The ARGoS Forum

Posted: **Tue May 19, 2020 3:55 am**

Hi
I m trying to move a foot bot towards a specific patch in LUA lets say from position (1,1) to a position (4,4) without using light source. I have obtained the current coordinates x and y of foot-bot using GPS sensor and stored them in a vector. Also stored target coordinates values in a spearate vector.

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local pos = { a=robot.positioning.position.x, b=robot.positioning.position.y }
local target = { a=4, b=4 }

I have subtracted the current coordinates vector from the target coordinates vector using this.

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local newvector = {a = target.a - pos.a, b = target.b - pos.b }

Also obtained the orientation angle of foot-bot using GPS sensor.

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robot.positioning.orientation.angle

I have rotated the new vector and tried to move the foot-bot but it is not moving.

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newvector.rotate (-orientation)
robot.wheels.set_velocity(newvector)

Even this rotating new vector doesn't work and I am confused about setting the coordinates towards new desired location. How can I set orientation towards new coordinates if I have the current x, y and orientation using GPS sensor.

Thanks and best regards

Posted: **Tue Jun 02, 2020 7:56 pm**

The method "set_velocity" does not accept a vector as input, but the wheel speeds.

Posted: **Wed Jun 03, 2020 4:29 am**

thanks for the reply, Can u please exactly tell where I have mistake in the code?

Posted: **Wed Jun 03, 2020 4:36 am**

robot.wheels.set_velocity(10,5) sets the left wheel to 10 cm/s and the right to 5 cm/s

Posted: **Wed Jun 03, 2020 5:18 am**

I know how to move normally with velocity. But this question was asked in a sense that how to set direction/orientation of foot-bot towards the specific patch. But this question is still unsolved. Please tell me the can I move robot towards a specific patch.

Posted: **Thu Jun 04, 2020 6:00 am**

Hi,
Currently robot has been placed on coordinates (-2,-2) as can be seen in attached screenshot.

: Screenshot from 2020-06-04 10-54-53.png (77.35 KiB) Viewed 22479 times

Now I want to move it to (0,0) coordinates without using any light source or omni-directional camera. I have tried the following lines of code, but it is not even moving the robot. The code I am using is given below:

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pos_x=robot.positioning.position.x
pos_y=robot.positioning.position.y

local target = { a=0, b=0 }
local newvector = {a = target.a - pos_x, b = target.b - pos_y }
local orientation=robot.positioning.orientation.angle

newvector.rotate(-orientation)
robot.wheels.set_velocity(10,10)

Please help me to solve this issue. Thanks

Posted: **Thu Jun 04, 2020 8:15 pm**

Look into the inverse kinematics of differential drive robots: http://rossum.sourceforge.net/papers/DiffSteer/. This is not a problem with ARGoS.

The ARGoS Forum

Moving foot-bot towards a patch in ARGoS using LUA

Moving foot-bot towards a patch in ARGoS using LUA

Re: Moving foot-bot towards a patch in ARGoS using LUA

Re: Moving foot-bot towards a patch in ARGoS using LUA

Re: Moving foot-bot towards a patch in ARGoS using LUA

Re: Moving foot-bot towards a patch in ARGoS using LUA

Re: Moving foot-bot towards a patch in ARGoS using LUA

Re: Moving foot-bot towards a patch in ARGoS using LUA