If given two non-decreasing values, `springlength` specifies a deadband for spring stiffness, inside of which the force is 0 and outside of which force behaves like a regular spring, with the setpoint corresponding to the nearest value. This can be used to create tendons whose limits are enforced by springs rather than constraints, which are cheaper and easier to analyse. See test/engine/testdata/tendon_springlength.xml example model.
Spring-limited spatial tendons whose lower range value is 0 are rendered as catenaries.
Fixes#520.
PiperOrigin-RevId: 484509706
Change-Id: I6698e94ee36168f52d501e83057559805e05172d
- Added new `cable` composite type:
* The `initial` parameter specifies the joint at the starting boundary: `free`, `ball`, or `none`.
* The boundary bodies are exposed with the names:`B_left` and `B_right`.
* The vertex initial positions can be specified directly in the XML with the parameter `vertex`.
* The orientation of the body frame **is** the orientation of the material frame of the curve.
- Added new `cable` passive force plugin:
* Twist and bending stiffness can be set separately with the parameters `twist` and `bend`.
* The stress-free configuration can be set to be the initial one or flat with the flag `flat`.
* New cable example showing the formation of plectoneme.
* New coil example.
* New belt example showing interaction between twist and anisotropy.
* Added test using cantilever exact solution.
PiperOrigin-RevId: 480033694
Change-Id: I491271bce8fccb185961477e903e5a72d172c8a3
- `anchor` determines the point of wrench application, in the frame of body2.
- `tfratio` scales applied torques relative to applied forces.
- Add visualisation of both anchor points to both weld and connect constraints.
- Add a test model showing how the new weld parameters behave.
PiperOrigin-RevId: 470021901
Change-Id: I3faba0e5dcab2e29ee81096f5ff71ff66d99758c
- `anchor` determines the point of wrench application, in the frame of body2.
- `tfratio` scales applied torques relative to applied forces.
- Add visualisation of both anchor points to both weld and connect constraints.
- Add a test model showing how the new weld parameters behave.
PiperOrigin-RevId: 469228149
Change-Id: I836b0791f10fb624607a12ef3c687da991c21789
- `anchor` determines the point of wrench application, in the frame of body2.
- `tfratio` scales applied torques relative to applied forces.
- Add visualisation of both anchor points to both weld and connect constraints.
- Add a test model showing how the new weld parameters behave.
PiperOrigin-RevId: 469190483
Change-Id: I20f6da85b09cd2c4c0b5d29eb8003eabb524e55e
- `distance` constraints were not very useful and increased the contact buffer within the constraint solver, violating a core design principle. Therefore they have been removed.
- The enum value `mjEQ_DISTANCE` is retained, but errors will be thrown in the parser and engine if these constraints are selected.
PiperOrigin-RevId: 467050101
Change-Id: Ie72a07e4fe338eea5107004a9fc0f5e47eb0c3b7
- Add `azimuth` and `elevation` to `visual.global`.
- Add `mjv_defaultFreeCamera`.
- Use `mjv_defaultFreeCamera` in `simulate`.
PiperOrigin-RevId: 465505244
Change-Id: I61e60f14a990d4e2d220958adb75c325001978ee
- Adhesion actuators using contact normals as force transmission mechanism.
- Related video: https://youtu.be/HdBue4MUZysCloses#229
PiperOrigin-RevId: 464389367
Change-Id: I9f69b3cd152d957e8f65870d208788463c036a6d
- Add basic test for keyframes.
- Add missing documentation for keyframe mocap positions and quaternions.
PiperOrigin-RevId: 459021649
Change-Id: I91cf7ecbddc6262e8c72a868eeb82d627f389fb3
Added analytic derivatives of smooth (unconstrained) dynamics forces, with respect to velocities:
- Centripetal and Coriolis forces computed by the Recursive Newton-Euler algorithm.
- Damping and fluid-drag passive forces.
- Actuation forces.
A new implicit-in-velocity integrator is implemented using the analytic derivatives. This integrator lies between the Euler and Runge Kutta integrators in terms of both stability and computational cost.
PiperOrigin-RevId: 450377010
Change-Id: Ie192b441876c22e732fb749333926f296e0a09cc
Alessio Quaglino