Jiminy-py

A new API for defining quantities in reward and termination conditions computations has been added. The first objective is to make much easier to new comers that are not used to rigid body dynamics, and secondly, to compute them as efficiently as possible. In this regard, a new quantity manager is responsible for keeping track of all quantities involved in computations and optimisation the overall computation path, by avoiding redundant computations through caching and sharing of intermediary quantities, but also by aggregating them whenever possible to take advantage of vectorisation optimally. Apart from that, the multi-robot simulations have been made much easier by supporting them via Python API. Finally, backlash in simple motor transmission are now natively supported, modelled an extra virtual joint together with a massless body.

New features

* [core] Add backlash support at motor-level. (767)
* [python/simulator|python/plot] First-class multi-robot support. (754) (764) (766)
* [gym/common] Introduce new first-class quantity manager. (749) (751) (752) (756)

Improvements

* [core] Clarify terminology: 'Rigid' by 'Mechanical', 'Original' by 'Theoretical', 'Actual' by 'Extended'. (753) (762) (763)
* [core] User is now systematically responsible for serializing constants before telemetry registration. (753)
* [core] Consistent export/import/get/set options between single- and multi-robot simulations. (758) (760) (761)
* [core/python] Add method to query heightmaps on multiple positions at once. (750)
* [gym/common] Plot state, action and features of all pipeline blocks. (750)
* [gym/common] PD controller now satisfies position, velocity and acceleration bounds. (750) (765) (768)
* [gym/common] Allows PD control with position action. (750)
* [gym/common] Decouple PD controller action order adapter from acceleration integration. (764)

Patches and bug fixes

* [core] Fix bias/noise check for EncoderSensor. (744)
* [core] Fix exception not caught during stepper integration. (747)
* [core] More appropriate tolerance when checking GCD to avoid false positive. (753)
* [python/viewer] Fix arrow maker with panda3d backend.
* [python/viewer] Fix viewer automatic closing during replay not working. (756)
* [gym/common] Fix corrupted robot proxy if model changes. (746)

Miscellaneous

* [core] Fix some symbols not exported by mistake. (742)
* [gym/common] Refactor 'compute_command' to operate in-place. (764)
* [gym/rllib] Migrate from ray[rllib]==2.5.0 to 2.9.*. (739)
* [misc] More robust build procedure. (739) (746)
* [misc] Upgrade C++ dependencies. (741)
* [misc] Fix numpy version requirement. (750)

A observer block for multiple punctual deformations has been implemented at position-level only. This is based on the work of [Matthieu Vigne et al.](https://hal.science/hal-03511198/document). In addition, a bunch of minor bugs has been fixed as usual.

New features

* [gym/common] Add 'DeformationEstimator' block. (732)

Improvements

* [core] More bad control flow checks. (730)
* [core/python] 'Model' can now be instantiated from Python. (730)
* [gym/common] Add 'compute_tilt_from_quat', 'swing_from_vector', and 'remove_twist_from_quat'. (731)
* [gym/common] Allow negative block update period to match env step. (734)

Patches and bug fixes

* [core] Fix broken 'getRigidVelocityFromFlexible'. (732)
* [core/python] Fix partially broken 'FunctionalController' bindings. (730)
* [core/python] Fix multiple typos. (731)
* [python/simulator] Fix 'robot' and 'robot_state' corrupted if robot is replaced. (731)
* [gym/common] Fix 'refresh_observation' being called before 'initialize_buffers' at simulation start. (731)
* [gym/common] Fix broken mahony filter for 'twist_time_constant != None'. (731)
* [gym/common] Fix support of non-batched mode for generic math. (731)
* [gym/common] Fix 'matrix_to_rpy' to be consistent with 'pin.matrixToRpy'. (731)
* [gym/envs] Fix broken 'Ant' environment. (731)

Miscellaneous

* [core] Print warnings even for release build type. (731)
* [gym/common|gym/toolbox] Promote generic SE3 math utilities from toolbox to common module. (731)
* [misc] Update documentation. (736)

The confusing and unnecessary notion of system, ie a named pair (robot, controller), has been completely removed. All robots now have a name, and the controller is now an integral part of the robot. Similarly, the single-robot wrapper around the multi-robot Engine has been removed from C++ core. Note that the Python wrapper `Simulator` is still single-robot for now. Finally, the numerical stability of the constraint solver has been improved using the under-relaxation technics.

Improvements

* [core] Add relaxation to PGS solver to mitigate convergence instabilities. (726)

Patches and bug fixes

* [core] More conservative step adjustment for adaptive steppers. (724)
* [python/plot] Synchronise x-axes on all tabs by default. (724)
* [gym/common] Ease debugging of Gym environments. (724)
* [gym/common] Do not enforce 'dtMax'. (727)

Miscellaneous

* [core] Remove confusing and unnecessary 'System' hierarchy. (728)
* [core] Remove single-robot 'Engine' class. (728)

A few bugs that have been recently have been finally fixed, including some poorly motivated changes in adaptive steppers that was causing numerical instabilities. In addition, a long-standing bug that was leading to integration failure in a very specific, but not so unusual, scenario.

Improvements

* [core] Error and warning reporting more consistent with Python. (716)

Patches and bug fixes

* [core] Fix exception handling for visco-elastic coupling and internal flex forces. (716)
* [core] Fix error estimation too optimistic for adaptive steppers. (716)
* [core] Fix partially broken step adjustment optim that could lead to integration fail. (721)
* [gym/zoo] Fix 'acrobot' and 'cartpole' env using wrong integrator. (719)

Miscellaneous

* [misc] Fix easy install doc. (721)
* [misc] Fix support of virtual env ('venv', 'pyenv', ...) when building dependencies. (721)

First, naming conventions has been reviewed over the whole C++ codebase to make sure they are grammatically correct and consistent. Secondly, return codes have been dropped in favour of throwing exception, which makes everything more readable and much more in line with Python.

Patches and bug fixes

* [core] Revert 'crba' to ensure positive definite inertia matrix. (709)
* [python/viewer] Fix video recording on Apple Silicon with meshcat. (706)
* [python/viewer] Fix meshcat not properly terminated. (715)
* [gym/common] Fix circular reference in 'BaseJiminyEnv' causing memory leak. (715)

Miscellaneous

* [core] More consistent naming conventions. (705)
* [core] Remove return codes and throw exceptions instead. (713)
* [python] Get rid of unmaintained 'dm-tree' dependency. (706)
* [misc] Update C++ dependencies to latest releases. (713)

This release addresses a few long-standings issues that has been planned a while ago. First, ground profile heightmaps are now converted in collision geometry object and decimated if requested. This was a pre-requisite for generic collision detection. Next, each engine now owns its own local random number generator instead of relying on some hidden global state that was causing concurrency issues. In additional, a few bugs have been fixed here and there. Notably, force sensors are now only measuring contact forces acting on a given body rather then all external forces. It is the first release to partially support Python 3.12 (`jiminy_py` module).

New features

* [core] Faster random number generator (PCG32).
* [core] Faster sampling of random matrices (uniform and normal distributions) from any generator (including numpy).
* [core] Heightmap discretization now returns a geometry object and support decimation.
* [python/viewer] Implement ground rendering from meshcat.

Improvements

* [core] Get rid of global random state.
* [core] 'ForceSensor' measures only contact forces.
* [core] Passing wrong size to 'isPositionValid' does not trigger exception anymore.
* [core/python] Slightly faster functional controller by removing useless layer of indirection.
* [gym_jiminy/common] 'sample' utility now supports any custom distribution.

Patches and bug fixes

* [core] Fix sensor delay computation.
* [core] Fix sensor measurements at start.
* [core] Fix broken PeriodicFourierProcess since 1.7.18.
* [python/viewer] Fix camera pose when travelling is enabled with panda3d.
* [gym_jiminy/common] Fix support of empty arrays for 'contains' space utility.

Miscellaneous

* [python/viewer] Detect Apple Silicon GPU to enable high-res shadow for panda3d.
* [misc] Add support of Python 3.12 for 'jiminy_py' module.