How to reorient the Gripper using the robot joints to pick up?

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Fery64
Posts: 88
Joined: 02 Feb 2022, 15:58

How to reorient the Gripper using the robot joints to pick up?

Post by Fery64 »

Hi All

I use the trajectory planning + Joint Velocity (gained from inverse differential kinematics) application over the distance intervals among the waypoints to get to the desired target point in my model.

There are 2 problems : The trajectory is not very nice : unstable velocity, high accelerations or jerk in the start point or in turning points.

2- The robot poses in an arbitrary orientation in the target point. so as you see in the following image, it can not pick the box up.

So my questions are : 1- How can I improve the trajectory? 2- What is the strategy to be able to reorient the Gripper : the Gripper is prismatic, and I have to use one of the Joints of the robot to turn. Please if possible mention it with coding.


https://tinypic.host/i/gripperorint.yv4ae
Image
Why can't I upload images here?

Fery64
Posts: 88
Joined: 02 Feb 2022, 15:58

Re: How to reorient the Gripper using the robot joints to pick up?

Post by Fery64 »

One way would be using rmlMovetoPosition, since it containts the quaternions, but that can not be a trajectory planning but only point to point movement.

coppelia
Site Admin
Posts: 10312
Joined: 14 Dec 2012, 00:25

Re: How to reorient the Gripper using the robot joints to pick up?

Post by coppelia »

Hello,

your questions are always way too large and vague. It is very difficult to answer appropriately in those situations. Also, learn to divide a task in many sub-tasks and assess them individually. If one of them does not work as expected, it will be much easier to ask for help.
You current question is about path planning, inverse kinematics, trajectory following, with a random set-up of yours. Seeing those long, intricate questions, where we have to guess what your intent is exactly, and what your level of understanding is, is very discouraging for anyone trying to help out.

Cheers

Fery64
Posts: 88
Joined: 02 Feb 2022, 15:58

Re: How to reorient the Gripper using the robot joints to pick up?

Post by Fery64 »

My main question was the topic of the question : Using only trajectory planning, the gripper does not orient correctly towards the object to pick it up. How should I do that?

coppelia
Site Admin
Posts: 10312
Joined: 14 Dec 2012, 00:25

Re: How to reorient the Gripper using the robot joints to pick up?

Post by coppelia »

Use simIK.findConfig to find a configuration of the robot that places the end-effector with a desired position and orientation. Then use path planning to drive to that configuration.

Have a look at the simple example model Models/robots/non-mobile/Mirobot.ttm

Cheers

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