Add OpenModelica integration script with simulation and result extraction

[Copilot]

Implements modelica.sh calculator script for Funz framework to simulate Modelica models via OpenModelica and extract results in Funz format.

Implementation

• modelica.sh: Bash script that validates dependencies, runs OpenModelica simulations via omc, and extracts results from MAT files using scipy/numpy. Outputs 7 calculated metrics (max_height, range, flight_time, final_velocity, impact_angle, energy_loss, energy_loss_percent) in Funz format (key = value;)

• ProjectileMotion.mo: Reference Modelica model implementing projectile motion physics for testing and demonstration

• tests/test_modelica.sh: Test suite validating script executability, error handling, and output format. Gracefully handles missing OpenModelica installations

• README.md: Usage documentation, prerequisites, and troubleshooting

Usage

./modelica.sh ProjectileMotion.mo
# Generates output.txt with Funz-formatted results

Script requires OpenModelica (omc) and Python packages (scipy, numpy).

Original prompt

try to upgrade the modelica.sh file with this script. Check it works well with tests.
`#!/bin/bash

Modelica Calculator Script for FZ

Requires OpenModelica to be installed (omc command available)

The compiled model file is passed as the first argument

MODEL_FILE="$1"

Check if OpenModelica is installed

if ! command -v omc &> /dev/null; then
echo "Error: OpenModelica (omc) not found. Please install OpenModelica."
echo "Visit: https://openmodelica.org/"
exit 1
fi

Check if model file exists

if [ ! -f "$MODEL_FILE" ]; then
echo "Error: Model file $MODEL_FILE not found"
exit 1
fi

Create OpenModelica script to simulate and extract results

cat > simulate.mos << EOF
// Load and simulate the model
loadFile("$MODEL_FILE");
simulate(ProjectileMotion, stopTime=10, numberOfIntervals=1000);

// Get final results using the result file
val(x, 0.0); // Check simulation worked
quit();
EOF

Run OpenModelica

omc simulate.mos > omc.log 2>&1
RESULT=$?

if [ $RESULT -ne 0 ]; then
echo "Error: OpenModelica simulation failed"
cat omc.log
exit 1
fi

Check if result file was created

if [ ! -f "ProjectileMotion_res.mat" ]; then
echo "Error: Result file not created"
exit 1
fi

Extract results using Python (OpenModelica Python API)

python3 << 'PYTHON_EOF'
import sys
try:
# Try to use OMPython for reading results
from OMPython import ModelicaSystem

# Alternative: use numpy and scipy to read MAT file
import scipy.io
import numpy as np

# Read the OpenModelica result file
mat = scipy.io.loadmat('ProjectileMotion_res.mat')

# Extract time and variables
# OpenModelica stores results in specific format
names = [name.strip() for name in mat['name']]
data = mat['data_2']  # Trajectory data

# Find variable indices
def get_var_idx(var_name):
    for i, name in enumerate(names):
        if name == var_name:
            return i
    return None

# Get time array
time_idx = get_var_idx('time')
if time_idx is None:
    time = np.linspace(0, 10, data.shape[1])
else:
    time = data[time_idx, :]

# Get trajectory variables
x_idx = get_var_idx('x')
y_idx = get_var_idx('y')
vx_idx = get_var_idx('vx')
vy_idx = get_var_idx('vy')

x = data[x_idx, :]
y = data[y_idx, :]
vx = data[vx_idx, :]
vy = data[vy_idx, :]

# Find when projectile lands (y crosses zero after launch)
landing_idx = None
for i in range(10, len(y)):  # Skip first few points
    if y[i] < 0:
        landing_idx = i - 1
        break

if landing_idx is None:
    landing_idx = len(y) - 1

# Calculate outputs
max_height = np.max(y)
range_distance = x[landing_idx]
flight_time = time[landing_idx]

v_final = np.sqrt(vx[landing_idx]**2 + vy[landing_idx]**2)
impact_angle = np.degrees(np.arctan2(abs(vy[landing_idx]), abs(vx[landing_idx])))

# Energy calculations (need mass and v0)
# These should come from parameters
# For now, estimate from initial velocity
v0 = np.sqrt(vx[0]**2 + vy[0]**2)
m = 1.0  # Default mass

ke_initial = 0.5 * m * v0**2
ke_final = 0.5 * m * v_final**2
energy_loss = ke_initial - ke_final
energy_loss_percent = 100 * energy_loss / ke_initial if ke_initial > 0 else 0

# Write results to output.txt in FZ format
with open('output.txt', 'w') as f:
    f.write(f"max_height = {max_height};\n")
    f.write(f"range = {range_distance};\n")
    f.write(f"flight_time = {flight_time};\n")
    f.write(f"final_velocity = {v_final};\n")
    f.write(f"impact_angle = {impact_angle};\n")
    f.write(f"energy_loss = {energy_loss};\n")
    f.write(f"energy_loss_percent = {energy_loss_percent};\n")

print("Simulation completed successfully")

except ImportError as e:
print(f"Error: Required Python package not found: {e}", file=sys.stderr)
print("Please install: pip install scipy numpy", file=sys.stderr)
sys.exit(1)
except Exception as e:
print(f"Error extracting results: {e}", file=sys.stderr)
sys.exit(1)

PYTHON_EOF

exit $?
`

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