Concepts: excessively draining, voltage drop, overcharging, trickle charge, heat

– Sensors = “eyes & ears” essential for autonomous functioning• Bumper switches, limit switch, IR sensors, light sensors

• Concepts: analog, digital, ADC, DAC

Design Process: Mechanical Design

• What are the subsystems?

– Control = radio link with a human operator

• 75 MHz transmitter & receiver, VEXnet joystick

• Concepts: frequency, FM, channels, crystals, RFI

– Logic = “brain” of the robot that coordinates flow of information and power

• VEX microcontroller, jumpers

• Concepts: input/output, digital electronics, logic gates

Design Process: Mechanical Design

• What are the subsystems?

– Programming = “rules” that govern robot behavior

• RobotC language (a version of C)

• Concepts: programming languages, tokens, syntax, comments, variables, loops, conditional statements, debugging, interpreted vs. compiled programs

Design Process: System Integration

• How are subsystems integrated into a complete working system?

– What comes first: structure, control, power?

– How do motion requirements affect structure and power subsystems?

– How do weight & speed affect power and motion?

– How do sensors affect the control subsystem?

– How do we switch between operator control mode and autonomous mode?

Design Iteration

Trial Run

Document results(observe, measure, video)

Modify(one change at a time)

Document changes(in design notebooks)

Evaluate(Decide needed changes)

Design Iteration

Trial Run

Document results(observe, measure, video)

Modify(one change at a time)

Document changes(in design notebooks)

Evaluate(Decide needed changes)

Design Iteration

Trial Run

Document results(observe, measure, video)

Modify(one change at a time)

Document changes(in design notebooks)

Evaluate(Decide needed changes)

Design Iteration

Trial Run

Document results(observe, measure, video)

Modify(one change at a time)

Document changes(in design notebooks)

Evaluate(Decide needed changes)

Play the game!(compete in final match)

Design Review