Unified Parameterization and Calibration of Serial, Parallel, and Hybrid Manipulators

In this work, we present methods allowing parallel, hybrid, and serial manipulators to be analyzed, calibrated, and controlled with the same analytical tools. We introduce a general approach to describe any robotic manipulator using established serial-link representations. We use this framework to generate analytical kinematic and calibration Jacobians for general manipulator constructions using null space constraints and extend the methods to hybrid manipulator types with complex geometry. We leverage the analytical Jacobians to develop detailed expressions for post-calibration pose uncertainties that are applied to describe the relationship between data set size and post-calibration uncertainty. We demonstrate the calibration of a hybrid manipulator assembled from high precision calibrated industrial components resulting in 91.1 μm RMS position error and 71.2 μrad RMS rotation error, representing a 46.7% reduction compared to the baseline calibration of assembly offsets.

Structural design for a hybrid stone carving manipulator

With people’s higher and higher requirements for environmental art, a large number of stone carving products are needed in the current urban construction. However, the traditional carving technology and equipment can not meet this demand. The development of robots to complete the processing of stone products, especially for the processing of special-shaped stones with complex shapes such as three-dimensional, multi-faceted and curved surfaces, has great social and economic benefits. In this paper, a stone carving manipulator is designed. In the processing of special-shaped curved stone, the structure of 3-TPS/TP hybrid manipulator is adopted, and its kinematic model and Jacobian matrix are established to realize the efficient automatic processing of special-shaped stone.

Singularity analysis of a 7-DOF spatial hybrid manipulator for medical surgery

This paper presents the singularity analysis of a 7-degrees of freedom (DOF) hybrid manipulator consisting of a closed-loop within it. From the past studies, it is well-known that the kinematic singularities play a significant role in the design and control of robotic manipulators. Kinematic singularities pose two-fold effects – first, they can induce the loss of one or more DOF of the manipulator and cause infinite joint rates at that particular joint, and second, they help to determine the trajectory or zone with high mechanical advantage. In current work, a 7-DOF hybrid manipulator is considered which is being developed at Council Of Scientific And Industrial Research–Central Scientific Instruments Organisation (CSIR–CSIO) Chandigarh to assist a surgeon during a medical-surgical task. To emulate the natural motion of a surgeon, the challenging configuration with redundant DOF is utilized. Jacobian has been computed analytically and analyzed at each instantaneous configuration with the evaluation of manipulability. Effect of a closed loop in the hybrid configurations is focused at, and utilizing the contour plots, good and worst working zones are identified in the workspace of the manipulator. The verification and validation of best and worst manipulability points (singularities) are done with the help of genetic algorithms, to determine locally and globally optimal configurations. Finally, on the basis of the singularity analysis, the present work concludes with few guidelines to the surgeon about the best and worst working zones for surgical tasks.

Development of a novel 6-DOF hybrid serial-parallel mechanism for pose adjustment of large-volume components

In this paper, a novel 6-degrees-of-freedom (DOF) hybrid mechanism is proposed to realize position and posture adjusting for large-volume equipment. The designed hybrid manipulator is composed of the lower and upper modules, namely, a 3-DOF redundant spatial parallel mechanism (SPM) and a 3-DOF planar parallel mechanism (PPM), which has three rotational and three translational DOFs. According to the step-by-step pose adjusting strategy, the kinematics analyses of the lower and upper modules have been carried out systematically. For the whole hybrid mechanism, a complete kinematic model has been established; and visualized workspace of the kinematic model with regular shape and large volume demonstrates profound application prospects in engineering. In order to evaluate the performance of the proposed mechanism, experimental tests have been conducted in an automated docking system for pose adjustment of large and heavy components. The analysis results demonstrate the effectiveness and practicability of the new mechanism.

Kinematic, Workspace and Force Analysis of a five-DOF Hybrid Manipulator R(2RPR)R/SP+RR

In the present study, the over-constrained hybrid manipulator R(2RPR)R/SP + RR is considered as the research objective. In this paper, kinematics of the hybrid manipulator, including the forward and inverse position, are analyzed. Then, the workspace is checked based on the inverse position solution to evaluate whether the workspace of the hybrid manipulator meets the requirements, and the actual workspace of the hybrid robot is analyzed. After that, the force analysis of the over-constrained parallel mechanism is carried out, and an ADAMS-ANSYS rigid-flexible hybrid body model is established to verify the simulation. Based on the obtained results from the force analysis, the manipulator structure is design. Then, the structure optimization is carried out to improve the robot stiffness. Finally, calibration and workspace verification experiments are performed on the prototype, cutting experiment of an S-shaped aluminum alloy workpiece is completed, and the experiment verifies the processing ability of the prototype and proves that the prototype has good application prospects.

A Novel Modular Approach for Kinematic Modelling and Analysis of Planar Hybrid Manipulators

For customized design of a hybrid-manipulator for a specific application, selection of an appropriate configuration is always a challenge. To assist in this foremost decision in data-driven synthesis, a novel approach is proposed for modular formation of quick configurations and developing respective kinematic model and differential relations for their performance analyses. This unified modular approach utilizes modular primitives to define a planar hybrid configuration. Three types of primitives are introduced as modular component, and pattern study is detailed. Modelling results from the proposed approach are compared to that with normally used partial differentiation with respect to the computational efforts, streamlined modular implementation and applicability in optimal design approaches. The strategy will help a designer as a tool for analysing several configurations. Two realistic case studies are demonstrated in the paper for application of the methodology in medical robotics field.