ABSTRACT
ObjectiveTo analyze the characteristics of plantar pressure of diabetic patients during gait cycle, and to design a offloading insole with variable stiffness. MethodsThe plantar pressure experiment was carried out and a database including 157 subjects was established. The differences of plantar pressure distribution were analyzed among diabetic patients with and without peripheral neuropathy, and healthy people. The insole pressure area was divided, and porous units were filled in different insole areas according to the pressure gradient. The fed-calf-insole finite element model of diabetic patients was constructed. The simulation analysis of different insole schemes was carried out under the conditions of push-off, footheel-strike and dynamic neutrality posture, and to explore the most reasonable insole stiffness design. ResultsCompared with the healthy group, the percentage of peak pressure and high pressure in the left and right heel areas of diabetic neuropathy patients showed a decreasing trend, in which the left peak pressure was significantly reduced by 11% (P = 0.026) and the percentage of high pressure was significantly reduced by 9.8% (P = 0.02). When the porous elements of 2.5 MPa and 1.9 MPa were used in the high pressure area of the insole metatarsal and high pressure area of the heel, the peak plantar pressure of footheel-strike, dynamic neutral and push-off was reduced by 42.4%, 27.4% and 26.4%, and the peak stress of the soft tissue was reduced by 49.8%, 43.6% and 25.1%, respectively. ConclusionThere is a higher risk of ulcer in the metatarsal region than in the heel region for diabetic patients. The variable stiffness insoles based on the optimization of plantar pressure and internal stress under multi-posture can effectively reduce the peak pressure of plantar and peak stress of soft tissue during walking, which provides a reference for the design of variable stiffness insoles.
ABSTRACT
Objective An X-shaped cushioning insole with variable stiffness was designed to explore its effects on plantar pressure and internal stress of diabetic patients with toe amputation. Methods Based on CT images, the feet-calf finite element model of diabetic patients with toe amputation was established, and the insole was divided into different areas according to distribution characteristics of the planter pressure. The three-dimensional (3D) printed cushioning insole with an X-shaped sandwich structure was designed. The modulus of the sandwichstructure was changed by changing thickness of the sandwich structure panel. For simulation analysis, the divided area was filled with the X-shaped sandwich structure with different modulus. Results The peak plantar pressure of diabetic patients with toe amputation was in calcaneal region, and the combined insoles with 1. 2 mpanel thickness in toe area, 1. 4 mm panel thickness in metatarsal area, 2. 0 mm panel thickness in middle area and 1. 6 mm panel thickness in heel area had the best decompression effect. Compared with bare feet, the peak pressure in heel area of the insole, the peak pressure in phalangeal head area and the stress in plantar softissues were reduced by 40. 18% , 31. 7% , and 50. 44% , respectively. Conclusions The 3D printed insoles with variable stiffness can effectively reduce surface pressure and internal stress of the sole and reduce probability of the 2nd toe amputation
ABSTRACT
Objective To design a notched flexible articulation applied to electric stapler and study its turning performance. Methods The notched flexible articulation was designed and modeled. The kinematics and statics models of the articulation were established for simulation calculations. The stress, deflection angle, top displacement and driving force of the articulation with 3 different turning structures were studied under equal and variable stiffness of symmetrical notches by using finite element simulation. An experimental platform for performance test of the turning structure was built to verify the simulation results and the model. Results The theoretical model of the turning structure in bending process was basically consistent with the experimental results. With the optimization of symmetrical notch stiffness, the maximum stress of the articulation with variable stiffness was reduced by 20.64% and 39.20%, respectively. The articulation with variable stiffness required the smallest tensile force during bending, which was 33.41% lower than that of the articulation with equal stiffness, and the tip displacement (30.8 mm) along the bending plane was the smallest. The maximum deflection angle for the articulation with 3 different turning structures all could reach 90°. Conclusions The kinematics and statics models of the articulation can be used for the calculation of its tensile force and position changes. The turning performance of the articulation with variable stiffness using symmetrical notch is better than that with equal stiffness. The notched flexible articulation meets the design requirements and the turning needs of electric stapler.
ABSTRACT
Flexible variable stiffness actuator is divided into four categories including elastic element, pneumatic element, electric-magnetic element and intelligent material. It is gradually applied in rehabilitation robot. It could adapt the change of patient's impedance in the upper and lower limb rehabilitation robots, ensure the safety of the wearer in the exoskeleton, and improve the biomimetics in the prosthesis. Variable stiffness driving mechanism for rehabilitation robot still has some disadvantages. It is proposed to have compact structure, low power consumption, good stiffness characteristics, high response rate and progressive output torque curve, etc.
ABSTRACT
BACKGROUND/AIMS: Loop formation during colonoscopy can adversely effect on completion rates, speed of intubation and patient tolerance of the procedure. The ability to vary endoscope shaft flexibility may help insertion to the cecum. The aim was to compare a variable colonoscope with adjustable shaft stiffness to a conventional colonoscope (CC). METHODS: Consecutive patients attending for day case colonoscopy were randomized for examination with either the conventional colonoscope (Olympus CF200Z) or a variable stiffness (VS) colonoscope (CFQ240AL). The time to the cecum, inserted length of scope at cecum, need for abdominal compression, need for rotation of body position and pain scores of patient were analyzed. RESULTS: Of 158 cases, 69 were performed with the CC, and 89 with VS. There was no difference in intubation time between VS (mean 5.15+/-2.61 min) and CC (6.01+/-3.31 min) in experienced group. However, intubation time was quicker with VS than with CC (VS: 8.48+/-5.59, CC: 11.58+/-4.70, p=0.039) and number of loop formation was less with VS (mean 1.20) than with CC (mean 1.84) (p=0.043) in trainee group. There were no significant differences in inserted length of scope at cecum, need for abdominal compression, pain score or need for patient rotation between VS and CC in two groups. CONCLUSIONS: There was no significant difference in cecal intubation time between two groups in experienced group. However, in trainee group, the intubation time was quicker and the number of loop formation were lower in VS group than CC group.