Han Jianda

Generalized Point Wise Min-Norm Control Based on Control Lyapunov Functions

A new nonlinear controller design method based on control Lyapunov functions, called generalized point wise min-norm controller, is presented in this paper, which is a generalized version of Freemans point wise min-norm controller in 1996. And the continuity of the new controller is proved using the set valued analysis theory. The greatest improvement of the new controller, comparing with the Freemans controller, is its greatly improved designing flexibility from the induced guide function. And it is shown that the new control method can be used together with some other controller design method with special performance index by the concept of guide function, especially those that the closed loop stability cannot be ensured sufficiently. Finally, an example is given combining with a linearized controller to both enlarge the large scale stability and preserve the local performance of that.

Environment modeling for long-range polar rover robots

Due to the harsh environments, polar region is now becoming one of the typical scenarios for mobile robots. As one kind of representative polar robots, the long-range polar rover robots require higher autonomy to perceive surrounding environments. To improve the real-time performance and environment model accuracy of environment modeling of outdoor environments, multi-scale 2.5D probabilistic elevation grids is proposed. From the perspective of space scale, the model lattices the environment into refined and coarse grids to adapt to different model accuracy requirements and real-time requirements. From the perspective of probability, the refined grids are estimated by Kalman filter while the coarse grids are represented by the statistics of the covered refined grids. Meanwhile, interpolation of the environment model based on hypothesis tests with the presence of ice cracks is studied. The experiments validate the effectivity of the proposed environment modelling and interpolation algorithms.

Aggressive maneuver oriented multi-rotor aircraft design, modeling and control

Nonzero inertial state stabilization control based on multi-rotor is a perspective, practical and challenging research in control research. For an under-actuated, nonlinear and non-stable objective such as quadrotor, near zero state is an fundamental and urgent task. This paper introduces an quadrotor test-bed design and attitude stabilization control. The dynamics of the quadrotor is deduced based on Newton-Euler equation, whose parameters are computed by 3D drawing software. LQR control method is implemented on a linearized model with respect to zero state, the simulation indicates that the controller is able to withstand a certain non-zero inertial state with satisfying convergence speed. Adjusted parameters are implemented to the LQR controller in the real quadrotor test-bed. The dedicated experiment demonstrates that, this algorithm is qualified for small non-zero state stabilization.

Modeling and controller design of hydraulic rotorcraft aerial manipulator

Traditional Rotary-wing Unmanned Aerial Vehicles (R-UAV) are mostly utilized to conduct surveillance. Installing a mechanical manipulator on R-UAV will result a Rotorcraft Aerial Manipulator (RAM) system. A RAM system enlarges the R-UAVs application scope. The RAM system proposed by this research is composed of R-UAV and a miniature hydraulic manipulator. With the combined merits of the two systems, this RAM system has enhanced flexibility and is capable of fulfilling more tasks. The hovering mode dynamics model of the RAM is established referring to the working characteristics of the hydraulic manipulator. An LQR controller is used to control the planar motion of the hydraulic manipulator. The motion of the manipulator will exert coupled force and moment influence on the RAM system. This coupled influence is taken as a disturbance to the R-UAV system which is restrained by a robust controller. Finally, through simulation, the effectiveness of the established dynamics model and the proposed control strategy is verified.

Review of orthopedic surgical robot and navigation technology

The accuracy, flexibility, and stability of surgical robot has been recognized by the medical community and the patients. Surgery robot has become an important method to achieve orthopedic surgery with the minimal invasiveness, digitization and intelligence. Orthopedic surgery has its own characteristics on surgical objective, surgical instruments, operating mode, and so on. Especially, the orthopedic surgical robot highly depends on the intraoperative navigation devices, which determines the technical specificity of orthopedic surgical robot and has broad clinical application. In this article, with the background of orthopedic surgical robot, we analyze and discuss the research situation of the orthopedic surgical robot and its navigation.

Real time nonlinear model predictive control induced by local linear controller

In this paper, a new nonlinear model predictive control (NMPC) algorithm guided by local linear controller is presented so that it is possible to be implemented in real time and obtain good performance. Firstly, in order to ensure the closed loop stability, a generalized pointwise min-norm (GPMN) controller formulation based on control Lyapunov functions (CLF) are given and parameterized. And then, the parameterized GPMN scheme is combined with the traditional NMPC algorithm. And the optimization variables in traditional NMPC are replaced by the parameters in GPMN, so that the computational burden of original NMPC algorithm can be reduced greatly. Finally, numerical simulations are conducted to verify the feasibility and validity of the new algorithms.

A study of acceleration sensor-based control for lead-screw drive system

In this paper the static and dynamic friction of the constructed lead-screw drive system are studied. The acceleration feedback control combined with the fuzzy parameter self-modulated method is presented and applied to the system to improve the performance. Experiments on the step response and disturbance suppression were performed, and the results obtained confirm the effectiveness of the presented method.