def _leg2d(self, time, marker_pos, normalized_force_plate_values,
cutoff, sample_rate):
"""This method effectively does the same thing that the Octave
routine does."""
# differentiate to get the marker velocities and accelerations
marker_vel = process.derivative(time, marker_pos,
method='combination')
marker_acc = process.derivative(time, marker_vel,
method='combination')
# filter all the input data with the same filter
marker_pos = process.butterworth(marker_pos, cutoff, sample_rate,
axis=0)
marker_vel = process.butterworth(marker_vel, cutoff, sample_rate,
axis=0)
marker_acc = process.butterworth(marker_acc, cutoff, sample_rate,
axis=0)
force_array = process.butterworth(normalized_force_plate_values,
cutoff, sample_rate, axis=0)
# compute the inverse dynamics
inv_dyn = lower_extremity_2d_inverse_dynamics
dynamics = inv_dyn(time, marker_pos, marker_vel, marker_acc,
force_array)
return dynamics
def time_derivative(self, col_names, new_col_names=None):
"""Numerically differentiates the specified columns with respect to
the time index and adds the new columns to `self.data`.
Parameters
==========
col_names : list of strings
The column names for the time series which should be numerically
time differentiated.
new_col_names : list of strings, optional
The desired new column name(s) for the time differentiated
series. If None, then a default name of `Time derivative of
<origin column name>` will be used.
"""
if new_col_names is None:
new_col_names = ['Time derivative of {}'.format(c) for c in
col_names]
for col_name, new_col_name in zip(col_names, new_col_names):
self.data[new_col_name] = \
process.derivative(self.data.index.values.astype(float),
self.data[col_name].values,
method='combination')
def find_constant_speed(time, speed, plot=False, filter_cutoff=1.0):
"""Returns the indice at which the treadmill speed becomes constant and
the time series when the treadmill speed is constant.
Parameters
==========
time : array_like, shape(n,)
A monotonically increasing array.
speed : array_like, shape(n,)
A speed array, one sample for each time. Should ramp up and then
stablize at a speed.
plot : boolean, optional
If true a plot will be displayed with the results.
filter_cutoff : float, optional
The filter cutoff frequency for filtering the speed in Hertz.
Returns
=======
indice : integer
The indice at which the speed is consider constant thereafter.
new_time : ndarray, shape(n-indice,)
The new time array for the constant speed section.
"""
sample_rate = 1.0 / (time[1] - time[0])
filtered_speed = process.butterworth(speed, filter_cutoff, sample_rate)
acceleration = process.derivative(time,
filtered_speed,
method='central',
padding='second order')
last = acceleration[int(0.2 * len(acceleration)):]
noise_level = np.max(np.abs(last - np.mean(last)))
reversed_acceleration = acceleration[::-1]
indice = np.argmax(reversed_acceleration > noise_level)
additional_samples = sample_rate * 0.65
new_indice = indice - int(round(additional_samples))
if plot is True:
fig, ax = plt.subplots(2, 1)
ax[0].plot(time, speed, '.', time, filtered_speed, 'g-')
ax[0].plot(
np.ones(2) * (time[len(time) - new_indice]),
np.hstack((np.max(speed), np.min(speed))))
ax[1].plot(time, acceleration, '.')
fig.show()
return len(time) - (new_indice), time[len(time) - new_indice]
def find_constant_speed(time, speed, plot=False, filter_cutoff=1.0):
"""Returns the indice at which the treadmill speed becomes constant and
the time series when the treadmill speed is constant.
Parameters
==========
time : array_like, shape(n,)
A monotonically increasing array.
speed : array_like, shape(n,)
A speed array, one sample for each time. Should ramp up and then
stablize at a speed.
plot : boolean, optional
If true a plot will be displayed with the results.
filter_cutoff : float, optional
The filter cutoff frequency for filtering the speed in Hertz.
Returns
=======
indice : integer
The indice at which the speed is consider constant thereafter.
new_time : ndarray, shape(n-indice,)
The new time array for the constant speed section.
"""
sample_rate = 1.0 / (time[1] - time[0])
filtered_speed = process.butterworth(speed, filter_cutoff, sample_rate)
acceleration = process.derivative(time, filtered_speed,
method='central',
padding='second order')
last = acceleration[int(0.2 * len(acceleration)):]
noise_level = np.max(np.abs(last - np.mean(last)))
reversed_acceleration = acceleration[::-1]
indice = np.argmax(reversed_acceleration > noise_level)
additional_samples = sample_rate * 0.65
new_indice = indice - additional_samples
if plot is True:
fig, ax = plt.subplots(2, 1)
ax[0].plot(time, speed, '.', time, filtered_speed, 'g-')
ax[0].plot(np.ones(2) * (time[len(time) - new_indice]),
np.hstack((np.max(speed), np.min(speed))))
ax[1].plot(time, acceleration, '.')
fig.show()
return len(time) - (new_indice), time[len(time) - new_indice]
def peak_detection(x):
dx = process.derivative(time, x, method="combination")
dx[dx > 0] = 1
dx[dx < 0] = -1
ddx = process.derivative(time, dx, method="combination")
peaks = []
for i, spike in enumerate(ddx < 0):
if spike == True:
peaks.append(i)
peaks = peaks[::2]
threshold_value = (max(x) - min(x))*threshold + min(x)
peak_indices = []
for i in peaks:
if x[i] > threshold_value:
peak_indices.append(i)
return peak_indices
import simulation
from grf_landmark_settings import settings
# load the data and find a controller
trial_number = '068'
trial = utils.Trial(trial_number)
trial._write_event_data_frame_to_disk('Longitudinal Perturbation')
event_data_frame = trial.event_data_frames['Longitudinal Perturbation']
event_data_frame = simulation.estimate_trunk_somersault_angle(event_data_frame)
# TODO : will likely need to low pass filter the two time derivatives
event_data_frame['Trunk.Somersault.Rate'] = \
process.derivative(event_data_frame.index.values.astype(float),
event_data_frame['Trunk.Somersault.Angle'],
method='combination')
event_data_frame['RGTRO.VelY'] = \
process.derivative(event_data_frame.index.values.astype(float),
event_data_frame['RGTRO.PosY'], method='combination')
# TODO : Ensure that the modified data frame is infact the one in the Trial
# object.
trial._write_inverse_dynamics_to_disk('Longitudinal Perturbation', force=True)
trial._section_into_gait_cycles('Longitudinal Perturbation', force=True)
gait_data = trial.gait_data_objs['Longitudinal Perturbation']
sensor_labels, control_labels, result, solver = \
trial.identification_results('Longitudinal Perturbation', 'joint isolated')
