Articulus Surgical Robotics

What I built

Cosmos is a real-time control and communication architecture for multi-DOF teleoperated surgical robots such as Pulsar. It supports deterministic tool-frame motion (RPY + insertion), dynamic instrument swaps, safety-aware state gating, and low-latency teleoperation under strict timing and reliability constraints. The architecture spans high-level teleoperation and kinematics down to FPGA-backed BLDC motor control, integrating commercial motor-control platforms such as ODrive and mjbots moteus for deterministic actuation, closed-loop stability, and fault-safe behavior. The software was designed with medical device software lifecycle expectations (ISO 62304) and relevant IEC electronics standards in mind.

Problem

Architect deterministic real-time control and communication pipelines for a multi-DOF surgical robotics platform, supporting tool-frame orientation and insertion control (RPY + linear tool-axis motion), dynamic instrument swaps, teleoperated micro/macro motion, and safety-aware behavior aligned with medical device software and electronics standards.

Approach

• Architected Cosmos’ core real-time pipeline: feedback ingestion → synchronized control loops → deterministic actuation
• Designed multithreaded execution models with explicit scheduling and timing guarantees
• Integrated DDS middleware (Cyclone DDS, Fast DDS) for low-latency, reliable communication across robotic subsystems
• Designed software structures aligned with ISO 62304 medical device lifecycle expectations
• Implemented safety and constraint handling: limits, saturation, fault responses, standards-aware workflows
• Built tool-frame motion control (RPY + insertion) and integrated FK/IK into teleoperation pipelines
• Designed instrument lifecycle handling: identification, frame updates, safety re-initialization
• Built observability tooling: high-rate logging and dashboards for bring-up, debugging, and validation
• Designed and tuned BLDC motor control loops (current, velocity, position) using FOC for surgical manipulators
• Integrated and validated commercial BLDC motor controllers (e.g., ODrive, mjbots moteus) within a real-time surgical control architecture.
• Developed FPGA-based real-time motor-control and IO pipelines (PWM generation, encoder decoding, safety interlocks)
• Integrated FPGA and motor-controller actuation paths with Cosmos’ real-time C++ control stack, debugging jitter, race conditions, and timing faults across hardware–software boundaries

Engineering decisions

Ownership

• Architecture ownership of Cosmos scheduling, determinism, and loop timing
• Direct collaboration with CEO on software strategy and delivery priorities
• Technical leadership across control architecture, computer vision, electronics, and hardware teams
• Designed software workflows aligned with ISO 62304 expectations
• Teleoperation behavior and tool-frame motion pipelines
• Ownership of BLDC motor control behavior, tuning, and closed-loop performance
• Integration and validation of ODrive and mjbots moteus motor controllers
• FPGA-based real-time IO, motor actuation pipelines, and safety interlocks
• Safety constraints, fault responses, and lifecycle re-initialization
• Observability tooling for validation and live demos

Results

• ~1–3 ms control-cycle compute budget under RT scheduling
• ~22–26 ms end-to-end command → motion latency
• Stable closed-loop BLDC actuation using ODrive and mjbots moteus under deterministic real-time constraints
• Safe dynamic instrument swaps without loss of control continuity
• Faster bring-up and debugging through integrated observability tooling

Stack