move_base obstacle clearing in open field problem

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Hi,

A project I am working on involves the use of a mobile robot in an open field using move_base to navigate autonomously and avoiding obstacles.

The obstacles in the costmaps only get cleared with raytracing when an obstacle further away is detected. This is a problem for me since most of the time there is no other obstacle that the sensor can see. For example, if someone were to walk in front of the robot, he would leave a trail in the costmap that never gets cleared because there is nothing behind it.

Does anyone know of a solution to this problem?

Thanks

Update

Here are my configuration files for the costmaps

Common parameters: obstacle_range: 3.0 raytrace_range: 3.5

robot_base_frame: base_footprint
update_frequency: 4.0
publish_frequency: 4.0
transform_tolerance: 0.5

footprint: [[-0.17, -0.18], [-0.17, 0.22], [0.17, 0.22], [0.17, -0.18]]
footprint_padding: 0.0

resolution: 0.05

static_layer:
   map_topic: /map

obstacle_layer:
    observation_sources: laser
    laser: {data_type: LaserScan, topic: /scan, clearing: true, marking: true, inf_is_valid: false, track_unknown_space: true} 

inflation_layer:
    cost_scaling_factor: 2
    inflation_radius: 1

Global parameters:

global_frame: map

rolling_window: true

plugins:
  - {name: static_layer,              type: "costmap_2d::StaticLayer"}
  - {name: inflation_layer,           type: "costmap_2d::InflationLayer"}

Local parameters:

global_frame: odom

rolling_window: true
width: 3
height: 3

plugins:
  - {name: obstacle_layer,            type: "costmap_2d::ObstacleLayer"}
  - {name: inflation_layer,           type: "costmap_2d::InflationLayer"}