Study on the control algorithm for lower limb exoskeleton based on ADAMS/Simulink co-simulation

A sliding mode control algorithm based on proportional switching function was developed to make the lower limb exoskeleton more fit the human walking gait trajectory. It could improve the comfort of the exoskeleton wearer and enhance the reliability of the system. The three-dimensional mechanical model of the exoskeleton built using software SolidWorks was introduced to ADAMS and then the model parameters were set. The model was combined with the software MATLAB so that the human-machine cooperation control algorithm for lower limb exoskeleton based on ADAMS and Simulink co-simulation was developed. The simulation result was compared with the desired trajectory and the trajectory under PID control. The research discovered that the ability of trajectory tracking under the sliding mode control was much better than that under PID control. It provided an important theoretical basis for the research on human-machine cooperation control algorithm

Bis[N-benzyl-2-(quinolin-8-yl­oxy)acetamide] monohydrate

In the title compound, 2C18H16N2O2·H2O, the dihedral angles between the quinoline rings and the benzene rings in the two independent acetamide mol­ecules are 80.09 (5) and 61.23 (5)°. The crystal packing is stablized by O—H⋯N and N—H⋯O hydrogen bonds between the acetamide and water mol­ecules

Vertex-disjoint triangles in K1,t-free graphs with minimum degree at least t

AbstractA graph is said to be K1,t-free if it does not contain an induced subgraph isomorphic to K1,t. Let h(t,k) be the smallest integer m such that every K1,t-free graph of order greater than m and with minimum degree at least t contains k vertex-disjoint triangles. In this paper, we obtain a lower bound of h(t,k) by a constructive method. According to the lower bound, we totally disprove the conjecture raised by Hong Wang [H. Wang, Vertex-disjoint triangles in claw-free graphs with minimum degree at least three, Combinatorica 18 (1998) 441–447]. We also obtain an upper bound of h(t,k) which is related to Ramsey numbers R(3,t). In particular, we prove that h(4,k)=9(k−1) and h(5,k)=14(k−1)

Design and simulation analysis of an improved lower limb exoskeleton

The lower extremity exoskeleton robot is a type of power assisted robot which can enhance the human walking function. A fundamental problem in the development of the exoskeleton is the choice of lightweight actuators. Thus in the mechanical structure design in this paper, the linear motor is selected as it greatly reduces the complexity of the mechanical structure. Furthermore, the limit switch inside the motor improves the safety performance. Based on the last version of the exoskeleton, the band positions, length adjusting holes and mechanical limit structures are increased. In addition, a control system based on DSP is designed. Furthermore, a kinematics analysis is carried out using the D-H parameter method and a dynamic analysis is developed using the Newton-Euler method. The driving force of every joint is obtained during the simulation using ADAMS software

Dynamics and kinematics analysis and simulation of lower extremity power-assisted exoskeleton

According to the walking character of lower extremity power-assisted exoskeleton that was designed by our Robotics Laboratory, D-H convention was applied to the kinematics analysis of this exoskeleton model. Lagrangian dynamics was used to analyzing dynamics for the single-foot support model, double-feet support model and double-feet support with one redundancy model respectively. The kinematical equation was obtained and MATLAB was used to verify its validity. Meanwhile, the kinetic equations and torque of each joint were obtained by virtue of ADAMS. Our study provided a theoretical foundation for the control strategies, and optimization design of the mechanical structure and promoted the practical application of this lower extremity power-assisted exoskeleton in further research

N′-(5-ethoxycarbonyl-3,4-dimethyl-pyrrol-2-yl-methylidene)-4-hydroxybenzohydrazide monohydrate, C17H21N3O5

Abstract C17H21N3O5, monoclinic, P21/n (no. 14), a = 9.2278(16) Å, b = 15.093(3) Å, c = 12.698(2) Å, β = 105.195(12)°, V = 1706.7(5) Å3, Z = 4, R gt(F) = 0.0553, wR ref(F 2) = 0.1662, T = 296 K

Ethyl 3,4-dimethyl-1H-pyrrole-2-carboxyl­ate

The non-H atoms of the title compound, C9H13NO2, are almost coplanar (r.m.s. deviation = 0.0358 Å). Weak inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into zigzag chains along the b axis with graph-set motif C(5). The chains are further linked into a three-dimensional network by C—H⋯O hydrogen bonds and C—H⋯π inter­actions

A Phase Change Storage Material that May be Used in the Fire Resistance of Building Structure

AbstractThis study prepared polyethylene glycol/silicon dioxide composite, a kind of form-stable phase change material. The composites can be made into mortar which is able to adhere to the surface of building structure and absorb the fire heat. This paper aims to study the effect of the composites on the fire resistance of building structure. Scanning electronic microscope and differential scanning calorimeter were adopted to investigate the structural and thermal properties of the composites. It was found that the polyethylene glycol was well dispersed into the network of solid SiO2. And the latent heat of PEG/SiO2 increased with the decrease of SiO2 content. The required weight percentage of SiO2 was found to be 15% at least if the composites remain solid without leakage. It was also found that a phase change of pure PEG6000 happened with an enthalpy of 158J/g while the 80 wt% PEG composite is 133J/g. In conclusion, the phase change storage material may be used for fire resistance of building structure

Diaqua­bis­[5-(pyrazin-2-yl-κN 1)-3-(pyridin-4-yl)-1H-1,2,4-triazol-1-ido-κN 1]cobalt(II) methanol disolvate

The CoII ion in the title mononuclear compound, [Co(C11H7N6)2(H2O)2]·2CH3OH, is located on an inversion center and is six-coordinated in a distorted octa­hedral geometry defined by four N atoms from two deprotonated 5-(pyrazin-2-yl-κN)-3-(pyridin-4-yl)-1H-1,2,4-triazol-1-ide (ppt) ligands and two water mol­ecules. In the crystal, the complex mol­ecules and lattice methanol mol­ecules are linked via O—H⋯N and O—H⋯O hydrogen bonds, generating a two-dimensional supra­molecular network parallel to (001). π–π inter­actions between the triazole and pyrazine rings and between the pyridine rings are present [centroid–centroid distances = 3.686 (3) and 3.929 (4) Å, respectively]