Search found 19 matches

by biscuit122
07 Nov 2018, 20:37
Forum: General questions
Topic: Can force/torque control of joint achieve positive and negative motion during one control loop?
Replies: 2
Views: 895

Re: Can force/torque control of joint achieve positive and negative motion during one control loop?

Hello, you can only set the amplitude of the force/torque. The sign is set via the joint target velocity. So set following: sim.setJointForce(handle,math.abs(f)) if f~=0 then sim.setJointTargetVelocity(handle,math.abs(vel)*f/math.abs(f)) end Cheers Thanks for your brilliant tutorial, which helps me...
by biscuit122
05 Nov 2018, 02:46
Forum: General questions
Topic: Can force/torque control of joint achieve positive and negative motion during one control loop?
Replies: 2
Views: 895

Can force/torque control of joint achieve positive and negative motion during one control loop?

In this tutorial, I set a sin function to define a joint force control. But it only move in one direction, so if I do not change target velocity, do you have method to move joint in two direction during one control loop? https://github.com/feig122/force_test
by biscuit122
11 Sep 2018, 13:11
Forum: General questions
Topic: Why does funtion sim.getJointForce have nil value at the first execution?
Replies: 1
Views: 158

Why does funtion sim.getJointForce have nil value at the first execution?

Hi, I have found that sim.getJointForce outputs a nil value at its first loop. Why does it appear?
I am looking forward to your answer. Thanks
by biscuit122
07 Sep 2018, 11:19
Forum: General questions
Topic: How to get the intrinsic velocity of a prismatic joint?
Replies: 0
Views: 140

How to get the intrinsic velocity of a prismatic joint?

Hi, I have got the current position of a prismatic joint using sim.getJointPosition . But I have not found any other functions in lua to acquire current velocity of a prismatic joint. Could you please tell me? Thanks for your help in advance. In addtion, I would like to change Control properties in ...
by biscuit122
01 Sep 2018, 14:51
Forum: General questions
Topic: The API function and joint dynamic properties of force control and position control for a primastic joint
Replies: 6
Views: 483

Re: The API function and joint dynamic properties of force control and position control for a primastic joint

To set a negative force, you'll have to set a negative target velocity ( sim.setJointTargetVelocity ). But you should keep the same amplitude of that target velocity. Cheers Thanks for your help and time. In your words, it means that a force controller needs setting target velocity and force for a ...
by biscuit122
13 Aug 2018, 12:06
Forum: General questions
Topic: The API function and joint dynamic properties of force control and position control for a primastic joint
Replies: 6
Views: 483

Re: The API function and joint dynamic properties of force control and position control for a primastic joint

Here a very simple example: set your joint in force/torque mode, enable the motor and the control loop. Then attach a threaded child script to the joint with following code: function sysCall_threadmain() local h=sim.getObjectAssociatedWithScript(sim.handle_self) local t=0 while true do sim.setJoint...
by biscuit122
01 Aug 2018, 04:04
Forum: General questions
Topic: The API function and joint dynamic properties of force control and position control for a primastic joint
Replies: 6
Views: 483

Re: The API function and joint dynamic properties of force control and position control for a primastic joint

Hello, if your joint is in force/torque mode , your motor enabled and the control loop disabled , then you can adjust your joint's behaviour with sim.setJointForce : the joint will apply the specified force/torque until the target velocity has been reached. You can adjust the target velocity with s...
by biscuit122
30 Jul 2018, 12:09
Forum: General questions
Topic: The API function and joint dynamic properties of force control and position control for a primastic joint
Replies: 6
Views: 483

The API function and joint dynamic properties of force control and position control for a primastic joint

Hi, can you help me to distinguish the difference between force control and position control for a primastic joint? I calculate the force to control a primastic joint. Can I use sim.setJointTargetPosition in script? How should I set the joint dynamic properties ?( including motor enabled, control pr...
by biscuit122
12 May 2018, 03:19
Forum: General questions
Topic: dynamic simulation problem of Stewart parallel mechanism
Replies: 2
Views: 230

Re: dynamic simulation problem of Stewart parallel mechanism

Your stewart platform seems to be quite nice. I don't see any obvious problem. However, make sure of following: The platform has a dimension of almost 1 meter in height. Is that intended? If yes, remember that if you want to move it fast, this can generate tremendous forces in the joints. Most engi...
by biscuit122
10 May 2018, 02:55
Forum: General questions
Topic: The measurement of force sensors in Stewart platform
Replies: 4
Views: 268

Re: The measurement of force sensors in Stewart platform

It is not directly computed by V-REP, but by the used physics engine (i.e. Bullet, ODE, Vortex or Newton). It also of course depends on your mass/inertia settings. Can you post your scene? Cheers Thank you so much. I have post my scence in this problem http://www.forum.coppeliarobotics.com/viewtopi...