Set an instant velocity on Gazebo

asked 2017-04-06 04:53:19 -0500

shenki
16 ●3 ●4 ●4

Hello,

I am working on Gazebo 7 with ROS kinetic. So, here is my problem, I have that code function :

    void SetVelocity(const double &_vel)
    {   
        this->model->GetJointController()->SetVelocityTarget(this->joint->GetScopedName(), _vel);
    }

It's used to set a velocity to my pioneer, it's working pretty well but I want the velocity to be instant. For exemple, when I set it to a velocity of 30 and then a velocity of 0, it will take so many time to stop. What are the solutions ? Here is the rest of the code :

        this->model = _model; 
        this->joint = _model->GetJoints()[0];
        this->pid = common::PID(0.1, 0, 0, 1000, -1000, 1000, -1000);
        this->model->GetJointController()->SetVelocityPID(this->joint->GetScopedName(), this->pid);

Thank in advance.

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answered 2017-04-06 09:52:06 -0500

shenki
16 ●3 ●4 ●4

updated 2017-04-06 09:56:00 -0500

For the moment I found that, it's working but it's not that good...

    public: void SetVelocity(const double &_vel)
    {
        double __vel = _vel;
        if(__vel>30)__vel=30;
        this->joint->SetDamping(0,old_value/10);
        this->joint->Update();
        this->model->GetJointController()->SetVelocityTarget(this->joint->GetScopedName(), __vel);
        old_value = __vel;
    }

This is stupid, so if someone has better, i'll take it, thank you !

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answered 2017-04-06 09:14:51 -0500

Stefan Kohlbrecher

24361 ●173 ●299 ●444 https://www.energy-rob...

You can set the velocity for joint directly via SetVelocity in Gazebo's Joint API, but this can lead to undesirable side-effects as the physics engine is bypassed to an extend. In my experience, applying efforts (for instance via PID control) tends to be more stable.

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Hello,

I tried SetVelocity and SetVelocityTarget via a joitController. The thing is if I set the velocity to 30, to pioneer will go at 30 of speed but after that, if I set velocity on 0, it won't stop, and I can't understand why, do you really think it could be better using efforts ?

shenki ( 2017-04-06 09:29:16 -0500 )edit

Well, I just tried it, the problem is still the same, even if my pioneer is going forward, asking him to get a force of 0 doesn't make it stop

shenki ( 2017-04-06 09:39:14 -0500 )edit

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