Robot Path Visualizer (Pygame)

This project demonstrates a tiny Python app that replays a precomputed robot trajectory (x, y, θ) using Pygame and NumPy. It rotates a robot sprite along the path and draws a trail, handy for quick demos and visual debugging of differential-drive motion.

Summary

• Loads simulationData.npy → shape (N, 3) as columns: x, y, theta_rad.
• Converts theta (radians) to degrees for sprite rotation.
• Animates robotImage.png (50×50) across a 1200×800 window.
• Draws a yellow polyline trail of visited points.

Files

• differential_robot.py → Generates simulationData.npy using a diff-drive ODE model + quick plots
• simulation_DDRobot.py → Visualizes the saved trajectory with Pygame (rotating sprite + trail)
• simulationData.npy → Generated trajectory file (created by differential_robot.py)
• robotImage.png → Robot sprite (will be scaled to 50x50)
• README.md

What it does

1) differential_robot.py - Simulation

• Defines robot params: wheel radius r and wheelbase s.
• Sets wheel angular velocities ΔL(t) and ΔR(t).
• Simulates the kinematics with SciPy `odeint`: \[ \dot{x} = \frac{r}{2}\cos(\theta)\,(\Delta_R + \Delta_L) \quad \dot{y} = \frac{r}{2}\sin(\theta)\,(\Delta_R + \Delta_L) \quad \dot{\theta} = \frac{r}{s}(\Delta_R - \Delta_L) \]
• Saves the result to simulationData.npy with shape (N, 3) = [x, y, theta] (theta in radians).
• Shows quick Matplotlib plots for sanity-check.

2) simulation_DDRobot.py - Visualization

• Opens a 1200×800 Pygame window.
• Loads simulationData.npy, converts theta to degrees (and flips sign for Pygame’s rotation).
• Draws robotImage.png at (x[i], y[i]) with correct rotation and a yellow path trail.

Coordinate system: Pygame’s origin is top-left, y increases downward.
If you want a math-style y-up view, pre-flip y in your data before saving.

Screenshots

Requirements

python -m pip install -r requirements.txt

• NumPy, SciPy, Matplotlib, Pygame

Run

1. Generate the trajectory

python differential_robot.py

• This creates simulationData.npy and shows plots.

2. Visualize the trajectory

python simulation_DDRobot.py

• Make sure robotImage.png is in the same folder.

Data Format

simulationData.npy: NumPy array with shape (N, 3)

• Column 0 → x (pixels)
• Column 1 → y (pixels)
• Column 2 → theta (radians)