A triple-step controller with linear active disturbance rejection control for a lower limb rehabilitation robot

Area of Science:

• Robotics
• Rehabilitation Engineering
• Control Systems

Background:

• Lower limb rehabilitation robots (LLRRs) aid hemiplegic patients' motor function recovery.
• Dynamic uncertainties in LLRRs challenge accurate trajectory tracking during rehabilitation.

Purpose of the Study:

• To design and validate a novel triple-step controller with linear active disturbance rejection control (TSC-LADRC) for LLRRs.
• To enhance control accuracy and robustness against dynamic uncertainties in LLRR-assisted rehabilitation.

Main Methods:

• Developed a TSC-LADRC integrating steady-state, feedforward, and feedback control.
• Utilized linear active disturbance rejection control (LADRC) for enhanced feedback control.
• Conducted numerical simulations and experiments with healthy subjects to validate the controller.

Main Results:

• Simulations showed TSC-LADRC significantly reduced tracking errors compared to a standard triple-step controller (TSC), especially under varying loads.
• Experimental results with healthy subjects demonstrated higher accuracy and lower energy consumption with TSC-LADRC than TSC.
• The controller effectively addressed dynamic uncertainties inherent in human-robot interaction.

Conclusions:

• TSC-LADRC offers superior performance in accuracy and robustness for LLRR trajectory tracking.
• The proposed control strategy has significant potential for improving hemiplegic patient rehabilitation.
• Reduced energy consumption suggests enhanced efficiency in robotic-assisted therapy.