## 4 Autonomous Shovel Technology
### Shovel Trajectory Planning
#### 4.2.1 Resistance Force Determined Trajectory Planning Method  
In a joint project by Russian scholar [PERSON] and the Minsk Machinery Research and Production Association, which was mainly about the development of the open-pit mining automatic loader, the calculation method of the effective trajectory for the excavator bucket was firstly studied based on mechanical control [51]. In order to shovel the materials better with the bucket, it is rather necessary to accurately predict the digging resistance from the obstacle. [PERSON] et al. [52], from Kaiserslautern University of Technology, Germany, predicted the excavation resistance of a slab excavator in unbonded granular material, excavating using the discrete element simulation method and the accuracy of the results was verified by experiments. [PERSON], from Stellenbosch University in South Africa, simulated and analyzed the bucket excavation process using the discrete element method simulation platform, but the predicted excavation resistance was found to be smaller than the actual value from experiments. In addition, the excavation resistance changing trends were almost the same in the entire excavation time domain [53; 54]. Since the shape and size of the ores are inconsistent after blasting, the resistance from the ore blocks on the scraper will change during the shovel loading process. Therefore, when establishing the resistance model, it is necessary to take the change in the shape and size of the ores into consideration. [PERSON] et al. [55], from Northeastern University, counted the rock materials with different particle sizes after blasting through discrete element and simulated their excavation process based on the actual prototype, then predicted the excavation resistance under several complex working conditions. It was found that the results from prediction were quite close with the resistances under actual situation. [PERSON] [56], from Dalian University of Technology, established a rapid online excavation trajectory planning method for the mining shovel, based on a dynamic excavation resistance prediction model, especially for complex ore piles. The experimental results showed that the running accuracy of the trajectory planned by this method can be improved by more than 14%, compared with the traditional mining resistance model, and the energy consumption was reduced by 8.86%. Although the excavation resistances predicted by the above method are close to those under actual conditions, it cannot be said that the predicted situation can fully explain the actual site, since the possible accidents, such as collapse or landslide, would happen during the actual excavation process. [PERSON] [57] believed that the material excavation could not be realized but only guided through the resistance model preset by the mathematical formula. Hence, he proposed to adjust the excavation trajectory according to the real-time magnitude of the resistance during the excavation process. [PERSON] [58] presented a rheological method for simulating the interaction force between the soil and bucket. Then, under real conditions, the excavation trajectory of the excavator bucket could be controlled and adjusted through detecting the force on it. [PERSON] et al. [49] established a mechanics feedback model for the bucket based on Coulomb earth pressure theory. With 100% full bucket rate as the prerequisite, the insertion depth was optimized to minimize the energy consumption and the optimal bucket trajectory was finally determined. [PERSON] et al. [59], from Carlton University in Canada, proposed a velocity-based admittance controller for the first time according to the characteristics of the scraper hydraulic cylinder induction force during the excavation process. Field tests were also conducted on the Atlas Copco scraper and proved that the shovel loaded more efficiently than manual operation. [PERSON] et al.