Robotics kinematics · embedded motor control · physics-grounded simulation
dodik8700@gmail.com · github.com/raviffg · Publications · Patents
I work on robotics kinematics, embedded motor control, and physics-grounded simulation tools across CAD/FEA, autonomous surgical modeling, and high-speed PCB layouts. My work focuses on where analytical solvers, finite-element meshes, and real hardware telemetry disagree—characterizing mechanical backlash, thermal runaway cliffs, and topological boundary failures. Below is a selection of research papers, patents, and engineering projects built between 2016 and 2026.
Four live views over the project geometry: a tetrahedral stress solve, a four-axis arm with an inverse-kinematics controller, a 25,600-point LiDAR scan, and a Pennes bioheat field on a deformable surface. Drag to orbit, scroll to zoom, right-drag to pan.
Newest first. Each row links to a self-hosted technical report; hover a thumbnail (or press live) to run the corresponding solver in the card.
A feature dependency graph is re-evaluated against 164 assembly mates to catch over-constrained and dangling references before export. Rank-nullity on the constraint Jacobian isolates every conflict with its participating mate indices.
Signed-distance tissue surfaces deform under needle load while a Pennes bioheat solve tracks the ablation isotherm in the same time step. Perfusion is corrected by the local volume ratio so the isotherm stays within 0.03 mm of the finite-difference reference.
Meshing, solve and post-processing run unattended on a finned cold plate; the 1,200 W conjugate case saturates at 284.6 MPa in the base fillet while the junction stays at 76 °C. Opening the fillet to R9 drops the peak to 231 MPa.
The return path of a 6.4 Gb/s differential pair is extracted from layout and checked across a plane split, together with the IPC-2152 trace heating. An 18-via fence at 0.35 mm pitch removes 87 mV of ground bounce without a stack-up change.
Closed-form inverse kinematics for a four-axis arm, with commutation-current signatures used to flag a stalled wrist before the encoder loses count. Scheduling the threshold with joint velocity buys 38 ms of lead at 0.5 m/s.
Log-odds mapping with 72-beam scans and a correlative scan matcher closes a laboratory circuit to 0.021 m, against 1.84 m of raw odometry drift. Unexplored cells stay at the prior, so unmapped space is never implied to be free.
Dial-indicator reversal tests quantify backlash per microstep setting and show the compliance floor at 0.042 mm, while corner overshoot is traced to the acceleration discontinuity in the G-code. A 0.4 mm corner arc removes it.
Allan variance separates angle random walk from bias instability before the quaternion EKF is tuned, so the process noise comes from the measurement rather than from trial and error. Attitude error settles below 0.5° within 40 s.
Wheel odometry, ultrasonic range gates and u-blox fixes are fused so GPS dropouts in a corridor do not fold the position estimate. An HDOP gate with a 5 s age check rejects the first four fixes after reacquisition.
Azimuth and elevation commands are generated from the Spencer ephemeris with a 20 Hz PI loop and a 0.08° dead band, so the controller cannot hunt inside the worm-drive backlash. Actuator power falls from 31 W to 9.6 W.
A quasi-static two-dimensional field solve over a split return plane gives 98.6 Ω differential impedance and shows where the return current is forced to detour. Across a 0.6 mm split the impedance rises to 112.4 Ω, a 0.066 reflection.
The coupled Lagrangian equations are integrated with fixed-step RK4 at 4 ms and sampled on a Poincaré section, exposing the chaotic sea at 42.36 J. Energy drift over 1,000 s is 0.03%, so the topology is a property of the dynamics.