Couldn't find /clock topic

edit

Hi,

I want to get the simulation time published on the clock topic because the current time in ROS is set by default in the system time of the machine!!

The problem is that I can't find any topic named /clock or a parameter named use_sim_time here is what I get:

rostopic list:

/bebop/autoflight/navigate_home
/bebop/autoflight/pause
/bebop/autoflight/start
/bebop/autoflight/stop
/bebop/bebop_nodelet/parameter_descriptions
/bebop/bebop_nodelet/parameter_updates
/bebop/bebop_nodelet_manager/bond
/bebop/camera_control
/bebop/camera_info
/bebop/cmd_vel
/bebop/fix
/bebop/flattrim
/bebop/flip
/bebop/image_raw
/bebop/image_raw/compressed
/bebop/image_raw/compressed/parameter_descriptions
/bebop/image_raw/compressed/parameter_updates
/bebop/image_raw/compressedDepth
/bebop/image_raw/compressedDepth/parameter_descriptions
/bebop/image_raw/compressedDepth/parameter_updates
/bebop/image_raw/theora
/bebop/image_raw/theora/parameter_descriptions
/bebop/image_raw/theora/parameter_updates
/bebop/joint_states
/bebop/land
/bebop/odom
/bebop/record
/bebop/reset
/bebop/set_exposure
/bebop/snapshot
/bebop/states/ardrone3/CameraState/Orientation
/bebop/states/ardrone3/GPSState/NumberOfSatelliteChanged
/bebop/states/ardrone3/MediaStreamingState/VideoEnableChanged
/bebop/states/ardrone3/PilotingState/AltitudeChanged
/bebop/states/ardrone3/PilotingState/AttitudeChanged
/bebop/states/ardrone3/PilotingState/FlatTrimChanged
/bebop/states/ardrone3/PilotingState/FlyingStateChanged
/bebop/states/ardrone3/PilotingState/NavigateHomeStateChanged
/bebop/states/ardrone3/PilotingState/PositionChanged
/bebop/states/ardrone3/PilotingState/SpeedChanged
/bebop/states/common/CommonState/BatteryStateChanged
/bebop/states/common/CommonState/WifiSignalChanged
/bebop/states/common/FlightPlanState/AvailabilityStateChanged
/bebop/states/common/FlightPlanState/ComponentStateListChanged
/bebop/states/common/MavlinkState/MavlinkFilePlayingStateChanged
/bebop/states/common/MavlinkState/MavlinkPlayErrorStateChanged
/bebop/states/common/OverHeatState/OverHeatChanged
/bebop/takeoff
/rosout
/rosout_agg
/tf
/tf_static

rosparam list:

/bebop/bebop_nodelet/GPSSettingsHomeTypeType
/bebop/bebop_nodelet/GPSSettingsReturnHomeDelayDelay
/bebop/bebop_nodelet/NetworkSettingsWifiSelectionBand
/bebop/bebop_nodelet/NetworkSettingsWifiSelectionChannel
/bebop/bebop_nodelet/NetworkSettingsWifiSelectionType
/bebop/bebop_nodelet/PictureSettingsVideoFramerateFramerate
/bebop/bebop_nodelet/PictureSettingsVideoRecordingModeMode
/bebop/bebop_nodelet/PictureSettingsVideoResolutionsType
/bebop/bebop_nodelet/PictureSettingsVideoStabilizationModeMode
/bebop/bebop_nodelet/PilotingSettingsAbsolutControlOn
/bebop/bebop_nodelet/PilotingSettingsBankedTurnValue
/bebop/bebop_nodelet/PilotingSettingsCirclingAltitudeValue
/bebop/bebop_nodelet/PilotingSettingsCirclingDirectionValue
/bebop/bebop_nodelet/PilotingSettingsCirclingRadiusValue
/bebop/bebop_nodelet/PilotingSettingsMaxAltitudeCurrent
/bebop/bebop_nodelet/PilotingSettingsMaxDistanceValue
/bebop/bebop_nodelet/PilotingSettingsMaxTiltCurrent
/bebop/bebop_nodelet/PilotingSettingsMinAltitudeCurrent
/bebop/bebop_nodelet/PilotingSettingsNoFlyOverMaxDistanceShouldnotflyover
/bebop/bebop_nodelet/PilotingSettingsPitchModeValue
/bebop/bebop_nodelet/SpeedSettingsHullProtectionPresent
/bebop/bebop_nodelet/SpeedSettingsMaxPitchRollRotationSpeedCurrent
/bebop/bebop_nodelet/SpeedSettingsMaxRotationSpeedCurrent
/bebop/bebop_nodelet/SpeedSettingsMaxVerticalSpeedCurrent
/bebop/bebop_nodelet/SpeedSettingsOutdoorOutdoor
/bebop/bebop_nodelet/bebop_ip
/bebop/bebop_nodelet/camera_info_url
/bebop/bebop_nodelet/cmd_vel_timeout
/bebop/bebop_nodelet/odom_frame_id
/bebop/bebop_nodelet/publish_odom_tf
/bebop/bebop_nodelet/reset_settings
/bebop/bebop_nodelet/states/enable_altitudechanged
/bebop/bebop_nodelet/states/enable_autotakeoffmodechanged
/bebop/bebop_nodelet/states/enable_camerastate_orientation
/bebop/bebop_nodelet/states/enable_commonstate_batterystatechanged
/bebop/bebop_nodelet/states/enable_commonstate_wifisignalchanged
/bebop/bebop_nodelet/states/enable_controllerstate_ispilotingchanged

My purpose is to generate a sinosoidal trajectory with cos( pi t) and the time t here has to be set to 0 when the simulation starts.

Any suggestion please !!