AVM navigator:navigation by map obstacle
fabrice2006 from France  [11 posts]
13 year
Hello, how does it works the plugin dectection of obstacle in the avm navigator  used within the navigation by map, i often have a red triangular with the message Obstacle and the robot go backward, but there's no obsctacle... Is it possible to desactivate this detection or bypass this dectecion of the obstacle?

Thanks for your help.

EDV  [328 posts] 13 year
How does work obstacle avoidance algorithm?

The robot processes the motion history of input images for the previous second. If any commands were given (i.e. the "forward" command) but no changes where seen in the input image (nothing happened) then the robot is assumed to be stuck (i.e. the robot is pushing against a wall). When stuck the module will set the movement variables to move backwards. The stuck situation is indicated by a red rectangle with a circle in the center.

I think your robot see picture that has too few details (not enough contrast objects) and when robot give command "forwards" he see that no changes happen. This situation is caused by less lighting (robot see darkness) or by cleared walls without any textures.

Unfortunately but current version of AVM Navigator has no way for disabling of this algorithm but I will include this option in next modification.

So you could try to bring some objects with contrast texture to robot environment or you would try to increase lighting.
EDV  [328 posts] 13 year
I plan to share some emulator program (based on Quake 3 mod) for acquaintance with "Marker mode" and "Navigation by map" modes.

But unfortunately this emulator is not ready for publishing yet.

So, let’s try to use this modes directly on real robot (step by step).

1. Connect your robot to AVM Navigator:

Just use the variables that described below for connection of your robot to AVM Navigator:

Use variable NV_TURRET_BALANCE for camera turning: NV_TURRET_BALANCE - indicates the turn degree amount. This value range from -100 to 100 with forward being zero.

Use for motor control NV_L_MOTOR and NV_R_MOTOR variables that have range from -100 to 100 for motion control ("-100 " - full power backwards, "100" - full power forwards, "0" - motor off).

If you use Lego NXT platform then you should just adjust variables NV_L_MOTOR and NV_R_MOTOR to the range of NXT parameters (motors range from 0 to 255 with 128 being neutral) by VBScript:

2. Call the dialog window of AVM Navigator (click on it at video processing pipeline) and then switch to “Nova gate mode”. Now you can control your robot by arrow keys and also you can turn robot camera by "Delete" and "Page Down" keys ("End" key will set the camera in front position).

3. Move your robot to the start position. In this position will be placed origin of navigation map.

4. Reset markers data information by click at "Clear/mark data" (if it needed).

5. Switch to "Marker mode" and then you should manually lead the robot along a route.

6. In the end of  route you should switch to "Nova gate mode" and then save route data (click "Save") to the file that will has different name with default "avm.dat".

7. Return to the start position and switch to "Navigation by map" mode then you should point robot to the target position at the navigation map (click the left mouse button on the map) and robot automatically will navigate to this point.

You should repeat items 2-6  several times for good detailing of navigation map.
EDV  [328 posts] 13 year
I have added option of disabling obstacle detection to Navigator dialog window . Now you can download next modification of AVM Navigator v0.7.1 from your account link.
fabrice2006 from France  [11 posts] 13 year
thanks very much i try it quickly

EDV  [328 posts] 13 year
I prepared emulator program (based on Quake 3 mod) for acquaintance with "Marker mode" and "Navigation by map" modes.

See "AVM Quake 3 mod" manual for more details:

You can try to download it from:

Also next modification of AVM Navigator v0.7.2 is released:


- The "Navigation map" was placed into main Navigator dialog window (also was added map scrolling and resizing abilities).

- Visual odometry algorithm was improved.

And now you can download next modification of AVM Navigator v0.7.2 from your account link.
EDV  [328 posts] 13 year
Next modification of AVM Navigator v0.7.2.1 is released.

Visual odometry algorithm was updated:

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