An Open-Loop vs. Closed-Loop Backhoe Excavator Control System

Abstract

The excavation process has got two main features. The first one is the soil digging. It can be regarded as a quasi-static process in fact, in which the acceleration could be neglected. The second one is the soil transportation and bucket discharging. It can be considered as a dynamic process. Some parts of these features would be automated. There are two main control systems, open and closed-loop control. The main aim of the paper is to present the application of these two systems and compare them. The control systems were tested during the digging process. It begins with the bucket on the primary digging position and ends when it is filled. The paper starts with description of the excavator control systems components. They have got hierarchical structure. The first is the hardware level: sensors, actuators, valves. The PLC executes a direct control on this level. The links between objects would be realized via CAN network. The excavator's control system realizes a simple excavator's bucket motion along prescribed trajectory algorithm. The software level assures calculation of the trajectory parameters, i.e. coordination of the milestones. The bucket velocity was the input quantity. It means that the valve's spool displacements are calculated for each actuator separately. Machine counterbalance and actuators parameters would be the limits of the process. The results of the two systems testing procedure would be presented and compared.

Earthmoving Construction Automation with Military Applications: Past, Present and Future

“…In [40], the time-varying sliding mode controller (TVSMC) combined with fuzzy algorithm has been used for an unmanned excavator system. The computer control system [41] was implemented in a 1.5 tonne 3-link (boom, arm and bucket) excavator. Developments in high-level control have been studied for task level execution such as positioning, path planning and disturbance mitigation.…”

Position control performance analysis of linear actuator in swashplate-controlled electro hydrostatic actuation system

“…Ding et al [28] implemented a synchronous control technique with load sensing, which is both precise and capable of handling anti-bias loads. Both open-loop and closed-loop control strategies were implemented in the excavator control system developed by Budny and Chlosta [29]. The valve's flow characteristic has to be manually adjusted by the operator under the open-loop control system.…”