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Chapter 2: Robot Anatomy

Learning Objectives​

By the end of this chapter, you will:

  • Identify the main components of every robot
  • Understand how different robot types differ in structure
  • Learn about power systems and their role in robotics
  • Understand the basic robot chassis types and their applications

Introduction​

Just as biologists study animal anatomy to understand how living things work, roboticists must understand robot anatomy to design and build effective robots. Every robot, from a simple vacuum to a humanoid, shares fundamental components organized in similar ways.

Basic Robot Components​

All robots share five core components:

1. Chassis (Structure)​

The robot's body or frame that holds everything together.

  • Provides mechanical strength
  • Determines the robot's size, shape, and form factor
  • Must be lightweight but sturdy
  • Examples: Metal frame, plastic body, aluminum exoskeleton

2. Actuators (Movement)​

Devices that create motion and apply force.

  • Electric motors are most common in robotics
  • Types: DC motors, servo motors, stepper motors
  • Hydraulic and pneumatic actuators used in heavy-duty applications
  • Enable the robot to move, manipulate, and interact

3. Sensors (Perception)​

Devices that detect information about the environment.

  • Vision sensors (cameras)
  • Distance sensors (ultrasonic, LiDAR)
  • Touch sensors (pressure, force)
  • Motion sensors (accelerometers, gyroscopes)
  • Environmental sensors (temperature, humidity)

4. Control System (Brain)​

The computer and electronics that make decisions.

  • Microcontroller or full computer
  • Receives sensor data
  • Processes information
  • Sends commands to actuators
  • Examples: Arduino, Raspberry Pi, NVIDIA Jetson

5. Power System (Energy)​

Batteries or power supplies that energize everything.

  • Rechargeable lithium batteries most common
  • Power consumption depends on actuators used
  • Runtime limited by battery capacity
  • Must account for voltage requirements of different components

Robot Chassis Types​

Different robot types use different chassis designs optimized for their environment and task:

Wheeled Robots​

  • Advantages: Fast, efficient, simple mechanics
  • Disadvantages: Limited on rough terrain, can't climb stairs
  • Uses: Vacuum cleaners, delivery robots, warehouse robots
  • Examples: iRobot Roomba, AMR (Autonomous Mobile Robots)

Legged Robots​

  • Advantages: Can traverse complex terrain, climb stairs, navigate obstacles
  • Disadvantages: Complex mechanics, energy-intensive, slower
  • Uses: Inspection, search and rescue, entertainment
  • Examples: Boston Dynamics Spot (4-legged), ASIMO (humanoid)

Aerial Robots (Drones)​

  • Advantages: Access to elevated areas, wide coverage, speed
  • Disadvantages: Limited flight time, weather-dependent, regulatory restrictions
  • Uses: Delivery, surveillance, photography, mapping
  • Examples: DJI Phantom, commercial drones

Manipulators (Robotic Arms)​

  • Advantages: High precision, strong grip, flexible movement
  • Disadvantages: Stationary unless on mobile base, limited workspace
  • Uses: Manufacturing, assembly, surgery, research
  • Examples: ABB Industrial Arms, Collaborative Robots (Cobots)

Hybrid Systems​

  • Combine multiple locomotion types for maximum flexibility
  • Example: Mobile manipulator = wheeled base + robotic arm
  • Used in modern manufacturing and research

Power Systems in Robotics​

Battery Chemistry and Types​

Lithium-Ion (Li-Ion)

  • Most popular in modern robots
  • Good energy density, reasonable cost
  • Used in: Drones, mobile robots, consumer electronics

Lead-Acid

  • Older technology, heavier
  • Good for stationary industrial robots
  • Lower cost but limited lifespan

Nickel-Metal Hydride (NiMH)

  • Safer than Li-Ion but lower energy density
  • Used in some educational robots

Power Considerations​

Every robot designer must balance:

  • Runtime: How long can the robot operate?
  • Weight: Heavier batteries add mass (especially problematic for aerial robots)
  • Cost: Battery can be 20-30% of robot cost
  • Charging Time: How quickly can it recharge for next deployment?
  • Safety: Proper thermal management to prevent fires

Did You Know?​

Boston Dynamics' Spot has a battery that lasts about 3 hours of continuous operation with a single charge. The team had to carefully design the robot's mechanical and electrical systems to maximize efficiency and runtime.

Key Takeaways​

  • Five Core Components: Chassis, Actuators, Sensors, Control System, Power System
  • Chassis Types: Wheeled (fast, simple), Legged (agile, complex), Aerial (fast, limited), Manipulators (precise, stationary)
  • Actuators Enable Motion: Motors convert electrical energy into mechanical movement
  • Power is Critical: Battery capacity and efficiency determine robot runtime
  • Integrated Design: All components must work together harmoniously

Try It!​

Activity: Analyze a Robot's Anatomy

Choose a real robot (you can find videos online of Boston Dynamics Spot, Roomba, or other robots). Try to identify:

  1. What is its chassis type? (wheeled, legged, aerial, arm?)
  2. What actuators might it use?
  3. What sensors can you see or infer?
  4. Where might the control system be located?
  5. How might it be powered?

Exercises​

🟢 Comprehension Questions

beginner
  1. List the five core components of any robot.
  2. What is the main advantage of wheeled robots compared to legged robots?
  3. Why is the power system important in robot design?

🟡 Application

intermediate
  1. If you needed to design a robot to explore a factory floor and detect obstacles, which chassis type would you choose and why?
  2. How would you decide between using a DC motor vs. a servo motor for a specific application?

🔴 Design Challenge

advanced
  1. Design a robot for a specific task (e.g., window cleaning on tall buildings). Sketch its anatomy and explain each component choice.

Further Reading​

Ready to continue? Next: Chapter 3 - Sensors and Actuators →