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Fix Isaac Lab force clear shapes #74

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Fix Isaac Lab force clear shapes #74

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43 changes: 35 additions & 8 deletions mimickit/engines/isaac_lab_engine.py
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ def __init__(self, config, num_envs, device, visualize):
self._env_spacing = config["env_spacing"]
self._obj_cfgs = []
self._obj_control_modes = []
self._has_body_forces = []

if ("control_mode" in config):
self._control_mode = engine.ControlMode[config["control_mode"]]
Expand Down Expand Up @@ -483,6 +484,7 @@ def set_body_forces(self, env_id, obj_id, body_id, forces):
env_ids=env_id,
body_ids=sim_body_id,
is_global=True)
self._has_body_forces[obj_id] = True
return

def get_obj_torque_limits(self, env_id, obj_id):
Expand Down Expand Up @@ -722,13 +724,37 @@ def _post_sim_step(self):
return

def _clear_forces(self):
for obj in self._objs:
if (obj.has_external_wrench):
forces = torch.zeros([1, 3], dtype=torch.float, device=self._device)
torques = torch.zeros([1, 3], dtype=torch.float, device=self._device)
obj.set_external_force_and_torque(forces=forces, torques=torques,
positions=None, env_ids=None,
body_ids=None, is_global=True)
num_envs = self.get_num_envs()
for obj_id, obj in enumerate(self._objs):
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@ustcscgyer ustcscgyer Feb 8, 2026 •
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I think a much easier fix would be just to change this line to

if(getattr(obj, 'has_external_wrentch', False)):

then you don't need any other changes.

Articulation still has has_external_wrentch but unfortunately it was only set after you call set_external_force_and_torque.

https://github.com/isaac-sim/IsaacLab/blob/8ccebfe7cf04e3117ed05e78a85178d8d175b4c5/source/isaaclab/isaaclab/assets/articulation/articulation.py#L1013

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@ustcscgyer ustcscgyer Feb 8, 2026

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I tested this change with latest Isaaclab from uv pip install isaaclab and it works.

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@xbpeng xbpeng Feb 9, 2026

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@ustcscgyer thanks for the suggested change! That looks good to me, simple and elegant. Lets go with this fix instead. Would you like to submit a separate PR with your fix?

@Michael-Jetson does this fix the issues you were encountering on your side?

has_external_wrench = getattr(obj, "has_external_wrench", None)
if (has_external_wrench is None):
data = getattr(obj, "data", None)
if (data is not None):
has_external_wrench = getattr(data, "has_external_wrench", None)

if isinstance(has_external_wrench, torch.Tensor):
has_external_wrench = bool(has_external_wrench.any().item())
elif isinstance(has_external_wrench, np.ndarray):
has_external_wrench = bool(has_external_wrench.any())

if (has_external_wrench is None):
has_external_wrench = self._has_body_forces[obj_id]

if (not has_external_wrench):
continue

obj_type = self.get_obj_type(obj_id)
if (obj_type == engine.ObjType.articulated):
num_bodies = int(self._body_order_sim2common[obj_id].numel())
forces = torch.zeros([num_envs, num_bodies, 3], dtype=torch.float, device=self._device)
else:
forces = torch.zeros([num_envs, 3], dtype=torch.float, device=self._device)

torques = torch.zeros_like(forces)
obj.set_external_force_and_torque(forces=forces, torques=torques,
positions=None, env_ids=None,
body_ids=None, is_global=True)
self._has_body_forces[obj_id] = False
return

def _validate_envs(self):
Expand Down Expand Up @@ -1075,6 +1101,7 @@ def _build_sim_tensors(self):
num_envs = self.get_num_envs()
num_objs = self.get_objs_per_env()
self._objs_need_reset = torch.zeros([num_envs, num_objs], device=self._device, dtype=torch.bool)
self._has_body_forces = [False for _ in range(num_objs)]
return

def _filter_env_collisions(self):
Expand Down Expand Up @@ -1147,4 +1174,4 @@ def _on_keyboard_event(self, event):
if (event.input in self._keyboard_callbacks):
callback = self._keyboard_callbacks[event.input]
callback()
return
return