Robot Management Layer (RML)

Overview

RML is the on-robot service that manages all external communication between the robot and cloud/edge infrastructure. It runs as a daemon with a small set of libraries and exposes two stable entry points to applications and operators:

• gRPC control/state API - authenticated, bidirectional commands and structured status
• WebRTC media - real-time video/audio and data channels via an SFU

Architecture

The Four Pipelines

RML runs four independent, cooperating pipelines on top of shared security, networking, and scheduling.

Media Pipeline (robot → cloud)

Handles real-time video/audio from robot to cloud.

Data Flow:

What’s optimized:

• Zero-copy ingest: RML reads encoded frames/packets by pointer from shared memory rings (no memcpy).
• WebRTC adaptation: TWCC/TCC, RTCP feedback, bandwidth estimators; simulcast enables per-viewer quality.
• Priority: Audio and control data outrank video when bandwidth is tight.

Telemetry Pipeline (robot ↔ cloud)

Pushes metrics for complete observability.

Data Flow:

Why 100 Hz vs 1 Hz?

• Robot state (joints, IMU, battery) changes at control rates; we sample at 100 Hz and downsample intelligently (e.g., unchanged joint positions suppressed).
• System metrics (CPU, thermal, memory) evolve slowly; 1 Hz captures meaningful trends without noise or overhead.

Command Pipeline (cloud → robot)

Carries teleoperation commands down to hardware with rigorous validation.

Data Flow:

On failure

• NACK with structured error codes (UNAUTHORIZED, STALE, RATE_LIMITED, SAFETY_VIOLATION, CONFLICT).
• Not applied to hardware; kept in audit log with reason.
• Optional alert if violations repeat (rate-limited to avoid noise).

Emergency Stop

• Minimal authentication (must be legitimate source).
• Skips dedup/time/rate checks for speed.
• Does not bypass hardware safety; mechanical/electrical limits still enforced.
• Direct path to RAL “hard-stop” → stop/hold/brake within milliseconds.

2.4 Alert Pipeline

Data Flow:

Routing policy (examples)

• Critical hardware (over-temp, driver fault, e-stop): page on-call immediately.
• Network issues: notify ops channel; auto-create incident if sustained.
• Informational: daily/weekly summaries.
• Escalation: if unacknowledged within SLO, escalate per schedule.

Cross-Cutting Features

Network Resilience

Adaptive Strategies:

    Network Quality          RML Response
    ───────────────          ────────────
    Excellent (>10Mbps) ──▶  4K video, 60fps, full telemetry
    Good (2-10Mbps) ──────▶  1080p, 30fps, sampled telemetry
    Fair (500kb-2Mbps) ───▶  480p, 15fps, critical telemetry
    Poor (<500kbps) ──────▶  Audio only, commands, alerts only

Data Prioritization (when bandwidth limited):

1. Teleoperation commands (never dropped)
2. Emergency alerts
3. Basic telemetry
4. Audio stream
5. Video stream (degraded/paused)
6. Detailed telemetry (buffered)

Security Architecture

Defense in Depth:

• Authentication: TLS, API keys with rotation
• Authorization: RBAC with per-command permissions
• Encryption: TLS (control), DTLS-SRTP (media)
• Audit: Every command logged with UUID, timestamp, signature

WebRTC Integration