【ros2 control 机器人驱动开发】简单双关节机器人学习-example 1-Toy模板网

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【ros2 control 机器人驱动开发】简单双关节机器人学习-example 1

前言

本系列文件主要有以下目标和内容：

为系统、传感器和执行器创建 HardwareInterface
以URDF文件的形式创建机器人描述
加载配置并使用启动文件启动机器人
控制RRBot的两个关节（两旋转关节机器人）
六自由度机器人的控制
实现机器人的控制器切换策略
使用 ros2_control 中的关节限制和传输概念

一、RR机器人

RRBot（ Revolute-Revolute Manipulator Robot）是一个简单的3连杆，2关节的机械臂，我们将使用它来演示各种功能。

它本质上是一个双倒立摆，并在模拟器中演示了一些有趣的控制概念，最初是为Gazebo教程介绍的。¹

创建description pkg

这里主要是完成机器人描述文件的创建，各个轴的物理尺寸、模型信息，各个轴的关节链接方式、链接点。

mkdir ~/ros2_control_demos
cd ~/ros2_control_demos

ros2 pkg create --build-type ament_cmake ros2_control_demo_description

# 文件结构
$ tree ros2_control_demo_description/
ros2_control_demo_description/
├── CMakeLists.txt
├── package.xml
└── rrbot
    ├── rviz
    │   └── rrbot.rviz
    └── urdf
        ├── rrbot.materials.xacro
        └── rrbot_description.urdf.xacro

# CMakeLists.txt

cmake_minimum_required(VERSION 3.8)
project(ros2_control_demo_description)

# find dependencies
find_package(ament_cmake REQUIRED)

install(
  DIRECTORY rrbot/urdf rrbot/rviz
  DESTINATION share/${PROJECT_NAME}/rrbot
)

ament_package()

# packages.xml

<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="3">
  <name>ros2_control_demo_description</name>
  <version>0.0.0</version>
  <description>TODO: Package description</description>
  <maintainer email="someone@example.com">Bing_Lee</maintainer>
  <url type="website">https://blog.csdn.net/Bing_Lee</url>
  <license>TODO: License declaration</license>

  <buildtool_depend>ament_cmake</buildtool_depend>

  <exec_depend>joint_state_publisher_gui</exec_depend>
  <exec_depend>robot_state_publisher</exec_depend>
  <exec_depend>rviz2</exec_depend>

  <export>
    <build_type>ament_cmake</build_type>
  </export>
</package>

# rrbot.rviz

Panels:
  - Class: rviz_common/Displays
    Help Height: 87
    Name: Displays
    Property Tree Widget:
      Expanded: ~
      Splitter Ratio: 0.5
    Tree Height: 1096
  - Class: rviz_common/Selection
    Name: Selection
  - Class: rviz_common/Tool Properties
    Expanded:
      - /2D Goal Pose1
      - /Publish Point1
    Name: Tool Properties
    Splitter Ratio: 0.5886790156364441
  - Class: rviz_common/Views
    Expanded:
      - /Current View1
    Name: Views
    Splitter Ratio: 0.5
Visualization Manager:
  Class: ""
  Displays:
    - Alpha: 0.5
      Cell Size: 1
      Class: rviz_default_plugins/Grid
      Color: 160; 160; 164
      Enabled: true
      Line Style:
        Line Width: 0.029999999329447746
        Value: Lines
      Name: Grid
      Normal Cell Count: 0
      Offset:
        X: 0
        Y: 0
        Z: 0
      Plane: XY
      Plane Cell Count: 10
      Reference Frame: <Fixed Frame>
      Value: true
    - Alpha: 1
      Class: rviz_default_plugins/RobotModel
      Collision Enabled: false
      Description File: ""
      Description Source: Topic
      Description Topic:
        Depth: 5
        Durability Policy: Volatile
        History Policy: Keep Last
        Reliability Policy: Reliable
        Value: /robot_description
      Enabled: true
      Links:
        All Links Enabled: true
        Expand Joint Details: false
        Expand Link Details: false
        Expand Tree: false
        Link Tree Style: Links in Alphabetic Order
        base_link:
          Alpha: 1
          Show Axes: false
          Show Trail: false
          Value: true
        camera_link:
          Alpha: 1
          Show Axes: false
          Show Trail: false
          Value: true
        camera_link_optical:
          Alpha: 1
          Show Axes: false
          Show Trail: false
        hokuyo_link:
          Alpha: 1
          Show Axes: false
          Show Trail: false
          Value: true
        link1:
          Alpha: 1
          Show Axes: false
          Show Trail: false
          Value: true
        link2:
          Alpha: 1
          Show Axes: false
          Show Trail: false
          Value: true
        tool_link:
          Alpha: 1
          Show Axes: false
          Show Trail: false
        world:
          Alpha: 1
          Show Axes: false
          Show Trail: false
      Mass Properties:
        Inertia: false
        Mass: false
      Name: RobotModel
      TF Prefix: ""
      Update Interval: 0
      Value: true
      Visual Enabled: true
  Enabled: true
  Global Options:
    Background Color: 48; 48; 48
    Fixed Frame: base_link
    Frame Rate: 30
  Name: root
  Tools:
    - Class: rviz_default_plugins/Interact
      Hide Inactive Objects: true
    - Class: rviz_default_plugins/MoveCamera
    - Class: rviz_default_plugins/Select
    - Class: rviz_default_plugins/FocusCamera
    - Class: rviz_default_plugins/Measure
      Line color: 128; 128; 0
    - Class: rviz_default_plugins/SetInitialPose
      Covariance x: 0.25
      Covariance y: 0.25
      Covariance yaw: 0.06853891909122467
      Topic:
        Depth: 5
        Durability Policy: Volatile
        History Policy: Keep Last
        Reliability Policy: Reliable
        Value: /initialpose
    - Class: rviz_default_plugins/SetGoal
      Topic:
        Depth: 5
        Durability Policy: Volatile
        History Policy: Keep Last
        Reliability Policy: Reliable
        Value: /goal_pose
    - Class: rviz_default_plugins/PublishPoint
      Single click: true
      Topic:
        Depth: 5
        Durability Policy: Volatile
        History Policy: Keep Last
        Reliability Policy: Reliable
        Value: /clicked_point
  Transformation:
    Current:
      Class: rviz_default_plugins/TF
  Value: true
  Views:
    Current:
      Class: rviz_default_plugins/Orbit
      Distance: 8.443930625915527
      Enable Stereo Rendering:
        Stereo Eye Separation: 0.05999999865889549
        Stereo Focal Distance: 1
        Swap Stereo Eyes: false
        Value: false
      Focal Point:
        X: 0.0044944556429982185
        Y: 1.0785865783691406
        Z: 2.4839563369750977
      Focal Shape Fixed Size: true
      Focal Shape Size: 0.05000000074505806
      Invert Z Axis: false
      Name: Current View
      Near Clip Distance: 0.009999999776482582
      Pitch: 0.23039916157722473
      Target Frame: <Fixed Frame>
      Value: Orbit (rviz)
      Yaw: 5.150422096252441
    Saved: ~
Window Geometry:
  Displays:
    collapsed: false
  Height: 1379
  Hide Left Dock: false
  Hide Right Dock: false
  Selection:
    collapsed: false
  Tool Properties:
    collapsed: false
  Views:
    collapsed: false
  Width: 2560
  X: 0
  Y: 1470

# rrbot_description.urdf.xacro

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">

  <xacro:macro name="rrbot" params="parent prefix *origin">

  <!-- Constants for robot dimensions -->
  <xacro:property name="mass" value="1" /> <!-- arbitrary value for mass -->
  <xacro:property name="width" value="0.1" /> <!-- Square dimensions (widthxwidth) of beams -->
  <xacro:property name="height1" value="2" /> <!-- Link 1 -->
  <xacro:property name="height2" value="1" /> <!-- Link 2 -->
  <xacro:property name="height3" value="1" /> <!-- Link 3 -->
  <xacro:property name="axel_offset" value="0.05" /> <!-- Space btw top of beam and the each joint -->

  <joint name="${prefix}base_joint" type="fixed">
    <xacro:insert_block name="origin" />
    <parent link="${parent}"/>
    <child link="${prefix}base_link" />
  </joint>

  <!-- Base Link -->
  <link name="${prefix}base_link">
    <collision>
      <origin xyz="0 0 ${height1/2}" rpy="0 0 0"/>
      <geometry>
        <box size="${width} ${width} ${height1}"/>
      </geometry>
    </collision>

    <visual>
      <origin xyz="0 0 ${height1/2}" rpy="0 0 0"/>
      <geometry>
        <box size="${width} ${width} ${height1}"/>
      </geometry>
      <material name="orange"/>
    </visual>
  </link>

  <joint name="${prefix}joint1" type="continuous">
    <parent link="${prefix}base_link"/>
    <child link="${prefix}link1"/>
    <origin xyz="0 ${width} ${height1 - axel_offset}" rpy="0 0 0"/>
    <axis xyz="0 1 0"/>
    <dynamics damping="0.7"/>
  </joint>

  <!-- Middle Link -->
  <link name="${prefix}link1">
    <collision>
      <origin xyz="0 0 ${height2/2 - axel_offset}" rpy="0 0 0"/>
      <geometry>
        <box size="${width} ${width} ${height2}"/>
      </geometry>
    </collision>

    <visual>
      <origin xyz="0 0 ${height2/2 - axel_offset}" rpy="0 0 0"/>
      <geometry>
        <box size="${width} ${width} ${height2}"/>
      </geometry>
      <material name="yellow"/>
    </visual>
  </link>

  <joint name="${prefix}joint2" type="continuous">
    <parent link="${prefix}link1"/>
    <child link="${prefix}link2"/>
    <origin xyz="0 ${width} ${height2 - axel_offset*2}" rpy="0 0 0"/>
    <axis xyz="0 1 0"/>
    <dynamics damping="0.7"/>
  </joint>

  <!-- Top Link -->
  <link name="${prefix}link2">
    <collision>
      <origin xyz="0 0 ${height3/2 - axel_offset}" rpy="0 0 0"/>
      <geometry>
        <box size="${width} ${width} ${height3}"/>
      </geometry>
    </collision>

    <visual>
      <origin xyz="0 0 ${height3/2 - axel_offset}" rpy="0 0 0"/>
      <geometry>
        <box size="${width} ${width} ${height3}"/>
      </geometry>
      <material name="orange"/>
    </visual>
  </link>

  <joint name="${prefix}tool_joint" type="fixed">
    <origin xyz="0 0 1" rpy="0 0 0" />
    <parent link="${prefix}link2"/>
    <child link="${prefix}tool_link" />
  </joint>

  <!-- Tool Link -->
  <link name="${prefix}tool_link">
  </link>

  </xacro:macro>

</robot>

# rrbot.materials.xacro
<?xml version="1.0"?>
<!--
Copied from ROS1 example -
https://github.com/ros-simulation/gazebo_ros_demos/blob/kinetic-devel/rrbot_description/urdf/materials.xacro
-->
<robot>

  <material name="black">
    <color rgba="0.0 0.0 0.0 1.0"/>
  </material>

  <material name="blue">
    <color rgba="0.0 0.0 0.8 1.0"/>
  </material>

  <material name="green">
    <color rgba="0.0 0.8 0.0 1.0"/>
  </material>

  <material name="grey">
    <color rgba="0.2 0.2 0.2 1.0"/>
  </material>

  <material name="orange">
    <color rgba="${255/255} ${108/255} ${10/255} 1.0"/>
  </material>

  <material name="brown">
    <color rgba="${222/255} ${207/255} ${195/255} 1.0"/>
  </material>

  <material name="red">
    <color rgba="0.8 0.0 0.0 1.0"/>
  </material>

  <material name="yellow">
    <color rgba="1.0 1.0 0.0 1.0"/>
  </material>

  <material name="white">
    <color rgba="1.0 1.0 1.0 1.0"/>
  </material>

</robot>

创建demos pkg

这个包用于引导编译所有相关依赖包，按照下边格式填好即可。

cd ~/ros2_control_demos

ros2 pkg create --build-type ament_cmake ros2_control_demos

# 文件结构
$ tree ros2_control_demos/
ros2_control_demos/
├── CMakeLists.txt
└── package.xml

# CMakeLists.txt

cmake_minimum_required(VERSION 3.8)
project(ros2_control_demos)

# find dependencies
find_package(ament_cmake REQUIRED)

ament_package()

# package.xml

<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="3">
  <name>ros2_control_demos</name>
  <version>0.0.0</version>
  <description>TODO: Package description</description>
  <maintainer email="someone@example.com">Bing_Lee</maintainer>
  <url type="website">https://blog.csdn.net/Bing_Lee</url>
  <license>TODO: License declaration</license>

  <buildtool_depend>ament_cmake</buildtool_depend>

  <exec_depend>ros2_control_demo_example_1</exec_depend>

  <export>
    <build_type>ament_cmake</build_type>
  </export>
</package>

二、创建controller相关

创建example pkg

cd ~/ros2_control_demos

ros2 pkg create --build-type ament_cmake ros2_control_demo_example_1

这里涉及hardware部分的实现，具体如下：

# rrobot.hpp
// Copyright 2020 ros2_control Development Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ROS2_CONTROL_DEMO_EXAMPLE_1__RRBOT_HPP_
#define ROS2_CONTROL_DEMO_EXAMPLE_1__RRBOT_HPP_

#include <memory>
#include <string>
#include <vector>

#include "hardware_interface/handle.hpp"
#include "hardware_interface/hardware_info.hpp"
#include "hardware_interface/system_interface.hpp"
#include "hardware_interface/types/hardware_interface_return_values.hpp"
#include "rclcpp/macros.hpp"
#include "rclcpp_lifecycle/node_interfaces/lifecycle_node_interface.hpp"
#include "rclcpp_lifecycle/state.hpp"
#include "ros2_control_demo_example_1/visibility_control.h"

namespace ros2_control_demo_example_1
{
class RRBotSystemPositionOnlyHardware : public hardware_interface::SystemInterface
{
public:
  RCLCPP_SHARED_PTR_DEFINITIONS(RRBotSystemPositionOnlyHardware)

  // 从机器人的URDF解析的数据中解析硬件接口.
  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  hardware_interface::CallbackReturn on_init(
    const hardware_interface::HardwareInfo & info) override;

  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  hardware_interface::CallbackReturn on_configure(
    const rclcpp_lifecycle::State & previous_state) override;

  // 导出此硬件接口的所有状态接口.
  // 必须根据为配置传入的硬件信息创建和传输状态接口.
  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  std::vector<hardware_interface::StateInterface> export_state_interfaces() override;

  // 导出此硬件接口的所有命令接口.
  // 命令接口必须根据为配置传入的硬件信息创建和传输.
  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  std::vector<hardware_interface::CommandInterface> export_command_interfaces() override;

  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  hardware_interface::CallbackReturn on_activate(
    const rclcpp_lifecycle::State & previous_state) override;

  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  hardware_interface::CallbackReturn on_deactivate(
    const rclcpp_lifecycle::State & previous_state) override;

  // 从执行器读取当前状态值.
  // 使用接口读取硬件当前状态，注意硬件状态应该是实时更新的.
  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  hardware_interface::return_type read(
    const rclcpp::Time & time, const rclcpp::Duration & period) override;

  // 将当前指令值写入执行器.
  // 使用接口将最新值设置到硬件中.
  ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
  hardware_interface::return_type write(
    const rclcpp::Time & time, const rclcpp::Duration & period) override;

private:
  // Parameters for the RRBot simulation
  double hw_start_sec_;
  double hw_stop_sec_;
  double hw_slowdown_;

  // Store the command for the simulated robot
  std::vector<double> hw_commands_;
  std::vector<double> hw_states_;
};

}  // namespace ros2_control_demo_example_1

#endif  // ROS2_CONTROL_DEMO_EXAMPLE_1__RRBOT_HPP_

// Copyright 2021 ros2_control Development Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/* This header must be included by all rclcpp headers which declare symbols
 * which are defined in the rclcpp library. When not building the rclcpp
 * library, i.e. when using the headers in other package's code, the contents
 * of this header change the visibility of certain symbols which the rclcpp
 * library cannot have, but the consuming code must have inorder to link.
 */

#ifndef ROS2_CONTROL_DEMO_EXAMPLE_1__VISIBILITY_CONTROL_H_
#define ROS2_CONTROL_DEMO_EXAMPLE_1__VISIBILITY_CONTROL_H_

// This logic was borrowed (then namespaced) from the examples on the gcc wiki:
//     https://gcc.gnu.org/wiki/Visibility

#if defined _WIN32 || defined __CYGWIN__
#ifdef __GNUC__
#define ROS2_CONTROL_DEMO_EXAMPLE_1_EXPORT __attribute__((dllexport))
#define ROS2_CONTROL_DEMO_EXAMPLE_1_IMPORT __attribute__((dllimport))
#else
#define ROS2_CONTROL_DEMO_EXAMPLE_1_EXPORT __declspec(dllexport)
#define ROS2_CONTROL_DEMO_EXAMPLE_1_IMPORT __declspec(dllimport)
#endif
#ifdef ROS2_CONTROL_DEMO_EXAMPLE_1_BUILDING_DLL
#define ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC ROS2_CONTROL_DEMO_EXAMPLE_1_EXPORT
#else
#define ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC ROS2_CONTROL_DEMO_EXAMPLE_1_IMPORT
#endif
#define ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC_TYPE ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
#define ROS2_CONTROL_DEMO_EXAMPLE_1_LOCAL
#else
#define ROS2_CONTROL_DEMO_EXAMPLE_1_EXPORT __attribute__((visibility("default")))
#define ROS2_CONTROL_DEMO_EXAMPLE_1_IMPORT
#if __GNUC__ >= 4
#define ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC __attribute__((visibility("default")))
#define ROS2_CONTROL_DEMO_EXAMPLE_1_LOCAL __attribute__((visibility("hidden")))
#else
#define ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC
#define ROS2_CONTROL_DEMO_EXAMPLE_1_LOCAL
#endif
#define ROS2_CONTROL_DEMO_EXAMPLE_1_PUBLIC_TYPE
#endif

#endif  // ROS2_CONTROL_DEMO_EXAMPLE_1__VISIBILITY_CONTROL_H_

attribute((visibility(“default”))) 是 GCC（GNU 编译器集合）中的一个特性，它允许程序员控制特定部分的代码的可见性。在 C 和 C++ 中，代码的可见性是指其他源文件能否访问特定的函数或变量。

当你在一个函数或变量声明中使用 attribute((visibility(“default”)))，表示这个函数或变量默认对所有其他源文件可见。也就是说，这个函数或变量可以在其他源文件中被调用，或者被其他源文件中的变量间接引用。

这种特性在编写库和模块时非常有用，因为它允许程序员更灵活地组织和隐藏代码。例如，你可以创建一个库，其中包含一些默认可见的函数和变量，这些函数和变量可以被其他源文件调用，但不被直接暴露给用户。这种方式可以隐藏库的内部实现细节，同时仍然允许用户使用库的功能。

需要注意的是，attribute((visibility(“default”))) 并不是 C 或 C++ 标准的一部分，而是 GCC 编译器的一个特性。这意味着不是所有的编译器都会支持这个特性，特别是那些不支持 GCC 的编译器。此外，不同的编译器可能对 attribute((visibility)) 的行为有微小的差异，所以在使用这个特性时需要特别小心。

# robot.cpp

// Copyright 2020 ros2_control Development Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "ros2_control_demo_example_1/rrbot.hpp"

#include <chrono>
#include <cmath>
#include <limits>
#include <memory>
#include <vector>

#include "hardware_interface/types/hardware_interface_type_values.hpp"
#include "rclcpp/rclcpp.hpp"

namespace ros2_control_demo_example_1
{
hardware_interface::CallbackReturn RRBotSystemPositionOnlyHardware::on_init(
  const hardware_interface::HardwareInfo & info)
{
  if (
    hardware_interface::SystemInterface::on_init(info) !=
    hardware_interface::CallbackReturn::SUCCESS)
  {
    return hardware_interface::CallbackReturn::ERROR;
  }

  // BEGIN: 这一段是出测试使用考虑，请勿拷贝至实际生产环境
  hw_start_sec_ = stod(info_.hardware_parameters["example_param_hw_start_duration_sec"]);
  hw_stop_sec_ = stod(info_.hardware_parameters["example_param_hw_stop_duration_sec"]);
  hw_slowdown_ = stod(info_.hardware_parameters["example_param_hw_slowdown"]);
  // END: 这一段是出测试使用考虑，请勿拷贝至实际生产环境

  hw_states_.resize(info_.joints.size(), std::numeric_limits<double>::quiet_NaN());
  hw_commands_.resize(info_.joints.size(), std::numeric_limits<double>::quiet_NaN());

  // 校验状态和命令接口是否只有一个
  for (const hardware_interface::ComponentInfo & joint : info_.joints)
  {
    // RRBotSystemPositionOnly 只有一种状态和命令(state,command)
    if (joint.command_interfaces.size() != 1)
    {
      RCLCPP_FATAL(
        rclcpp::get_logger("RRBotSystemPositionOnlyHardware"),
        "Joint '%s' has %zu command interfaces found. 1 expected.", joint.name.c_str(),
        joint.command_interfaces.size());
      return hardware_interface::CallbackReturn::ERROR;
    }

    if (joint.command_interfaces[0].name != hardware_interface::HW_IF_POSITION)
    {
      RCLCPP_FATAL(
        rclcpp::get_logger("RRBotSystemPositionOnlyHardware"),
        "Joint '%s' have %s command interfaces found. '%s' expected.", joint.name.c_str(),
        joint.command_interfaces[0].name.c_str(), hardware_interface::HW_IF_POSITION);
      return hardware_interface::CallbackReturn::ERROR;
    }

    if (joint.state_interfaces.size() != 1)
    {
      RCLCPP_FATAL(
        rclcpp::get_logger("RRBotSystemPositionOnlyHardware"),
        "Joint '%s' has %zu state interface. 1 expected.", joint.name.c_str(),
        joint.state_interfaces.size());
      return hardware_interface::CallbackReturn::ERROR;
    }

    if (joint.state_interfaces[0].name != hardware_interface::HW_IF_POSITION)
    {
      RCLCPP_FATAL(
        rclcpp::get_logger("RRBotSystemPositionOnlyHardware"),
        "Joint '%s' have %s state interface. '%s' expected.", joint.name.c_str(),
        joint.state_interfaces[0].name.c_str(), hardware_interface::HW_IF_POSITION);
      return hardware_interface::CallbackReturn::ERROR;
    }
  }

  return hardware_interface::CallbackReturn::SUCCESS;
}

hardware_interface::CallbackReturn RRBotSystemPositionOnlyHardware::on_configure(
  const rclcpp_lifecycle::State & /*previous_state*/)
{
  // BEGIN: 这一段是出测试使用考虑，请勿拷贝至实际生产环境
  RCLCPP_INFO(
    rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Configuring ...please wait...");

  // configure 前延时
  for (int i = 0; i < hw_start_sec_; i++)
  {
    rclcpp::sleep_for(std::chrono::seconds(1));
    RCLCPP_INFO(
      rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "%.1f seconds left...",
      hw_start_sec_ - i);
  }
  // END: 这一段是出测试使用考虑，请勿拷贝至实际生产环境

  // 在切换状态到configure时总是初始化所有值
  for (uint i = 0; i < hw_states_.size(); i++)
  {
    hw_states_[i] = 0;
    hw_commands_[i] = 0;
  }

  RCLCPP_INFO(rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Successfully configured!");

  return hardware_interface::CallbackReturn::SUCCESS;
}

std::vector<hardware_interface::StateInterface>
RRBotSystemPositionOnlyHardware::export_state_interfaces()
{
  std::vector<hardware_interface::StateInterface> state_interfaces;
  for (uint i = 0; i < info_.joints.size(); i++)
  {
    state_interfaces.emplace_back(hardware_interface::StateInterface(
      info_.joints[i].name, hardware_interface::HW_IF_POSITION, &hw_states_[i]));
  }

  return state_interfaces;
}

std::vector<hardware_interface::CommandInterface>
RRBotSystemPositionOnlyHardware::export_command_interfaces()
{
  std::vector<hardware_interface::CommandInterface> command_interfaces;
  for (uint i = 0; i < info_.joints.size(); i++)
  {
    command_interfaces.emplace_back(hardware_interface::CommandInterface(
      info_.joints[i].name, hardware_interface::HW_IF_POSITION, &hw_commands_[i]));
  }

  return command_interfaces;
}

hardware_interface::CallbackReturn RRBotSystemPositionOnlyHardware::on_activate(
  const rclcpp_lifecycle::State & /*previous_state*/)
{
  // BEGIN: 这一段是出测试使用考虑，请勿拷贝至实际生产环境
  RCLCPP_INFO(
    rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Activating ...please wait...");

  for (int i = 0; i < hw_start_sec_; i++)
  {
    rclcpp::sleep_for(std::chrono::seconds(1));
    RCLCPP_INFO(
      rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "%.1f seconds left...",
      hw_start_sec_ - i);
  }
  // END: 这一段是出测试使用考虑，请勿拷贝至实际生产环境

  // command和state开始时应该是相同的
  for (uint i = 0; i < hw_states_.size(); i++)
  {
    hw_commands_[i] = hw_states_[i];
  }

  RCLCPP_INFO(rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Successfully activated!");

  return hardware_interface::CallbackReturn::SUCCESS;
}

hardware_interface::CallbackReturn RRBotSystemPositionOnlyHardware::on_deactivate(
  const rclcpp_lifecycle::State & /*previous_state*/)
{
  // BEGIN: 这一段是出测试使用考虑，请勿拷贝至实际生产环境
  RCLCPP_INFO(
    rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Deactivating ...please wait...");

  for (int i = 0; i < hw_stop_sec_; i++)
  {
    rclcpp::sleep_for(std::chrono::seconds(1));
    RCLCPP_INFO(
      rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "%.1f seconds left...",
      hw_stop_sec_ - i);
  }

  RCLCPP_INFO(rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Successfully deactivated!");
  // END: 这一段是出测试使用考虑，请勿拷贝至实际生产环境

  return hardware_interface::CallbackReturn::SUCCESS;
}

hardware_interface::return_type RRBotSystemPositionOnlyHardware::read(
  const rclcpp::Time & /*time*/, const rclcpp::Duration & /*period*/)
{
  // BEGIN: 这一段是出测试使用考虑，请勿拷贝至实际生产环境
  RCLCPP_INFO(rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Reading...");

  for (uint i = 0; i < hw_states_.size(); i++)
  {
    // 模拟RRBot的运动，这一块是延时运动更新state逐步靠近command位置
    hw_states_[i] = hw_states_[i] + (hw_commands_[i] - hw_states_[i]) / hw_slowdown_;
    RCLCPP_INFO(
      rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Got state %.5f for joint %d!",
      hw_states_[i], i);
  }
  RCLCPP_INFO(rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Joints successfully read!");
  // END: 这一段是出测试使用考虑，请勿拷贝至实际生产环境

  return hardware_interface::return_type::OK;
}

hardware_interface::return_type RRBotSystemPositionOnlyHardware::write(
  const rclcpp::Time & /*time*/, const rclcpp::Duration & /*period*/)
{
  // BEGIN: 这一段是出测试使用考虑，请勿拷贝至实际生产环境
  RCLCPP_INFO(rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Writing...");

  for (uint i = 0; i < hw_commands_.size(); i++)
  {
    // 仿真发送命令到hardware
    RCLCPP_INFO(
      rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Got command %.5f for joint %d!",
      hw_commands_[i], i);
  }
  RCLCPP_INFO(
    rclcpp::get_logger("RRBotSystemPositionOnlyHardware"), "Joints successfully written!");
  // END: 这一段是出测试使用考虑，请勿拷贝至实际生产环境

  return hardware_interface::return_type::OK;
}

}  // namespace ros2_control_demo_example_1

#include "pluginlib/class_list_macros.hpp"

PLUGINLIB_EXPORT_CLASS(
  ros2_control_demo_example_1::RRBotSystemPositionOnlyHardware, hardware_interface::SystemInterface)

创建bringup

cd ~/ros2_control_demos/ros2_control_demo_example_1
tree bringup/
bringup/
├── config
│   ├── rrbot_controllers.yaml
│   ├── rrbot_forward_position_publisher.yaml
│   └── rrbot_joint_trajectory_publisher.yaml
└── launch
    ├── rrbot.launch.py
    ├── test_forward_position_controller.launch.py
    └── test_joint_trajectory_controller.launch.py

2 directories, 6 files

rrbot_controllers.yaml定义controller总体参数属性和接口名称

# rrbot_controllers.yaml

controller_manager:
  ros__parameters:
    update_rate: 10  # Hz

    joint_state_broadcaster:
      type: joint_state_broadcaster/JointStateBroadcaster

    forward_position_controller:
      type: forward_command_controller/ForwardCommandController

    joint_trajectory_position_controller:
      type: joint_trajectory_controller/JointTrajectoryController


forward_position_controller:
  ros__parameters:
    joints:
      - joint1
      - joint2
    interface_name: position


joint_trajectory_position_controller:
  ros__parameters:
    joints:
      - joint1
      - joint2

    command_interfaces:
      - position

    state_interfaces:
      - position

    action_monitor_rate: 20.0 # Defaults to 20

    allow_partial_joints_goal: false # Defaults to false
    open_loop_control: true
    allow_integration_in_goal_trajectories: true
    constraints:
      stopped_velocity_tolerance: 0.01 # Defaults to 0.01
      goal_time: 0.0 # Defaults to 0.0 (start immediately)

launch文件，负责启动controller_manager、robot_state_publisher等

# rrbot.launch.py

# Copyright 2021 Stogl Robotics Consulting UG (haftungsbeschränkt)
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, RegisterEventHandler
from launch.conditions import IfCondition
from launch.event_handlers import OnProcessExit
from launch.substitutions import Command, FindExecutable, LaunchConfiguration, PathJoinSubstitution

from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageShare


def generate_launch_description():
    # Declare arguments
    declared_arguments = []
    declared_arguments.append(
        DeclareLaunchArgument(
            "gui",
            default_value="true",
            description="Start RViz2 automatically with this launch file.",
        )
    )

    # Initialize Arguments
    gui = LaunchConfiguration("gui")

    # Get URDF via xacro
    robot_description_content = Command(
        [
            PathJoinSubstitution([FindExecutable(name="xacro")]),
            " ",
            PathJoinSubstitution(
                [
                    FindPackageShare("ros2_control_demo_example_1"),
                    "urdf",
                    "rrbot.urdf.xacro",
                ]
            ),
        ]
    )
    robot_description = {"robot_description": robot_description_content}

    robot_controllers = PathJoinSubstitution(
        [
            FindPackageShare("ros2_control_demo_example_1"),
            "config",
            "rrbot_controllers.yaml",
        ]
    )
    rviz_config_file = PathJoinSubstitution(
        [FindPackageShare("ros2_control_demo_description"), "rrbot/rviz", "rrbot.rviz"]
    )

    control_node = Node(
        package="controller_manager",
        executable="ros2_control_node",
        parameters=[robot_description, robot_controllers],
        output="both",
    )
    robot_state_pub_node = Node(
        package="robot_state_publisher",
        executable="robot_state_publisher",
        output="both",
        parameters=[robot_description],
    )
    rviz_node = Node(
        package="rviz2",
        executable="rviz2",
        name="rviz2",
        output="log",
        arguments=["-d", rviz_config_file],
        condition=IfCondition(gui),
    )

    joint_state_broadcaster_spawner = Node(
        package="controller_manager",
        executable="spawner",
        arguments=["joint_state_broadcaster", "--controller-manager", "/controller_manager"],
    )

    robot_controller_spawner = Node(
        package="controller_manager",
        executable="spawner",
        arguments=["forward_position_controller", "--controller-manager", "/controller_manager"],
    )

    # Delay rviz start after `joint_state_broadcaster`
    delay_rviz_after_joint_state_broadcaster_spawner = RegisterEventHandler(
        event_handler=OnProcessExit(
            target_action=joint_state_broadcaster_spawner,
            on_exit=[rviz_node],
        )
    )

    # Delay start of robot_controller after `joint_state_broadcaster`
    delay_robot_controller_spawner_after_joint_state_broadcaster_spawner = RegisterEventHandler(
        event_handler=OnProcessExit(
            target_action=joint_state_broadcaster_spawner,
            on_exit=[robot_controller_spawner],
        )
    )

    nodes = [
        control_node,
        robot_state_pub_node,
        joint_state_broadcaster_spawner,
        delay_rviz_after_joint_state_broadcaster_spawner,
        delay_robot_controller_spawner_after_joint_state_broadcaster_spawner,
    ]

    return LaunchDescription(declared_arguments + nodes)

# 运行launch文件
ros2 launch ros2_control_demo_example_1 rrbot.launch.py

# 打印当前运行节点
ros2 node list

# 输出
/controller_manager
/forward_position_controller
/joint_state_broadcaster
/robot_state_publisher

hardware_interface::SystemInterface类的说明：²

rclcpp_lifecycle::node_interfaces::LifecycleNodeInterface类的说明：³

也可通过上一篇博客《 ROS2 LifecycleNode讲解及实例》中的介绍学习。

【ros2 control 机器人驱动开发】简单双关节机器人学习-example 1,ROS2机器人操作系统,机器人,人工智能

三、测试运行

运行主程序：

# 编译项目
colcon build --packages-up-to ros2_control_demos

# 运行项目
ros2 launch ros2_control_demo_example_1 rrbot.launch.py

新启动一个窗口，查看当前controller状态：

# 查看当前controller状态
ros2 control list_controllers

# -----------OUT PUT-----------------
forward_position_controller[forward_command_controller/ForwardCommandController] active    
joint_state_broadcaster[joint_state_broadcaster/JointStateBroadcaster] active

测试forward_command_controller

可以看到forward_command_controller和joint_state_broadcaster两个处于active状态，我们先测试forward_command_controller，运行命令如下：

# 这里会每隔8s测试性输出一个指令
ros2 launch ros2_control_demo_example_1 test_forward_position_controller.launch.py

运行结果如下：
【ros2 control 机器人驱动开发】简单双关节机器人学习-example 1,ROS2机器人操作系统,机器人,人工智能

测试joint_trajectory_controller

ctrl+c停止前一个窗口

# 加载joint_trajectory_controller
ros2 control load_controller joint_trajectory_position_controller --set-state inactive

# 切换controller使用状态
ros2 control set_controller_state forward_position_controller inactive
ros2 control set_controller_state joint_trajectory_position_controller active

# 查看当前controller状态
ros2 control list_controllers

# -----------OUT PUT-----------------
joint_trajectory_position_controller[joint_trajectory_controller/JointTrajectoryController] active    
joint_state_broadcaster[joint_state_broadcaster/JointStateBroadcaster] active    
forward_position_controller[forward_command_controller/ForwardCommandController] inactive

运行测试指令：

ros2 launch ros2_control_demo_example_1 test_joint_trajectory_controller.launch.py

运行结果如下：

【ros2 control 机器人驱动开发】简单双关节机器人学习-example 1,ROS2机器人操作系统,机器人,人工智能

总结

这里就是example1的整体解说了，对于controller及其定义以及如何调试运行都做了说明，整个项目代码避免有小伙伴写错已上传至gitee代码库，地址如下**Bing Lee / Learn Ros2 Moveit**，请期待下一篇此系列文章。

【ros2 control 机器人驱动开发】简单双关节机器人学习-example 1,ROS2机器人操作系统,机器人,人工智能

Example 1: RRBot — ROS2_Control: Rolling Dec 2023 documentation ↩︎
ROS2 Control: hardware_interface::SystemInterface Class Reference ↩︎
Class LifecycleNodeInterface ↩︎文章来源地址https://www.toymoban.com/news/detail-762559.html

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