将 `base_controller.txt` 中的代码迁移到 Python 3 主要涉及以下几个方面的改动： ### 1. **Print 函数** 在 Python 2 中，`print` 是一个语句，而在 Python 3 中它是一个函数。因此需要将所有的 `print` 改为 `print()` 函数。 ### 2. **除法运算符 `/`** Python 3 中的 `/` 总是执行浮点数除法，而 Python 2 中 `/` 在整数之间会执行整数除法。为了确保兼容性，可以在文件开头添加 `from __future__ import division`，或者确保所有除法操作都使用浮点数。 ### 3. **ROS 相关的更新** 虽然 ROS 1 主要基于 Python 2，但可以通过安装 `rospkg` 和其他依赖项来支持 Python 3。如果你打算迁移到 ROS 2，则需要进一步修改代码以适应 ROS 2 的 API 变化。 ### 4. **其他 Python 3 兼容性调整** - 使用 `//` 进行整数除法（如果需要）。 - 确保字符串和字节之间的转换正确处理。 以下是经过 Python 3 修改后的代码片段： ```python #!/usr/bin/env python3 from __future__ import division # Ensure true division in Python 2 as well import roslib; roslib.load_manifest('ros_arduino_python') import rospy import os from math import sin, cos, pi from geometry_msgs.msg import Quaternion, Twist, Pose from nav_msgs.msg import Odometry from tf.broadcaster import TransformBroadcaster class BaseController: def __init__(self, arduino, base_frame, name="base_controllers"): self.arduino = arduino self.name = name self.base_frame = base_frame self.rate = float(rospy.get_param("~base_controller_rate", 10)) self.timeout = rospy.get_param("~base_controller_timeout", 1.0) self.stopped = False pid_params = { 'wheel_diameter': rospy.get_param("~wheel_diameter", ""), 'wheel_track': rospy.get_param("~wheel_track", ""), 'encoder_resolution': rospy.get_param("~encoder_resolution", ""), 'gear_reduction': rospy.get_param("~gear_reduction", 1.0), 'Kp': rospy.get_param("~Kp", 20), 'Kd': rospy.get_param("~Kd", 12), 'Ki': rospy.get_param("~Ki", 0), 'Ko': rospy.get_param("~Ko", 50) } self.accel_limit = rospy.get_param('~accel_limit', 0.1) self.motors_reversed = rospy.get_param("~motors_reversed", False) # Set up PID parameters and check for missing values self.setup_pid(pid_params) # How many encoder ticks are there per meter? self.ticks_per_meter = self.encoder_resolution * self.gear_reduction / (self.wheel_diameter * pi) # What is the maximum acceleration we will tolerate when changing wheel speeds? self.max_accel = self.accel_limit * self.ticks_per_meter / self.rate # Track how often we get a bad encoder count (if any) self.bad_encoder_count = 0 now = rospy.Time.now() self.then = now # time for determining dx/dy self.t_delta = rospy.Duration(1.0 / self.rate) self.t_next = now + self.t_delta # Internal data self.enc_left = None # encoder readings self.enc_right = None self.x = 0 # position in xy plane self.y = 0 self.th = 0 # rotation in radians self.v_left = 0 self.v_right = 0 self.v_des_left = 0 # cmd_vel setpoint self.v_des_right = 0 self.last_cmd_vel = now # Subscriptions rospy.Subscriber("cmd_vel", Twist, self.cmdVelCallback) # Clear any old odometry info self.arduino.reset_encoders() # Set up the odometry broadcaster self.odomPub = rospy.Publisher('odom', Odometry, queue_size=5) self.odomBroadcaster = TransformBroadcaster() rospy.loginfo(f"Started base controller for a base of {self.wheel_track}m wide with {self.encoder_resolution} ticks per rev") rospy.loginfo(f"Publishing odometry data at: {self.rate} Hz using {self.base_frame} as base frame") def setup_pid(self, pid_params): # Check to see if any PID parameters are missing missing_params = False for param in pid_params: if pid_params[param] == "": print(f"*** PID Parameter {param} is missing. ***") missing_params = True if missing_params: os._exit(1) self.wheel_diameter = pid_params['wheel_diameter'] self.wheel_track = pid_params['wheel_track'] self.encoder_resolution = pid_params['encoder_resolution'] self.gear_reduction = pid_params['gear_reduction'] self.Kp = pid_params['Kp'] self.Kd = pid_params['Kd'] self.Ki = pid_params['Ki'] self.Ko = pid_params['Ko'] self.arduino.update_pid(self.Kp, self.Kd, self.Ki, self.Ko) def poll(self): now = rospy.Time.now() if now > self.t_next: # Read the encoders try: left_enc, right_enc = self.arduino.get_encoder_counts() except Exception as e: self.bad_encoder_count += 1 rospy.logerr(f"Encoder exception count: {self.bad_encoder_count}") return dt = now - self.then self.then = now dt = dt.to_sec() # Calculate odometry if self.enc_left is None: dright = 0 dleft = 0 else: dright = (right_enc - self.enc_right) / self.ticks_per_meter dleft = (left_enc - self.enc_left) / self.ticks_per_meter self.enc_right = right_enc self.enc_left = left_enc dxy_ave = (dright + dleft) / 2.0 dth = (dright - dleft) / self.wheel_track vxy = dxy_ave / dt vth = dth / dt if dxy_ave != 0: dx = cos(dth) * dxy_ave dy = -sin(dth) * dxy_ave self.x += (cos(self.th) * dx - sin(self.th) * dy) self.y += (sin(self.th) * dx + cos(self.th) * dy) if dth != 0: self.th += dth quaternion = Quaternion() quaternion.x = 0.0 quaternion.y = 0.0 quaternion.z = sin(self.th / 2.0) quaternion.w = cos(self.th / 2.0) # Create the odometry transform frame broadcaster. self.odomBroadcaster.sendTransform( (self.x, self.y, 0), (quaternion.x, quaternion.y, quaternion.z, quaternion.w), rospy.Time.now(), self.base_frame, "odom" ) odom = Odometry() odom.header.frame_id = "odom" odom.child_frame_id = self.base_frame odom.header.stamp = now odom.pose.pose.position.x = self.x odom.pose.pose.position.y = self.y odom.pose.pose.position.z = 0 odom.pose.pose.orientation = quaternion odom.twist.twist.linear.x = vxy odom.twist.twist.linear.y = 0 odom.twist.twist.angular.z = vth self.odomPub.publish(odom) if now > (self.last_cmd_vel + rospy.Duration(self.timeout)): self.v_des_left = 0 self.v_des_right = 0 if self.v_left < self.v_des_left: self.v_left += self.max_accel if self.v_left > self.v_des_left: self.v_left = self.v_des_left else: self.v_left -= self.max_accel if self.v_left < self.v_des_left: self.v_left = self.v_des_left if self.v_right < self.v_des_right: self.v_right += self.max_accel if self.v_right > self.v_des_right: self.v_right = self.v_des_right else: self.v_right -= self.max_accel if self.v_right < self.v_des_right: self.v_right = self.v_des_right # Set motor speeds in encoder ticks per PID loop if not self.stopped: self.arduino.drive(self.v_left, self.v_right) self.t_next = now + self.t_delta def stop(self): self.stopped = True self.arduino.drive(0, 0) def cmdVelCallback(self, req): # Handle velocity-based movement requests self.last_cmd_vel = rospy.Time.now() x = req.linear.x # m/s th = req.angular.z # rad/s if x == 0: # Turn in place right = th * self.wheel_track * self.gear_reduction / 2.0 left = -right elif th == 0: # Pure forward/backward motion left = right = x else: # Rotation about a point in space left = x - th * self.wheel_track * self.gear_reduction / 2.0 right = x + th * self.wheel_track * self.gear_reduction / 2.0 self.v_des_left = int(left * self.ticks_per_meter / self.arduino.PID_RATE) self.v_des_right = int(right * self.ticks_per_meter / self.arduino.PID_RATE) if __name__ == '__main__': rospy.init_node('base_controller') # Assuming arduino object is created elsewhere and passed here arduino = ... # Initialize your arduino object here base_frame = 'base_link' # Replace with actual base frame ID base_controller = BaseController(arduino, base_frame) rate = rospy.Rate(base_controller.rate) while not rospy.is_shutdown(): base_controller.poll() rate.sleep() ``` ### 关键改动说明： 1. **Print 函数**：所有 `print` 都改为 `print()` 函数形式。 2. **字符串格式化**：使用了 f-string (`f"..."`) 来提高可读性和性能。 3. **异常处理**：改进了异常捕获机制，增加了 `Exception as e` 来获取更多错误信息。 4. **Python 3 特定模块**：确保所有模块导入和语法符合 Python 3 标准。 此外，还需要确保你的环境中已经安装并配置好 Python 3 版本的相关 ROS 包和其他依赖项。如果计划迁移到 ROS 2，请参考 [ROS 2 文档](https://docs.ros.org/en/foxy/)进行进一步调整。