Additive manufacturing (AM) brings out a revolution of how the products are designed and manufactured. To obtain desired components, advanced design for additive manufacturing (ADfAM) is widely emphasized in geometry, material, and function design. 3D slicing and path planning, which are the critical steps of ADfAM, directly determine manufacturing process variables, shape, and performance of printed parts. For widely used planar slicing, the contradiction between accuracy and build time has attracted considerable attention and efforts, leading to various novel and optimization methods. Nevertheless, curved surfaces and slopes along the build direction constrain the surfaces to be smooth due to the inherent staircase effect of AM. Meanwhile, there is significant anisotropy of the printed piece making it sensitive to any shear (or bending) stress. Moreover, support structures for the overhang part are necessary when building along one direction, resulting in time-consuming and cost-expensive process. Due to the rapid development of 3D slicing and path planning, and various newly proposed methods, there is a lack of comprehensive knowledge. Notwithstanding, there are fewer literature reviews concerning planar slicing and filling strategy. Less attention has been paid to non-planar slicing, path planning on curved surfaces, and multi-degree of freedom (DOF) AM equipment, as well as printing under pressure. Hence, it is significant to get a comprehensive understanding of current status and challenges. Then, with suitable technologies, the printed parts with improved surface quality, minimum support structures, and better isotropy could be acquired. Finally, the recommendation for the future development of slicing and path planning is also provided.

Parallel mechanisms is used in the large capacity servo press to avoid the over-constraint of the traditional redundant actuation. Currently, the researches mainly focus on the performance analysis for some specific parallel press mechanisms. However, the type synthesis and evaluation of parallel press mechanisms is seldom studied, especially for the four degrees of freedom(DOF) press mechanisms. The type synthesis of 4-DOF parallel press mechanisms is carried out based on the generalized function(G_F) set theory. Five design criteria of 4-DOF parallel press mechanisms are firstly proposed. The general procedure of type synthesis of parallel press mechanisms is obtained, which includes number synthesis, symmetrical synthesis of constraint G_F sets, decomposition of motion G_F sets and design of limbs. Nine combinations of constraint G_F sets of 4-DOF parallel press mechanisms, ten combinations of G_F sets of active limbs, and eleven combinations of G_F sets of passive limbs are synthesized. Thirty-eight kinds of press mechanisms are presented and then different structures of kinematic limbs are designed. Finally, the geometrical constraint complexity(GCC), kinematic pair complexity(KPC), and type complexity(TC) are proposed to evaluate the press types and the optimal press type is achieved. The general methodologies of type synthesis and evaluation for parallel press mechanism are suggested.

During extraterrestrial planetary exploration programs, autonomous robots are deployed using a separate immovable lander and rover. This mode has some limitations. In this paper, a concept of a novel legged robot with decoupled functions was introduced that has inbuilt features of a lander and rover. Currently, studies have focused mainly on performance analysis of the lander without a walking function. However, a systematic type synthesis of the legged mobile lander has not been studied. In this paper, a new approach to the type synthesis used for the robot was proposed based on the Lie group theory. The overall concept and design procedure were proposed and described. The motion requirements of the robot and its legs were extracted and described intuitively. The layouts of the subgroups or submanifolds of the limbs were determined. A family of particular joints with one rotation and one translation was proposed for the first time. The structures of the limbs were synthesized. Numerous structures of the legs were produced and listed corresponding to the desired displacement manifolds. Numerous novel structures of the legs for legged mobile lander were evaluated and listed. Then, four qualitative criteria were introduced. Based on the proposed criteria, a particular case of legs' configuration with a rhombus joint was selected as the best one among them. A typical structure of the legged mobile lander was obtained by assembling the structures of the proposed legs with a rhombus joint. Finally, the typical robot was used as an example to verify the capabilities of the novel robot using a software simulation (adams).

The wheel-legged hybrid structure has been utilized by ground mobile platforms in recent years to achieve good mobility on both flat surfaces and rough terrain. However, most of the wheel-legged robots only have one-directional obstacle-crossing ability. During the motion, most of the wheel-legged robots’ centroid fluctuates violently, which damages the stability of the load. What’s more, many designs of the obstacle-crossing part and transformation-driving part of this structure are highly coupled, which limits its optimal performance in both aspects. This paper presents a novel wheel-legged robot with a rim-shaped changeable wheel, which has a bi-directional and smooth obstacle-crossing ability. Based on the kinematic model, the geometric parameters of the wheel structure and the design variables of the driving four-bar mechanism are optimized separately. The kinetostatics model of the mobile platform when climbing stairs is established to determine the body length and angular velocity of the driving wheels. A prototype is made according to the optimal parameters. Experiments show that the prototype installed with the novel transformable wheels can overcome steps with a height of 1.52 times of its wheel radius with less fluctuation of its centroid and performs good locomotion capabilities in different environments.