Server Example: Length Constraints Newton’s Cradle

Overview

Hangs a Newton’s cradle from spatial tendons, attaches a box and two ANYmal robots with spring and tension-driven tendons, and exports the world to XML. Despite the target name, the example uses the tendon API (World::addSpatialTendon); the older wire API now wraps tendons. See Tendons.

Screenshot

length_constraints_newtons_cradle example

Target

CMake target: length_constraints_newtons_cradle.

Run

Run the build-tree executable:

./build-examples/examples/length_constraints_newtons_cradle

On Windows, run length_constraints_newtons_cradle.exe instead. This example uses RaisimServer. Start rayrai_tcp_viewer and connect to port 8080.

Details

Hangs four steel balls from static pins with cable tendons that have a 2 m upper length limit; the first cable is drawn wider and in red. The last ball starts pulled out to the side.
Hangs a box and an ANYmal C from spring tendons (stiffness 200 and 1000).
Lifts an ANYmal B with a tendon driven by Tendon::setTension and removes that tendon with World::removeTendon after 5000 loop iterations.
Exports the world to exportedWorld.xml next to the executable.
Integrates only while a viewer is connected.