Search found 30 matches

by biscuit122
17 Nov 2018, 20:55
Forum: General questions
Topic: install Vortex on Vrep in Linux
Replies: 4
Views: 1500

install Vortex on Vrep in Linux

Hi, I would like to use Vortex physical engine on Vrep in Linux. But I found no Linux version on cm-lab website. Do you know how to solve this problem? Thank you in advance.
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: 1347

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: 1347

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: 566

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: 1024

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: 1184

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: 1184

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: 1184

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: 1184

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: 631

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...