Earticle

The purpose of this study was to determine the effect of facilitating normalization of scapular location and trunk stability on antigravity posture and upper limb function in the patient with cerebellar ataxia. A subject of this study was a 62-year-old male with cerebellar ataxia. Measurement tools were made with observation of scapular alignment, sit-to-stand test (SST), functional reach test (FRT), and Berg balance scale (BBS). A subject underwent therapist-guided techniques aiming to facilitate scapular positioning and trunk stability, which was performed for 30 minutesaveraging, three times per week for 4 weeks. Clinical observation reported improved scapular and pelvic alignments after the intervention. In addition, the SST, FRT, and BBS scores were remarkably improved after the intervention. These findings indicate that technique to facilitate scapular positioning and trunk stability may be advantageous to improve balance function of patients with cerebellar ataxia.

During the design process of the DC motor composite positioning control system (CPCS), in order to solve the contradiction between the positioning accuracy and the stability, we introduce the equioscillation and equiprecision lines in the root locus plane, analyze and compare root locus maps, the frequency characteristics, and the dynamic responses for PID and CPCS on MATLAB. The results show: within the high-order control system root locus configuration boundary, there always exist three specific boundaried subspaces. Under the condition of simplifying the transferring function to fifth-order from using zero, poles cancellation method, the subspaces’ controllability and observability are not changed. The determination of status feedback matrix K and estimator gain L for the high-order control system can be transformed to solving the third-order dynamic equations for specific boundary conditions, and by constructing the dynamic regulator or compensator achieve zero-pole optimal configuration.

In order to evaluate the stability of chatter vibration in turning precess, the micro-positioning cutting test with artificial tool vibration by piezoelectric actuation were carried out. In experiment, the phase lags between cutting forces and chip thickness variations were measured, and the dimensionless penetration-rate coefficient（$\overline{K^*}$） which is the most important parameter on the stability for chatter vibration was calculated. The results show that$\overline{K^*}$ can be applicable to the stability criterion for regenerative chatter vibration.