View Full Version : Collision without forces

03-26-2012, 01:38 PM

I would like to build an excavator and be able to pick up some objects (e.g. boxes) with the bucket . Therefore, the bucket (I built collision objects in form of boxes around it that stick to the bucket) shall collide with the objects.
When I activate physics and forces my collision objects either fall on the ground or - if I deactivate gravity - they fly slightly away.
I just want to activate collisions for the bucket but no forces, is this somehow supported?


03-27-2012, 04:12 AM
Once the bucket collides with an object are you going to set the object's position to be inside the bucket? If so, it maybe easier for you to work with proximity sensors if you just want to know when objects are near eachother. When a proximity event occurs you can disable the sensor on the object and place it in the bucket.

04-05-2012, 04:55 AM
Thanks a lot for your reply. I guess the proximity sensors are not exactly what I need, I really wanted to solve the problem with mere collision detection.
I now figured out how to build an arm of an excavator with joints and motors and tried to grab my object. When I am moving my joints with "joint.setMotorAngle" and density and maxTorque settings which seem to work well for the movement I get severe problems when I am colliding with the ground object and the error: ODE Message 3: LCP internal error.
The collision with the floor leads to jerky movements or makes the whole excavator disappear.
Does anybody have any advice regarding the tuning of the values of the physics engine (like density, hardness, friction, maxTorque) in this case for me?
I spent two hours on adjusting all kinds of parameters but I could not find any configuration which seems to help with the collision problem.
I attached the Vizard file and .ive scene to my posting.
Moreover, I have no idea what I can do to overcome the error messages that appear on collisions, like:
ODE Message 3: LCP internal error, s <= 0 (s=-8.0282e+005)
** WARNING: Physics engine returned invalid data for node 3

I would be really, really grateful for any help or advice on my problem.

11-22-2015, 05:26 PM
I am a new student for vizard .. trying to see how it can help.. your work is awesome as i can see the excavator links moving. could you tell me if i can do it in osgb format(mean moving links). i tried but couldn't. As I have a seperate part files and complete assembly files in osgb format... but couldn't rotate any part.. hope you can help if i will send you osgb file formats..

Waiting for your reply:)