关于《ROS 2机器人开发》中修改参数的求助

565712988

《ROS 2机器人开发》书中114页通过节点修改参数，书里面讲述的例子是修改的模型这个参数，如果想修改检测次数upsample_times这个参数应该怎么做，我模仿书中修改模型model参数的例子写了但是不行，请教一下应该怎么办？
是不是SetParameters里面的integer_value不是检测次数
new_model_value.integer_value=int(detect_times)这一行应该是有问题，请教应该怎么修改。

import rclpy
from rclpy.node import Node
from chapt4_interfaces.srv import FaceDetector
from sensor_msgs.msg import Image
import cv2
from cv_bridge import CvBridge
from rcl_interfaces.srv import SetParameters
from rcl_interfaces.msg import Parameter,ParameterValue,ParameterType
import time


class FaceDetectorClient(Node):
    def __init__(self,node_name,image_path):
        super().__init__(node_name)
        self.client =self.create_client(FaceDetector,'face_detect')
        self.bridge=CvBridge()
        self.image_path=image_path
        self.image =cv2.imread(self.image_path)


    def send_request(self):
        while self.client.wait_for_service(timeout_sec=1) is False:
            self.get_logger().info('服务端未上线...')
        request=FaceDetector.Request()
        request.image=self.bridge.cv2_to_imgmsg(self.image)
        future=self.client.call_async(request)
        rclpy.spin_until_future_complete(self,future)
        response=future.result()
        self.get_logger().info(f'收到响应：图像共有：{response.number}张脸，耗时{response.use_time}')
        # self.show_face_location(response)


    def show_face_location(self,response):
        for i in range(response.number):
            top =response.top[i]
            right=response.right[i]
            bottom=response.bottom[i]
            left=response.left[i]
            cv2.rectangle(self.image,(left,top),(right,bottom),(0,0,255),2)
        cv2.imshow('人脸检测结果',self.image)
        cv2.waitKey(0)

    def call_set_parameter(self,parameters):
        update_param_client=self.create_client(SetParameters,'/face_detect_node/set_parameters')

        while update_param_client.wait_for_service(timeout_sec=1) is False:
            self.get_logger().info('等待参数更新服务端上线...')
            time.sleep(1.0)
        request=SetParameters.Request()
        request.parameters=parameters
        future=update_param_client.call_async(request)
        rclpy.spin_until_future_complete(self,future)
        response=future.result()
        return response

    def update_detect_model(self,model_name):
        param=Parameter()
        param.name='set_model'
        new_model_value=ParameterValue()
        new_model_value.type=ParameterType.PARAMETER_STRING
        new_model_value.string_value=model_name
        param.value=new_model_value
        response=self.call_set_parameter([param])
        for result in response.results:
            if result.successful:
                self.get_logger().info(f'参数{param.name}设置为{model_name}')
            else:
                self.get_logger().info(f'参数设置失败，原因为{result.reason}')

    def update_detect_times(self,detect_times):
        param=Parameter()
        param.name='upsample_times'
        new_model_value=ParameterValue()
        new_model_value.type=ParameterType.PARAMETER_STRING
        new_model_value.integer_value=int(detect_times)
        param.value=new_model_value
        response=self.call_set_parameter([param])
        for result in response.results:
            if result.successful:
                self.get_logger().info(f'参数{param.name}设置为{detect_times}')
            else:
                self.get_logger().info(f'参数设置失败，原因为{result.reason}')            


def main(args=None):
    rclpy.init(args=args)
    node=FaceDetectorClient('face_detect_client',image_path='/home/bonoit/Desktop/1.jpg')

    node.update_detect_model('cnn')
    node.send_request()
    node.update_detect_model('hog')
    node.send_request()
    
    detect_times=2
    node.update_detect_times(detect_times)
    node.send_request()

    rclpy.spin(node)
    node.destroy_node()
    rclpy.shutdown()

小鱼

@565712988 您在设置整型参数时存在类型定义错误的问题。根据ROS2参数接口定义，整型参数需要使用PARAMETER_INTEGER类型标识，并通过integer_value字段赋值。请按以下修改：

def update_detect_times(self, detect_times):
    param = Parameter()
    param.name = 'upsample_times'
    new_model_value = ParameterValue()
    # 修改此处类型定义和赋值方式
    new_model_value.type = ParameterType.PARAMETER_INTEGER
    new_model_value.integer_value = int(detect_times)  # 直接赋值整数值
    param.value = new_model_value
    
    response = self.call_set_parameter([param])
    for result in response.results:
        if result.successful:
            self.get_logger().info(f'参数{param.name}设置为{detect_times}')
        else:
            self.get_logger().info(f'参数设置失败，原因为{result.reason}')

需要特别注意的三个关键点：

类型匹配：ROS2参数类型必须严格匹配，PARAMETER_INTEGER对应integer_value字段，PARAMETER_STRING对应string_value字段
参数声明：确保服务端节点已正确声明该参数（类似以下声明代码）：

self.declare_parameter('upsample_times', 1)  # 默认值

参数验证：建议在服务端添加参数验证回调函数，方便调试参数设置：

def parameter_callback(parameters):
    for param in parameters:
        if param.name == 'upsample_times':
            if param.type_ != Parameter.Type.INTEGER:
                raise ValueError('upsample_times must be an integer')
    return SetParametersResult(successful=True)

修改完成后，启动节点时添加参数调试信息：

ros2 run your_package face_detector --ros-args --log-level debug

当您看到类似以下成功日志时，表示参数设置成功：

[INFO] [参数upsample_times设置为2]

如果仍然失败，请检查：

参数服务是否正常运行：ros2 service list | grep set_parameters
参数名称是否匹配：ros2 param list /face_detect_node
参数类型是否正确：ros2 param get /face_detect_node upsample_times