A new class of stabilizing controllers for stochastic nonlinear systems with mismatched conditionsLi, Guifang; Chen, Ye-Hwa
doi: 10.1177/0142331217740623pmid: N/A
This paper considers global asymptotic stabilization in probability for a class of cascaded stochastic nonlinear systems. The uncertainties do not meet the general matched conditions, and only boundedness of the uncertainties is assumed. Drawing on the stochastic asymptotic stability theorem, a novel robust controller is constructed based on the state transformation technique and the gradient method, which ensures that the closed-loop systems are globally asymptotically stable in probability. A numerical example is given to illustrate the effectiveness of the result.
Virtual exoskeleton-driven uncalibrated visual servoing control for mobile robotic manipulators based on human–robot–robot cooperationJi, Peng; Zeng, Hong; Song, Aiguo; Yi, Ping; Xiong, PengWen; Li, Huijun
doi: 10.1177/0142331217741538pmid: N/A
This paper presents an uncalibrated visual servoing control system based on the human–robot–robot cooperation (HRRC). In case of malfunctions of the joint sensors of a robotic manipulator, the proposed system enables the mobile robot to continue operating the manipulator to complete the task that requires careful handling. With the aid of a virtual exoskeleton, an operator may use a human–computer interaction (HCI) device to guide the malfunctioning manipulator. During the guiding process, the virtual exoskeleton serves as a connector between the HCI device and the manipulator. However, when using the HCI device to guide the virtual exoskeleton, there could be a risk of a large-residual problem at any time caused by non-uniform guiding. To solve this problem, a residual switching algorithm (RSA) has been proposed that can identify whether the residual should be calculated based on the motion characteristics of the artificial guiding, reducing the computational cost and ensuring the tracking stability. To enhance the virtual exoskeleton’s ability to drive the manipulator, a multi-joint fuzzy driving controller has been proposed, which can drive the corresponding joint of the manipulator in accordance with an offset vector between the virtual exoskeleton and the manipulator. Lastly, the guiding experiments have verified that, compared with the contrast algorithm, the proposed RSA has a better tracking performance. A peg-in-hole assembly experiment has shown that the proposed control system can assist the operator to control efficiently the robotic manipulator with malfunctioning joint sensors.
Active disturbance rejection controller design for stable walking of a compass-like bipedSong, Sumian; Tang, Chong; Wang, Zidong; Yan, Gangfeng
doi: 10.1177/0142331217741957pmid: N/A
This paper aims to develop an active disturbance rejection controller design scheme for compass-like biped robots. In the previous study, with a special designed mechanical structure on compass-like biped, we have generated a high-efficient walking gait. The original controller applied linearization approximation based on the method transverse coordinate control, with which the ability of disturbance rejection is insufficient. We introduce the active disturbance rejection controller method into the control scheme, which only requires the information of angular momentum and has the ability to compensate the model error and the external disturbance. With the new control strategy, the linearization approximation method is replaced by an active disturbance rejection controller and the robustness is improved. In order to further apply this control method, a switching control strategy has been proposed and a series of numerical simulations show that active disturbance rejection controller has a good disturbance rejection effect.