Low Pass Filter

The LowPassFilter is a ROS 2 chainable controller designed to apply a low-pass filter to state interfaces, smoothing noisy signals while maintaining real-time performance.

Publishers

• interface_values [control_msgs::msg::DynamicInterfaceValues]: Publishes the filtered state interface values.

Parameters

• state_interface_prefix [string, default: ”“]: Prefix to be prepended to the state interface names.
• state_interface_names [string_array, default: []]: Names of state interfaces to be filtered.
• sampling_frequency [double, default: 100.0]: Filter sampling frequency in Hz.
• damping_frequency [double, default: 0.1]: Filter damping frequency in Hz (Is it?).
• damping_intensity [double, default: 0.707]: Defines how sharp the filter is. 0.707 is the default value for a Butterworth filter.
• publish_interface_values [bool, default: false]: If true, the state interface values will be published to a topic.
• zero_threshold [double, default: 0.0025]: If the filtered value is below this threshold, it will be set to zero.

Interfaces

Exported State Interfaces

• {node_name}/{state_interface_prefix}/{state_interface_name}: Filtered data.

Example Usage

low_pass_filter:
  ros__parameters:
    state_interface_prefix: <namespace>/imu
    state_interface_names: [angular_velocity.z]
    sampling_frequency: 100.0
    damping_frequency: 0.1
    damping_intensity: 15.0
    publish_interface_values: false
    zero_threshold: 0.0025