Search

Force control is one of the core modules for surface finishing such as grinding, polishing and sanding. However, the current force control methods based on human skills lack in-depth analysis of data patterns or are only applicable to flat surfaces. In addition, surface finishing is mainly performed by hand, resulting in low processing efficiency and poor product consistency. Therefore, this paper proposes a force control method that incorporates human skills to achieve relatively accurate force skill transfer and complex surface finishing. Firstly, human skills consisting of the force skill and the motion skill are learned. The force skill is used to generate the desired force. Then, a series of discrete poses are obtained based on human demonstration and combined with the motion skill to generate the desired trajectory. Finally, a computed-torque impedance control method is proposed to achieve relatively accurate force skill transfer and complex surface finishing by incorporating the desired trajectory and the desired force. The experiments are conducted on a platform composed of a 7-DOF collaborative robot manipulator from Franka Emika and a complex violin surface. The results demonstrate that the proposed force control method can achieve relatively accurate force skill transfer and improve the surface quality of the workpiece. [ABSTRACT FROM AUTHOR]

Humanoid robots have attracted much attention by virtue of their compatibility with human environments. However, biped humanoids with immense promise still cannot function steadily and reliably in real‐world settings in the current state. Hence, rationally combining a humanoid robot with different stable mobile platforms is a favoured solution for diverse scenarios. Here, a new versatile humanoid robot platform, aiming to provide a generic solution that can be flexibly deployed in diverse scenarios, for example, indoors and fields is presented. Versatile humanoid robot platform incorporates multimodal perception, and extensible interfaces on hardware and software, allowing it to be rapidly integrated with different mobile platforms and end‐effectors, only through easy‐to‐assemble interfaces. Additionally, the platform has achieved impressive integration, lightness, dexterity, and strength in its class, with human‐like size and rich perception, targeted to have human‐intelligent manipulation skills for human‐engineered environments. Overall, this article elaborates on the reasoning behind the design choices, and outlines each subsystem. Lastly, the essential performance of the platform is successfully demonstrated in a set of experiments with precise and dexterous manipulation, and human–robot collaboration requirements. [ABSTRACT FROM AUTHOR]

Transferring versatile skills of human behavior to teleoperate manipulators to execute tasks with large uncertainties is challenging in robotics. This paper proposes a hybrid mapping method with position and stiffness for manipulator teleoperation through the exoskeleton device combining with the surface electromyography (sEMG) sensors. Firstly, according to the redefinition of robot workspace, the fixed scale mapping in free space and virtual impedance mapping in fine space are presented for position teleoperation. Secondly, the stiffness at the human arm endpoint is predicted and classified into three levels based on the K nearest neighbor (KNN) and XGBoost, and the stiffness mapping method is utilized to regulate the stiffness behavior of manipulator. Finally, the proposed method is demonstrated in three complementary experiments, namely the trajectory tracking in free space, the obstacle avoidance in fine space and the human robot interaction in contact space, which illustrate the effectiveness of the method. [ABSTRACT FROM AUTHOR]

Abstract: Because of the joints flexibility and the distortion of long tubular booms, high precision tracking and positioning performance of large space manipulator can hardly be achieved. As a result, during space capture process, big position error and escaping velocity between the end effector and the target object would exist even when the manipulator is pre-located. To solve this problem, a typical kind of flexible interface fit for space capture application is introduced to improve the capture ability of the end effector. Moreover, a visual based equivalent capture strategy is put forward to avoid the complicate modeling problem of the unknown correcting force that acts on the grapple of the target during capture process. The proposed strategy makes the complicate capture problem to be a simple position tracking problem. Meanwhile, a sliding mode controller based on the fuzzy switching gain is designed to suppress the disturbance by unknown extern force. Experiments show that the proposed strategy can improve the autonomous capture ability of the large end effector. [Copyright &y& Elsevier]

Instead of directly sampling the phase currents, a technique that adopts a single current sensor in the dc link to reconstruct three-phase currents has arisen. Through this approach, the cost of servo systems can be reduced and the reliability can be improved. However, the duration of an effective vector may be so short that the phase current cannot be measured reliably by the conventional space-vector pulsewidth modulation (PWM) algorithm. In this paper, a new phase-current reconstruction method, switching-state phase shift (SSPS), is proposed based on the PWM pattern modification. The modification is performed by applying phase shifts to the switching-state waveforms of the inverter. The algorithm can realize high-quality reconstruction to the phase current with less impacts on the output current ripples and switching losses. Moreover, it can maximize the linear-modulation region by saturation handling. Measurements on the permanent-magnet synchronous motor servo drives show that the SSPS can offer an attractive performance during both steady-state and dynamic operations in the phase-current reconstruction and regulation. [ABSTRACT FROM PUBLISHER]