Forum Post

[OpenArm Troubleshooting] Torque Saturation and Current Spikes Under Load (Advanced)

Current spikes appear only under real load? Separate cable drag, payload effects, and control limits with synchronized traces.

Forum / Posts Index / OpenArm

Post

Some OpenArm failures only show up when the robot is under real load: current spikes appear, torque saturates earlier than expected, and suddenly a controller that looked stable in air becomes unreliable in contact or payload tasks.

How are you diagnosing unexpected current spikes and torque saturation on OpenArm without immediately blaming the controller gains?

Please share how you separate payload effects, friction, cable drag, controller limits, and sensor timing issues before changing too many variables at once.

If you reply, include one exact saturation symptom and one exact measurement or hardware/software check that moved the diagnosis forward.

Related troubleshooting path: Planning fails from collision model mismatch · MIT control gains tuning

Module: OpenArm · Audience: builders-integrators · Type: question

Tags: openarm, torque, current-spikes, saturation

Comment 1

Advanced context: We saw current spikes on joint 2 jumping from 4 A baseline to 9 A during acceleration with the same payload that used to run fine. In-air moves looked clean, but loaded cornering caused torque clamp events.

Comment 2

Advanced context: Most useful check was syncing current logs with commanded jerk and video of cable motion. Spikes aligned with one cable bend region, so friction and routing were contributing alongside controller limits.

Comment 3

Advanced context: Fix was a combination: reroute cable harness, lower jerk 20%, and keep a watchdog on sustained current over 8 A for more than 150 ms. After that, 2-hour stress runs stayed below saturation.

Comment 4

Advanced context follow-up: Follow-up question for advanced teams: do you log synchronized current, jerk, and cable-state traces, and which metric turned out to be the best early-warning signal?

Quick Symptom Selector

Pick your closest symptom to follow the right troubleshooting path.

Not selected yet.

Quick FAQ

How can I isolate mechanical drag vs controller limits?

Synchronize current and jerk traces with cable motion observations to find correlated mechanical contributors.

python tools/log_current_and_jerk.py --task stress_path --duration 120
python tools/correlation_report.py --signals current,jerk,cable_state
What mitigation order works best?

Fix mechanical constraints first, then reduce trajectory aggressiveness, then retune control if needed.

Can I copy these commands as-is?

Use them as a checklist template first. Confirm interface names, fixture IDs, and safety conditions in your own cell before execution.