use case rl control robotics

Spikeforge — UC-7: Reinforcement Learning for Control & Robotics

A fully scoped production use case. Extends the reference slice in use_case_streaming_timeseries.md; consumes the shared enablers from production_toolkit_plan.md; listed in the umbrella production_use_cases.md.

One-line summary. Train SNN policies with temporal memory for control in simulation and deploy the compact, event-driven controller on CPU/embedded — with no neuromorphic chip.

What it demonstrates. Recurrent temporal state as a compact controller: a spiking policy trained in simulation, exported via NIR for cross-simulator parity, and served as a stateful controller.

Design/spec only. Every claim about current code is grounded in a file/line reference so a Code-mode agent can execute this file-by-file. No implementation starts in this document.

---

1. Problem and users

What. Given an environment with observations and a reward, train an SNN policy whose recurrent state replaces an explicit frame stack, then deploy it as a stateful controller on CPU/embedded, on hardware with no neuromorphic chip.

Users. Robotics/controls engineers; RL researchers exploring neuromorphic policies; teams that need a compact controller with bounded per-step cost.

Why SNN here. A recurrent spiking controller carries temporal state in membrane potentials, giving memory in a compact, event-driven form and a bounded per-step compute footprint that suits a control loop.

Success criteria (SLAs).

• Return: episode return within a configured fraction (e.g. ≥ 90%) of a dense baseline on a standard control task, averaged over ≥ 5 seeds.
• Stability: no seed collapses below a floor return; reported as mean ± spread, not a best-of.
• Sample efficiency: episodes-to-threshold within a configured budget; reported honestly if worse than the dense baseline.
• Deployability: per-step control latency p99 within the loop budget on CPU; NIR export validates and cross-simulator parity holds. Zero hardware.

---

2. Reference architecture

flowchart LR
    A[Simulation environment] --> B[Observation adapter]
    B --> C[Encoding contract]
    C --> D[Spiking policy InferenceSession]
    D --> E[Action head]
    E --> A
    D --> F[DeploymentBundle and NIR]
    F --> D
    F --> G[NIR cross-simulator]
    D --> H[spikeforge-serve controller]
    H --> I[spikeforge-clients SDK]
    H --> J[Control metrics]
    K[Offline rollout training] --> F

Loading

Legend: training is a closed interaction loop; deployment reuses the same per-step body through the stateful runtime.

---

3. Offline: data, encoding, model, training

3.1 Environment and data

• Sources: a standard control environment behind an env adapter (a Gymnasium-style reset()/step(action) duck-typed interface) plus a deterministic synthetic environment for CI. The env adapter is the shim between the environment's step and the spike encode contract (paralleling sequence_source.py).
• Contract: the observation normalization and encode choice are frozen in preprocessing.json in the bundle so a deployed controller encodes identically to training (W2).

3.2 Encoding

• Primary coding: rate over a short observation window (robust for control) with delta as the streaming alternative and latency when spike timing matters; frozen EncodeSpec.
• Input shape: [T, B, D] (or [T, B, L, D] when a short history is used), matching the sequence/recurrent presets.

3.3 Model

• Topology: recurrent_net for the recurrent policy; the topology builder.py to compose a compact actor/critic trunk. Declared once as a TopologySpec.
• Heads: policy/action head (discrete or continuous) plus an optional value head; both reuse the same spiking trunk.
• Training: a rollout harness driving the env adapter with the existing per-step simulator body, plus a policy-gradient/surrogate-gradient objective on TrainingEngine primitives; checkpointing via checkpoint_mixin.py.
• Cross-sim export: NIR envelope from serialization.py for cross-simulator checks; refusal stays typed (UnsupportedStageError).

3.4 Evaluation

• Episode return mean ± spread over ≥ 5 seeds vs a dense baseline; samples-to- threshold; per-step cost.
• Parity: NIR drift (within_tolerance) and determinism (determinism.py); manifest per run (manifest.py).

---

4. Online: bundle, runtime, service

4.1 Deployment bundle

• model.spkf with manifest.json (spec, versions, expected return, action space), weights.pt, encode_config.json, preprocessing.json (observation normalization), graph.nir.json, checksums/signature.
• Anchors: bundle.py, bundle_manifest.py.

4.2 Stateful runtime

• InferenceSession.load(bundle), .reset() (episode start), .step(obs) -> action, .run_stream(observations); recurrent state via StateTree — reset() maps exactly to an environment reset.
• Shares the per-step body with the closed loop so training and deployment cannot diverge (step.py).

4.3 Service

• spikeforge-serve: POST /v1/predict (per-observation action), POST /v1/reset (episode boundary), GET|WS /v1/stream, GET /health, GET /metrics, GET /v1/bundle (app.py, service.py).
• Per-episode session ids; bounded batching; concurrency cap; auth; timeouts tied to the control-loop budget.

4.4 Clients and I/O

• spikeforge-clients SDKs drive predict/reset for a controller (client.py); spikeforge-io replays a recorded trajectory as a regression fixture (replay.py).

4.5 Observability

• Prometheus over the registry (registry.py): per-step latency histogram, return/episode metrics, spike sparsity, action saturation.
• Serving benchmark p50/p99 + throughput, wired into the regression gate (compare.py).

4.6 Compression option

• Pruning (pruning.py) plus weight-only quantization (quantize.py) to shrink the controller; return drift from PruningReport is recorded, and a regression beyond tolerance refuses the artifact.

4.7 Test-deploy matrix row

• Test-deploy the recurrent policy on reference, norse, and lava_loihi2 with a parity report (test_deploy.py); estimate: true, available: false with a reason when an SDK is absent.

---

5. Phased delivery

Phase	Deliverable	Depends on	Acceptance
P0	Env adapter + rollout harness + deterministic CI env	—	rollout reproducible; observation spec frozen
P1	Recurrent spiking policy trained; return/sample-efficiency report	P0	return ≥ 90% of dense baseline over ≥ 5 seeds
P2	InferenceSession controller (step/reset) + tests	W1	deployed rollout == training rollout within tolerance
P3	DeploymentBundle + NIR export + tamper check	W1	fresh-process rebuild exact; NIR validates
P4	spikeforge-serve /predict + /reset + /stream	W2, W3	in-process parity; reset at episode boundary
P5	/metrics, control-loop latency CI gate, serving benchmark	W6	p99 within loop budget in CI
P6	Container, promotion/rollback, drift/return monitor	W7	promote/rollback demo; return-regression alarm fires

MVP = P0–P4. That is the smallest end-to-end slice that demonstrates the chip-less control story.

---

6. Dependencies and out of scope

Depends on: PT-W1 (released spikeforge/serving/ stateful runtime + bundle); PT-W2 (frozen EncodeSpec); PT-W3 spikeforge-serve; PT-W6 observability/benchmarks; PT-W7 I/O adapters. Tracked by umbrella issue #12; reference implementation UC-1 (released in spikeforge 0.3.0).

Out of scope: real-robot sim-to-real transfer claims (simulation-trained only); measured power (estimate: true); safety certification; distributed multi-agent training; online learning on the deployed controller.

7. Risks

Risk	Mitigation
RL returns are noisy across seeds	report mean ± spread over ≥ 5 seeds; never best-of
Sample inefficiency vs dense baseline	report honestly; scope claims to compactness/latency, not sample efficiency
Train/deploy divergence through the env adapter	one frozen encode/preprocessing contract; reset maps to episode reset
NIR cannot express a stage	keep the topology within NIR-mappable primitives; typed refusal otherwise

8. GitHub issue payload

• Title: [UC-7] Reinforcement learning for control and robotics
• Labels: enhancement, architecture
• Body: see plans/use_case_rl_control_robotics.md — goal, reference architecture (obs adapter → encode → recurrent InferenceSession → action head → sim loop; deploy via spikeforge-serve → clients → /metrics), rate/delta coding, recurrent_net, acceptance (return ≥ 90% of dense baseline over ≥ 5 seeds, p99 within loop budget), MVP phases P0–P4, dependencies PT-W3/W6/W7.