A force-controlled planar haptic device for movement control analysis of the human arm.
This paper describes the design and application of a haptic device to study the mechanical properties of the human arm during interaction with compliant environments. Estimates of the human endpoint admittance can be obtained by recording position deviations as a result of force perturbations. Previous studies attempted to estimate the impedance by recording force as a result of position perturbations, but these experiments do not require a feasible task of human beings. A general problem of force-controlled haptic devices is the occurrence of contact instability, especially where a small virtual mass is required. This negative effect is reduced by the use of a lightweight but stiff manipulator and a robust servo-based admittance controller. The virtual admittance is accurate to at least 13 Hz, attaining a minimum virtual mass of 1.7 kg (isotropic, without damping and stiffness). The properties of known test loads were estimated with an accuracy higher than 98%, up to 20 Hz. The application of the manipulator is evaluated by an experiment with a subject performing a position maintenance task. With this device it is possible to study the adaptability of the neuromuscular system to a variety of environments, enabling a new and functional approach to human motion research.
D000328:Adult; D001132:Arm / Q000294:innervation / Q000502:physiology*; D001186:Artificial Limbs / Q000639:trends*; D001696:Biomechanical Phenomena; D005246:Feedback / Q000502:physiology; D006801:Humans; D008297:Male; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology; D012371:Robotics / Q000295:instrumentation* / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology