学习完gazebo如何控制机器人后转为学习webots。
主要参考了CSDN：全网最全的Webots资料在这里
https://blog.csdn.net/weixin_43455581/article/details/108711611
https://blog.csdn.net/crp997576280/category_9855084.html
官网的很多例题，并给出了简介，需要什么功能照着简介找对应的就可以了
具体内建控制器怎么写，建模怎么弄，可以参考webots软件自带的例程webtos/projects/samples
名词介绍，这里的世界文件为.wbt，而不是.world。且devices包含以前的执行器和传感器等。
新建工程目录，不要直接直接在原来的webots目录下，这样由于webots保护，无法创建一些文件。
wizard->new project directory。然后再进行下面的步骤
自带的机器人都被封装了，需要右键转换成基本节点才能见到内部的构成
如何创建一个机器人
- 类似gazebo内带的构建机器人方法一样，可以用可视化的模型树建模。当然比较简单了。
- 使用solidworks导出三维模型 模型.wrl .stl等，可以在webot中file->import。然后进行webots中的零部件装配。gazebo让人诟病的就是零部件装配全靠手动写xacro等建模文件，否则很不精确。
- 使用urdf2webots功能包，将urdf转为proto(VRML语言)格式，proto类似gazebo使用的sdf(xml语言)格式一样是仿真软件自己指定的仿真描述文件。详情github搜urdf2webots就可以下载，然后进入包输入pip install -r requiredments.txt 安装，输入 phthon demo.py --input=xxx.urdf。得到当前终端目录下有一个叫xxx.pr中to的文件。然后在webots中按加号插入模型，在
PROTO nodes(Current Project)中导入当前工程路径下的protos文件夹下。重新打开该窗口就可以发现有一个模型image.png只做到这这步，下次再打开模型就消失了。需要转换其为基本节点：点击模型->covert to base node(s)image.png
新建世界
file->new world。会出现一片漆黑，然后左边场景树。一个是worldinfo一个是viewpoint。点击场景树中的选项，其下方有个参数编辑区，截图修改场景树中模型或属性的数值。其中worldinfo就类似gazebo中的world，定义了一堆世界信息比如重力加速度、仿真步长等。
image.png
- 地面：PROTO nodes(Webots Projects)->objects -> floors
- 光源：点光源、平行光源、锥形光源。分别存在 Base nodes -> pointLight/DIrctionLight/SpotLight
创建环境物体
先插入solid节点，然后点击场景树中solid，选中其children，添加shape。appearance是gazebo中的纹理textures，而geometry描述实体形状。点击geometry添加一个sphere球(也可以添加mesh网格)。此时geometry 后出现Sphere，然后点开可以修改半径和细分度。然后为appearance添加纹理，双击textures，添加imageTextures。在纹理图片中的url属性中选择纹理图片路径
image.png
。
现在只是有可视形状(对应gazebo中vision)。还没有物理属性，所以无法对仿真做出动作响应。点击physics，添加physics节点，然后可以设置 质量、密度(mass density二选一，其中一个必须为-1)。这样他就有了物理属性，但是有物理属性后，他还没有碰撞实体，现在只有shape这个现实外形。因此对boundingObject(类似collision)进行设置。可以直接复制vision也就是children中的shape属性给他使用
image.png
控制器代码， wizard-> new robot_controller 创建对应语言的控制器文件。具体查看博客内容作为控制代码模板。然后在机器人的controller中选择对应控制器。 其中控制器参数是用来传入程序的入口参数？在webot_ros中用来指定机器人的unique name。
与gazebo和ros通信有gazebo_ros_control一样。webot有webots_ros，其实也是机器人控制器或插件内实现了服务器、数据、话题等并发布到ros网络上。可通过apt安装。但是建议通过clone https://github.com/cyberbotics/webots_ros 然后重点查看src中的complete_test.cpp和robot_infomation_parser.cpp 前者是api例子，后者是程序模板。而webot.launch 教我们如何通过launch启动webot，其实是运行一个叫webot的python脚本(需要设置成可执行文件权限)。而phthon脚本通过终端命令来启动webots。然后可以向这个默认的webot.launch文件指定.wbt(世界文件)，然后包含这个默认webots.launch文件来编写用户自己的文件来启动webot。
image.png
可能出现
image.png
只需要
export WEBOTS_HOME=~/software/webots 然后重新运行即可。
image.png
场地还是很好看的，以后可以借用一下。
启动后输入rosservice list 可以发现好多服务，可以用来获取各种信息，包括传感器，关节等。这点和gazebo_ros_control 一致。
剩下的怎么写就可以看博客的 ros通信下。包括cmakelist 源码等。代码例程也可以看webots_ros包下的实例代码`robot_infomation_parser.cpp。
比如
CMakeLists中的find_package 加入webots_ros
webots_ros发布的topic/service的名字格式为：robot_unique_name(webots模型中name字段内容+ 进程ID号 + device_name)/ service或topic_name。
而修改controllerArgs字段为 --name=myrobot_name，则可以设置robot_unique_name为一个固定的值，否则程序每次启动进程ID不同影响程序编写通用性。
以下模板不是webots 控制器的代码模板，而是webots+ros中 ros的使用代码。
模板一
#include
#include
#include "ros/ros.h"
#include
#include
#include
#include
#include
#include
#include
#define TIME_STEP 32
#define NMOTORS 4
#define MAX_SPEED 4
ros::NodeHandle *n;
static int controllerCount;
static std::vector controllerList;
ros::ServiceClient timeStepClient;
webots_ros::set_int timeStepSrv;
static const char *motorNames[NMOTORS] = {"wheel1", "wheel2", "wheel3", "wheel4"};
// 更新速度
void updateSpeed() {
double speeds[NMOTORS];
speeds[0] = MAX_SPEED;
speeds[1] = MAX_SPEED;
speeds[2] = MAX_SPEED;
speeds[3] = MAX_SPEED;
for (int i = 0; i < NMOTORS; ++i) {
ros::ServiceClient set_velocity_client;
webots_ros::set_float set_velocity_srv;
set_velocity_client = n->serviceClient(std::string("my_robot/") + std::string(motorNames[i]) +
std::string("/set_velocity"));
set_velocity_srv.request.value = speeds[i];
set_velocity_client.call(set_velocity_srv);
}
}
// 获取可用控制器的名称
void controllerNameCallback(const std_msgs::String::ConstPtr &name) {
controllerCount++;
controllerList.push_back(name->data);
ROS_INFO("Controller #%d: %s.", controllerCount, controllerList.back().c_str());
}
//退出函数
void quit(int sig) {
ROS_INFO("终止节点运行.");
timeStepSrv.request.value = 0;
timeStepClient.call(timeStepSrv);
ros::shutdown();
exit(0);
}
int main(int argc, char **argv) {
setlocale(LC_CTYPE,"zh_CN.utf8");
ros::init(argc, argv, "my_robot", ros::init_options::AnonymousName);
n = new ros::NodeHandle;
signal(SIGINT, quit);
std::string controllerName;
/********************************************** 当作模板即可 ****************************************************/
// 订阅主题model_name以获得可用控制器列表
ros::Subscriber nameSub = n->subscribe("model_name", 100, controllerNameCallback);
while (controllerCount == 0 || controllerCount < nameSub.getNumPublishers()) {
ros::spinOnce();
ros::spinOnce();
ros::spinOnce();
}
ros::spinOnce();
// 设置基本仿真步长
timeStepClient = n->serviceClient("my_robot/robot/time_step");
timeStepSrv.request.value = TIME_STEP;
// 多控制器时可选
if (controllerCount == 1){
controllerName = controllerList[0];
}
else {
int wantedController = 0;
std::cout << "选择要使用的控制器的编号 :\n";
std::cin >> wantedController;
if (1 <= wantedController && wantedController <= controllerCount)
controllerName = controllerList[wantedController - 1];
else {
ROS_ERROR("无效的控制器编号.");
return 1;
}
}
ROS_INFO("Using controller: '%s'", controllerName.c_str());
nameSub.shutdown();
/********************************************** 电机模式设置 ****************************************************/
for (int i = 0; i < NMOTORS; ++i) {
ros::ServiceClient set_position_client;
webots_ros::set_float set_position_srv;
set_position_client = n->serviceClient(std::string("my_robot/") + std::string(motorNames[i]) +
std::string("/set_position"));
//设置速度模式
set_position_srv.request.value = INFINITY;
if (set_position_client.call(set_position_srv) && set_position_srv.response.success)
ROS_INFO("motor %s 工作模式为速度模式.", motorNames[i]);
else
ROS_ERROR("无法调用motor %s的set_position服务 .", motorNames[i]);
// 创建速度client
ros::ServiceClient set_velocity_client;
set_velocity_client = n->serviceClient(std::string("my_robot/") + std::string(motorNames[i]) +
std::string("/set_velocity"));
// 创建服务
webots_ros::set_float set_velocity_srv;
set_velocity_srv.request.value = 0.0;
if (set_velocity_client.call(set_velocity_srv) && set_velocity_srv.response.success == 1)
ROS_INFO("Velocity set to 0.0 for motor %s.", motorNames[i]);
else
ROS_ERROR("Failed to call service set_velocity on motor %s.", motorNames[i]);
}
/********************************************** 传感器使能 ****************************************************/
// 使能 camera
ros::ServiceClient set_camera_client;
webots_ros::set_int camera_srv;
ros::Subscriber sub_camera;
set_camera_client = n->serviceClient("my_robot/kinect_color/enable");
camera_srv.request.value = 64;
set_camera_client.call(camera_srv);
/******************************************** 主循环 ****************************************************** */
while (ros::ok()) {
updateSpeed(); // 更新小车速度
if (!timeStepClient.call(timeStepSrv) || !timeStepSrv.response.success) {
ROS_ERROR("Failed to call service time_step for next step.");
break;
}
ros::spinOnce();
}
timeStepSrv.request.value = 0;
timeStepClient.call(timeStepSrv);
ros::shutdown();
return 0;
}
模板二
// Copyright 1996-2020 Cyberbotics Ltd.
//
// 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
#include "ros/ros.h"
// include files to use services like 'robot_get_time'.
// srv files needed to use webots service can be found in the /srv folder where you found this example.
// for more info on how to create and use services with ROS refer to their website: http://wiki.ros.org/
// here 'webots_ros' is the name of the package used for this node. Replace it by your own package.
#include
#include
#include
// include files to use standard message types in topic
// Webots only use basic messages type defined in ROS library
#include
#define TIME_STEP 32
static int controllerCount;
static std::vector controllerList;
// catch names of the controllers availables on ROS network
void controllerNameCallback(const std_msgs::String::ConstPtr &name) {
controllerCount++;
controllerList.push_back(name->data);
ROS_INFO("Controller #%d: %s.", controllerCount, controllerList.back().c_str());
}
void quit(int sig) {
ROS_INFO("User stopped the 'robot_information_parser' node.");
ros::shutdown();
exit(0);
}
int main(int argc, char **argv) {
std::string controllerName;
std::vector deviceList;
// create a node named 'robot_information_parser' on ROS network
ros::init(argc, argv, "robot_information_parser", ros::init_options::AnonymousName);
ros::NodeHandle n;
signal(SIGINT, quit);
// subscribe to the topic model_name to get the list of availables controllers
ros::Subscriber nameSub = n.subscribe("model_name", 100, controllerNameCallback);
while (controllerCount == 0 || controllerCount < nameSub.getNumPublishers()) {
ros::spinOnce();
ros::spinOnce();
ros::spinOnce();
}
ros::spinOnce();
// if there is more than one controller available, it let the user choose
if (controllerCount == 1)
controllerName = controllerList[0];
else {
int wantedController = 0;
std::cout << "Choose the # of the controller you want to use:\n";
std::cin >> wantedController;
if (1 <= wantedController && wantedController <= controllerCount)
controllerName = controllerList[wantedController - 1];
else {
ROS_ERROR("Invalid number for controller choice.");
return 1;
}
}
// leave topic once it is not necessary anymore
nameSub.shutdown();
// call get_type and get_model services to get more general information about the robot
ros::ServiceClient getTypeClient = n.serviceClient(controllerName + "/robot/get_type");
webots_ros::get_int getTypeSrv;
ros::ServiceClient getModelClient = n.serviceClient(controllerName + "/robot/get_model");
webots_ros::get_string getModelSrv;
getTypeClient.call(getTypeSrv);
if (getTypeSrv.response.value == 40)
ROS_INFO("This controller is on a basic robot.");
else if (getTypeSrv.response.value == 41)
ROS_INFO("This controller is on a supervisor robot.");
else
ROS_INFO("This controller is on a differential wheels robot.");
if (getModelClient.call(getModelSrv)) {
if (!getModelSrv.response.value.empty())
ROS_INFO("The model of this robot is %s.", getModelSrv.response.value.c_str());
else
ROS_ERROR("The robot doesn't seems to have a model.");
} else
ROS_ERROR("Could not get the model of this robot.");
// call deviceList service to get the list of the name of the devices available on the controller and print it
// the deviceListSrv object contains 2 members: request and response. Their fields are described in the corresponding .srv
// file
ros::ServiceClient deviceListClient =
n.serviceClient(controllerName + "/robot/get_device_list");
webots_ros::robot_get_device_list deviceListSrv;
if (deviceListClient.call(deviceListSrv)) {
deviceList = deviceListSrv.response.list;
ROS_INFO("The controller has %lu devices availables:", deviceList.size());
for (unsigned int i = 0; i < deviceList.size(); i++)
ROS_INFO("Device [%d]: %s.", i, deviceList[i].c_str());
} else
ROS_ERROR("Failed to call service deviceList.");
}
webots 控制器代码
#include
// Added a new include file
#include
#define TIME_STEP 64
int main(int argc, char **argv) {
wb_robot_init();
// get the motor devices
WbDeviceTag left_motor = wb_robot_get_device("left wheel motor");
WbDeviceTag right_motor = wb_robot_get_device("right wheel motor");
// set the target position of the motors
wb_motor_set_position(left_motor, 10.0);
wb_motor_set_position(right_motor, 10.0);
while (wb_robot_step(TIME_STEP) != -1);
wb_robot_cleanup();
return 0;
}
webots 速度控制
#include
// Added a new include file
#include
#define TIME_STEP 64
#define MAX_SPEED 6.28
int main(int argc, char **argv) {
wb_robot_init();
// get a handler to the motors and set target position to infinity (speed control)
WbDeviceTag left_motor = wb_robot_get_device("left wheel motor");
WbDeviceTag right_motor = wb_robot_get_device("right wheel motor");
wb_motor_set_position(left_motor, INFINITY);
wb_motor_set_position(right_motor, INFINITY);
// set up the motor speeds at 10% of the MAX_SPEED.
wb_motor_set_velocity(left_motor, 0.1 * MAX_SPEED);
wb_motor_set_velocity(right_motor, 0.1 * MAX_SPEED);
while (wb_robot_step(TIME_STEP) != -1) {
}
wb_robot_cleanup();
return 0;
}
webots控制器 详细教程
https://www.cyberbotics.com/doc/guide/tutorial-4-more-about-controllers?tab-language=c++
如何搭建一个机器人教程
https://www.cyberbotics.com/doc/guide/tutorial-6-4-wheels-robot?tab-language=c
image.png
结构是，父实体(父link) 具有children 为几个关节，而这几个关节每个都有各自连接的另一端为endpoint(子link)。而每个jiont都应该加上 对应的motor，这样才可以驱动关节运动。
Cmakelist
cmake_minimum_required(VERSION 3.0.2)
project(webots_controller)
find_package(catkin REQUIRED COMPONENTS
message_generation
roscpp
rospy
sensor_msgs
std_msgs
tf
webots_ros
)
catkin_package(
# INCLUDE_DIRS include
# LIBRARIES webots_controller
CATKIN_DEPENDS message_runtime message_generation roscpp rospy sensor_msgs std_msgs tf webots_ros
# DEPENDS system_lib
)
include_directories(
# include
${catkin_INCLUDE_DIRS}
)
add_executable(first_webots_ros_simulation src/first_webots_ros_simulation.cpp)
target_link_libraries(first_webots_ros_simulation
${catkin_LIBRARIES}
package.xml
webots_controller
0.0.0
The webots_controller package
robert
TODO
catkin
rospy
roscpp
std_msgs
sensor_msgs
message_generation
tf
webots_ros
webots_ros
rospy
roscpp
std_msgs
sensor_msgs
message_runtime
tf
message_generation