Perry Y. Li

 "Combining Digital Hydraulics with Electrification"

• Plenary talk given at the 2025 Scandinavian International Conference on Fluid Power (SICFP' 25) held at Linkoping University, Sweden, on June 2, 2025.

In this presentation, I argue that combining digital hydraulics (with on/off valves) and small electric motors make complementary use of the power-density advantage of fluid power and the efficiency and controllability benefits of electric actuation, while avoiding their respective drawbacks. Three examples where this prinicple is utilized are given: 1) The Hybrid Hydraulic Electric Architecture (HHEA); 2) Softswitch for pressure rail switching (not discussed due to shortness of time); 3) Digital displacement winch drive.  

"Modifying Familiar Hydraulic Equations to Account for Fluid Compressibilities, with Application to Pump/Motor Efficiencies"

• CCEFP Webinar, June 2020

(This is a more detailed presentation of the material in the FPMC 2020 video)

 "Self-Sensing Dual Push-Pull Solenoids using a Finite-Dimensional Flux Observer,”

•   2020 American Control Conference, July 2020.

In this paper, we present our self-sensing algorithm for determining the position of a pair of solenoids in the push-pull configuration using electrical information (voltages and currents) only. Accuracy up to 0.061mm (or 1.5% of the stroke) is achieved. The key is a consistent model that accounts for eddy current dynamics.

 "Combining Hydraulic and Electric Actuation To Improve Efficiency and Control  Effectiveness for Off-Road Mobile Machines"

• Plenary talk given at the 8th International Conference of Control, Dynamics Systems and Robotic (CDSR 2020), November 2020.

In this presentation, I present the "hybrid hydraulic-electric architecture" for high power mobile machines such as excavators, wheel-loaders, combines and the like. This architecture reaps the benefits of electrification (high efficiency and controllability) without paying the cost of high power electrical components. Control problems, both for minimizing energy use and for following user commands, are presented.