The development of a reliable pick-and-place system for industrial robotics is facing an urgent demand because many manual-labor works, such as piece-picking in warehouses and fulfillment centers tend toward automation. This paper presents an integrated gripper that combines a linkage-driven underactuated gripper with a suction gripping system for picking up a variety of objects in different working environments. The underactuated gripper consists of two fingers, and each finger has three degrees of freedom that are obtained by stacking one five-bar mechanism over one double parallelogram. Furthermore, each finger is actuated by two motors, both of which can be installed at the base owing to the special architecture of the proposed robotic finger. A suction cup is used to grasp objects in narrow spaces and cluttered environments. The combination of the suction and traditional linkage-driven grippers allows stable and reliable grasping under different working environments. Finally, practical experiments using a wide range of objects and under different grasping scenarios are performed to demonstrate the grasping capability of the integrated gripper.

Underactuated robotic grippers have the advantage of lower cost, simpler control, and higher safety over the fully actuated grippers. In this study, an underactuated robotic finger is presented. The design issues that should be considered for stable grasping are discussed in detail. This robotic finger is applied to design a two-fingered underactuated gripper. Firstly, a new three-DOF linkage-driven robotic finger that combines a five-bar mechanism and a double parallelogram is presented. This special architecture allows us to put all of the required actuators into the palm. By adding a torsion spring and a mechanical stopper at a passive joint, this underactuated finger mechanism can be used to perform parallel grasping, shape-adaptive grasping, and environmental contact-based grasp. Secondly, the dynamic model of this robotic finger is developed to investigate how to select an appropriate torsion spring. The dynamic simulation is performed with a multi-body dynamic simulator to verify our proposed approach. Moreover, static grasp models of both two-point and three-point contact grasps are investigated. Finally, different types of grasping modes are verified experimentally with a two-fingered underactuated robotic gripper.

Light machining tasks by robots are becoming an important issue to replace shortages of human resources. To improve the quality, safety and overall performance of manufacturing process, the modeling for estimation of forces and torques during the machining operations is on demand. In parallel, the digital model has also been developed which allow to detect the foul conditions, save energy & time and optimization of the real manufacturing process. Digital twins are one of them which use the offline and online data to simulate the physical manufacturing process. However, the empowerment of digital twins can be improved further by developing more accurate mathematical model which allow to simulate the physical machining process in real time. Accordingly, this paper presents a formulation for the mechanics of robotic light machining tasks to empower the digital twin. In this paper, a generalized impulse model is employed to analyze a light machining task that combines the linear and angular motions. For the implementation of an impulse model-based approach, the concept of both effective mass and effective inertia is newly introduced to reflect the dynamics of the environment, which depends on the hardness of the material and process parameters (feed rate and speed (rpm) etc.) of the machining task. Furthermore, optimal feed rates are calculated with consideration of effective mass/effective inertia and minimum task completion time. Moreover, simulations are carried out to choose the feasible direction of linear and angular velocities and optimal non-singular workspace for light machining tasks. Finally, the proposed methodology is validated through a quantitative comparison of simulation and experimental results by performing the drilling and milling tasks. A 6-DOF Universal robot (UR 5e) is used for simulations and experiments to corroborate the effectiveness of the proposed algorithms for light machining tasks. The developed methodology will certainly empower the digital twin for their physical analog during light machining operations.

This paper proposes a hybrid singulation approach combining dynamic scattering and pushing techniques. Using the impulse-based dynamic model, a guideline is provided to decide whether scattering or pushing is conducted for object singulation. The Soma cube consisting of seven blocks is used as the test example. The target is to singulate all the blocks. The dynamic scattering technique was initially applied to separate blocks in the formation. However, scattering alone does not provide target singulation in all the cases. So we combine the quasi-static pushing technique to complete the singulation of all the blocks. In pushing, image segmentation based on principal component analysis (PCA) algorithm was employed to singulate multiple blocks in clutter and prehensile manipulation was used to remove isolated blocks. Several 2-D formations of the Soma cube are used as the test cases. To validate the effectiveness of our approach, we have conducted comparative analysis which clearly shows that the hybrid singulation achieves singulation in much less time as compared to the pure pushing approach.

This research proposes an innovative dental robot with a 7-DOFs parallel-serial hybrid structure to precisely and efficiently execute dental caries removal surgery. The versatile system is distinguished by its unique 7 DOFs, comprising three rotational and three translational movements, with an additional degree for resin injection. This novel hybrid design combines the advantages of serial and parallel mechanical structures enabling highly flexible operations and large rotational capacity within a compact size. According to its multifunctional integrated design, this dental robot can efficiently perform a series of complex surgical tasks, including caries removal, resin injection and light curing. This robot’s two critical design metrics: the local kinematic isotropic index and the local transmission index are determined. In its application to caries removal, the system augmented with commercial haptic feedback devices for leader-follower control, demonstrates its potential in enhancing surgical efficiency and reducing cross-infection risks through its noncontact treatment method. In the experiment, the outcomes of the overall workload are assessed via the NASA task load index (NASA-TLX) and the evaluation of usability is also conducted using system usability scale (SUS). Finally, the robot’s precision is tested to determine its reliability in executing tasks.

Unlike general scissors, many commercial hairdressing scissors reflect ergonomic design with handles that provide users with comfort, minimizing fatigue and the risk of injury. However, there has not been a lot of prior research on quantitatively evaluating the merits of ergonomic design. This paper proposes a quantitative criterion to evaluate the performance of commercial hairdressing scissors. An experiment was conducted using several hairdressing scissors to establish the quantitative evaluation criterion. It was discovered that more fingers were involved than required to create a scissoring, and these fingers exerted antagonistic forces during the scissoring. Incorporating this property, a dynamic model of scissor mechanics was developed to analyze the characteristics of redundant finger forces, and a corresponding load distribution algorithm was derived. Three different types of scissor designs were compared through simulation. It was observed that the more ergonomic design was applied to the scissor, the less rotational kinetic energy was consumed. As a result, we propose rotational kinetic energy consumption as the quantitative evaluation criterion. The results of this research will be useful in designing specific scissor designs.