Help me create a fighting robot

Let's Make Robots Beginners
1

I’m trying to create a fighting robot that’s 6 inches tall. I want it to be able to move and fight like the boxing robots “Noisy Boy”, “Atom” and “Midas” from the movie Real Steel but at a 6 inch scale. I want the motions to be smooth and realistic. I didn’t know where to start so I asked ChatGPT for help. Is it possible to make something like this if you followed the instructions? I know nothing about robotics or coding but want this vision to come to life. If you could build it for me or help me build it that would be great thank you!

  1. Concept

  2. Mechanics:

  • Up to ~12–15 Degrees of Freedom (DoF) for realistic human-like movement:
    • Arms: Shoulder (2–3 DoF), elbow (1–2 DoF), wrist (1 DoF).
    • Legs: Hip (2–3 DoF), knee (1–2 DoF), ankle (1–2 DoF).
    • Torso: Waist rotation (1 DoF), maybe an upper torso bend (1 DoF).
    • Head/Neck: Optional 1–2 DoF for expression.
  1. Compact Actuation:
  • Rather than basic plastic-geared servos, consider advanced smart servos or even custom direct-drive mini actuators.
  1. Onboard/Offboard AI:
  • For truly “intelligent” fighting, a local microcomputer or an offboard machine-learning pipeline that commands the robot in real time.
  1. Realistic Fighting Styles & Motion:
  • Keyframe-based animation plus inverse kinematics (IK) for fluid transitions.
  • Advanced AI for move selection, combos, reactive blocks.
  1. Multi-Sensor Feedback:
  • IMU (accelerometer, gyroscope) for balance/detecting hits.
  • Possibly a micro-camera or time-of-flight (ToF) sensor for environment perception.
  1. Parts & Materials

Actuators (Servos or Custom Mini Actuators):

  1. Robotis Dynamixel XL-320 or XL-330 Series:
  • Key Features: High precision, feedback on position, speed, load, temperature. Daisy-chain wiring.
  • Pros: Great for advanced control and “smooth” motion. Feedback loops help for dynamic movements.
  • Cons: Possibly larger than typical micro servos, but still relatively small.
  • Cost per unit: $40–$80 each
  1. LewanSoul (Lobot) LX-16A Smart Servos:
  • Key Features: Serial bus interface, position/voltage/current feedback, metal gear.
  • Cost per unit: $20–$40 each
  1. Custom Brushless Direct-Drive Mini Actuators
  • Note: Typically, these are found in high-end robotics labs. They’re incredibly small, expensive, and often custom-fabricated. If you want “ultimate performance,” you could explore collaborating with a specialized manufacturer or using micro brushless motors with tiny planetary gearboxes.
  • Cost: Can be $100+ per joint.

Number of Actuators Needed: ~12–15 total for full realism.

Electronics & Control:

  1. Main Controller Board
  • Option A: Raspberry Pi Zero 2 W
    • Enough power to run some level of TensorFlow Lite or advanced Python scripts.
    • Wi-Fi/Bluetooth built in.
  • Option B: NVIDIA Jetson Nano (2GB or 4GB)
    • More AI horsepower, but physically bigger. Squeezing it into a 6-inch shell is extremely tight. Often used in advanced robotics.
    • Could be integrated offboard with a tether or custom enclosure.
  • Option C: Espressif ESP32 + External AI
    • Do motion control on the ESP32, and connect wirelessly to a more powerful offboard system that runs the AI.
  1. Secondary Microcontroller or Smart Servo Controller
  • If using Dynamixel or LewanSoul servos, you can use their dedicated controllers or a standard board (e.g., Arduino Mega) with a half-duplex UART or a custom serial bus.
  • Servo HAT/Shield from SparkFun or Adafruit if using conventional PWM servos.
  1. Power Distribution
  • For 12–15 advanced servos, you need a stable power supply (likely 7.4V LiPo or 11.1V LiPo stepped down to servo voltage).
  • Consider a high-current BEC (Battery Eliminator Circuit) or DC-DC converter that can handle 5–10A or more.
  1. Batteries
  • 2S or 3S LiPo packs with ~800–1200mAh capacity for short run times. For high servo load, you may want 1000–1500mAh.
  • Charger: Must be a specialized LiPo balance charger.
  1. Sensors
  • IMU (MPU-6050, ICM-20948, etc.): For orientation, acceleration, and basic hit detection.
  • Small Depth/ToF Sensor (VL53L1X): For distance measuring or potentially detecting an opponent.
  • Tiny Camera (OV2640 or similar): If you want vision-based AI

Frame & Mechanical Parts:

  1. High-End 3D-Printed Materials
  • Resin (SLA) printing for finer detail or Carbon Fiber Nylon (FDM) for higher strength.
  • You will need precise servo mounting geometry.
  • Optional: Use CNC-milled aluminum for critical structural parts if budget/weight constraints allow.
  1. Linkage & Hardware
  • High-quality metal servo horns, ball-bearing joints, and miniature universal joints where needed.
  • Tiny screws (M1.6, M2, M2.5) with locknuts.
  1. Armor/Outer Shell
  • Could be 3D-printed polymer for a stylized “Real Steel” look.
  • Possibly snap-on plates for easy servo access.

Approximate Costs:

  • Servos (15x): $600–$1,200 total (using Dynamixel or advanced LewanSoul).
  • Controller (Pi Zero 2 / Jetson Nano): $15–$150.
  • Misc. Microcontroller Board / Controllers: $20–$80.
  • Power System (Battery + DC-DC + Charger): $100–$200.
  • Mechanical Frame & Hardware: $50–$300 (depending on materials).
  • Sensors: $50–$100.

3. Build Phases

Steps:

  1. Servo Bench Testing
  • Power a single advanced servo (e.g., Dynamixel XL-330).
  • Send position commands via a microcontroller or PC-based interface.
  • Check torque, speed, range of motion.
  1. Simple Joint Prototype
  • Design and 3D-print a single arm or leg segment with 2–3 servos.
  • Test movement in free space to ensure no binding.
  • Confirm the servo’s load capacity is enough for your planned limb length and mass.
  1. Electronics Setup
  • Select your main microcontroller (e.g., Raspberry Pi Zero 2).
  • Install the Dynamixel or LewanSoul library (or corresponding servo library).
  • Write a simple test script to move each servo from 0° to 180° (or min to max) slowly.

Phase 2: Advanced Prototype

Steps:

  1. Full Robot Skeleton Assembly:
  • Print or CNC the entire frame.
  • Mount each servo carefully, ensuring alignment.
  • Route wiring (Dynamixels allow daisy-chain; LewanSoul uses a similar bus). Keep cables tidy.
  1. Balance & Weight Distribution:
  • At 6 inches, every gram counts. Place heavier components (battery, main controller) near the torso center to aid stability.
  1. Electrical Integration:
  • Attach battery + DC-DC converter, ensure stable 7.4V or servo-appropriate voltage.
  • Connect the microcontroller / Pi Zero 2 W with a servo bus line.
  • If using separate servo power lines, tie grounds together with controller ground.
  1. Code: Basic IK & Pose Control:
  • For lifelike motion, use pre-defined keyframes or inverse kinematics (IK) for arms/legs.
  • Example approach:
    1. Define a series of “joint angles” for a punch, block, or idle stance.
    2. Interpolate between these angles over time to create smooth transitions.
  • Optional: Implement a small IK solver for arms or legs. (Libraries exist, or you can code your own using geometric approaches.)

Phase 3: Final Integration & Cosmetics

Steps:

  1. Shell / Armor Plates
  • 3D-print or mold external shells to replicate a “Real Steel” aesthetic.
  • Ensure quick access for battery swaps and servo maintenance.
  1. Sensor Integration
  • Install IMU in the torso (less vibration). Use extended cables as needed.
  • If using a micro camera or ToF sensor, mount it near the “head” or chest.
  • Make sure to calibrate the IMU for accurate orientation data.
  1. Cable Management & Final Power Tests
  • Use braided cable sleeves or spiral wraps.
  • Double-check battery runtime under load. Possibly set up a “sleep mode” or minimal power usage approach.
  1. Protective Measures
  • Over-current protection or fuses for high-end servos.
  • Use standoffs and rubber grommets to minimize mechanical vibration on the Pi or microcontroller.

Phase 4: Advanced AI & Combat Logic

Approaches:

  1. Offboard AI + Onboard Motion Execution
  • A separate powerful machine (desktop PC or laptop with GPU) runs a real-time model.
  • It sends high-level commands (e.g., “punch_combo_1,” “block_high,” “sidestep”) via Wi-Fi/Bluetooth.
  • The robot’s onboard controller executes the servo motions for each command.
  1. Onboard AI with Raspberry Pi Zero 2 W or Jetson
  • TensorFlow Lite or PyTorch Mobile for a small neural network.
  • A “state machine + neural net” approach:
    • State Machine handles sequences: idle → punch → retreat → block → idle.
    • Neural Net decides transitions based on sensor input (IMU hits, camera detection of an opponent’s move).
  1. Motion Synthesis with IK
  • Implement a real-time IK solver to adapt foot placement or arm extension to varying conditions.
  • This is advanced but can produce more fluid “alive” motion.

Advanced Example: Reactive Blocking

  1. The IMU senses a sudden jolt from the right side.
  2. AI logic decides “opponent is attacking from right.”
  3. The robot quickly transitions from idle to a “right block” stance by interpolating angles for the right arm.
  4. Meanwhile, the left arm might prepare a counterpunch.

4. Iteration, Prototyping & Problem-Solving

  1. Servo Overheating
  • High-torque moves in a tiny frame can overwork servos.
  • Solution: Add “rest” poses, limit maximum torque settings, or add small vents/fans if absolutely needed.
  1. Battery Drain & Power Spikes
  • Many servos accelerating simultaneously can cause voltage dips.
  • Solution: Use a larger-capacity LiPo or add supercapacitors. Stage motions so not all servos accelerate at once.
  1. Wiring Collisions
  • Tightly packed limbs cause wires to snag or pinch.
  • Solution: Route cables carefully, use custom cable lengths, add protective sheathing.
  1. Balancing & Falling Over
  • A short robot is tricky to balance with high-speed moves.
  • Solution: Widen the stance or foot size, keep center of gravity low, or adopt smaller ranges of motion at the ankles and hips. Tweak servo speed/acceleration for stable transitions.
  1. Software Bugs / Delayed Responses
  • Complex code for AI plus servo control can cause lag.
  • Solution: Optimize your loops, possibly use a multi-threaded approach or a real-time OS.
  1. Mechanical Wear & Tear
  • Repeated punching motions at high torque can strip gears.
  • Solution: Use metal-geared servos or direct-drive brushless actuators. Periodically inspect and replace worn parts.
2

Although discontinued, it sounds like this would have been perfect for you. You might even find some used online:

6.5" tall.

Moving smoothly comes down to the servos used, and the control software / inverse kinematics. There’s a Japanese software developer who make the Kondo humanoid robot walk incredibly smoothly, but can’t find the videos at this time unfortunately.

If the robot moves slowly, you can get some great motion (shown here using a quadruped):