Exploration of an admittance control method for multi-segment spinal motion loading

Area of Science:

• Biomechanics
• Robotics
• Spinal Research

Background:

• In vitro spinal biomechanics research relies on loading methods with limitations in physiological realism and motion control.
• Existing methods struggle to accurately mimic complex spinal movements.

Purpose of the Study:

• To introduce and assess a novel spinal loading method integrating robotic admittance control with dynamic movement primitives (DMPs).
• To enable realistic motion loading of multi-segment spines in vitro.
• To evaluate the reliability and accuracy of this new method.

Main Methods:

• Developed a robotic testing system with a 6-DOF robotic arm and 6-axis force sensor.
• Acquired, modeled, and reproduced spinal traction trajectories using DMPs.
• Validated the method on ovine thoracolumbar specimens (T12-L3) for flexion-extension and lateral bending.

Main Results:

• Successfully established a spinal loading method using robotic admittance control and DMPs.
• Achieved a mean trajectory reproduction error of less than 2.5 mm.
• Demonstrated no significant difference in measured range of motion compared to previous studies (P < 0.05).

Conclusions:

• The proposed method accurately reproduces physiological spinal motion characteristics.
• This technique is feasible and valid for in vitro studies of three-dimensional spinal biomechanics.
• Offers enhanced realism and controllability for spinal loading.