3D Printing of Objects with Continuous Spatial Paths by A Multi-Axis Robotic FFF Platform

Conventional Fused Filament Fabrication (FFF) equipment can only deposit materials in a single direction, limiting the strength of printed products. Robotic 3D printing provides more degrees of freedom (DOF) to control the material deposition and has become a trend in additive manufacturing. However, there is little discussion on the strength effect of multi-DOF printing. This paper presents an efficient process framework for multi-axis 3D printing based on the robot to improve the strength. A multi-DOF continuous toolpath planning method is designed to promote the printed part’s strength and surface quality. We generate curve layers along the model surfaces and fill Fermat spiral in the layers. The method makes it possible to take full advantage of the multi-axis robot arm to achieve smooth printing on surfaces with high curvature and avoid the staircase effect and collision in the process. To further improve print quality, a control strategy is provided to synchronize the material extrusion and robot arm movement. Experiments show that the tensile strength increases by 22–167% compared with the conventional flat slicing method for curved-surface parts. The surface quality is improved by eliminating the staircase effect. The continuous toolpath planning also supports continuous fiber-reinforced printing without a cutting device. Finally, we compared with other multi-DOF printing, the application scenarios, and limitations are given.

Estimation of Runoff Potential by the Application of Curve Number Method in GIS Platform

Estimation of direct runoff is essential for planning and development of watershed. In this study estimation of the same is carried out by applying Soil Conservation Service-Curve Number (SCS-CN) model technique with Geographic Information System (GIS) approach. The SCS-Curve Number model is a hydrological model which is widely used for estimation of runoff volume generated from the rainfall event. The said model mathematically describe the rainfall – runoff relationship and uses rainfall data and Curve Number (CN) as the inputs. The Curve Number is an empirical index depends on the soil complex, land use and hydrological condition of the area. The SCS-CN method with GIS approach has been adopted for predicting the runoff volume in the catchment of upper Mahanadi, which is upstream of the confluence of Mahanadi and Pairi River. The catchment area under consideration is 8086 sq.km. The study area climate condition is tropical monsoon type which receives the normal annual rainfall of 1360 mm. The maximum precipitation about 86% of the total precipitation, observed in the monsoon period from July to Mid of September. Survey of India (SOI) topographic sheets and Indian Remote Sensing satellite image LISS-III were used to prepare thematic maps of the study area. Thematic maps and hydrological data were used to generate Curve Number map and Hydrological Soil Group map. The SCS-CN method is very useful to compute runoff volume from the land, which quatify the direct drain to the river or streams. The outcome of this study is useful for watershed planning and development effectively for the study area.

Computer Aid of Mechanism Behaviour

It is often needed to define the velocity and acceleration of the body or some point of mechanism, if the input parameters of driver are known. As one of the most commonly used mechanisms in manufacturing or real practice can be considered the slotted-link mechanism. This mechanism is the part of the various machines and it has some special configurations created by making link infinite in length. It is often used to transform rotary motion into linear motion. The article deals with the computer aid of mechanism behaviour, specifically there are compared two approaches to the kinematic analysis of mechanism, the possibility to generate curve trajectory of selected point of mechanism or to make its motion envelope. The solution is presented on the mechanism usually used for the sliding feed of the packages in real practice.

A neuromechanical model for the neuronal basis of curve walking in the stick insect

The coordination of the movement of single and multiple limbs is essential for the generation of locomotion. Movement about single joints and the resulting stepping patterns are usually generated by the activity of antagonistic muscle pairs. In the stick insect, the three major muscle pairs of a leg are the protractor and retractor coxae, the levator and depressor trochanteris, and the flexor and extensor tibiae. The protractor and retractor move the coxa, and thereby the leg, forward and backward. The levator and depressor move the femur up and down. The flexor flexes, and the extensor extends the tibia about the femur-tibia joint. The underlying neuronal mechanisms for a forward stepping middle leg have been thoroughly investigated in experimental and theoretical studies. However, the details of the neuronal and mechanical mechanisms driving a stepping single leg in situations other than forward walking remain largely unknown. Here, we present a neuromechanical model of the coupled three joint control system of the stick insect's middle leg. The model can generate forward, backward, or sideward stepping. Switching between them is achieved by changing only a few central signals controlling the neuromechanical model. In kinematic simulations, we are able to generate curve walking with two different mechanisms. In the first, the inner middle leg is switched from forward to sideward and in the second to backward stepping. Both are observed in the behaving animal, and in the model and animal alike, backward stepping of the inner middle leg produces tighter turns than sideward stepping.

An Improved Moving Least Squares Method for Curve and Surface Fitting

The moving least squares (MLS) method has been developed for the fitting of measured data contaminated with random error. The local approximants of MLS method only take the error of dependent variable into account, whereas the independent variable of measured data always contains random error. Considering the errors of all variables, this paper presents an improved moving least squares (IMLS) method to generate curve and surface for the measured data. In IMLS method, total least squares (TLS) with a parameterλbased on singular value decomposition is introduced to the local approximants. A procedure is developed to determine the parameterλ. Numerical examples for curve and surface fitting are given to prove the performance of IMLS method.

Arc Envelope Grinding of Non-Axisymmetric Aspheric Surface Using Equal-Envelope Height

An arc envelope grinding method for non-axisymmetric aspheric surface was proposed in order to achieve the mould core used for the precision injection molding of optic reflector. In grinding, the arc-shaped diamond grinding wheel trued on CNC grinder was used to envelope workpiece and generate curve surface, and the spacing distance between tool paths is controlled by the equal-envelope height between wheel and workpiece. In this paper, arc envelope grinding principle was investigated in connection with wheel coordinate calculation and tool path number. The theoretical analysis and grinding experiment showed that arc envelope grinding may improve form grinding efficiency especially for large curvature and smoothness of ground surface and a smooth curve surface can be produced when the equal-envelope height is less than a certain value.