Path Planning work with ACMR?

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danielamaria20
Posts: 16
Joined: 09 Mar 2013, 18:10

Path Planning work with ACMR?

Post by danielamaria20 » 09 Jul 2013, 17:00

Hi, I been trying for the last 4 hours to follow all the steps to create a path planning, but I'm only successful with objects.
When I try with ACMR dosent work. I'm doing something wrong or the path planning its only for objects?

Thanks

coppelia
Site Admin
Posts: 7123
Joined: 14 Dec 2012, 00:25

Re: Path Planning work with ACMR?

Post by coppelia » 09 Jul 2013, 17:18

Hello Daniela,

The path planning functionality will calculate a collision-free path based on a rigid structure of shapes that should reach a target position/orientation without collision. It just calculates a path, but doesn't tell anything about how to follow that path.

The ACMR5 robot model is controlled via motors located between consecutive segments. It is relying on physics to move (i.e. it will fall, collide and exert friction with the ground). What you have to do is:
  • use a simple collision shape to calculate the collision-free path. Typically a sphere or cuboid that should be more than 3-4 times the dimensions of the front ACMR5 segment
  • sample the calculated path with following API function: simGetPositionOnPath. That will return the coordinate of the sampled point.
  • control the motors of the ACMR5 in a way that makes the front segment follow the coordinates mentionned in previous point
Path planning with the ACMR5 robot is a very tricky and complicated task, and above solution is just a simple and not perfect way of solving it. Solving the task more efficiently and elegantly would probably require to write a specific path planning algorithm just for that type of robot.

Cheers

danielamaria20
Posts: 16
Joined: 09 Mar 2013, 18:10

Re: Path Planning work with ACMR?

Post by danielamaria20 » 09 Jul 2013, 17:32

Thanks, you were very helpfull.
Just let me get this straight, I will have to do the pathhplaning for a cuboid and put in "the head" and then make a algorithm in ACMR to control all the movements and follow the points of the cuboid? This movements is based in all joints and wheels?

thanks !

coppelia
Site Admin
Posts: 7123
Joined: 14 Dec 2012, 00:25

Re: Path Planning work with ACMR?

Post by coppelia » 09 Jul 2013, 19:10

What you basically do, is compute a collision-free path of a cuboid or sphere. Then make the robot follow the calculated path, which hopefully will be also collision-free for the snake. But you will have to actuate the motors in-between the individual segments. That is a very complex task if you are not experiences with snake-like robots.

Cheers

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