Understanding robot components from a designer's perspective: what they enable, not how they work internally. Learn to choose parts based on the capabilities and behaviors you want to create.
Sensors are a robot's senses. Just as humans have five senses, robots use sensors to perceive their environment. The sensors you choose determine what your robot can "know" about the world.
The sensors you choose fundamentally shape your robot's behavior. A robot with only touch sensors behaves like someone navigating in the dark - reactive and cautious. Add distance sensors and it gains spatial awareness. Add a camera and it can recognize faces.
Like human perception: Imagine designing experiences for someone who can only hear (ultrasonic sensor), versus someone who can see (camera), versus someone who can feel texture (touch sensor). Each sense opens different interaction possibilities.
What they enable: Obstacle avoidance, following objects, maintaining distance from walls/people
Common types:
Design use cases: Self-driving toys, personal space robots, navigation systems
What they enable: Following light/dark, detecting day/night, line following, basic color detection
Common types:
Design use cases: Light-seeking behaviors, color-sorting, nightlight robots, solar-tracking
What they enable: Collision detection, button presses, tactile interaction, grip sensing
Common types:
Design use cases: Pet-like responses to petting, collision avoidance, grip feedback, interactive surfaces
What they enable: Sound-activated behaviors, clap detection, voice control, noise monitoring
Common types:
Design use cases: Sound-reactive art, voice-controlled robots, musical robots, noise-level monitors
What they enable: Balance, tilt detection, gesture recognition, motion detection
Common types:
Design use cases: Balancing robots, gesture control, self-leveling platforms, security detection
What they enable: Face recognition, object tracking, QR code reading, visual navigation
Common types:
Design use cases: Face-following robots, visual search, AR markers, autonomous navigation
Actuators are a robot's muscles. They convert electrical signals into physical action - movement, sound, light. The actuators you choose determine what your robot can physically do and express.
Your choice of actuators defines your robot's physical vocabulary. Wheels enable navigation, servos enable gestures, LEDs enable emotional expression through light. Each actuator type opens different expressive possibilities.
What they enable: Wheels, fans, continuous spinning, variable speed movement
Common types:
Control: Requires motor driver (L298N $3, TB6612 $5) for direction and speed
Design use cases: Mobile robots, vehicles, spinning kinetic art, propellers
What they enable: Limbs, grippers, camera pan/tilt, precise angle control
Common types:
Design use cases: Gesturing robots, grippers, head/eye movement, animatronics
What they enable: CNC-like precision, repeatable positioning, smooth slow motion
Common types:
Control: Requires stepper driver (ULN2003 $2, A4988 $5)
Design use cases: Drawing robots, plotters, precise art installations, scanning mechanisms
What they enable: Status indication, emotional display, environmental feedback, art
Common types:
Design use cases: Emotional displays, status lights, ambient lighting, wearable tech, art installations
What they enable: Text, images, UI, expressions, data visualization
Common types:
Design use cases: Robot faces, data dashboards, interactive interfaces, status screens
What they enable: Beeps, music, voice, sound effects, feedback
Common types:
Design use cases: Voice responses, musical robots, notification sounds, accessibility features
Controllers are the robot's brain - processing sensor data, making decisions, and controlling actuators. Your choice between Arduino and Raspberry Pi fundamentally shapes what your robot can do.
This is often the first major decision in robot design. Arduino excels at real-time sensor/motor control. Raspberry Pi excels at complex computation, vision, and networking. Many advanced robots use both.
Best for: Sensor-motor coordination, precise timing, simple logic, low power
Popular boards:
Programming: Arduino IDE (C++), block-based options available
Choose Arduino when: Your robot needs precise motor control, quick sensor response, runs on battery, doesn't need AI/vision
Best for: Computer vision, AI/ML, voice recognition, complex logic, web servers
Popular boards:
Programming: Python (beginner-friendly), also C++, JavaScript, etc.
Choose Raspberry Pi when: Your robot needs camera vision, speech recognition, learning/AI, web connectivity, complex decisions
Arduino + Raspberry Pi combo: Pi handles vision/AI, Arduino handles motors/sensors
Communication: Connect via USB serial or I2C bus
Example architecture:
Use case: Advanced autonomous robots, vision-guided vehicles, AI pet robots
Arduino wins:
Raspberry Pi wins:
Power management and wireless communication are often overlooked but critical design constraints. Battery choice affects runtime, weight, and robot size. Communication method affects control options.
AA Batteries (4-6 pack):
Lithium Polymer (LiPo):
USB Power Banks:
Estimating runtime:
Battery mAh ÷ Total current draw = Hours of runtime
Example current draws:
Design tip: Add 20% buffer for safety
Bluetooth (HC-05 module, $5-8):
WiFi (ESP32, $8-12):
RF Remote (433MHz, $5-10):
LoRa (for 1-10km range): $20-30, outdoor autonomous robots
USB charging (TP4056 module, $1-3):
Wireless charging (Qi coils, $10-15):
Auto-dock charging:
Choosing components isn't about technical specs - it's about matching capabilities to your design intent. Start with the behaviors you want, then work backwards to the components that enable them.
Don't start by browsing electronics catalogs. Start by describing your robot's desired behaviors in plain language, then identify which sensors and actuators make those behaviors possible.
Ask yourself:
Example: "I want a robot that follows people but maintains a polite distance, and expresses curiosity through light patterns."
Behavior to capability translation:
Now you know: Need camera/PIR + distance sensor + LEDs + DC motors
Selection criteria:
Example choices: PIR sensor ($2) instead of camera ($15), ultrasonic sensor ($3), WS2812B strip ($12), TT motors ($6)
Start simple, upgrade later:
Progressive enhancement: Basic tactile sensor → Distance sensor → Camera
Each upgrade unlocks new capabilities but core behavior works at every stage
$50 Beginner Robot:
$200 Advanced Robot:
Kits (pros):
Kits (cons):
Recommendation: Start with kit to learn basics, then build custom robots using individual components for your specific designs
Understanding robot anatomy from a designer's perspective means knowing what each component enables, not how it works internally. This knowledge lets you make intentional choices that serve your creative vision.
Think of sensors, actuators, and controllers like an artist thinks of paints, brushes, and canvas - each has unique properties and possibilities. Your job is to combine them in ways that create the experience you envision.
In the next section on Making Simple Robots, we'll put this component knowledge into practice by building your first robots step-by-step using Arduino and Raspberry Pi.
Apply what you've learned through hands-on robot design exercises, case studies, and maker challenges.
Practice ↗