1. Custom Electric Bicycle Mechanics & Drive Systems
System Profile:
- Platform: Custom-built Mid-Drive / Direct-Drive Hybrid Framework.
- Controller: VESC 6+ Open-Source ESC running custom Firmware.
- Battery: 52V 20Ah 21700 M50LT lithium-ion pack (13S4P configuration).
Torque Tuning & Field-Oriented Control (FOC):
- Motor Current Limits: Max Motor Current set to 85A; Motor Absolute Current capped at 120A to protect phase wires.
- Field Weakening Current: Configured at 15A with a start threshold of 80% duty cycle, expanding top-speed capability by ~18% without overheating the stator.
- Throttle Mapping: Polynomial curve mapping applied to torque-request mode, delivering precise low-speed technical climbing control.
Troubleshooting: Locked Freewheel Mechanisms:
- Symptom: Unintended motor drag during non-assisted pedaling and mechanical lockup of the rear cassette when coasting.
- Root Cause Analysis: Disassembly revealed premature wear of the internal sprinter clutch paws and contamination of low-viscosity pawl grease with fine trail dust, causing the pawls to bind in the engaged position.
- Resolution: Replaced stock pawl assembly with high-engagement hardened steel pawls (54-tooth ratchet ring), flushed assembly with isopropyl alcohol, and re-lubricated using specialized low-viscosity synthetic grease (MobilITH SHC 100).
2. Residential Solar NEM Profiles & Battery Arbitrage
An analysis of residential clean energy production, local energy storage, and dynamic tariff optimization under California's Net Energy Metering (NEM 3.0) structure.
System Configuration:
- Solar Array: 8.4 kW DC Photovoltaic system with microinverters.
- Battery Storage: 13.5 kWh LFP (Lithium Iron Phosphate) integrated storage.
- Tariff: Time-Of-Use (TOU) Peak hours between 4:00 PM and 9:00 PM.
NEM 3.0 Arbitrage Strategy Matrix:
+-----------------------+-----------------------+---------------------------------------+
| Operating Mode | Time Window | System Strategy & Dispatch Rules |
+-----------------------+-----------------------+---------------------------------------+
| Solar Self-Consumption| 08:00 AM - 04:00 PM | Direct PV supply to household load |
| Peak Export Arbitrage | 04:00 PM - 09:00 PM | Max battery discharge to grid (TOU) |
| Grid Import & Hold | 09:00 PM - 08:00 AM | Reserve storage for peak window |
+-----------------------+-----------------------+---------------------------------------+
3. Lightweight Linux Agent Development on Chrome OS
Technical Implementation Features:
- Language & Runtime: Rust (zero-overhead memory safety, static binary execution).
- Container Integration: Utilizes Linux epoll and cgroup v2 APIs to monitor container memory pressure and thread allocation without triggering Chrome OS host throttling.
- Inter-Process Communication: Communicates system status metrics to Chrome OS web dashboards via lightweight, local Unix Domain Sockets (/var/run/agent.sock).
- Resource Overhead: Total memory footprint < 4.2 MB RAM; CPU usage < 0.1% under idle polling states.