articulation support NONE drive_type

docs/source/overview/sim/sim_articulation.md

@@ -32,7 +32,7 @@ The `drive_props` parameter controls the joint physics behavior. It is defined u
 | `max_effort` | `float` / `Dict` | `1.0e10` | Maximum effort (force/torque) the joint can exert. |
 | `max_velocity` | `float` / `Dict` | `1.0e10` | Maximum velocity allowed for the joint ($m/s$ or $rad/s$). |
 | `friction` | `float` / `Dict` | `0.0` | Joint friction coefficient. |
-| `drive_type` | `str` | `"force"` | Drive mode: `"force"` or `"acceleration"`. |
+| `drive_type` | `str` | `"force"` | Drive mode: `"force"`(driven by a force), `"acceleration"`(driven by an acceleration) or `none`(no force). |
 
 ### Setup & Initialization
 

embodichain/lab/sim/cfg.py

@@ -388,11 +388,12 @@ def attr(self) -> SoftBodyAttr:
 class JointDrivePropertiesCfg:
     """Properties to define the drive mechanism of a joint."""
 
-    drive_type: Literal["force", "acceleration"] = "force"
+    drive_type: Literal["force", "acceleration", "none"] = "force"
     """Joint drive type to apply.
 
     If the drive type is "force", then the joint is driven by a force and the acceleration is computed based on the force applied.
     If the drive type is "acceleration", then the joint is driven by an acceleration and the force is computed based on the acceleration applied.
+    If the drive type is "none", then no force will be applied to joint.
     """
 
     stiffness: Union[Dict[str, float], float] = 1e4

embodichain/lab/sim/objects/articulation.py

@@ -1386,9 +1386,9 @@ def _set_default_joint_drive(self) -> None:
 
         drive_pros = self.cfg.drive_pros
         if isinstance(drive_pros, dict):
-            drive_type = drive_pros.get("drive_type", None)
+            drive_type = drive_pros.get("drive_type", "none")
         else:
-            drive_type = getattr(drive_pros, "drive_type", None)
+            drive_type = getattr(drive_pros, "drive_type", "none")
 
         # Apply drive parameters to all articulations in the batch
         self.set_drive(

embodichain/lab/sim/objects/robot.py

@@ -855,9 +855,9 @@ def _set_default_joint_drive(self) -> None:
 
         drive_pros = self.cfg.drive_pros
         if isinstance(drive_pros, dict):
-            drive_type = drive_pros.get("drive_type", None)
+            drive_type = drive_pros.get("drive_type", "force")
         else:
-            drive_type = getattr(drive_pros, "drive_type", None)
+            drive_type = getattr(drive_pros, "drive_type", "force")
 
         # Apply drive parameters to all articulations in the batch
         self.set_drive(

embodichain/lab/sim/utility/sim_utils.py

@@ -73,6 +73,8 @@ def get_dexsim_drive_type(drive_type: str) -> DriveType:
         return DriveType.FORCE
     elif drive_type == "acceleration":
         return DriveType.ACCELERATION
+    elif drive_type == "none":
+        return DriveType.NONE
     else:
         logger.error(f"Invalid dexsim drive type: {drive_type}")
 
@@ -97,6 +99,8 @@ def get_drive_type(drive_pros):
         drive_type = DriveType.FORCE
     elif drive_type == "acceleration":
         drive_type = DriveType.ACCELERATION
+    elif drive_type == "none":
+        return DriveType.NONE
     else:
         logger.log_error(f"Unknow drive type {drive_type}")