Title: Add joint acceleration target to Articulation

[vluduk]

Currently, Articulation provides only:

set_joint_position_target
set_joint_velocity_target

However, many use cases—especially those involving vehicles and motor-driven systems—require direct control over joint acceleration for smooth and responsive motion.

Is there an existing way in Isaac Lab to specify a target acceleration for a joint? If not, are there plans to add this feature in a future release?

[RandomOakForest]

Isaac Lab's Articulation class currently doesn't provide a direct method for specifying joint acceleration targets like set_joint_acceleration_target. However, there are two alternative approaches to achieve acceleration control:

1. Indirect Control Through Effort Commands
For dynamic systems where

$$\tau = M(q)\ddot{q} + C(q,\dot{q}) + g(q)$$

you can:

1. Compute desired joint torques using inverse dynamics
2. Apply them via existing effort control:

robot.set_joint_effort_target(computed_torques)
robot.write_data_to_sim()

This method requires accurate system modeling (mass matrix M, Coriolis terms C, gravity g)¹².

2. Velocity-Driven Acceleration
Using finite differencing on velocity measurements:

current_vel = robot.data.joint_vel
desired_accel = (target_vel - current_vel) / dt
applied_effort = kp * (target_vel - current_vel) + kd * desired_accel
robot.set_joint_effort_target(applied_effort)

This creates a virtual acceleration control loop using velocity targets³.

Key Implementation Notes:

• Joint acceleration data must be computed manually via velocity differencing³
• Requires disabling default PD controllers by setting stiffness=0 and damping=0⁴⁵
• Effort limits must be configured appropriately in actuator models²
• Physics engine constraints (max joint velocity/force) affect achievable accelerations⁶²

References

Footnotes

1. https://isaac-sim.github.io/IsaacLab/main/source/overview/core-concepts/actuators.html ↩

2. https://isaac-sim.github.io/IsaacLab/main/source/api/lab/isaaclab.actuators.html ↩ ↩² ↩³

3. https://docs.robotsfan.com/isaaclab_official/main/_modules/isaaclab/assets/articulation/articulation_data.html ↩ ↩²

4. https://docs.robotsfan.com/isaaclab_official/v1.2.0/source/tutorials/01_assets/run_articulation.html ↩

5. https://isaac-sim.github.io/IsaacLab/main/source/tutorials/01_assets/run_articulation.html ↩

6. https://docs.omniverse.nvidia.com/isaacsim/latest/advanced_tutorials/tutorial_advanced_joint_tuning.html ↩

[vluduk]

Thanks for the advice!

Will do that