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Hello everyone,

I am currently working on performing the Residual Reduction Algorithm (RRA), but I have been running into a persistent issue. Every time I try to run the RRA, I receive the following error:

Method Assembler::assemble() failed because:
Unable to achieve required assembly error tolerance.
Assembly error tolerance achieved: 5.2566849063404494e-09 required: 1e-10. Model relaxing constraints and trying again.
Requested COM adjustment time range 0.01 to 31.12, clamped to nearest available data times: 0.01 to 31.12.
Computing average residuals between 0.01 and 31.12...
InverseDynamics: ERROR - over-constrained system - need at least as many forces as there are degrees of freedom.

I think the problem might be related to missing Degrees of Freedom (DoF) in the script for the tracking tasks file. I used the default tracking tasks file from OpenSim, "gait10dof_Kinematics_Tracking_Tasks", and added all the necessary DoFs. I double-checked everything, and the DoFs in the tracking tasks file seem to match the forces in the IK file. I also tried excluding the DoFs that do not contain forces or values, but this did not solve the issue either.

Has anyone experienced a similar issue or can offer any insights on what might be going wrong? I would really appreciate any suggestions or ideas.

Here are the files I am using:

Tracking tasks file with all DoFs: gait10dof_Kinematics_Tracking_Tasks_New_FullDoF
Tracking tasks file without DoFs that have values 0: gait10dof_Kinematics_Tracking_Tasks_New_LowerDoF
Set file for GRF: LR02_CMJ_Set.xml
Reserve Actuators file: Reserve_Actuators.xml
IK file: LR_02_dl_CMJ_IK_SmallerFile.mot (this file contains only the first few seconds of the trial)
Here are all the DoFs from the file:

pelvis_tilt, pelvis_list, pelvis_rotation, pelvis_tx, pelvis_ty, pelvis_tz, hip_flexion_r, hip_adduction_r, hip_rotation_r, knee_angle_r, med_cond_adduction_r (0 values), lat_cond_adduction_r (0 values), knee_angle_r_beta, ankle_angle_r, subtalar_angle_r (0 values), mtp_angle_r (0 values), hip_flexion_l, hip_adduction_l, hip_rotation_l, knee_angle_l, med_cond_adduction_l (0 values), lat_cond_adduction_l (0 values), knee_angle_l_beta, ankle_angle_l, subtalar_angle_l (0 values), mtp_angle_l (0 values), lumbar_extension, lumbar_bending, lumbar_rotation, arm_flex_r, arm_add_r, arm_rot_r, elbow_flex_r, pro_sup_r, wrist_flex_r (0 values), wrist_dev_r (0 values), arm_flex_l, arm_add_l, arm_rot_l, elbow_flex_l, pro_sup_l, wrist_flex_l (0 values), wrist_dev_l (0 values)

Thanks in advance for your help!

Best regards,
Max

Hi, you need a tracking task for every free coordinate. The issue might also be your actuator file. Similarly, in RRA you need a strong coordinate actuator for every free coordinate, but weak residual actuator for pelvis coordinates.
(weld and locked coordinates must be excluded)

Hope this helps.

Hi,

Thanks a lot for your reply, I appreciate it!

Could you elaborate a bit on what you mean with a free coordinate? Or do you have an example tracking task?
I'm still quite new to all this.

Hi, sorry for brevity. Free coordinates are independent without any constraint, so the optimizer can change their values. The Coordinate::isConstrained method could help you find them; for example in Python:
Here is the tracking task of Rajagopal2016 model. For example, you can see the mtp_r coordinate is locked, and the knee_angle_r_beta has a coupler constraint, so they were excluded from both the tracking task and the actuator files:

https://github.com/opensim-org/opensim- ... walk_1.xml
https://github.com/opensim-org/opensim- ... uators.xml

Hope this helps.

It certainly does! Thanks a lot.