feat(controls): Wheel slip detector (Issue #262) #266
@ -5,21 +5,10 @@ from launch.actions import DeclareLaunchArgument
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import os
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from ament_index_python.packages import get_package_share_directory
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def generate_launch_description():
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pkg_dir = get_package_share_directory("saltybot_wheel_slip_detector")
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config_file = os.path.join(pkg_dir, "config", "wheel_slip_config.yaml")
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return LaunchDescription([
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DeclareLaunchArgument(
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"config_file",
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default_value=config_file,
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description="Path to configuration YAML file",
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),
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Node(
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package="saltybot_wheel_slip_detector",
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executable="wheel_slip_detector_node",
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name="wheel_slip_detector",
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output="screen",
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parameters=[LaunchConfiguration("config_file")],
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),
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DeclareLaunchArgument("config_file", default_value=config_file, description="Path to configuration YAML file"),
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Node(package="saltybot_wheel_slip_detector", executable="wheel_slip_detector_node", name="wheel_slip_detector", output="screen", parameters=[LaunchConfiguration("config_file")]),
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])
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18
jetson/ros2_ws/src/saltybot_wheel_slip_detector/package.xml
Normal file
18
jetson/ros2_ws/src/saltybot_wheel_slip_detector/package.xml
Normal file
@ -0,0 +1,18 @@
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<?xml version="1.0"?>
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<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
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<package format="3">
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<name>saltybot_wheel_slip_detector</name>
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<version>0.1.0</version>
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<description>Wheel slip detection by comparing commanded vs actual velocity.</description>
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<maintainer email="seb@vayrette.com">Seb</maintainer>
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<license>Apache-2.0</license>
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<buildtool_depend>ament_python</buildtool_depend>
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<depend>rclpy</depend>
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<depend>geometry_msgs</depend>
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<depend>std_msgs</depend>
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<depend>nav_msgs</depend>
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<test_depend>pytest</test_depend>
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<export>
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<build_type>ament_python</build_type>
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</export>
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</package>
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@ -1,13 +1,6 @@
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#!/usr/bin/env python3
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"""Wheel slip detector for SaltyBot.
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Detects wheel slip by comparing commanded velocity vs actual encoder velocity.
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Publishes Bool when slip is detected for >0.5s, enabling speed reduction response.
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"""
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from typing import Optional
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import math
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import rclpy
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from rclpy.node import Node
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from rclpy.timer import Timer
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@ -15,82 +8,60 @@ from geometry_msgs.msg import Twist
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from nav_msgs.msg import Odometry
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from std_msgs.msg import Bool
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class WheelSlipDetectorNode(Node):
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"""ROS2 node for wheel slip detection."""
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def __init__(self):
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super().__init__("wheel_slip_detector")
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self.declare_parameter("frequency", 10)
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frequency = self.get_parameter("frequency").value
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self.declare_parameter("slip_threshold", 0.1)
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self.declare_parameter("slip_timeout", 0.5)
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self.slip_threshold = self.get_parameter("slip_threshold").value
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self.slip_timeout = self.get_parameter("slip_timeout").value
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self.period = 1.0 / frequency
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self.cmd_vel: Optional[Twist] = None
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self.actual_vel: Optional[Twist] = None
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self.slip_duration = 0.0
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self.slip_detected = False
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self.create_subscription(Twist, "/cmd_vel", self._on_cmd_vel, 10)
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self.create_subscription(Odometry, "/odom", self._on_odom, 10)
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self.pub_slip = self.create_publisher(Bool, "/saltybot/wheel_slip_detected", 10)
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self.timer: Timer = self.create_timer(self.period, self._timer_callback)
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self.get_logger().info(
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f"Wheel slip detector initialized at {frequency}Hz. "
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f"Threshold: {self.slip_threshold} m/s, Timeout: {self.slip_timeout}s"
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)
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self.get_logger().info(f"Wheel slip detector initialized at {frequency}Hz. Threshold: {self.slip_threshold} m/s, Timeout: {self.slip_timeout}s")
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def _on_cmd_vel(self, msg: Twist) -> None:
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"""Update commanded velocity from subscription."""
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self.cmd_vel = msg
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def _on_odom(self, msg: Odometry) -> None:
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"""Update actual velocity from odometry subscription."""
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self.actual_vel = msg.twist.twist
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def _timer_callback(self) -> None:
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"""Detect wheel slip and publish detection flag."""
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if self.cmd_vel is None or self.actual_vel is None:
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slip_detected = False
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else:
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slip_detected = self._check_slip()
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if slip_detected:
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self.slip_duration += self.period
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else:
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self.slip_duration = 0.0
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is_slip = self.slip_duration > self.slip_timeout
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if is_slip != self.slip_detected:
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self.slip_detected = is_slip
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if self.slip_detected:
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self.get_logger().warn(f"WHEEL SLIP DETECTED: {self.slip_duration:.2f}s")
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else:
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self.get_logger().info("Wheel slip cleared")
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slip_msg = Bool()
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slip_msg.data = is_slip
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self.pub_slip.publish(slip_msg)
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def _check_slip(self) -> bool:
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"""Check if velocity difference indicates slip."""
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cmd_speed = math.sqrt(self.cmd_vel.linear.x**2 + self.cmd_vel.linear.y**2)
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actual_speed = math.sqrt(self.actual_vel.linear.x**2 + self.actual_vel.linear.y**2)
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vel_diff = abs(cmd_speed - actual_speed)
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if cmd_speed < 0.05 and actual_speed < 0.05:
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return False
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return vel_diff > self.slip_threshold
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def main(args=None):
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rclpy.init(args=args)
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node = WheelSlipDetectorNode()
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@ -102,6 +73,5 @@ def main(args=None):
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node.destroy_node()
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rclpy.shutdown()
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if __name__ == "__main__":
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main()
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@ -0,0 +1,4 @@
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[develop]
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script-dir=$base/lib/saltybot_wheel_slip_detector
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[install]
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install-scripts=$base/lib/saltybot_wheel_slip_detector
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@ -1,7 +1,5 @@
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from setuptools import find_packages, setup
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package_name = "saltybot_wheel_slip_detector"
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setup(
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name=package_name,
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version="0.1.0",
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@ -19,9 +17,5 @@ setup(
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description="Wheel slip detection from velocity command/actual mismatch",
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license="Apache-2.0",
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tests_require=["pytest"],
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entry_points={
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"console_scripts": [
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"wheel_slip_detector_node = saltybot_wheel_slip_detector.wheel_slip_detector_node:main",
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],
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},
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)
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entry_points={"console_scripts": ["wheel_slip_detector_node = saltybot_wheel_slip_detector.wheel_slip_detector_node:main"]},
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)
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Block a user