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The subject of the paper is the mechatronic design of a novel robotic hand, cassino-underactuated-multifinger-hand (Ca.U.M.Ha.), along with its prototype and the experimental analysis of its grasping of soft and rigid objects with different shapes, sizes and materials. The paper aims to discuss these issues.

Ca.U.M.Ha. is designed with four identical underactuated fingers and an opposing thumb, all joined to a rigid palm and actuated by means of double-acting pneumatic cylinders. In particular, each underactuated finger with three phalanxes and one actuator is able to grasp cylindrical objects with different shapes and sizes, while the common electropneumatic operation of the four underactuated fingers gives an additional auto-adaptability to grasp objects with irregular shapes. Moreover, the actuating force control is allowed by a closed-loop pressure control within the pushing chambers of the pneumatic cylinders of the four underactuated fingers, because of a pair of two-way/two-position pulse-width-modulation (PWM) modulated pneumatic digital valves, which can also be operated under ON/OFF modes.

The grasping of soft and rigid objects with different shapes, sizes and materials is a very difficult task that requires a complex mechatronic design, as proposed and developed worldwide, while Ca.U.M.Ha. offers these performances through only a single ON/OFF or analogue signal.

Ca.U.M.Ha. could find several practical applications in industrial environments since it is characterized by a robust and low-cost mechatronic design, flexibility and easy control, which are based on the use of easy-running components.

Ca.U.M.Ha. shows a novel mechatronic design that is based on a robust mechanical design and an easy operation and control with high dexterity and reliability to perform a safe grasp of objects with different shapes, sizes and materials.

A mathematical model to predict the layered process error and an optimization algorithm to define the fabricating orientation based on the minimum process error for layered manufacturing fabrication has been developed. Case studies to determine the preferred orientation candidates for fabricating spherical objects, cube objects and objects with irregular geometrical shapes have been conducted and the results were used to validate the sensitivity, accuracy, and capability of the developed model and optimization algorithm. Different orientation candidates determined by minimum processing error and by minimum processing time were also compared. The developed model and the optimization algorithm can be used, in conjunction with other processing parameters such as processing time and support structure, to define an optimal processing planning for layered manufacturing fabrication.

Soft grippers have safer and more adaptable human–machine and environment–machine interactions than rigid grippers. However, most soft grippers with single gripping postures have a limited gripping range. Therefore, this paper aims to design a soft gripper with variable gripping posture to enhance the gripping adaptability.

This paper proposes a novel soft gripper consisting of a conversion mechanism and four spring-reinforced soft pneumatic actuators (SSPAs) as soft fingers. By adjusting the conversion mechanism, four gripping postures can be achieved to grip objects of different shapes, sizes and weights. Furthermore, a quasi-static model is established to predict the bending deformation of the finger. Finally, the bending angle of the finger is measured to validate the accuracy of the quasi-static model. The gripping force and gripping adaptability are tested to explore the gripping performance of the gripper.

Through experiments, the results have shown that the quasi-static model can accurately predict the deformation of the finger; the gripper has the most significant gripping force under the parallel posture, and the gripping adaptability of the gripper is highly enhanced by converting the four gripping postures.

By increasing the gripping posture, a novel soft gripper with enhanced gripping adaptability is proposed to enlarge the gripping range of the soft gripper with a single posture. Furthermore, a quasi-static model is established to analyze the deformation of SSPA.

In advanced robotics applications in unstructured environments (e.g. those foreseen in space) some degree of dexterity and autonomy is necessary in order to safely and successfully execute the required tasks. With this respect, besides the kinematic configuration, important aspects to be considered in the design of robotic end‐effectors are the sensorial equipment and proper control strategies. In this paper, an activity for designing and experimenting a gripper for this operation in unstructured environments is reported, and laboratory results are presented and discussed.

This study aims to introduce a multi-configuration, three-finger dexterous hand with integrated high-dimensional sensors and provides an analysis of its design, modeling and kinematics.

A mechanical design scheme of the three-finger dexterous hand with a reconfigurable palm is proposed based on the existing research on dexterous hands. The reconfigurable palm design enables the dexterous hand to achieve four grasping modes to adapt to multiple grasping tasks. To further enhance perception, two six-axis force and torque sensors are integrated into each finger. The forward and inverse kinematics equations of the dexterous hand are derived using the D-H method for kinematics modeling, thus providing a theoretical model for index analysis. The performance is evaluated using three widely applied indicators: workspace, interactivity of fingers and manipulability.

The results of kinematics analysis show that the proposed hand has excellent dexterity. Additionally, three different experiments are conducted based on the proposed hand. The performance of the dexterous hand is also verified by fingertip force, motion accuracy test, grasping and in-hand manipulation experiments based on Feix taxonomy. The results show that the dexterous hand has good grasping ability, reproducing 82% of the natural movement of the human hand in daily grasping activities and achieving in-hand manipulations such as translation and rotation.

A novel three-finger dexterous hand with multi-configuration and integrated high-dimensional sensors is proposed. It performs better than the previously designed dexterous hand in actual experiments and kinematic performance analysis.

In order to fully understand the properties of porous asphalt, investigation should be conducted from different point of views. This is from the fact that porous asphalt mixture designed with the same aggregate gradation and air void content can give different infiltration rate due to the different formation of the internal structure. Therefore, the purpose of this paper is to investigate the micro-structural properties and functional performance of porous asphalt simultaneously.

The aim is to develop imaging techniques to process and analyze the internal structure of porous asphalt mixture. A few parameters were established to analyze the air void properties and aggregate interlock within the gyratory compacted samples captured using a non-destructive scanning technique of X-ray computed tomography (CT) throughout the samples. The results were then compared with the functional performance in terms of permeability. Four aggregate gradations used in different countries, i.e. Malaysia, Australia, the USA and Singapore. The samples were tested for resilient modulus and permeability. Quantitative analysis of the microstructure was used to establish the relationships between the air void properties and aggregate interlock and the resilient modulus and permeability.

Based on the results, it was found that the micro-structural properties investigated have successfully described the internal structure formation and they reflect the results of resilient modulus and permeability. In addition, the imaging technique which includes the image processing and image analysis for internal structure quantification seems to be very useful and perform well with the X-ray CT images based on the reliable results obtained from the analysis.

In this study, attention was limited to the study of internal structure of porous asphalt samples prepared in the laboratory using X-ray CT but can also be used to assess the quality of finished asphalt pavements by taking core samples for quantitative and qualitative analysis. The use of CT for material characterization presents a lot of possibilities in the future of asphalt concrete mix design.

Based on the validation process which includes comparisons between the values obtained from the image analysis and those from the performance test and it was found that the developed procedure satisfactorily assesses the air voids distribution and the aggregate interlock for this reason, it can be used.

Virtual maintenance simulation is of great importance to help designers find and avoid design problems. During its simulation phase, besides the high precision requirement, collision detection must be suitable for all irregular objects in a virtual maintenance environment. Therefore, in this paper, a collision detection approach is proposed based on encapsulation for irregular objects in the virtual maintenance environment.

First, virtual maintenance simulation characteristics and several commonly used bounding boxes methods are analyzed, which motivates the application of encapsulation theory. Based on these, three different encapsulation methods are oriented to the needs of simulation, including encapsulation of rigid maintenance objects, flexible maintenance objects and maintenance personnel. In addition, to detecting collisions accurately, this paper divides the detection process into two stages. That is, in the first stage, a rough detection is carried out and then a tiny slice space is constructed to generate corresponding capsule groups, which will be redetected in the secondary stage. At last, several case studies are applied to illustrate the performance of the methodology.

The automatic construction algorithm for bounding boxes can be adapted to all forms of objects. The number of detection primitives are greatly reduced. It introduces the reachable space of the human body in maintainability as the collision search area.

The advantages of virtual maintenance simulation could also be advantageous in the industry with further studies. The paper believes this study is of particular interest to the readers of your journal.

Varied shapes and sizes of different products with irregular rough surface and fragile properties give a challenge to traditional contact gripping. Single Bernoulli grippers are not suited to handle fragile objects as the impact of center negative pressure force could result in large deformation and stress which damage the materials, and they are also have some limitations for gripping objects with different large and small shapes. Thus, this paper aims to design a non-contact gripper for soft, rough-surfaced and fragile objects gripping with multi Bernoulli heads, which have optimal structures and parameters.

The compressed air is ejected into four Bernoulli heads through radial and long flow channels, then passes through four strip-shaped narrow gaps after fully developing in the annular cavity to provide negative pressure. Based on the mathematic model and the computational model, the key structural parameters affecting the gripping performance are selected, and parameters optimization of the gripper is performed by computational fluid dynamics simulation analysis and performance evaluation. The orthogonal method is used and L16 orthogonal array is selected for experimental design and optimization. The characteristics of the designed gripper are tested from the aspects of pressure distribution and lifting force.

From the applications in gripping different objects, the designed non-contact gripper can grip varied shapes and sizes of soft, rough-surfaced, fragile and sliced objects with little effect of torque.

In this paper, a non-contact gripper is designed for handling soft, rough-surfaced and fragile objects based on the Bernoulli principle. A systematic approach, which consists of modeling, simulation, optimization and measurement is provided for the non-contact gripper design and tests.

This paper aims to study six degrees-of-freedom (6DOF) pose measurement of reflective metal casts by machine vision, analyze the problems existing in the positioning of metal casts by stereo vision sensor in unstructured environment and put forward the visual positioning and grasping strategy that can be used in industrial robot cell.

A multikeypoints detection network Binocular Attention Hourglass Net is constructed, which can complete the two-dimensional positioning of the left and right cameras of the stereo vision system at the same time and provide reconstruction information for three-dimensional pose measurement. Generate adversarial networks is introduced to enhance the image of local feature area of object surface, and the three-dimensional pose measurement of object is completed by combining RANSAC ellipse fitting algorithm and triangulation method.

The proposed method realizes the high-precision 6DOF positioning and grasping of reflective metal casts by industrial robots; it has been applied in many fields and solves the problem of difficult visual measurement of reflective casts. The experimental results show that the system exhibits superior recognition performance, which meets the requirements of the grasping task.

Because of the chosen research approach, the research results may lack generalizability. The proposed method is more suitable for objects with plane positioning features.

This paper realizes the 6DOF pose measurement of reflective casts by vision system, and solves the problem of positioning and grasping such objects by industrial robot.

Passively compliant underactuated mechanisms are one way to obtain the gripper which could accommodate to any irregular and sensitive grasping object. The purpose of the underactuation is to use less active inputs than the number of degrees of freedom of the gripper mechanism to drive the open and close motion of the gripper. Another purpose of underaction is to reduce the number of control variables.

The underactuation can morph shapes of the gripper to accommodate different objects. As a result, the underactuated grippers require less complex control algorithms. The fully compliant mechanism has multiple degrees of freedom and can be considered as an underactuated mechanism.

This paper presents a new design of the adaptive underactuated compliant gripper with distributed compliance. The optimal topology of the gripper structure was obtained by optimality criteria method using mathematical programming technique. Afterwards, the obtained model was improved by iterative finite element optimization procedure. The gripper was constructed entirely of silicon rubber.

The main points of this paper are the explanation of the development and production of the new compliant gripper structure.