Stability Tests of Agricultural and Operating Machines by Means of an Installation Composed by a Rotating Platform (the “Turntable”) with Four Weighting Quadrants

The stability of agricultural machines, earth-moving machines, snow-compaction machines and, in general, of all vehicles that may operate on sloping terrains is a very important technical feature and should not be underestimated. In fact, it is correlated, above all, to the safety of the operators, but also to the preservation of the structural integrity of these vehicles, to the prosecution of the activities and to the preservation of the economic investment. Although these facts are well-known, the international legislation and technical standards do not yet have a sufficient level of detail to give an all-inclusive quantification of the stability of the vehicle under examination in all its working conditions, e.g., at different inclination angles of the support surface, at different climbing angles of the vehicle on the slope, with different tires and inflating pressures, and on different terrains. Actual standards limit the stability tests to the experimental measurement of the lateral rollover angle only. Furthermore, the realization of unconventional test equipment able to widen the usually-tested scenarios could not be simple, due to the necessary size that such equipment should have (to perform tests not in scale) and to the related difficulties of handling full-scale vehicles. This work illustrates the applications of a new rig for testing the stability of vehicles, able to address all the above-illustrated issues and of possible future adoption to certify the stability performance of machines and perform homologations. This installation, named “rotating platform” or “turntable”, has the peculiarity of being able to move the machine positioned on it according to two rotational degrees of freedom: (1) overall inclination of the support plane, (2) rotation of the support plane around an axis perpendicular to the plane. The same installation is also designed to record the weight supported by each wheel of the machine placed on it (by means of four sensorized quadrants), both when the platform is motionless and while the above-described movements of tilt and rotation are being carried out, thus locating precisely the spatial position of the vehicle center of gravity. The presented physical-mathematical models highlight the great potential of this facility, anticipate the outcomes of the recordings that the experimenters will have at disposal when the test rig will be effectively active, and help the future understanding of trends of data, thus maximizing the available information content.

Loci of Points Equally Spaced from Two Given Geometrical Figures. Part 2: Loci of Points Equally Spaced from a Point and a Conical Surface

In this paper are studied surfaces which are loci of points (LOP) equally spaced from a point and a conical surface under a variety of the point and conical surface’ mutual arrangement. Mathematical models of such surfaces are studied, and mathematical analysis of their properties is performed, as well as 3D models of considered surfaces are constructed. Possible cases of mutual arrangement for the point and the conical surface: • the point is at the conical surface’s vertex; • the point is on the conical surface; • the point is inside the conical surface: –– on the axis, –– not on the axis; • the point is outside the conical surface. The point is on the vertex of the conical surface Γ — the obtained conical surface Ω has the same vertex, whose generatrixes are perpendicular to the generatrixes of the surface Γ. The point is on the conical surface Γ — LOP equally spaced from the surface Γ and the point O separates into a straight-line l and a surface Φ of 4th order. The line l is located in the axial plane passing through the point O and is perpendicular to the generatrix of the conical surface Γ. Obtained surface Φ has a symmetry plane passing through the axis of the conical surface Γ and the point O. Many sections of the obtained surface Φ are Pascal snails. The point is inside the conical surface on the axis. Obtained surface α is a rotation surface, and the axis z is its axis of rotation. All the sections of the surface by planes perpendicular to the axis z are circles. Point is outside the conical surface. A very interesting surface Ω has been obtained, with the following properties: the surface Ω has a support plane, which is tangent to the surface Ω on a hyperbole; the surface Ω has 2 symmetry planes; there are a circle, parabola and Pascal’s snail among the surface Ω sections. In this paper have been considered analogues between surfaces of LOP equally spaced from the cylindrical surface and the point, and from the conical surface and the point.

Ground Reaction Forces for Various Standing Tasks Considering Generic Terrain

Many of the tasks presented to people in everyday life include standing on terrain that is not level or coplanar. Uneven terrain can affect the way in which people distribute their weight between their feet. This paper proposes a method for predicting human standing posture and the associated ground reaction forces (GRFs) taking into account a generic orientation of the ground support plane. Postures are predicted using multi-objective optimization (MOO) techniques and a 55 DOF digital human model. The human performance measures used in the cost function include musculoskeletal discomfort, delta potential energy, and visual displacement. The GRF are determined by a linear distribution model derived from the zero moment point (ZMP) and the Lagrangian recursive dynamic formulation. Postural stability based on the location of the ZMP will be discussed. Three postural cases are considered: standing on flat ground, standing with one foot on a stair, and standing with arbitrary support plane angles. Three different simulations are carried out for each case representing different tasks. Predicted GRFs have realistic values and follow the general trends expected for each of the postural cases.

New Support Fast Generation and Application in Stereolithgraphy Apparatus

In sterolithgraphy rapid prototyping, the support can constraint the parts deformation, and avoid a lot of problems such as collapse, shift and imbalance of the parts. It is of great importance in improving the overall efficiency of rapid prototyping technics software through enhancing the support generation efficiency. Based on this, this paper proposes a discrete-marking support algorithm for treatment of processing on manufactured part model of all Triangle-based discrete-marking on the support plane. The new mesh discrete-marking and automatic support generation algorithm has been successfully applied to the Sterolithography apparatus (SLA). Practical application indicates that the new support generation algorithm improve considerably the support technics efficiency.