Home

Features

• Highly and easily configurable:

  • Mechanical flexibility modelling
  • Sensor noise, jitter and delay modelling
  • Support external forces on frames (both impulse or via time-continuous callback)
  • Support user-defined internal dynamics
  • Support both finite time and time-continuous update period for each sensor and the controller independently
  • Model uncertainties regarding the kinematics and dynamics properties

• Deterministic or non deterministic on demand but still PERFECTLY REPEATABLE

  • Note that the result of the simulation slightly differs on different computer even using dbash, as the version of Python libraries such as Numpy is host-dependent.

• Designed for fast R&D prototyping of biped locomotion at Wandercraft :

  • Support step-by-step (optimized for performance) or one-shot simulation
  • Fully wrapped in Python. Designed for (almost) never have to recompile C++.
  • Add variables to the logger on-the-fly without compiling
    • Useful to debugging and dynamic plots updated over time (not implemented so far)
  • Can generated log data fully compatible with tsv and logviewer
    • --gepetto_walk is broken because StateMachine.State is undefined in Jiminy Engine

• Fast Python Interface:

  • C++ / Python shared pointer to avoid boost converts back-and-forth

• Very fast:

  • No real-time logging on hard drive (only in CPU cache then RAM)
    • The log can be exported in CSV or binary on demand afterwards
  • No real-time display by default
    • A Python class offering this functionality is available
  • • Exo: 100ms for 1000 integration steps, corresponding to about 2s of flat foot walking *
  • • Cartpole: 20ms for 1000 integration steps, corresponding to about 3s of simulation *

• Highly parallelizable:

  • Thread safe (single process - single core)
  • Synchronous by default (a Python class offering asynchronous controller update is available)
  • No shared memory
  • NO WANDERBRAIN

• Well-suited for Reinforcement Learning:

  • Fully compatible with Gym OpenAI and any libraries built on top of it

Drawbacks

• Support only multiple point contact with the ground applied on frame
  • The ground is flat
  • No modelling of internal collisions contrary to Gazebo, ie for rotary joints
  • No collision between links
  • • It should be enough for walking (both flat foot and foot rolling), turnaround ...etc *

Development status

• Open-source Jiminy core: (mostly) stable
  • • Few bugs still to fix regarding the flexibilities and joint limits constraints *
• Open-source Gym/Jiminy interface: stable
• Mock of a High-Level Controller: doing
• Modelling must be improved:
  • Only "perfect" sensor data with noise/delay/jitter is available
    • • No complementary filter for IMUs, no voltage to force converter for Force sensors... *
  • Only "perfect" Low-level controller:
    • • No voltage-current to torque-velocity conversion. No response time. *
• Error handling must be improved
  • • Old-fashioned message + return code