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 — 4bsw [2017/08/04 18:58] (current)rebeccacao created 2017/08/04 18:58 rebeccacao created 2017/08/04 18:58 rebeccacao created Line 1: Line 1: + ===== Modeling in Solidworks ===== + Since all of the parts can be found in [[http://​www.education.rec.ri.cmu.edu/​downloads/​lego/​solidmodel/​ | NXT Parts Library]], the only knowledge of Solidworks needed is the knowledge of knowing how to assemble the parts. + \\ + The instructions can be found in [[https://​www.youtube.com/​edit?​o=U&​video_id=DkepJ3yaSwo |this]] YouTube link. + + + ==== Sec 1: Motion Analysis in Solidworks ==== + After you have successfully assembled the parts, you can start motion analysis in Solidworks, where the instructions can be found in [[https://​www.youtube.com/​edit?​o=U&​video_id=KvBB7KIOGFA|this]] Youtube link. + \\ + + ==== Sec 2: Results from Solidworks ==== + The results for the linear motion of node "​a1"​ is shown: + {{ :​xinke:​4b:​solidworks_linear_a1.png?​500 |}} + \\ + The results for the linear motion of node "​b1"​ is shown: + {{ :​xinke:​4b:​solidworks_linear_b1.png?​500 |}} + \\ + The results for the angular motion of bar "​V"​ is shown: + {{ :​xinke:​4b:​solidworks_alpha_data.png?​500 |}} + \\ + The results for the angular motion of bar "​U"​ is shown: + {{ :​xinke:​4b:​solidworks_gamma_data.png?​500 |}} + \\ + \\ + + Although the results from Solidworks and MATLAB has the same trend and the same overall shape, there is an apparent vertical shrink in the results from Solidworks. In addition, the first derivative terms are worse than the original terms, and the second derivative terms are the worst out of the three. ​ + \\ + \\ + + Since the MATLAB code is based on numerical methods, where there isn't as many decimal places saved in the file compared to Solidworks, rounding and error propagation can present itself as the MATLAB code runs on. For example, in the MATLAB code, there is a zero tolerance, meaning, the two displacement equations derived above doesn'​t have to add up to zero, but it has to be less than 4e-4. This already presents an approximation of the initial state of the 4 bar mechanism. However, the zero tolerance value is needed, because the lengths and the angles measured from Solidworks are all rounded values. + \\ + \\ + + Furthermore,​ the results from the velocity equations are dependent on the displacement equations and the results from the acceleration equations are dependent on both the displacement and velocity equations. Therefore, the error from the solutions of the displacement equations will propagate onto the solutions of the velocity equations, then the acceleration equations. ​ + \\ + \\ + \\ + \\ 