# Bio-Inspired Model-Based Design and Control of Bipedal Robot
## 5 Solution Testing and Discussion  
Testing of the proposed solution was divided into two parts. In the first stage, all parameters of the robot affecting walking were measured and their deviation from the simulation model was calculated. Each property was measured five times and then the average value was calculated. The results of the first part of the testing process are listed in Table 6.  
From the measurement results of the first part, certain differences between the physical and simulation models can be observed. The weight difference is attributed to neglecting the weights of the cabling, different fillings of the plastic parts, material inhomogeneity of the printed parts and also inaccurate weight data of the used electronic parts. The differences between the measured and the original values of the L1, L2 and L5 lengths were expected and are attributed to the replacement of the servo motor carriers. The original method designed in a three-dimensional model consisted of a detachable joint between a printed servo motor carrier and the wall which with the servo motor was supposed to rotate. In practice, the great flexibility of the carrier, which stood away from the given wall, was manifested, which was caused by the weight of the entire robot. This caused the bending of the shoulders, which led to deviations in the positions of the controlled joints. The chosen modification consisted of replacing the printed carrier with a standardized one, which was attached to the wall with self-tapping steel screws. These percentage deviations are large, but the reduction of the distances between the centers of the coordinate axes in these joints is desired. The deviations between the lengths of L4 and L5 are negligible and are attributed to either measurement error or plastic extensibility. The reduction of the step width in the starting position can be attributed to the resulting deviations in the parameters L1, L2 and L5. The reason is the different starting point of the measurement of this distance, which was not possible to implement in the physical model. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Test No.**} & **Property** & **Value** & **Value** & **Deviation** \\  & **[Unit]** & **(Physical Model)** & **(Simulation Model)** & **Deviation** \\ \hline
1 & weight [kg] & 3.06 & 2.75 & 0.31 \\
2 & length L1 [mm] & 16 & 31 & 15 \\
3 & length L2 [mm] & 29 & 51 & 22 \\
4 & length L3 [mm] & 254 & 252 & 2 \\
5 & length L4 [mm] & 263 & 262 & 1 \\
6 & length L5 [mm] & 18 & 27 & 9 \\
7 & length L6 [mm] & 62 & 25 & 37 \\  & step length in & & & \\
8 & the starting & 80 & 91 & 11 \\  & position [mm] & & & \\  & frame height in & & & \\
9 & the starting & 599 & 570 (644) & 26 \\  & position [mm] & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Results of testing the dimensions of the biped robot structure. Therefore, a new frame height was derived from the simulation model and compared with the measured value. The resulting deviation is largely attributed to the resulting deviations between the lengths of L6, L3, L4 and L1. All the differences identified in this phase of testing can be involved in the next phases of the spiral model of the engineering design of mechatronic systems in order to achieve an ideal overlap between the design, simulation and final implementation of the solution. The second part of the testing was focused on monitoring of stability of the robot at different step lengths. The measurement in which the robot passed all eight steps from the generated trajectory was considered successful. Five measurements were taken at each step length. The robot walked on a horizontal concrete pad in a closed room. The robot walked independently without physical contact with another object. A successful step is considered the one after which the walking cycle is completed without falling. The beginning of the measurement of all cycles was in phase BAC 3.