Improving horizontal plane locomotion via leg angle control

Area of Science:

• Robotics and Biomechanics
• Insect Locomotion
• Control Systems Engineering

Background:

• The lateral leg spring (LLS) model accurately simulates horizontal plane locomotion in sprawled insects like the cockroach Blaberus discoidalis.
• Passive stability in LLS models relies on constant leg touch-down angles, unlike 3D point mass models which yield unstable gaits.

Purpose of the Study:

• To develop a control law for the LLS model that enhances gait stability through dynamic leg touch-down angle adjustments.
• To investigate if this control strategy aligns with natural insect neural activity and sensory capabilities.

Main Methods:

• A novel control law was implemented, modifying leg touch-down angles in response to perturbations during locomotion.
• Control actions were applied once per stance phase, utilizing previous leg angles relative to the body frame.
• The control law was designed to use variables readily detectable by insect mechanoreceptors.

Main Results:

• The control law significantly improved the stability of periodic gaits in the LLS model.
• Previously unstable periodic gaits were successfully stabilized.
• The basin of stability for periodic gaits was maintained or enhanced by the control strategy.

Conclusions:

• The developed control law effectively enhances gait stability in insect locomotion models.
• The control strategy's consistency with insect neural activity and sensory mechanisms suggests potential for bio-inspired robotics.
• The magnitude of angle variations used in control is comparable to natural leg movements during insect locomotion.