This paper is seeking to add a CNC G-code to hexapod CNC system. The mentioned G-code is five axis tool radius compensation. Once the tool radius is changed, especially in the case of tool size changing with tool wear in machining, a new NC program has to be recreated. Five axis tool radius compensation corrects cutter path automatically. This G-code contains all the main parts of a standard code such as: interpreter, interpolator and inverse kinematics unit. The interpreter unit extracts the position and orientation from the received code and sends it to the interpolation and kinematics units to correct the errors and achieve the desired six pods lengths. In the tool radius compensation algorithm, the unique vector of the movement direction of the tool tip and the normal vector of the machining surface have been used to calculate the direction of the tool radius compensation. The offset path is calculated by offsetting the tool path along the direction of the offset vector. Accuracy of the proposed method is tested with a number of experiments. The experimental results confirmed the accuracy of the proposed methods.

Background: tibia is the most common bone to result in non-union after a fracture. Among the various approaches to non-union treatment, Ilizarov technique offers the advantage of simultaneous management of non-union, deformity bone defect and infection. We are reporting our results with such treatment in tibial non-union.Methods: 26 cases of tibial non-union that were treated with Ilizarov technique were evaluated clinically and radiographically in a retrospective manner, with and average follow-up of one year (7-21) months 12 cases were infected, 14 non-infected non-unions.Results: union was achieved in all the cases with a mean duration of 4 months (3-10 months). Pintract infection was observed in 6 cases. 2 required change of pintract, and one case of severe cellulites needed earlier discontinuation of Ilizarov fixation and use of cast brace which resulted in union. One case of knee and one ankle stiffness were observed.Conclusions: Ilizarov technique is a reliable method for treatment of tibial non-union, and is specifically useful for complicated cases.

A hexapod machine tool with a parallel structure has six degrees of freedom. This machine has a highdexterity unlike traditional machine tools. The hexapod can be used in machining free form surfaces.Free form surfaces are widely used in today’s industries. These surfaces are much encountered in auto, aerospace and mold design industries. Consequently, machining of these surfaces has attracted theattention of researchers. In this field much research has been done on five axis machine tools. In thispaper machining free form surfaces with hexapod machine tool has been investigated. The main topic ofthis paper is the feasibility of using hexapod as a machine tool table and machining with it. First, theinterpolation of free form surfaces for parallel structure machines is explained. Then NURBS curvesand surfaces are described and its formulation in matrix form is explained. After that, extractinginformation of free form surfaces with NURBS formulation is explained. Subsequently, someexplanations about preparation of machining are given. Finally, two free form surfaces designed inCatia have been machined with the developed hexapod machine tool.

In this paper, an analytical study of the forced vibrations of hexapod table is studied. Considering external force as a time sinusoid force, forced vibrations of the platform are investigated. Resonance frequencies and vibrations of the moving platform are also calculated in different directions. The results of the analytical approach are verified using FEM simulation. Modelling the harmonic milling forces, a careful examination of the forced vibration are carried out in different cutting conditions and different configurations. Resonance frequencies and the range of vibrations are then calculated. Finally, knowing the resonance frequencies and the vibrations of hexapod table, different configurations of the table, which results in dynamic instability, are investigated.

Background: Fractures of distal radius are common injuries. Unstable distal radius fractures present a challenge to the treating orthopaedic surgeon. One of the therapeutic methods is Ilizarov hybrid external fixator. In this study short-term result of this method in a small group is reported.Methods: 18 consecutive patients with unstable fracture of distal radius were treated with non-bridging hybrid Ilizarov external fixator for 7 weeks. Clinical and radiological evaluation was performed at one and 7 days, and at 6 weeks and 6 months after surgery.Results: All fractures united but anatomic reduction was achieved in only 16 cases (90%). The achieved range of motion was: 80% flexion, 85% extension and 90% supination and pronation. Compared to the normal side, no extensor tendon injury and tendonitis of pin loosening occurred. Only 5 mild pin track infection was observed that resolved by findings of oral antibiotic therapy.Conclusion: The technique of hybrid non bridging external fixator is safe and reliable option method for unstable intra and extra-articular distal radius fractures. It permits free wrist motion during treatment preventing joint stiffness.

Hexapod walking robots can be employed for both walking and manipulation purposes. When manipulating, they have 6 degrees of freedom for top platform, high rigidity, high load capacity, high speed, and accuracy. On the other hand, it is well known that they have limited workspace when they are fixed in place for manipulation. Designing a hexapod robot resulting in a maximized workspace can greatly affect the efficiency of the robot when manipulating. Since radially symmetric hexapod walking robots can be modeled as three 2-RPR planar parallel mechanisms, we have used the methods and calculations that are used in this kind of mechanism for designing a radially symmetric hexapod walking robot. In this paper, after a thorough review on existing methods for calculating and improving 2-RPR planar parallel mechanism workspace, an algorithm is presented that results in a maximized reachable workspace. The merit of the method is that there is no need to calculate the workspace volume when maximizing it. Also, following this algorithm is necessary for design of the maximized workspace robot. In other words, the output of the presented optimization algorithm is a set of robot kinematic parameters, which guarantees the maximized volume of the robot’s reachable workspace.

One of the most important issues related to arc ducts is the erosion of the river bank in the outer arc, which is largely due to the existence of secondary currents, in which the mechanism of these currents was elaborated in the previous section. Protecting and fixing the river walls generally involves both direct and indirect methods (relaxants and deviators). One of the most important diversion protection structures is river flows. In this research, hexapod materials were evaluated for scouring in permeable spills. The results obtained from the simulation show that the use of Hexapod spray with 12, 20, 27 and 35% permeability reduced scours by 17, 27. 9, 38 and 45. 3%, respectively, compared to the control without permeability. Increasing the permeability of the hexapod spoil reduces scouring around the spillway. Increasing the permeability of Hexapod spray guns from 12 to 35 percent resulted in a reduction of sputum by 34. 1 percent. This phenomenon is due to the easier flow of water through the hexapod sprayer and creates less pollen, which reduces scouring. Also, with an increase in the landing value from 0. 2 to 0. 36, the scour is 11. 8 times higher. Of course, it should be noted that increasing the landing number increases the permeability of the spillway to increase scouring. So that with the installation of permeable sprinkler 35% in the number of 0. 2 and 0. 36, respectively, we saw a decrease of 20 and 61% scouring compared to the control model, respectively.

In this research work a hexapod robot having 6DOF has been addressed while its feet are driven using four bar linkage mechanism. Although each foot has only one active DOF for its linkage, the robot overally behaves very similar to hexapod insect, called cockroach, rather than other hexapod robot with 6 DOF. This is one of the most important advantages of the proposed mechanism here using 4-bar linkage mechanism. This is the new aspect of the mechanism here comparing to some similar work on hexapod robots. In this paper at first, motion analysis of cockroach has been studied, then equivalent robotic system is identified by using 4-bar linkage mechanism for its feet motion, and its kinematics equations and numerical simulations have been addressed. Finally, robot statics stability and dynamics equations are derived and then driving power and dynamics simulations have been studied and addressed.