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Cancer represents a major threat to human health. Magnetic resonance imaging (MRI) provides superior performance to other imaging-based examination methods in the detection of tumors and offers distinct advantages in biopsy and seed implantation. However, because of the MRI environment, the material requirements for actuating devices for the medical robots used in MRI are incredibly demanding. This paper describes a novel double tendon-sheath transmission device for use in MRI applications. LeBus grooves are used in the original transmission wheels, thus enabling the system to realize long-distance and large-stroke transmission with improved accuracy. The friction model of the transmission system and the transmission characteristics model of the novel tendon-sheath structure are then established. To address the problem that tension sensors cannot be installed in large-stroke transmission systems, a three-point force measurement method is used to measure and set an appropriate preload in the novel tendon-sheath transmission system. Additionally, experiments are conducted to verify the accuracy of the theoretical model and multiple groups of tests are performed to explore the transmission characteristics. Finally, the novel tendon-sheath transmission system is compensated to improve its accuracy and the experimental results acquired after compensation show that the system satisfies the design requirements.

The advanced missile uses blended control of aero-fin and reaction-jet to improve missile maneuverability. The blended control design, which is multi-inputs and multi-outputs (MIMO), severe nonlinear, and model uncertain, is much more complex than conventional aero-fin control. A novel nonlinear backstepping control approach is proposed to design the blended autopilot. Missile model is reformed to a new one by state reconstruction technique so that it is easy to be handled by the backstepping method. Then a Lyapunov function is chosen to avoid oscillation caused in normal backstepping way when control parameters are mismatched. In distribution of both inputs, optimal energy logic is proposed. In addition, a fuzzy cerebellar model articulation controller (FCMAC) neural network is used to guarantee controller robustness to uncertainties. Finally, simulation results demonstrate the efficiency and advantages of the proposed method.

For the purpose of effectively coping with the danger from infrared imaging guided weapons, Directional Infrared Countermeasure (DIRCM) technology is greatly developed in recent years, which has got promising to be the main trend of future Infrared Countermeasure (IRCM) technology. Focused on the research requirement for infrared image-forming system's performance on the conditon of DIRCM laser's irradiation, the whole process of DIRCM laser's interaction with atmospheric environment and infrared image-forming system, including laser's emitting, lasing atomspheric transmission, optic transmission and detector's response of the input laser into infrared image-forming system, was well investigated and modeled, upon which the simulation model of infrared image-forming system's performance under DIRCM laser's irradiation was built. Finally, the proposed calculation method and simulation model in this paper were demonstrated valid for simulating infrared image-forming system's real reaction performance to DIRCM laser's irradiation, which are able to obtain efficient simulation results not only on the DIRCM laser's infrared imaging grey level, facula appearance and grey texture, but also on the infrared image-forming system's saturation and damage effects caused by the DIRCM laser's irradiation at different situations, such as different distances, illuminations, etc. Meanwhile, above results were verified by real experiment which employed laser to irradiate real infrared thermal imaging system, the simulation data were testified close to real experiment datas, the validation of proposed method and model also gets proved. The proposed work provides foundation for further research into DIRCM's jamming performance against infrared imaging guided weapons.

Joint clearance is one of important factors which affect motion precision of machines. In this paper the mathematical model of a new-type joint, tripod-ball sliding joint, is established, and the new concepts of basal system and active system are put forward. Based on the mode-change criterion established here, the consistent equations of motion in full-scale are derived by using Kane method. The dynamic behavior of the crank-slider mechanism with clearance in the tripod-ball sliding joint is investigated. The results including motion error and impact acceleration are obtained and the advantage of this new joint is shown.

Clearance is inevitable in the kinematic joints of mechanisms. In this paper the dynamic behavior of a crank-slider mechanism with clearance in its tripod-ball sliding joint is investigated theoretically and experimentally. The mathematical model of this new-type joint is established, and the new concepts of basal system and active system are put forward. Based on the mode-change criterion established in this paper, the consistent equations of motion in full-scale are derived by using Kane method. The experimental rig was set up to measure the effects of the clearance on the dynamic response. Corresponding experimental studies verify the theoretical results satisfactorily. In addition, due to the nonlinear elements in the improved mathematical model of the joint with clearance, the chaotic responses are found in numerical simulation.