流程和跑gmapping是类似的,只不过hector_slam不需要里程计数据,所以,只要数据集中有 /scan 和 /tf 就可以。
1 数据集预处理
这里我用slam benchmark 数据集,网址:
http://ais.informatik.uni-freiburg.de/slamevaluation/datasets.php
这个数据集非常小,里面真的是只有 /scan 和 /tf ,但是这个数据集的格式为.clf,需要把它转换成.bag文件才能在ros中使用。网上已经有人做了这件事情,那我就直接用了,python文件如下:
#!/usr/bin/env python
#coding=utf8
'''This is a converter for the Intel Research Lab SLAM dataset
( http://kaspar.informatik.uni-freiburg.de/~slamEvaluation/datasets/intel.clf )
to rosbag'''
import rospy
import rosbag
from sensor_msgs.msg import LaserScan
from nav_msgs.msg import Odometry
from math import pi
from tf2_msgs.msg import TFMessage
from geometry_msgs.msg import TransformStamped
import tf
import sys
def make_tf_msg(x, y, theta, t,base,base0):
trans = TransformStamped()
trans.header.stamp = t
trans.header.frame_id = base
trans.child_frame_id = base0
trans.transform.translation.x = x
trans.transform.translation.y = y
q = tf.transformations.quaternion_from_euler(0, 0, theta)
trans.transform.rotation.x = q[0]
trans.transform.rotation.y = q[1]
trans.transform.rotation.z = q[2]
trans.transform.rotation.w = q[3]
msg = TFMessage()
msg.transforms.append(trans)
return msg
if __name__ == "__main__":
if len(sys.argv) < 3:
print("请输入dataset文件名。")
exit()
print("正在处理" + sys.argv[1] + "...")
with open(sys.argv[1]) as dataset:
with rosbag.Bag(sys.argv[2], 'w') as bag:
i = 1
for line in dataset.readlines():
line = line.strip()
tokens = line.split(' ')
if len(tokens) <= 2:
continue
if tokens[0] == 'FLASER':
msg = LaserScan()
num_scans = int(tokens[1])
if num_scans != 180 or len(tokens) < num_scans + 9:
rospy.logwarn("unsupported scan format")
continue
msg.header.frame_id = 'base_laser_link'
t = rospy.Time(float(tokens[(num_scans + 8)]))
msg.header.stamp = t
msg.header.seq = i
i += 1
msg.angle_min = -90.0 / 180.0 * pi
msg.angle_max = 90.0 / 180.0 * pi
msg.angle_increment = pi / num_scans
msg.time_increment = 0.2 / 360.0
msg.scan_time = 0.2
msg.range_min = 0.001
msg.range_max = 50.0
msg.ranges = [float(r) for r in tokens[2:(num_scans + 2)]]
bag.write('scan', msg, t)
odom_x, odom_y, odom_theta = [float(r) for r in tokens[(num_scans + 2):(num_scans + 5)]]
tf_msg = make_tf_msg(odom_x, odom_y, odom_theta, t,'odom','base_link')
bag.write('tf', tf_msg, t)
elif tokens[0] == 'ODOM':
odom_x, odom_y, odom_theta = [float(t) for t in tokens[1:4]]
t = rospy.Time(float(tokens[7]))
tf_msg = make_tf_msg(0, 0, 0, t,'base_link','base_laser_link')
bag.write('tf', tf_msg, t)
把它放到一个ros包中,这样rosrun就能找到它了。使用前还得把它的属性改成可执行文件:
chmod +x clf_to_rosbag.py
这个脚本接收两个参数,第一个为输入文件路径,第二个为输出文件路径。例如:
$ rosrun gmapping clf_to_rosbag.py /home/nlsde/qintianhao/benchmark/laser_benchmark/aces.clf /home/nlsde/qintianhao/benchmark/laser_benchmark/rosbag_laser_benchmark/aces.bag
脚本执行后,就会在相应路径生成.bag文件了。
参考:
https://blog.csdn.net/u013859301/article/details/52986476
2 下载源码
这里可以省点事儿了,直接安装就行了:
$sudo apt-get install ros-indigo-hector-slam
3 写launch文件
这里我们需要写两个文件,一个是.launch的启动文件,一个是.xml的参数文件。
hector_mapping_demo.launch文件如下:
<launch>
<!-- this launch used to run hector mapping by rosbag-->
<param name="use_sim_time" value="true"/>
<node pkg="tf" type="static_transform_publisher" name="map_to_odom" args="0.0 0.0 0.0 0 0 0.0 /odom /base_footprint 100" />
<node pkg="tf" type="static_transform_publisher" name="base_frame_laser" args="0 0 0 0 0 0 /base_footprint /scan 100" />
<!-- hector mapping -->
<include file="$(find turtlebot_navigation)/launch/includes/hector_mapping.launch.xml"/>
</launch>
这里需要给出两个静态的tf变换,单位为m,周期通常设为100ms。第一个是里程计到基座的转换,第二个是基座到雷达的转换。讲道理hector_slam是能够提供第一个转换的,但是在我跑的时候去掉第一个就是不行,不知道为什么。
xml文件中是hector_slam的参数,hector_slam已经给出了默认参数,在/opt/ros/indigo/share/hector_mapping/launch/mapping_default.launch中,这里我们参考默认参数,给出适合自己的数据集的参数文件hector_mapping.launch.xml:
<launch>
<node pkg="hector_mapping" type="hector_mapping" name="hector_mapping" output="screen">
<!-- Frame names -->
<param name="pub_map_odom_transform" value="true"/>
<param name="map_frame" value="map" />
<param name="scan_topic" value="scan" />
<param name="base_frame" value="base_footprint"/>
<param name="odom_frame" value="odom"/>
<!-- Tf use -->
<param name="use_tf_scan_transformation" value="true"/>
<param name="use_tf_pose_start_estimate" value="false"/>
<!-- Map size / start point -->
<param name="map_resolution" value="0.05"/>
<param name="map_size" value="2048"/>
<param name="map_start_x" value="0.5"/>
<param name="map_start_y" value="0.5" />
<param name="laser_z_min_value" value = "-1.0" />
<param name="laser_z_max_value" value = "1.0" />
<param name="map_multi_res_levels" value="2" />
<!--
this is not include in mapping_default.launch
<param name="map_pub_period" value="2" />
<param name="laser_min_dist" value="0.4" />
<param name="laser_max_dist" value="5.5" />
<param name="output_timing" value="false" />
<param name="pub_map_scanmatch_transform" value="true" />
<param name="tf_map_scanmatch_transform_frame_name" value="scanmatcher_frame" />
-->
<!-- Map update parameters -->
<param name="update_factor_free" value="0.4"/>
<param name="update_factor_occupied" value="0.9" />
<param name="map_update_distance_thresh" value="0.4"/>
<param name="map_update_angle_thresh" value="0.06" />
<!-- Advertising config -->
<param name="advertise_map_service" value="true"/>
<param name="scan_subscriber_queue_size" value="5"/>
</node>
</launch>
其实需要调整的就三个参数:scan_topic , base_frame,odom_frame, 把他们分别和launch文件和bag发布的话题对应起来就可以了。
4 运行
roscore
roslaunch turtlebot_navigation hector_mapping_demo.launch
rosbag play --clock aces.bag
rosrun rviz rviz
rqt
参考
https://www.cnblogs.com/nowornever-L/p/5731729.html
https://www.ncnynl.com/archives/201702/1365.html
https://blog.csdn.net/dawn_jin/article/details/64127605
https://www.ncnynl.com/archives/201702/1367.html