Robotics Fundamentals

A robot is a machine that senses its surroundings, makes a decision with a program, and acts with motors or other parts. A remote-controlled toy is not a robot; a robot vacuum that turns at a wall is.

• Sense: sensors turn the world into numbers (distance, light, touch, tilt).
• Think: a controller runs a program of rules (if the front is blocked, turn).
• Act: actuators such as motors, servos, lights and grippers.
• Feedback: the robot senses the effect of its action and corrects, like a thermostat.
• Industrial, service and educational robots differ mainly in size, power, safety rules and cost.

Activity. Draw the sense-think-act diagram for three machines around you (for example a lift, an automatic door, a washing machine).

Standard to meet. Name one sensor, one rule and one actuator in each diagram.

Most robot accidents come from skipping a simple check. Make safety a habit before the first motor turns.

• Low voltage only: keep every supply at or below 12 V in this course.
• Check polarity (plus and minus) before connecting; reversed batteries can damage parts and heat wires.
• Fit a main power switch in the battery line and an easy stop in the code.
• Never charge or leave lithium batteries unattended; use the charger made for that battery; stop if a pack swells or smells.
• Test with wheels lifted off the table first. Keep fingers, hair and sleeves clear of moving parts.
• Wear eye protection when cutting, soldering or testing; solder only with a trained supervisor.

Activity. Write a one-page safety card for your build and sign it with your supervisor.

Standard to meet. List voltage, fuse or protection, switch, charging rule and first-test method on the card, and get the supervisor to sign.

Choose the right motor for the job. Three types cover most small robots.

• DC gear motor: spins continuously; speed rises with voltage; gearing trades speed for pushing force (torque).
• Servo: turns to an angle and holds it; good for arms and steering.
• Stepper: moves in fixed steps; good for exact positions without feedback.
• A motor driver board switches the motor power; a controller pin cannot drive a motor directly.
• PWM (pulse width modulation) changes average power by switching fast: 50% duty is about half power.

Activity. Test motor speed at 25%, 50%, 75% and 100% duty and record distance covered in 5 seconds.

Standard to meet. Complete the table with units, show the speed rising with duty, and note any stall or heat.

Sensors are never perfect. Learn what they measure, their range and how they mislead.

• Distance (ultrasonic or infrared): range from a few centimetres to a few metres; soft or angled surfaces confuse them.
• Line sensors: reflected light differs on dark and light surfaces; room light changes readings, so calibrate.
• Touch switches: simple and reliable bumpers.
• Tilt and motion (IMU, a motion sensor chip): gives rotation and acceleration; readings need smoothing.
• Calibrate: record readings on black and white, then set the threshold half way. Test again at the room's real light.
• Noise: average several readings to smooth jumps.

Activity. Calibrate two sensors and record raw readings in three lighting conditions.

Standard to meet. Complete the readings table, calculate the threshold, and test and note behaviour in each light.

A small controller board runs your rules. Three ideas cover most beginner programs: variables, conditions and loops.

• Variables store readings and settings, for example speed = 150.
• Conditions choose actions: if left sensor sees the line then turn left.
• Loops repeat forever: read, decide, act.
• Write in small steps: first read and print a sensor value, then move one motor, then combine.
• Add comments and names that say what a thing means.
• Test one change at a time; keep a version of the working program.

Activity. Write, run and comment a program that prints sensor values, then one that drives straight for 2 seconds and stops.

Standard to meet. Run programs without error, explain each block with comments, and save a version.

Every build needs enough power. Use three ideas: voltage (push), current (flow) and capacity (storage).

• Ohm's law: V = I x R (volts = amps x ohms). A 6 V supply across a 12 ohm load gives 0.5 A.
• Power P = V x I. 6 V x 0.5 A = 3 W.
• Battery runtime (ideal) = capacity in mAh divided by current in mA. Real runtime is about 70% of ideal because of losses and ageing.
• Use wire thick enough for the current and a fuse above normal current but below the wire rating.
• Keep motor power wiring away from sensor signal wires to cut noise.
• Draw the wiring diagram before you build and check each connection against it.

Activity. Calculate current, power and runtime for your robot and compare with a timed run.

Standard to meet. Show units in calculations, and keep measured runtime within 30% of the prediction or explain the gap.

Build in stages and test at every stage. Write down what you expect before each test.

• Stage 1: chassis, motors, wheels, switch and fuse; test with wheels lifted.
• Stage 2: sensors; read and print values.
• Stage 3: simple rules; run on a taped course.
• Stage 4: tune speed and thresholds one at a time.
• A test plan has: goal, setup, steps, expected result, actual result, fix.
• Run each test five times; a robot that works once is not yet reliable.

Activity. Build, tune and test; record at least five tests in a table.

Standard to meet. Pass 3 of 5 final runs with the robot, show the fixes made in the test table, and verify the safety switch.

Good robot builders find faults fast, write them down and ask what the machine should and should not do.

• Debug in order: power, wiring, sensor readings, code logic, mechanics. Change one thing at a time.
• Document: parts list with cost, wiring diagram, program, test table, photos, lessons learned.
• Ethics and safety: who could be hurt, who is replaced, who is watched. Keep humans in charge of anything risky.
• Jobs: technician, maintenance, integration, programming assistant, education, field service.
• Limits: this course does not qualify anyone to work on industrial robots; that needs formal training and machine-safety knowledge.

Activity. Complete your build file and present it for 10 minutes to a peer circle, including one ethics question.

Standard to meet. Include all six items in the file, present one fault found and one limit, and collect written feedback from two peers.

On the slide: L1 Basic · Parts of a robot

Notes: Name the sense, think and act parts of a simple robot. Notes: use a toy or a picture; learners label sensor, controller and motor with no powered kit.

On the slide: L2 Awareness · Safe handling

Notes: Follow low-voltage and battery safety rules and say why wheels are lifted for the first test. Notes: run a walk-through of the switch, the charger match and the lifted-wheel test before any power is applied.

On the slide: L3 Foundation · Wire and drive a motor

Notes: Wire a motor driver and make a motor turn both ways at two speeds. Notes: check the 50 per cent duty setting gives about half the speed; learners record voltage and current.

On the slide: L4 Practitioner · Line follower or obstacle stopper

Notes: Build and test a small robot and write its threshold from real readings. Notes: practice case is 900 on white and 300 on black, threshold 600; learners repeat with their own sensor.

On the slide: L5 Specialist · Debug and improve

Notes: Find faults using a test log and improve reliability and battery life. Notes: use 2400 mAh at 800 mA, which gives 3 hours ideal and about 2.1 hours real; learners compare their robot to the estimate.

On the slide: L6 Advanced · Mentor a build group

Notes: Supervise a group build, check safety and mark each log. Notes: use a safety sign-off sheet; learners must not allow industrial machines in the course.

On the slide: L7 Super expert · Specify a robot project

Notes: Write a project specification with safety case, test plan and budget for a larger low-voltage robot. Notes: review risks, parts and a test plan; the work stays under the 12 V and no-mains limits of this course.