Quick query, moving from different views

[Ellie]

Hi! I have to hand this coursework in tomorrow, slight snag in the mapping part of it. I'm moving from "robot view" to "display view". Basically the robot is drawing a map of the screen based on what it picks up on radar -

pseudocoding it because my Uni uses turn it in:


robot x = get robot's x position
robot y = get robot's y position
robot t = get robot's theta (angle relative to the room)

distance = get sonar distance from sonar at 10 degrees

Get the x and y of the picked up object relative to the robot.
x = cos(10) * distance
y = sin(10) * distance

Relative to the bot, there is an object at (x,y)
Convert to the display coordinate system

display x = (cos(-t) * x) - (sin(-t) * y)
display y = (sin(-t) * x) + (cos(-t) * y)

Basically have rotated it around (0,0) -t degrees

Translate based on the robot's position

display x -= robot x
display y -= robot y

add point to map: (display x, display y)



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My question is simply: is the above correct? Should it work?

It's not working, I'm getting garbage, but I need to acertain whether it's my coding or the robot itself that is broken.

Thanks in advance.

 

[9robin3]

what is this anyway? some kind of homework?:/

 

[Ellie]

Imagine a robot in a room. The robot has an x and y position, relative to the room. It also has a rotation. It happens to spot an object that is 300mm away, at an angle of 10 degrees from the robot.

What I need to do is plot that point relative to the room, not to the robot. Does that make sense?

Yes this is coursework.

 

[Ellie]

It turns out my calculations are (probably) correct, and that it's the robot that's broken. It is reporting back completely wrong values for X, Y, T.