Key technologies of TianGong-2 robotic hand and its on-orbit experiments

Cui

et al. 2019

Self Cite

Purpose The purpose of this study is to develop a robotic hand–arm system for on-orbit servicing missions at the Tiangong-2 (TG-2) Space Laboratory. Design/methodology/approach The hand–arm system is mainly composed of a lightweight arm, a dexterous hand, an electrical cabinet, a global camera, a hand–eye camera and some human–machine interfaces. The 6-DOF lightweight arm and the 15-DOF dexterous hand adopt the modular design philosophy that greatly reduces the design cycle and cost. To reduce the computational burden on the central controller and simplify system maintenance, an electrical system which has a hierarchical structure is introduced. Findings The prototypical operating experiments completed in TG-2 space laboratory demonstrate the performance of the hand–arm system and lay foundations for the future applications of space manipulators. Originality/value The main contributions of this paper are as follows a robotic hand–arm system which can perform on-orbit servicing missions such as grasping the electric drill, screwing the bolt, unscrewing J599 electrical connector has been developed; a variable time step motion plan method is proposed to adjust the trajectories of the lightweight arm to reduce or eliminate the collision force; and a dexterous hand uses the coordinated grasp control based on the object Cartesian stiffness to realize stable grasp. To solve the kinematic mapping from the cyber glove commands to the dexterous hand, a fingertip-position-based method is proposed to acquire precise solutions.

Section: Prototype Design Of the Hand–arm Systemmentioning

confidence: 99%

Section: Key Technologies Of the Hand–arm Systemmentioning

confidence: 99%

Robotic hand-arm system for on-orbit servicing missions in Tiangong-2 Space Laboratory

Cui

et al. 2019

Self Cite

“…Then, for each input position and orientation ξ t , we calculated the distribution ofẋ t as shown in (8):…”

Section: ) Reproducing the Directed Trajectories And Confidence Intementioning

confidence: 99%

“…On September 15, 2016, the TianGong-2 manipulator system was launched with the TianGong-2 space laboratory, to gain experience for on-orbit servicing tasks using manipulators. Many on-orbit servicing tasks were scheduled, including screwing off an electrical connector, removing a multilayer covering and loosening bolts using a hand drill [8]. As a result, it is necessary to propose a proper control method to carry out the above The associate editor coordinating the review of this manuscript and approving it for publication was Luigi Biagiotti .…”

Section: Introductionmentioning

confidence: 99%

A Novel Semi-Autonomous Teleoperation Method for the TianGong-2 Manipulator System

Jiang

et al. 2019

IEEE Access

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Semi-autonomous teleoperation based on Learning from Demonstration is an effective method of remote operation of space manipulators, especially in the scenarios with limited communication and repeated operation problems. However, the joint trajectories generated by those methods may not be suitable for space manipulator control. In this paper, we present a novel semi-autonomous teleoperation method, which has been used for the TianGong-2 manipulator system. The proposed method can not only reproduce trajectories for the tasks according to the current environment, but also generate the smoother and smaller joint control torques. To implement the method, we first collected kinesthetic demonstrations by the space manipulator teaching platform as prior knowledge. Then, based on these kinesthetic demonstrations, we designed the joint control commands with Dynamics Constraint Learning from Demonstration algorithm. We finally evaluated our method with the simulation and on-orbit experiment by locating the dexterous hand to the pre-screwing bolt. Our results show a significant reduction of joint control torque fluctuations and peak-to-peak values, and also can reduce energy consumption.

“…The Space Station Remote Manipulator System (SSRMS) [5], special purpose dexterous manipulator [6], and European Robotic Arm [7] applied to the International Space Station [8] are all 7-degree-of-freedom (7-DOF) redundant manipulators. Space robots also include the Chinese Space Station Remote Manipulator System (CSSRMS) [9], TianGong-2 manipulator [10], Robonaut 2 [11], Japanese Experiment Module Remote Manipulator System [12], and ETS-VII manipulator [13]. CSSRMS consists of a core module manipulator (CMM) and an experimental module manipulator (EMM) [14], which are also 7-DOF redundant manipulators with link offset.…”

Section: Introductionmentioning

confidence: 99%

Precise semi-analytical inverse kinematic solution for 7-DOF offset manipulator with arm angle optimization

Xie

Jiang

et al. 2021

Front. Mech. Eng.

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Seven-degree-of-freedom redundant manipulators with link offset have many advantages, including obvious geometric significance and suitability for configuration control. Their configuration is similar to that of the experimental module manipulator (EMM) in the Chinese Space Station Remote Manipulator System. However, finding the analytical solution of an EMM on the basis of arm angle parameterization is difficult. This study proposes a high-precision, semi-analytical inverse method for EMMs. Firstly, the analytical inverse kinematic solution is established based on joint angle parameterization. Secondly, the analytical inverse kinematic solution for a non-offset spherical-roll-spherical (SRS) redundant manipulator is derived based on arm angle parameterization. The approximate solution of the EMM is calculated in accordance with the relationship between the joint angles of the EMM and the SRS manipulator. Thirdly, the error is corrected using a numerical method through the analytical inverse solution based on joint angle parameterization. After selecting the stride and termination condition, the precise inverse solution is computed for the EMM based on arm angle parameterization. Lastly, case solutions confirm that this method has high precision, and the arm angle parameterization method is superior to the joint angle parameterization method in terms of parameter selection.