Walking with robot-generated haptic forces in a virtual environment: a new approach to analyze lower limb...

Area of Science:

• Neurorehabilitation
• Biomechanics
• Virtual Reality

Background:

• Haptic feedback in virtual environments (VEs) can induce gait adaptation in individuals with and without stroke.
• Adaptation effects are primarily observed in spatiotemporal gait parameters like speed.
• Concurrent kinematic and coordination changes in lower limbs during haptic feedback walking remain under-explored.

Purpose of the Study:

• To investigate the effects of haptic tensile forces on bilateral lower limb coordination during treadmill walking in individuals with chronic stroke.
• To compare kinematic and coordination changes induced by haptic feedback with those from using an instrumented cane.
• To evaluate the utility of 3D phase diagrams and Sobolev norms in quantifying gait coordination.

Main Methods:

• Chronic stroke participants were stratified into lower (LF) and higher (HF) functioning subgroups based on gait speed.
• Participants walked in a VE with robot-generated haptic leash forces or an instrumented cane.
• Kinematic data of thigh, leg, and foot segments were analyzed, along with intersegmental coordination using 3D phase diagrams and Sobolev norms.

Main Results:

• All groups exhibited kinematic changes in lower limb segments with increased gait speed during and after haptic force application and with cane use.
• Intersegmental coordination, assessed via 3D phase diagrams, showed increased trajectory areas and angular velocity, particularly during the paretic leg's stance-to-swing transition.
• Sobolev norm values, reflecting angular position and velocity, increased proportionally for both limbs, indicating enhanced bilateral coordination.

Conclusions:

• Tensile haptic forces and cane use can concurrently alter lower limb intersegmental coordination patterns in individuals with chronic stroke.
• These kinematic and coordination changes, particularly the increase in Sobolev norms, appear favorable for functional gait recovery.
• 3D phase diagrams and Sobolev norm values are promising tools for detecting and quantifying gait coordination changes in neurorehabilitation.