博客地址：https://www.cnblogs.com/zylyehuo/

Switching Sampling Space of Model Predictive Path-Integral Controller to Balance Efficiency and Safety in 4WIDS Vehicle Navigation

GitHub项目链接



部署环境

  • Ubuntu 20.04
  • ROS Noetic
  • gcc 9.4.0
  • numpy 1.20.3
  • numexpr 2.7.3
  • cmake 3.12.4（3.5 及以上，不能用 cmake 4 系列）
  • 松灵 ranger mini 3.0
  • 禾赛 32线雷达
  • xsense IMU

整体运行指令流程

nullspace_mpc_README.md

# 打开禾赛雷达

cd /home/yehuo/Lidar/Hesai

source devel/setup.bash

roslaunch hesai_lidar cloud_nodelet.launch lidar_type:="PandarXT-32" frame_id:="PandarXT-32"

# 时间同步命令

# sudo apt install linuxptp

ifconfig -a

sudo ptp4l -m -4 -i enp11s0 -S

# 打开imu

cd /home/yehuo/IMU/xsense/Xsens_MTi_ROS_Driver_and_Ntrip_Client/src/xsens_ros_mti_driver/build

sudo chmod 777 /dev/ttyUSB0

source devel/setup.bash

roslaunch xsens_mti_driver  xsens_mti_node.launch  # display.launch

# 打开点云地图

cd  /home/yehuo/location/location_ws

source devel/setup.bash

roslaunch pointcloudmap_load pointcloudmap_load.launch

# 启动定位程序

cd /home/yehuo/location/location_ws

source devel/setup.bash

roslaunch neu_localization  neu_localization.launch

# 启动四轮四转向车(遥控器使能)

cd /home/yehuo/agilexrobotics/agilexrobotics_ws

source devel/setup.bash

rosrun ranger_bringup bringup_can2usb.bash

roslaunch ranger_bringup ranger_mini_v2.launch

# 启动 nullspace_mpc 项目

cd /home/yehuo/nullspace_mpc_test

make navigation_nullspace_mpc



与原项目的区别

基于禾赛3d雷达进行定位，使用的是自己的定位程序

  • 为了与原项目的程序相容，基于 pointcloud_to_laserscan 功能包将三维的点云数据改为二维的激光数据
  • 此外，将实际场景的三维地图转变为二维地图

实物上需要启动 xsense IMU 的驱动

实物上需要启动底盘的驱动

实物上需要进行时间的同步

rqt_graph 比对

仿真

实物

rqt_tf_tree 比对

仿真

实物

  <node pkg="tf" type="static_transform_publisher" name="map2odom" args="0.0  0.0  0.0  0 0 0 1 map odom 100" />

  <!--发布 map 坐标系 → odom 坐标系 的静态变换 -->

  <node pkg="tf" type="static_transform_publisher" name="base_link2laser_link" args="0.0  0.0  0.0  0 0 0 1 base_link laser_link 100" />

  <!-- body_imu 改为 base_link ;base_link 改为 laser_link -->

具体改动代码

三维点云.pcd地图转换为二维栅格.pgm地图

点云pcd文件转二维栅格地图

cd /home/yehuo/pcd2pgm/pcd2pgm_ws

source devel/setup.bash

rosrun pcd_to_pgm pcd_to_pgm_node map/custom/drone_map_01.pcd map/custom/drone_map_01 0.05 0.1 2.0

/home/yehuo/nullspace_mpc_test/launch/navigation.launch

<launch>

  <!-- ##### SETTINGS { ##### -->

  <!-- often changed arguments -->

  <arg name="enable_gazebo" default="false"/>

  <arg name="gazebo_world_name" default="maze" /> <!-- empty, empty_garden, cylinder_garden, maze -->

  <arg name="joy_operation" default="true" />

  <arg name="local_planner" default="nullspace_mpc" /> <!-- mppi_3d_a, mppi_3d_b, mppi_4d, mppi_h, nullspace_mpc -->

  <!-- arguments -->

  <arg name="workspace" default="$(env HOME)/nullspace_mpc" />

  <arg name="rvizconfig" default="$(arg workspace)/data/rviz/navigation.rviz" />

  <arg name="open_rviz" default="true"/>

  <arg name="scan_topic"     default="/scan"/>  <!-- "/laser_link/scan" -->

  <arg name="cmd_vel_topic"  default="/cmd_vel"/>

  <arg name="odom_topic"     default="/odometry"/>      <!-- "/groundtruth_odom" -->

  <arg name="set_base_frame" default="base_link"/>

  <arg name="set_odom_frame" default="odom"/>

  <arg name="set_map_frame"  default="map"/>

  <arg name="initial_pose_x" default="0.0"/>

  <arg name="initial_pose_y" default="0.0"/>

  <arg name="initial_pose_yaw" default="0.0"/>

  <arg name="do_evaluation" default="true" />

  <arg name="scenario_config_path" default="file_not_specified"/>

  <arg name="eval_result_dir" default="file_not_specified"/>

  <arg name="controller_mode" default="default" doc="Mode for nullspace_mpc: choose 'default' or 'lite' to adjust performance"/>

  <arg name="show_gazebo_gui" default="false"/>  <!-- true -->

  <arg name="gazebo_headless" default="false"/>

  <rosparam param="/use_sim_time">false</rosparam> <!-- set use_sim_time true to syncronize time with gazebo --> <!-- true -->

  <!-- ##### } SETTINGS ##### -->

  <!-- ##### COMMON NODES { ##### -->

  <!-- launch gazebo world -->

  <group if="$(arg enable_gazebo)">

    <include file="$(arg workspace)/launch/gazebo_world.launch">

      <arg name="gazebo_world_name" value="$(arg gazebo_world_name)" />

      <arg name="use_joystick" value="$(arg joy_operation)" />

      <arg name="use_vel_driver" value="false" />

      <arg name="open_rviz" value="false" />

      <arg name="show_gazebo_gui" value="$(arg show_gazebo_gui)" />

      <arg name="gazebo_headless" value="$(arg gazebo_headless)" />

    </include>

  </group>

  <!-- map server -->

  <!-- <node pkg="map_server" type="map_server" name="map_server" args="$(arg workspace)/data/map/$(arg gazebo_world_name)/map.yaml" /> -->

  <node pkg="map_server" type="map_server" name="map_server" args="/home/yehuo/pcd2pgm/pcd2pgm_ws/map/custom/drone_map_01.yaml" />

  <!-- 3d map visualizer -->

  <!-- <group if="$(arg enable_gazebo)">

    <include file="$(find map_visualizer)/launch/map_visualizer.launch">

      <arg name="map_name" value="$(arg gazebo_world_name)" />

    </include>

  </group> -->

  <!-- amcl -->

  <!-- <node pkg="amcl" type="amcl" name="amcl">

      <param name="initial_pose_x"            value="$(arg initial_pose_x)"/>

      <param name="initial_pose_y"            value="$(arg initial_pose_y)"/>

      <param name="initial_pose_a"            value="$(arg initial_pose_yaw)"/>

      <remap from="scan"                      to="$(arg scan_topic)"/>

      <rosparam file="$(arg workspace)/config/amcl.yaml" command="load" />

  </node> -->

  <!-- rviz -->

  <group if="$(arg open_rviz)">

    <node name="rviz" pkg="rviz" type="rviz" args="-d $(arg rvizconfig)" required="true" />

  </group>

  <!-- run pointcloud_to_laserscan node -->

    <node pkg="pointcloud_to_laserscan" type="pointcloud_to_laserscan_node" name="pointcloud_to_laserscan">

        <remap from="cloud_in" to="/cloud_registered_body"/>

    </node>

  <!-- ##### } COMMON NODES ##### -->

  <!-- ##### LAUNCH SELECTED LOCAL PLANNER { ##### -->

  <!-- Nullspace MPC -->

  <group if="$(eval local_planner=='nullspace_mpc')">

      <!-- nullspace_mpc with controller_mode to adjust performance -->

      <include file="$(find nullspace_mpc)/launch/nullspace_mpc.launch">

          <arg name="controller_mode" value="$(arg controller_mode)"/>

      </include>

      <!-- reference_costmap_generator -->

      <include file="$(find reference_costmap_generator)/launch/reference_costmap_generator.launch" />

      <!-- launch global planner -->

      <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">

          <param name="base_local_planner" value="base_local_planner/TrajectoryPlannerROS" />

          <rosparam file="$(arg workspace)/config/base_local_planner.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_common_global.yaml" command="load" ns="global_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_common_local_nullspace_mpc.yaml" command="load" ns="local_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_local.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_global.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/move_base.yaml" command="load" />

          <remap from="cmd_vel" to="/no_use/cmd_vel"/>

          <remap from="odom" to="$(arg odom_topic)"/>

          <remap from="scan" to="$(arg scan_topic)"/>

      </node>

      <!-- launch vel_driver to operate 4WIDS vehicle with /cmd_vel-->

      <include file="$(find vel_driver)/launch/vel_driver.launch" />

  </group>

  <!-- MPPI-3D (a) (exploring 3 dimensional space: vx, vy, omega) -->

  <group if="$(eval local_planner=='mppi_3d_a')">

      <include file="$(find mppi_3d)/launch/mppi_3d_a.launch" />

      <!-- reference_costmap_generator -->

      <include file="$(find reference_costmap_generator)/launch/reference_costmap_generator.launch" />

      <!-- launch global planner -->

      <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">

          <param name="base_local_planner" value="base_local_planner/TrajectoryPlannerROS" />

          <rosparam file="$(arg workspace)/config/base_local_planner.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_common_global.yaml" command="load" ns="global_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_common_local.yaml" command="load" ns="local_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_local.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_global.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/move_base.yaml" command="load" />

          <remap from="cmd_vel" to="/no_use/cmd_vel"/>

          <remap from="odom" to="$(arg odom_topic)"/>

          <remap from="scan" to="$(arg scan_topic)"/>

      </node>

      <!-- launch vel_driver to operate 4WIDS vehicle with /cmd_vel-->

      <include file="$(find vel_driver)/launch/vel_driver.launch" />

  </group>

  <!-- MPPI-3D (b) (exploring 3 dimensional space: vx, vy, omega) -->

  <group if="$(eval local_planner=='mppi_3d_b')">

      <include file="$(find mppi_3d)/launch/mppi_3d_b.launch" />

      <!-- reference_costmap_generator -->

      <include file="$(find reference_costmap_generator)/launch/reference_costmap_generator.launch" />

      <!-- launch global planner -->

      <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">

          <param name="base_local_planner" value="base_local_planner/TrajectoryPlannerROS" />

          <rosparam file="$(arg workspace)/config/base_local_planner.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_common_global.yaml" command="load" ns="global_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_common_local.yaml" command="load" ns="local_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_local.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_global.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/move_base.yaml" command="load" />

          <remap from="cmd_vel" to="/no_use/cmd_vel"/>

          <remap from="odom" to="$(arg odom_topic)"/>

          <remap from="scan" to="$(arg scan_topic)"/>

      </node>

      <!-- launch vel_driver to operate 4WIDS vehicle with /cmd_vel-->

      <include file="$(find vel_driver)/launch/vel_driver.launch" />

  </group>

  <!-- MPPI-4D (exploring 4 dimensional space) -->

  <group if="$(eval local_planner=='mppi_4d')">

      <include file="$(find mppi_4d)/launch/mppi_4d.launch" />

      <!-- reference_costmap_generator -->

      <include file="$(find reference_costmap_generator)/launch/reference_costmap_generator.launch" />

      <!-- launch global planner -->

      <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">

          <param name="base_local_planner" value="base_local_planner/TrajectoryPlannerROS" />

          <rosparam file="$(arg workspace)/config/base_local_planner.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_common_global.yaml" command="load" ns="global_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_common_local.yaml" command="load" ns="local_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_local.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_global.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/move_base.yaml" command="load" />

          <remap from="cmd_vel" to="/no_use/cmd_vel"/>

          <remap from="odom" to="$(arg odom_topic)"/>

          <remap from="scan" to="$(arg scan_topic)"/>

      </node>

      <!-- launch vel_driver to operate 4WIDS vehicle with /cmd_vel-->

      <include file="$(find vel_driver)/launch/vel_driver.launch" />

  </group>

  <!-- MPPI-H (switching MPPI-3D and MPPI-4D in real-time) -->

  <group if="$(eval local_planner=='mppi_h')">

      <include file="$(find mppi_h)/launch/mppi_h.launch" />

      <!-- reference_costmap_generator -->

      <include file="$(find reference_costmap_generator)/launch/reference_costmap_generator.launch" />

      <!-- launch global planner -->

      <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">

          <param name="base_local_planner" value="base_local_planner/TrajectoryPlannerROS" />

          <rosparam file="$(arg workspace)/config/base_local_planner.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_common_global.yaml" command="load" ns="global_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_common_local.yaml" command="load" ns="local_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_local.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_global.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/move_base.yaml" command="load" />

          <remap from="cmd_vel" to="/no_use/cmd_vel"/>

          <remap from="odom" to="$(arg odom_topic)"/>

          <remap from="scan" to="$(arg scan_topic)"/>

      </node>

      <!-- launch vel_driver to operate 4WIDS vehicle with /cmd_vel-->

      <include file="$(find vel_driver)/launch/vel_driver.launch" />

  </group>

  <!-- (not supported) move_base [base local planner] -->

  <group if="$(eval local_planner=='base')">

      <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">

          <param name="base_local_planner" value="base_local_planner/TrajectoryPlannerROS" />

          <rosparam file="$(arg workspace)/config/base_local_planner.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_common_global.yaml" command="load" ns="global_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_common_local.yaml" command="load" ns="local_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_local.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_global.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/move_base.yaml" command="load" />

          <remap from="cmd_vel" to="$(arg cmd_vel_topic)"/>

          <remap from="odom" to="$(arg odom_topic)"/>

          <remap from="scan" to="$(arg scan_topic)"/>

      </node>

      <!-- launch vel_driver to operate 4WIDS vehicle with /cmd_vel-->

      <include file="$(find vel_driver)/launch/vel_driver.launch" />

  </group>

  <!-- (not supported) move_base [teb local planner] -->

  <group if="$(eval local_planner=='teb')">

      <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">

          <param name="base_local_planner" value="teb_local_planner/TebLocalPlannerROS" />

          <rosparam file="$(arg workspace)/config/teb_local_planner.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_common_global.yaml" command="load" ns="global_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_common_local.yaml" command="load" ns="local_costmap" />

          <rosparam file="$(arg workspace)/config/costmap_local.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/costmap_global.yaml" command="load" />

          <rosparam file="$(arg workspace)/config/move_base_teb.yaml" command="load" />

          <remap from="cmd_vel" to="$(arg cmd_vel_topic)"/>

          <remap from="odom" to="$(arg odom_topic)"/>

          <remap from="scan" to="$(arg scan_topic)"/>

      </node>

      <!-- launch vel_driver to operate 4WIDS vehicle with /cmd_vel-->

      <include file="$(find vel_driver)/launch/vel_driver.launch" />

  </group>

  <!-- ##### } LAUNCH SELECTED LOCAL PLANNER ##### -->

  <!-- ##### { OPTIONAL NODES ##### -->

    <!-- evaluator -->

    <group if="$(arg do_evaluation)">

        <include file="$(find mpc_nav_evaluator)/launch/mpc_nav_evaluator.launch">

            <arg name="scenario_config_path" value="$(arg scenario_config_path)" />

            <arg name="eval_result_dir" value="$(arg eval_result_dir)" />

        </include>

    </group>

<!-- ##### } OPTIONAL NODES ##### -->

</launch>

/home/yehuo/nullspace_mpc_test/src/control/nullspace_mpc/config/nullspace_mpc.yaml

# topic names

## subscribing topics

odom_topic: /odometry   ## 仿真使用 /groundtruth_odom 实物使用 /odometry

ref_path_topic: /move_base/NavfnROS/plan

collision_costmap_topic: /move_base/local_costmap/costmap

distance_error_map_topic: /distance_error_map

ref_yaw_map_topic: /ref_yaw_map

## publishing topics

control_cmd_vel_topic: /cmd_vel

mppi_absvel_topic: /mpc/cmd/absvel

mppi_vx_topic: /mpc/cmd/vx

mppi_vy_topic: /mpc/cmd/vy

mppi_omega_topic: /mpc/cmd/omega

calc_time_topic: /mpc/calc_time

mppi_overlay_text_topic: /mpc/overlay_text

mppi_optimal_traj_topic: /mpc/optimal_traj

mppi_sampled_traj_topic: /mpc/sampled_traj

mppi_via_state_seq_topic: /mpc/via_state_seq

mpc_eval_msg_topic: /mpc/eval_info

# navigation params

navigation:

  xy_goal_tolerance: 0.5  # [m]

  yaw_goal_tolerance: 0.15 # [rad] set 6.28 to ignore angular error

  goal_snap_distance_for_via_pos: 0.3 # [m]

  goal_snap_distance_for_via_angle: 1.5 # [rad]

# target_system params

target_system:

  l_f: 0.5 # [m]

  l_r: 0.5 # [m]

  d_l: 0.5 # [m]

  d_r: 0.5 # [m]

  tire_radius: 0.2 # [m]

# controller params

controller:

  name: "nullspace_mpc"

  control_interval: 0.05 # [s]

  num_samples: 200 # number of samples

  prediction_horizon: 15 # [steps]

  step_len_sec: 0.125 # [s]

  param_exploration: 0.01

  param_lambda: 250.0

  param_alpha: 0.975

  idx_via_states: [4, 9, 15] # index of via states in the prediction horizon (indices must be less than prediction_horizon)

  sigma: [

    0.2, 0.25, 0.393, # noise for via state at step 4

    0.2, 0.25, 0.393, # noise for via state at step 9

    0.2, 0.01, 0.393, # noise for via state at step 15

  ]

  reduce_computation: true # if true, noise sampling is done only once and the same noise is used for all processes.

  weight_cmd_change: [0.0, 0.0, 0.0] # penalty weight for variation of [vx, vy, omega]

  weight_vehicle_cmd_change: [1.4, 1.4, 1.4, 1.4, 0.1, 0.1, 0.1, 0.1] # penalty weight for variation of [fl_steer, fr_steer, rl_steer, rr_steer, fl_vel, fr_vel, rl_vel, rr_vel]

  ref_velocity: 2.0 # [m/s]

  weight_velocity_error: 10.0

  weight_angular_error: 30.0

  weight_collision_penalty: 50.0

  weight_distance_error_penalty: 40.0

  weight_terminal_state_penalty: 0.0

  use_sg_filter: true # set true to use Savitzky-Golay filter for smoothing the control input

  sg_filter_half_window_size: 8 # value in the range of 1 ~ (prediction_horizon - 1) is allowed.

  sg_filter_poly_order: 2

# Note:

## - to change the velocity limit of the controller, check ../include/nullspace_mpc/common_type.hpp

## - to edit the prediction model or the cost function, check ../include/nullspace_mpc/nullspace_mpc_setting.hpp

实物部署【Switching Sampling Space of Model Predictive Path-Integral Controller to Balance Efficiency and Safety in 4WIDS Vehicle Navigation】的更多相关文章

  1. MVC(Model(模型) View(视图) Controller(控制器))

    复习 1.      商品表 增删改查 index.php  add.php   view.php   edit.php   action.php 2.      MVC(Model(模型)  Vie ...

  2. ASP.NET MVC轻教程 Step By Step 4——Model、View和Controller

    ASP.NET MVC中的Model(数据模型)主要包括定义数据结构.数据库读写.数据验证等等和对象处理相关的工作. 在解决方案资源管理器中找到Model文件夹,点击右键,添加一个新类,名为“Mess ...

  3. Asp.Net Core 入门（四）—— Model、View、Controller

    和我们学习Asp.Net MVC一样,Asp.Net Core MVC的Model.View.Controller也和我们熟悉的Asp.Net MVC中的相似.不同的是我们在使用Asp.Net Cor ...

  4. MATLAB模型预测控制（MPC,Model Predictive Control）

    模型预测控制是一种基于模型的闭环优化控制策略. 预测控制算法的三要素:内部(预测)模型.参考轨迹.控制算法.现在一般则更清楚地表述为内部(预测)模型.滚动优化.反馈控制. 大量的预测控制权威性文献都无 ...

  5. 【控制】模型预测控制 MPC 【合集】Model Predictive Control

    1.模型预测控制--运动学模型 2.模型预测控制--模型线性化 3.模型预测控制--模型离散化 4.模型预测控制--预测 5.模型预测控制--控制律优化二次型优化 6.模型预测控制--反馈控制 7.模 ...

  6. 2013/11/22工作随笔-缓存是放在Model层还是放在Controller层

    web网站的典型代码框架就是MVC架构,Model层负责数据获取,Controller层负责逻辑控制,View层则负责展示. 一般数据获取是去mysql中获取数据 但是这里有个问题,我们不会每次请求都 ...

  7. 1、ASP.NET Core2.0之Model、View、Controller

    一.新建空项目 打开VS2017,新建→项目,选择如下: 点击,确定,弹出的界面选择如下: 选择空项目,因为选择其他的话会自动生成很多用不到的类,显得项目不够“清爽”,ASP.NET Core选择2. ...

  8. 浅谈ThinkPHP3.2的子域名部署和路由优化（一）

    前言:建立一个网站系统,往往包含多个子网站,例如PC官网,移动端官网,后台管理,数据源自一个相同的数据库,整个架构上,从ThinkPHP来看,可以大体理解为Model(M)是一样的,Controlle ...

  9. Azure ARM (10) ARM模式下的虚拟机和Classic Model虚拟机的区别

    <Windows Azure Platform 系列文章目录> 本文内容比较多,请大家仔细阅读,谢谢! 请读者注意,在Azure ARM平台,有两种虚拟机模式:经典虚拟机和ARM虚拟机 A ...

  10. 关于.net MVC5+EF6 网站部署的问题

    创建mvc web application,采用code first 的方式,MVC5,EF6.0 整了一个网站.开发完之后.直接publish.就这样部署到服务器上了. 在使用过程中发现,网站打开的 ...

随机推荐

  1. 【iOS】从实际出发理解多线程（二）--NSThread高级操作

    上篇文章讲了一下NSThread的基本操作,本篇讲一下NSThread的一些高级用法. 线程间资源共享&线程加锁 在程序运行过程中,如果存在多线程,呢么各个线程读写资源就会存在先后.同时读写资 ...

  2. uniapp开发的h5引入uni.webview.js注意事项

    webview加载的h5页面明明按照uniapp官方文档引入了uni-webview.js,但仍无法使用uni.navigateTo等方法? 若是普通html那可能是引入方式不对,若webview中加 ...

  3. 【STM32系列】"Flash Timeout Reset the Target and try it again."问题解决方式之一

    前言 博主使用DAP下载器烧录程序到STM32G4的时候,遇到了Flash Timeout的问题,原本以为是锁芯片了,正发愁呢,没想到随便改一下就好了. 问题 解决方法 魔术棒 -> Debug ...

  4. Typora小教程

    公式与代码 数学公式

  5. 操作系统层面反删除恢复文件损坏太多处理—-oracle碎片恢复

    联系:手机/微信(+86 13429648788) QQ(107644445) 标题:操作系统层面反删除恢复文件损坏太多处理--碎片恢复 作者:惜分飞版权所有[未经本人同意,不得以任何形式转载,否则有 ...

  6. MySQL专题面试题-二叉树、红黑树、B 树、B+树

    演示网址:https://www.cs.usfca.edu/~galles/visualization/Algorithms.html 所谓的索引,就是帮助MySQL高效获取数据的排好序的数据结构,基 ...

  7. 分布式Redis解决方案之Redisson

    1.前言 Redisson是Redis官方推荐的Java版的Redis客户端.底层使用netty框架,并提供了与java对象相对应的分布式对象.分布式集合.分布式锁和同步器.分布式服务等一系列的Red ...

  8. MySQL中OPTIMIZE TABLE和慢查询分析

    先来看看手册中关于 OPTIMIZE 的描述: OPTIMIZE [LOCAL | NO_WRITE_TO_BINLOG] TABLE tbl_name [, tbl_name] ...如果您已经删除 ...

  9. 图片压缩优化结合Base64存储的系统改进方案

    需要帮助用户解决图片压缩优化结合Base64存储的问题.用户之前已经提到他们目前将图片以Base64格式存储在数据库中,导致接口传输数据过大,加载时间长达3秒.他们现在想通过图片压缩来优化系统,但不采 ...

  10. 基于JavaWeb理财系统-项目实战

    文档地址: 链接:https://pan.baidu.com/s/1rTKBpgDe2hW6EW9Cjwf9gg?pwd=6lsy  提取码:6lsy 0.课程介绍 我们非常高兴地为大家推出一门全新的 ...