Motion Control Anomaly with Realman Manipulator in Isaac lab 2.1

Omniverse Isaac Sim
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Isaac Sim Version

4.5.0
4.2.0
4.1.0
4.0.0
[√] 4.5.0
2023.1.1
2023.1.0-hotfix.1
Other (please specify):

Operating System

[√] Ubuntu 22.04
Ubuntu 20.04
Windows 11
Windows 10
Other (please specify):

GPU Information

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Topic Description

We are currently controlling a Realman manipulator (with joint configuration similar to Franka Panda) in the Isaac Lab 2.1 simulation environment and encountering an issue with motion control.

​​Expected Behavior:​​
When sending control commands, we intend for the end-effector / terminal link (Link 7) to perform ​​pure translational motion​​ along the positive X-axis of the base_link coordinate frame (i.e., the globally defined “forward” direction).

​​Observed Behavior:​​
The actual movement in simulation severely deviates from expectations. The end-effector (Link 7) fails to execute the desired forward translational motion.

Instead, the motion appears to be primarily driven by ​​Link 6​​ (the direct parent link of Link 7). Specifically:

  • Link 7 shows minimal forward displacement
  • The manipulator exhibits dominant motion characteristics of ​​Joint 6​​ (connecting Link 6)
  • Manifestations include:
    • Link 7 retracting backward or moving laterally
    • Unplanned rotational movements (yaw/rotation around Joint 6)
    • Failure to translate along its local forward direction

​​Core Issue Analysis:​​
Current control inputs fail to drive Link 7 along its intended trajectory. The behavior suggests either:

  1. Control targets are incorrectly applied to Link 6 / Joint 6
  2. Kinematic solving errors (coordinate frame misinterpretation)
  3. Possible influence from kinematic singularities
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For any Isaac Lab topics, please submit your topic to its GitHub repo (GitHub - isaac-sim/IsaacLab: Unified framework for robot learning built on NVIDIA Isaac Sim)

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