# Knowledge-Based Automated Mechanical Design of a Robot Manipulator
## 3 Results  
The functionality of our methos from previous chapter was tested on a case study. The chosen task is a manipulation between two industrial machines. The models of this workspace are shown in Figure 8. The manipulated object is a cylindrical steel object weighting 2.15 kg. The workspace environment was bounded by the industrial machines, which acted as obstacles. The task trajectory was defined by four target points, two on each machine, which define the position and orientation of the manipulated object in space. The drive unit database consists of compact drive units from HarmonicDrive CanisDrive series and Spinea DS series.  
This workspace has been modeled in MATLAB as an environment for the evaluation in the genetic optimization algorithm described in Section 2.1. The output of the genetic algorithm is a 5 DOF manipulator shown in Figure 9. For clarity, let us call this kinematic structure \"A\". The output also includes joint angle values throughout the movement. These values were then used for motion analyses in CAD software.  
As stated in previous chapters, the kinematic structure was used to build a 3D model of the manipulator with the use of the smallest drive units available in the element database. This model was then used for motion analysis to measure the forces and torques acting on  
Figure 8: Task workspace; (**a**) CAD model, (**b**) model in MATLAB.  
Figure 9: Optimized kinematic structure A; (**a**) schematic, (**b**) view in MATLAB.  
drive units and mechanical elements in the manipulator. Then the iterative process from Section 2.2.1 was run to check and optimize the design. The preliminary design is shown in Figure 10.  
The design process of the CAD model for the kinematic structure A failed in the design iteration of the third link due to system collisions (Figure 11). When designing the drive unit of the third joint, a larger drive unit was chosen, for which the third arm member with the required length of 107 mm could not be realized, and therefore the kinematic structure A was eliminated by the algorithm and the design returns to the design of a new kinematic structure. The options for the optimization algorithm to generate a new kinematic structure were changed to reflect this collision. The minimum length for a manipulator link was extended to 200 mm.  
After changing the optimization options, a new kinematic structure B was generated (Figure 12). Again, it is a 5 DOF manipulator. The difference between Structures A and B is not only in link lengths, but also in the rotation of individual joints.  
Figure 11: A drive unit change during design iterations; (**a**) preliminary, (**b**) after change, with the resulting collision (red ellipse).  
Figure 10: Initial 3D model for kinematic structure A.  
Table 2 shows the basic parameters of the designed robotic arm; these are the selected end-effector and drive units, the designed cross sections of individual links, and the total weight of the manipulator.  
The sizes of the structural flange elements are determined by the sizes of the drive unit flange. These elements can be, however, optimized by changing the material thickness without changing the overall dimensions. These changes will only affect the total weight and are therefore not included in the resulting table.