# Motion Generation for Crane Simulators Using Streamlined Motion Blending Technology
## 4 Modeling of Typical Motion Components
### Modeling of a Special Motion Component  
Reset motion is to add an additional motion in addition to the normal motion reproduction algorithm. The purpose is to ensure that the motion simulator performs a reset motion in the absence of human body detection after each violent motion is simulated. If there is no reset motion component, after long-term operation of the motion platform, a variety of small errors will gradually accumulate, resulting in greatly reduced accuracy of motion simulation, and the platform cannot reproduce the desired motion.  
In the debugging process of this project, it is found that, if no special reset operation is automatically performed in the process of motion simulation, the normal simulation motion of the platform will collapse after about two hours of continuous work, indicating the importance of regular reset:  
(1) The choice of time window for executing reset  
Obviously, selecting the appropriate reset time window in the working cycle of the quay crane needs to follow the following principles:  
1 In this time window period, the driver's room should have basically returned to or very close to the initial equilibrium point.  
2 In addition to random small disturbances such as wind-induced vibration, the actual motion of the cab in the virtual world should be able to maintain a relatively static or uniform forward state for a long time during the selected reset time window.  
According to the above principles, the final reset time window is: the time period during which the trolley moves from the sea side to the land side, passes through the rail gap between the front girder and the rear girder for a certain distance, remains stationary, and the spreader descends, that is, section B-A in Figure 2. At this time, the trolley is located in the shore bridge portal frame with large stiffness, and the vibration caused by the previous crossing rail joints has been attenuated. Therefore, in addition to the weak random vibration, the driver's room is almost static, and the duration of this time period is long, about 5 seconds. According to experience, the time required for the simulation platform to reset without notice is not more than 1 second.  
(2) Reset algorithm  
For the reset time window selected in the motion simulation of the crane studied in this paper, the reset we need is based on the reset function of the classical washout algorithm, which is more thorough in the physical layer of the terminal. The algorithm is simpler and faster, which can eliminate the motion drift caused by the cumulative error.  
The steps of the algorithm are:  
STEP1: Stop all other motion components and obtain complete control of the motion platform;  
STEP2: Obtain the elongation of six electric cylinders by encoder, which are expressed as \(\{l_{1},\ l_{2},\ l_{3},\ l_{4},\ l_{5},\ l_{6}\}\);  
STEP3: Compare with the reference electric cylinder elongation \(\{L_{10},\ L_{20},\ L_{30},\ L_{40},\ L_{50},\ L_{60}\}\) of the initial equilibrium point of the platform, and calculate the difference \(\{\Delta I_{1},\Delta I_{2},\Delta I_{3},\Delta I_{4},\Delta I_{5},\Delta I_{6}\}\);  
Figure 12: Underdamped vibration curve of traveling mechanism acceleration.  
STEP4: Take the reset running time for 1 second, let the electric cylinder complete the calculation of \(\{\Delta I_{1},\Delta I_{2},\Delta I_{3},\Delta I_{4},\Delta I_{5},\Delta I_{6}\}\) in 1 second.  
This reset algorithm is also a streamlined reset algorithm without intermediate links. Overall, if the reset motion is also treated as a motion component controlled by a motion model, the details of the model are:  
The symbol of motion component model: ResetPlatform;  
The main content of the model: Complete STEP 1 to STEP 4 operation;  
Triggering condition: The trolley runs from the sea side to the land side to point B shown in Figure 2;  
Exit condition: Automatic exit.