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dynamixel_utils.py
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dynamixel_utils.py
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DESC = """
Checks basic behaviors of the motors by subjecting them to chirp and step signals
USAGE:
python dynamixel_utils.py --motor_id "[6,8]" --motor_type "MX" --baudrate 1000000 --device /dev/ttyUSB0 --protocol 2
"""
from dynamixel_py import *
import time as t
import numpy as np
import scipy.io as sio
import click
# Make pretty plots to show off your movements
def plot_paths(paths, filename, qpos_lims=None, qvel_lims=None, ctrl_lims=None, update_rate=100):
import matplotlib as mpl
mpl.use('TkAgg')
import matplotlib.pyplot as plt
for i in range(len(paths)):
plt.clf()
# time
if('time' in paths[i].keys()):
time = paths[i]['time']
else:
n = len(paths[i]['qpos'])
time = np.linspace(0, n, n)/update_rate
# positions
ax = plt.subplot(3, 1, 1)
plt.plot(time,paths[i]['qpos'], '-')
ax.set_prop_cycle(None)
plt.plot(time, paths[i]['ctrl'], '-', alpha=0.3, linewidth=5.0)
plt.title(filename)
plt.ylabel('qpos')
if(qpos_lims):
ax.set_ylim(qpos_lims[0], qpos_lims[1])
# Velocities
ax = plt.subplot(3, 1, 2)
h0 = plt.plot(time,paths[i]['qvel'], '-')
ax.set_prop_cycle(None)
vel = (paths[i]['qpos'][1:,:] - paths[i]['qpos'][:-1,:])/(time[1:]-time[:-1]).reshape(-1,1)
h1 = plt.plot(time[:-1], vel, '--', alpha=0.3)
plt.ylabel('qvel')
plt.legend((h0[0], h1[0]), ('qvel', 'fd(qpos)'))
if(qvel_lims):
ax.set_ylim(qvel_lims[0], qvel_lims[1])
# controls
ax = plt.subplot(3, 1, 3)
plt.plot(time, paths[i]['ctrl'], '-', alpha=0.3, linewidth=5.0)
plt.ylabel('ctrl')
plt.xlabel('time')
if(ctrl_lims):
ax.set_ylim(ctrl_lims[0], ctrl_lims[1])
# save plots
plt.tight_layout()
fn = filename+'_path'+str(i)+'.png'
plt.savefig(fn)
print("path saved to " + fn)
# subject motors to chirp
def chirp(dy, dxl_ids, frequency=2.0, time_horizon=5.0, pos_min=0, pos_max=np.pi/2.):
clk =[]
qpos=[]
qvel=[]
ctrl=[]
pos_mean = (pos_max + pos_min)/2.0
pos_scale = (pos_max - pos_min)/2.0
print("Subjecting system to chirp signal");
t_s = time.time()
t_n = time.time() - t_s
while(t_n < time_horizon):
t_n = time.time() - t_s
qp, qv = dy.get_pos_vel(dxl_ids)
des_pos = [pos_mean - pos_scale*np.sin(frequency*2.0*np.pi*t_n)*np.cos(frequency*2.0*t_n)]*np.ones(len(dxl_ids))
dy.set_des_pos(dxl_ids, des_pos)
clk.append(t_n)
qpos.append(qp)
qvel.append(qv)
ctrl.append(des_pos.copy())
# Paths
paths =[]
path = dict(
time=np.array(clk),
qpos=np.array(qpos),
qvel=np.array(qvel),
ctrl=np.array(ctrl)
)
paths.append(path)
return paths
# subject motors to step
def step(dy, dxl_ids, frequency=1.0, time_horizon=5.0, pos_min=0, pos_max=np.pi/2):
clk =[]
qpos=[]
qvel=[]
ctrl=[]
pos_mean = (pos_max + pos_min)/2.0
pos_scale = (pos_max - pos_min)/2.0
print("Subjecting system to step signal")
t_s = time.time()
t_n = time.time() - t_s
while(t_n < time_horizon):
t_n = time.time() - t_s
qp, qv = dy.get_pos_vel(dxl_ids)
des_pos = [pos_mean + .95*pos_scale*(2.*(int(frequency*2*t_n)%2) -1.)]*np.ones(len(dxl_ids))
dy.set_des_pos(dxl_ids, des_pos)
clk.append(t_n)
qpos.append(qp)
qvel.append(qv)
ctrl.append(des_pos.copy())
# Paths
paths =[]
path = dict(
time=np.array(clk),
qpos=np.array(qpos),
qvel=np.array(qvel),
ctrl=np.array(ctrl)
)
paths.append(path)
return paths
# Test my update rate. I got good reflexes
def test_update_rate(dy, dxl_ids, cnt = 1000):
print("Testing update rate of dxl -----")
t_s = time.time()
for i in range(cnt):
dxl_present_position, dxl_present_velocity = dy.get_pos_vel(dxl_ids)
dy.set_des_pos(dxl_ids, dxl_present_position)
t_e = time.time()
update_rate = cnt/(t_e-t_s)
print("Update rate of dxl %3.2f hz (%1.4f s)" % (update_rate, 1.0/update_rate))
return update_rate
@click.command(help=DESC)
@click.option('--motor_id', '-i', type=str, help='motor ids', default="[1, 2]")
@click.option('--motor_type', '-t', type=str, help='motor type', default="X")
@click.option('--baudrate', '-b', type=int, help='port baud rate', default=1000000)
@click.option('--device', '-d', type=str, help='device name', default="/dev/ttyUSB0")
@click.option('--protocol', '-p', type=int, help='communication protocol 1/2', default=2)
@click.option('--swing', '-s', type=click.FloatRange(0,3.14), help='amplitude for chirp and step in radian', default=0.25)
def main(motor_id, motor_type, device, baudrate, protocol, swing):
# Connect
print("============= dxl ==============")
dxl_ids = eval(motor_id)
dy = dxl(motor_id=dxl_ids, motor_type=motor_type, baudrate=baudrate, devicename=device, protocol=protocol)
dy.open_port()
dy.engage_motor(dxl_ids, False)
# Query
dxl_present_position, dxl_present_velocity = dy.get_pos_vel(dxl_ids)
print("Joint Positions ----------------")
print(dxl_present_position)
print("Joint Velocities ---------------")
print(dxl_present_velocity)
# Test update rate
update_rate = test_update_rate(dy, dxl_ids, 200)
# Move all the joints and plot the trace
dy.engage_motor(dxl_ids, True)
trace = chirp(dy, dxl_ids, frequency=1.0, time_horizon=np.pi*1.0, pos_min=3.14-swing, pos_max=3.14+swing)
plot_paths(trace, 'chirp', qvel_lims=[-10, 10], update_rate=update_rate)
sio.savemat('chirp.mat', {'trace':trace})
trace = step(dy, dxl_ids, 1, 4, pos_min=3.14-swing, pos_max=3.14+swing)
plot_paths(trace, 'step', qvel_lims=[-10, 10], update_rate=update_rate)
sio.savemat('step.mat', {'trace':trace})
dxl_present_position, dxl_present_velocity = dy.get_pos_vel(dxl_ids)
print("Joint Positions ----------------")
print(dxl_present_position)
# Close
dy.close(dxl_ids)
print("Connection closed succesfully")
if __name__ == '__main__':
main()