ROS机器人Diego制作5-角速度的标定
ROS机器人Diego制作5-角速度的标定
说明:
- 介绍角速度标定,校准旋转角度偏差
角速度标定方法:
- 角速度标定,即控制机器人人转动固定的角度,看机器人是否按照控制指令完成,在这里我们让机器人转360度
- python代码如下:
#!/usr/bin/env python
import rospy
from geometry_msgs.msg import Twist, Quaternion
from nav_msgs.msg import Odometry
import tf
from math import radians, copysign
from transform_utils import quat_to_angle, normalize_angle
import PyKDL
from math import pi
class CalibrateAngular():
def __init__(self):
# Give the node a name
rospy.init_node('calibrate_angular', anonymous=False)
# Set rospy to execute a shutdown function when terminating the script
rospy.on_shutdown(self.shutdown)
# How fast will we check the odometry values?
self.rate = 10
r = rospy.Rate(self.rate)
# The test angle is 360 degrees
self.test_angle = 2*pi #这里注意,在ROS中使用的弧度,不能直接写360
self.speed = 0.1 # radians per second
self.tolerance = 1 # degrees converted to radians
self.odom_angular_scale_correction = 1
self.start_test = True
# Publisher to control the robot's speed
self.cmd_vel = rospy.Publisher('/cmd_vel', Twist, queue_size=5)
# The base frame is usually base_link or base_footprint
self.base_frame = rospy.get_param('~base_frame', '/base_link')
# The odom frame is usually just /odom
self.odom_frame = rospy.get_param('~odom_frame', '/odom')
# Initialize the tf listener
self.tf_listener = tf.TransformListener()
# Give tf some time to fill its buffer
rospy.sleep(2)
# Make sure we see the odom and base frames
self.tf_listener.waitForTransform(self.odom_frame, self.base_frame, rospy.Time(), rospy.Duration(60.0))
rospy.loginfo("Bring up rqt_reconfigure to control the test.")
reverse = 1
while not rospy.is_shutdown():
if self.start_test:
# Get the current rotation angle from tf
self.odom_angle = self.get_odom_angle()
rospy.loginfo("self.odom_angle: "+str(self.odom_angle))
last_angle = self.odom_angle
turn_angle = 0
self.test_angle *= reverse
error = self.test_angle - turn_angle
rospy.loginfo("errir: "+str(error))
# Alternate directions between tests
reverse = -reverse
while abs(error) > self.tolerance and self.start_test:
if rospy.is_shutdown():
return
rospy.loginfo("*************************** ")
# Rotate the robot to reduce the error
move_cmd = Twist()
move_cmd.angular.z = copysign(self.speed, error)
rospy.loginfo("move_cmd.angular.z: "+str(move_cmd.angular.z))
self.cmd_vel.publish(move_cmd)
r.sleep()
# Get the current rotation angle from tf
self.odom_angle = self.get_odom_angle()
rospy.loginfo("current rotation angle: "+str(self.odom_angle))
# Compute how far we have gone since the last measurement
delta_angle = self.odom_angular_scale_correction * normalize_angle(self.odom_angle - last_angle)
rospy.loginfo("delta_angle: "+str(delta_angle))
# Add to our total angle so far
turn_angle += abs(delta_angle)
rospy.loginfo("turn_angle: "+str(turn_angle))
# Compute the new error
error = self.test_angle - turn_angle
rospy.loginfo("error: "+str(error))
# Store the current angle for the next comparison
last_angle = self.odom_angle
# Stop the robot
self.cmd_vel.publish(Twist())
# Update the status flag
self.start_test = False
params = {'start_test': False}
dyn_client.update_configuration(params)
rospy.sleep(0.5)
# Stop the robot
self.cmd_vel.publish(Twist())
def get_odom_angle(self):
# Get the current transform between the odom and base frames
try:
(trans, rot) = self.tf_listener.lookupTransform(self.odom_frame, self.base_frame, rospy.Time(0))
except (tf.Exception, tf.ConnectivityException, tf.LookupException):
rospy.loginfo("TF Exception")
return
# Convert the rotation from a quaternion to an Euler angle
return quat_to_angle(Quaternion(*rot))
def shutdown(self):
# Always stop the robot when shutting down the node
rospy.loginfo("Stopping the robot...")
self.cmd_vel.publish(Twist())
rospy.sleep(1)
if __name__ == '__main__':
try:
CalibrateAngular()
except:
rospy.loginfo("Calibration terminated.")
脚本使用:
- 接下来运行如下命令,控制小车旋转:
rosrun diego_nav calibrate_angular.py
- 影响角速度的主要参数是wheel_track,所以如果发现机器人不能按照要求旋转固定角度,可以调整此参数。
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