Abstract
This paper proposes an efficient and accuracy inverse kinematic algorithm for 7-DOF redundant manipulators with obstacles avoidance and singularities avoidance based on the hybrid of analytical and numerical method (IK-HAN). Specially, the paper focuses on how to solve the inverse kinematics problem accurately and efficiently for a novel configuration, i.e. SSRMS-type manipulator. First, the elbow orientation is introduced and the algebraic relationship between the elbow orientation and joint angles is derived. Second, the optimization algorithm is designed to find the optimal elbow orientation based on Particle Swarm Optimization. To improve the efficiency, the equivalent optimization model based on the azimuth angle is investigated. Third, optimal models are developed to avoid obstacles and singularities and improve manipulability in the constraint domain. Moreover, how to employ optimization resolution to solve the inverse kinematics problem is discussed. Finally, the validity of the algorithm is verified via kinematics simulations and the result illustrates that the algorithm performs well in accuracy, stability and efficiency.
Highlights
The redundant manipulators have great advantages in dealing with complicated problems than 6-DOF robots, such as obstacles avoidance [1], singularities handing [2], arm angle limits [3] minimum base disturbance [4], so they are applied in many fields including aerospace docking [5] bionic arms [6] and medical robots [7]
As this paper focuses on the inverse kinematics rather than the trajectory planning, we assume without loss of generality that the desired pose in each moment has been known
This paper has proposed a novel inverse kinematic algorithm for Space Station Remote Manipulator System (SSRMS)-type 7-DOF redundant robots based on a hybrid of analytical and numerical method
Summary
The redundant manipulators have great advantages in dealing with complicated problems than 6-DOF robots, such as obstacles avoidance [1], singularities handing [2], arm angle limits [3] minimum base disturbance [4], so they are applied in many fields including aerospace docking [5] bionic arms [6] and medical robots [7]. Reference [17] analyzed singularities of the algorithm and analytical methods of inverse kinematics for joint limit avoidances Another popular manipulator for 7R is Space Station Remote Manipulator System (SSRMS) [18], which is a topological configuration of SRS but has more complex structures - additional link offsets at the shoulder, elbow and wrist parts. This paper introduces a novel notation - the elbow orientation (EO) as an additional control parameter and proposes a hybrid of analytical and numerical method (HAN) to solve the real-time inverse kinematics for SSRMS accurately and efficient. For a fixed shoulder in space along with a given pose of the wrist, the manipulator can be fully determined if only the EO is specified It is chosen as an additional control parameter to figure out unique joints.
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