SconePy

SconePy is a Python API for SCONE, designed and streamlined for Reinforcement Learning applications with biomechanical simulations. Features include:

• Direct access to biomechanical sensors and actuators via NumPy arrays
• Support for neural delays to sensors and actuators, to enhance realism
• Easy access to model and simulation components for efficient reward shaping

In order to use SconePy, you need:

• A system running Windows, Linux or macOS
• The latest SCONE release
• Python 3.9

After SCONE is installed, simply open and run <home>/SCONE/SconePy/sconepy_example.py to see SconePy in action.

The example will run a simple feedback simulation using different simulation engines. SconePy supports simulations with OpenSim3, OpenSim4, and hyfydy (recommended for large optimizations).

In addition, a SconePy gym environment is currently being developed and will become available on GitHub.

Please visit the SCONE User Forum for any questions or comments related to using SconePy.

sconepy_example.py

import numpy as np
import time
from sconetools import sconepy
 
# Reset a model and run a simulation
def run_simulation(model, store_data, random_seed, max_time=3, min_com_height=0.3):
	# reset the model to the initial state
	model.reset()
	model.set_store_data(store_data)
 
	# initialize the rng
	rng = np.random.default_rng(random_seed)
 
	# Initialize muscle activations to random values
	muscle_activations = 0.1 + 0.4 * rng.random((len(model.muscles())))
	model.init_muscle_activations(muscle_activations)
 
	# Tweak the initial pose of the model
	dof_positions = model.dof_position_array()
	dof_positions += 0.1 * rng.random(len(dof_positions)) - 0.05
	model.set_dof_positions(dof_positions)
	for d in model.dofs():
		if d.name() == 'pelvis_ty':
			d.set_pos(0.1 + d.pos()) # set the value of a
 
	# IMPORTANT: set the actual pose and equilibrates the muscles
	model.init_state_from_dofs()
 
 	# Start the simulation, with time t ranging from 0 to 5
	for t in np.arange(0, max_time, 0.01):
		# Set actuator_inputs based on muscle force, length and velocity
		mus_in = model.muscle_force_array()
		mus_in += model.muscle_fiber_length_array() - 1
		mus_in += 0.2 * model.muscle_fiber_velocity_array()
		model.set_actuator_inputs(mus_in)
 
		# Advance the simulation to time t
		# Internally, this performs as many simulations steps as required
		# The internal step size is variable, and determined by the 'accuracy'
		# setting in the .scone file
		model.advance_simulation_to(t)
 
		# Abort the simulation if the model center of mass falls below 0.3 meter
		com_y = model.com_pos().y
		if com_y < min_com_height:
			print(f'Aborting simulation at t={model.time():.3f} com_y={com_y:.4f}')
			break
 
	# Write results to the SCONE results folder
	# The resulting .sto file can be openend directly in SCONE Studio for analysis
	if store_data:
		dirname = 'sconepy_example_' + model.name()
		filename = model.name() + f'_{random_seed}_{model.time():0.3f}_{model.com_pos().y:0.3f}'
		model.write_results(dirname, filename)
		print(f'Results written to {dirname}/{filename}; please use SCONE Studio to replay the .sto file.', flush=True)
 
 
def measure_performance(model_file):
	# load the model
	start_time = time.perf_counter()
	model = sconepy.load_model(model_file)
	load_time = time.perf_counter() - start_time
 
	# run a couple of simulations
	random_seed = 1
	model_time = 0.0
	duration = 0.0
	start_time = time.perf_counter()
	while duration < 2.0:
		run_simulation(model, False, random_seed, max_time=2, min_com_height=-10)
		duration = time.perf_counter() - start_time
		random_seed += 1
		model_time += model.time()
 
	# show results
	real_time_factor = model_time / duration
	print(f'Loading {model_file} took {load_time*1000:.2f}ms - Simulating took {duration:.2f}s for {model_time:0.2f}s ({real_time_factor:0.2f}x real-time)', flush=True)
 
 
# Set the SCONE log level between 1-7 (lower is more logging)
sconepy.set_log_level(3)
print('SCONE Version', sconepy.version())
 
# change the datatype of returned arrays to 32-bit floats
sconepy.set_array_dtype_float32()
store_data = True
 
# Run performance benchmarks
if sconepy.is_supported('ModelHyfydy'):
	measure_performance('data/H0918_hfd.scone')
 
if sconepy.is_supported('ModelHyfydy'):
	measure_performance('data/H0918_hfd_v2.scone')
 
if sconepy.is_supported('ModelOpenSim3'):
	measure_performance('data/H0918_osim3.scone')
 
if sconepy.is_supported('ModelOpenSim4'):
	measure_performance('data/H0918_osim4.scone')