In this paper, a jackknife avoidance trajectory tracking control strategy for tractor-trailer vehicle is proposed based on constrained Model Predictive Control (MPC) in the process of reversing perpendicular parking. ...
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ISBN:
(数字)9781728107707
ISBN:
(纸本)9781728107714
In this paper, a jackknife avoidance trajectory tracking control strategy for tractor-trailer vehicle is proposed based on constrained Model Predictive Control (MPC) in the process of reversing perpendicular parking. Firstly, a critical hitch angle is provided for jackknife avoidance and collision-free constraint, through analyzing the influencing factors of the size and stability of the vehicle hitch angle. Next, the conundrums of preventing collision and avoiding jackknife are converted into constraint problem. Therefore, the jackknife and collision problem of tractor-trailer could be solved by using MPC algorithm with the advantage of being able to handle multiple constraints issues. Finally, the simulation results illustrate that the presented control strategy plays an expected role during reversing process of this kind of complicated vehicle system.
This paper develops a double closed-loop control strategy aiming at the trajectory tracking control of wheeled mobile robots (WMRs) under the skidding and slipping. Firstly, a skidding kinematic model and a slipping d...
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ISBN:
(数字)9781728107707
ISBN:
(纸本)9781728107714
This paper develops a double closed-loop control strategy aiming at the trajectory tracking control of wheeled mobile robots (WMRs) under the skidding and slipping. Firstly, a skidding kinematic model and a slipping dynamic model are proposed to describe the WMR under the skidding and slipping, respectively. Then, an anti-skidding controller based on Lyapunov direct control and an anti-slipping controller based on terminal sliding mode control (TSMC) are separately devoted. All of them consist an double closed-loop control strategy to effectively solve the skidding and the slipping at the same time. In addition, the radial basis function neural network (RBFNN) is employed to estimate the disturbance force caused by slipping, thereby satisfactory adaptive and robust capabilities can be provided for the WMR. The simulation results in last demonstrate the effectiveness of the proposed control strategy.
In order to meet design requirements in minimally invasive surgery (MIS), it is necessary to conduct basic operations in the narrow working space. Taking a grasper for example, a 4DOF MIS instrument driven by servo mo...
In order to meet design requirements in minimally invasive surgery (MIS), it is necessary to conduct basic operations in the narrow working space. Taking a grasper for example, a 4DOF MIS instrument driven by servo motors and transmitted by cables is designed. The design of the end of surgical instrument driven by cables is suitable for long-distance transmission, which improves dexterity of the surgical instrument working in narrow space. The mechanism principle including the wrist, graspers and shaft rolling are described. Kinematic coupling between the wrist and grasper are analyzed. Prototype of the surgical instrument is presented. This instrument prototype can be applied in most MIS operations.
Robots are integrating into human society and become an important part. The robots and human must be considered as a whole system and the robots should be intelligent both in digital and physical like human to coopera...
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ISBN:
(数字)9781728158716
ISBN:
(纸本)9781728158723
Robots are integrating into human society and become an important part. The robots and human must be considered as a whole system and the robots should be intelligent both in digital and physical like human to cooperate and interact with human non-physically or physically. For improving the physical intelligence of the robot, a magnetorheological fluid actuator (MRA) is proposed and studied in this paper. A collision model and a speed peak force planning method are proposed and some experiments are conducted. It shows that the collision peak force of the MRA with external objects can be easily controlled to different levels by controlling the compliance of the MRA for safe physical interaction with human or some striking works like hammering a nail.
The null space of the Jacobian for the redundant manipulators can be utilized to reach dual control goals and optimal effects. For the flexible base redundant manipulator system, the reaction force from the motion of ...
The null space of the Jacobian for the redundant manipulators can be utilized to reach dual control goals and optimal effects. For the flexible base redundant manipulator system, the reaction force from the motion of the manipulator should be carefully handled while the end effector is tracking a desired trajectory. Different optimal goals are discussed, including the minimization of base deflection force/torque and base energy dissipation path. Considering the base reaction dynamic, the reaction force/torque is treated as the input of the base and the deflection energy is treated as the output, an integrated optimal goal is built and solved based on the LQR control to get an optimal feedback for the closed-loop dynamics. We discuss the different optimal goals and implement trough the redefined acceleration. We test the different control laws on the three- link manipulators which mounted on a three-DoF flexible base. Simulation results demonstrate that optimal goal in LQR form can be advantageous in terms of flexible base manipulator.
A six-degree-of-freedom parallel manipulator system based on 6-PURU structure is developed for vehicles' motion simulation. The main research in this paper is focused on dynamic modeling of the proposed parallel s...
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A six-degree-of-freedom parallel manipulator system based on 6-PURU structure is developed for vehicles' motion simulation. The main research in this paper is focused on dynamic modeling of the proposed parallel system. The kinematic model of the proposed system is established via kinematic influence coefficient method, in which the velocity and acceleration mappings between the passive components and actuated components are more accurate compared to the equivalent 6-PUS or 6-PSS systems. Based on the kinematics analysis, the dynamic model of the parallel kinematic machine is then formulated via the principle of virtual work. Finally a numerical calculation is performed based on the proposed dynamic model which matches the simulation results of commercial software. The approach outlined in this paper is generic and can be extended to a variety of applications.
To ensure applications requirements of rocket storage tank precision polishing, a 6-dof parallel collision detection mechanisms mounted on the end of rocket tank polishing robot used for heavy load condition is design...
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ISBN:
(数字)9781728137261
ISBN:
(纸本)9781728137278
To ensure applications requirements of rocket storage tank precision polishing, a 6-dof parallel collision detection mechanisms mounted on the end of rocket tank polishing robot used for heavy load condition is designed in this paper. Its each branch chain consists of spherical joint, revolute joint and prismatic joint, in which the prismatic joint is driven by the cylinder. The collision detection principle is to judge whether an external collision occurs by real-time detecting the changes of cylinder pressure and cylinder displacement. Besides, the kinematics of parallel mechanisms is analyzed and a numerical iteration algorithm for forward kinematics based-on our previous work is proposed here. The proposed algorithm can be not only used for 6-dof parallel mechanism but also for more or less than 6-dof ones in which Jacobian matrix is not square. Moreover, it is not sensitive to the iteration initial value. Then, a linear trajectory is simulated to verify the effectiveness of the proposed algorithm. Finally, the simulation results prove the accuracy of the proposed algorithm.
A piezoresistive pressure sensor based on 4H-SiC was developed for working over 500℃. The designed pressure range is 0-7MPa for special aviation applications. As demonstrated with experimental results, in this pressu...
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A piezoresistive pressure sensor based on 4H-SiC was developed for working over 500℃. The designed pressure range is 0-7MPa for special aviation applications. As demonstrated with experimental results, in this pressure range, the sensor shows excellent accuracy and repeatability from 30℃ to 500℃. Compared with previous studies, in MEMS processing of the sensor chip, a suitable alloy system was determined to form a stable high-temperature ohmic contact. Besides, the chip was packaged with mechanical structure and ceramic glue of similar thermal expansion coefficient to avoid thermal stress induced when increasing temperature. With the above measures taken, the sensor performance can be significantly improved. The design, fabrication, and package of this sensor provide support for high-temperature use. Additionally, this work can be a reference for future research in this field.
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