Java backend & AI application engineering · LiDAR-inertial odometry research
I build backend services and AI applications in Java, and I do research on LiDAR-inertial odometry in ROS/C++. The common thread is the same habit in both: take a system that already runs, find where it breaks under real conditions, and prove the fix with evidence rather than a demo.
Blog · Java 17 / Spring Boot · ROS 2 / C++
local-deals-service — high-concurrency coupon flash-sale backend (Spring Boot). Reworked a tutorial-grade Redis Stream order pipeline into a production-shaped one: RocketMQ transactional messages bind the Lua stock deduction to message delivery, Canal replays the MySQL binlog into Elasticsearch (IK tokenizer + geo filtering in a single query), WebSocket over Redis pub/sub pushes order results across instances, and a JMeter plus fault-injection harness asserts MySQL / Redis / Stream / DLQ state instead of just the HTTP error rate.
ragent — industrial document RAG service for iron-ore domain knowledge, built on Ragent 1.1.0 (Java 17, Spring Boot 3.5, PostgreSQL + pgvector). Reuses the upstream SSE, model-adapter and ingestion layers, and adds structure-aware XLSX chunking with exact cell provenance, request-level retrieval, evidence-constrained task closure, and a fixed regression evaluation set (3 documents, 24 questions, 15 parse anchors, with hash-verified paired replay). Measured: oversized chunks 70 → 0 and duplicates 17 → 0; context precision 17.1% → 29.2% at half the average retrieved context, against Hit@5 95.2% → 90.5%. A fair-refill mechanism that missed its quality gate stays behind a feature flag, default off. The project claims better chunking, retrieval behaviour and auditability — not better answer accuracy, which held at 79.2% strict pass either side of the change. Closing the trace-cancellation races here produced the upstream PR below.
Merged upstream:
| Project | Contribution | PR |
|---|---|---|
| ccfos/huatuo — eBPF Linux kernel observability (Go) | Unit tests for SplitCommaList and ValueMatcher; corrected a misleading retry-delay log in the Java profiler; errcheck cleanup |
#318 #321 #337 #338 |
| 6-robot/jie_3d_nav — ROS 2 3D navigation with a web UI | ROS 2 Foxy reproduction path, PCD map import, web map viewing fixes | #1 |
| v4rl-ucy/ellipselio — ellipsoid-based LiDAR-inertial odometry | Experimental ROS 2 Foxy compatibility, merged as foxy-experimental |
#4 |
| ouguangjun/kilo-map — LiDAR odometry and mapping | Fixed a crash from a missing ImGui::End() when the Selection panel is collapsed |
#2 |
Open for review: nageoffer/ragent#80 — finalize a trace
run as CANCELLED when the user aborts mid-stream · scomup/likd-tree#1
— PCD nearest-neighbour search demo.
LiDAR-inertial odometry and mapping: degeneracy and uncertainty handling in the estimator, continuous-time trajectory formulations, and fusing leg odometry on quadruped platforms. Most of it lives in private research builds on top of FAST-LIO2, LIO-SAM, Traj-LO, LegKILO and voxel-based mapping, together with automation for running algorithms across benchmark datasets and ins-d-qpvt-tum for turning INS-D serial output into TUM ground-truth trajectories. The ROS 2 and C++ contributions above came out of this work.
Backend & AI
Robotics & systems
Algorithm reproduction notes and experiment records: qiyu-lu.github.io