Design and Analysis of a Novel Shoulder Exoskeleton Based on a Parallel Mechanism

Power-assisted upper-limb exoskeletons are primarily used to improve the handling efficiency and load capacity.However,kinematic mismatch between the kinematics and biological joints is a major problem in most existing exoskeletons,because it reduces the boosting effect and causes pain and long-term joint damage in humans.In this study,a shoulder augmentation exoskeleton was designed based on a parallel mechanism that solves the shoulder dislocation problem using the upper arm as a passive limb.Consequently,the human–machine synergy and wearability of the exoskeleton system were improved without increasing the volume and weight of the system.A parallel mechanism was used as the structural body of the shoulder joint exoskeleton,and its workspace,dexterity,and stiffness were analyzed.Additionally,an ergonomic model was developed using the principle of virtual work,and a case analysis was performed considering the lifting of heavy objects.The results show that the upper arm reduces the driving force requirement in coordinated motion,enhances the load capacity of the system,and achieves excellent assistance.

Effect of salvianolic acid A and C compatibility on inflammatory cytokines in rats with unilateral ureteral obstruction

OBJECTIVE:To investigate the effect of salvianolic acid A and C component molecules,which are involved in drug compatibility,on inflammatory cytokine expression that affects human chemokine ligand 5(CCL5) and chemokine ligand 10(CXCL10)levels in rats with unilateral ureteral obstruction(UUO).METHODS:Fifty Sprague Dawley rats were randomly divided into five groups:normal,model,salvianolic acid A,salvianolic acid C and salvianolic acid A and C groups.The normal group was used as the control,and the other groups of rats had a UUO model established.The control group had free access to food and water,and the other groups received the corresponding drugs for 2 weeks.After the last administration,urine β_2-microglobulin(β_2-MG) and N-acetyl-β-D-glucosaminidase(NAG) levels were analyzed.After 24 h,all rats were sacrificed and the serum was analyzed for creatinine(Cr) and blood urea nitrogen(BUN) levels.Rat kidneys were removed,and CCL5 and CXCL10 inflammatory cytokine mRNA expression was measured using real-time fluorescent quantitative reverse transcription-polymerase chain reaction(RT-PCR).Kidney fibrosis was observed using hematoxylin-eosin(HE)staining and Masson trichrome staining.RESULTS:In the salvianolic acid A and salvianolic acid C treatment groups,serum Cr and urine NAG levels were significantly lower than in the model group(both P < 0.05).In all treatment groups,urine pYMG levels were significantly lower than in the model group(all P < 0.05).Compared with model group,the pathological changes and collagen deposition improved to varying degrees(both P <0.05).CCL5 and CXCL10 mRNA expression decreased to different degrees compared with the model group(both P < 0.05).CONCLUSION:Salvianolic acid A and C are component molecules of drug compatibility,and they may protect renal function and improve tubular function and renal pathology to a certain degree in UUO.This improvement may be related to a reduction in inflammatory cytokines CCL5 and CXCL10 secretion in the UUO rat kidney.