[가상 자료: 강의 실습용. 실제 규격·논문이 아니며, 번역·요약 연습을 위해 지어낸 문서입니다.]

TECHNICAL NOTE TN-2026-088 (FICTIONAL)
Subject: Contact Resistance Growth in Conductive Charging Interfaces for Mobile Robot Fleets
Issued by: Industrial Mobility Working Group (fictional body)

1. Scope
This note describes progressive contact resistance growth at conductive charging interfaces used by automated guided vehicles (AGV) and autonomous mobile robots (AMR) in high-duty-cycle manufacturing environments, and its effect on fleet availability.

2. Mechanism
Each docking cycle produces micro-arcing at the moment of contact. Over several thousand cycles this forms an oxide film on the contact surface. Contact resistance rises gradually; charging current falls while the charger still reports a nominal connection. The result is incomplete charge rather than a hard fault.

3. Failure signature
The signature is gradual, not a step change:
  a. Intermittent "charge failure" events clustering in the shift with the highest duty cycle;
  b. Rising dwell time at charging stations, with no change in the number of transport jobs;
  c. Later-stage connector overheating as resistance grows further;
  d. Normal visual inspection results, because surface discoloration is slight.

4. Contributing factors
  4.1 Plating specification. Hard gold over nickel typically sustains 20,000-50,000 cycles before measurable growth; tin or tin-alloy plating may degrade after 5,000-10,000 cycles under the same conditions.
  4.2 Contact normal force below the supplier's specified range accelerates film formation.
  4.3 Airborne particulates, especially in electrode and mixing areas, accelerate the process.

5. Recommended controls
  5.1 Trend the charging dwell time per robot rather than counting charge failure alarms alone.
  5.2 Treat three or more identical charge failures within seven days as a maintenance trigger, not an operator-clearable event.
  5.3 When a connector supplier or plating specification changes, re-baseline dwell time for at least four weeks before accepting equivalence.
  5.4 Do not compensate by extending charging time. This masks the trend and increases thermal stress.

6. Limitations
Cycle figures above are drawn from a limited field dataset and vary widely with duty cycle, plating thickness and environment. They are directional guidance only. No industry standard currently defines an allowable contact resistance growth rate for this application; acceptance limits must be set by each integrator.