kRPC

kRPC (Kerbal Remote Procedure Call) is a mod for Kerbal Space Program that exposes the game’s API over TCP/IP, allowing external programs (like Python scripts) to control vessels, read telemetry, and interact with the game world.

Why kRPC?

Kerbal Space Program’s native scripting language (kOS) is limited:

• No access to external libraries
• Limited math capabilities (no numpy, scipy)
• Single-threaded

kRPC breaks these limitations by streaming game data to an external Python server, enabling:

• Full scipy/numpy ecosystem
• Complex state estimation (Kalman filters)
• Control allocation (pseudo-inverse solvers)
• Machine learning integration

AEGIS Architecture

┌─────────────┐      TCP/IP      ┌─────────────┐
│  KSP Game   │  ←──────────→  │   Python    │
│  (Unity)    │   kRPC Mod      │   Server    │
│  50Hz tick  │                 │  (AEGIS)    │
└─────────────┘                 └─────────────┘

Key Conventions (AEGIS)

• Stream API: Always use conn.add_stream() — never poll vessel.flight() directly (avoids TCP latency)
• Engine discovery: vessel.parts.with_tag("AegisEngine") (ADR-016)
• WSL2 connection: Windows host IP from /etc/resolv.conf (ADR-015)
• Ports: 50000 (RPC), 50001 (stream) — not default 5005/5006

Alternatives Considered

Approach	Pros	Cons
kOS	Native, simple	Limited math, no external libs
kRPC + Python	Full ecosystem, fast prototyping	Requires TCP overhead
kRPC + C++	Performance	Longer development time
Direct Unity modding	Full control	Complex, fragile

Related Concepts

• Kerbal Space Program — The game/simulation platform
• Flight Software — Real-world spacecraft software
• Hardware-in-the-Loop Testing with real hardware
• Digital Twin — Simulation-based development

Sources

• AEGIS Project (AGENTS.md, architecture docs)