Tunnel Boring Device Parallel Link Thrust Jack Control
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Solution Overview
Problem
Conventional tunnel boring devices face challenges in controlling external forces of all directions and magnitudes during tunnel excavation, especially when excavating sharp curves with small radii of curvature, due to fluctuations in thrust forces, radial forces, and torque, which can lead to improper axial force control and reduced resistance capabilities.
Innovation Solution
A tunnel boring device equipped with a parallel link mechanism comprising (6+n) thrust jacks, where stroke control is performed on six jacks and force control on the remaining n jacks, utilizing sensors to compute and allocate target forces effectively, allowing for better resistance and control of external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hydraulic circuits of two particular jacks are made to communicate to reduce device complexity, then the size of control hydraulic devices is reduced, but the ability to properly control axial force of jacks is lost when external forces fluctuate greatly
Solution Approach 1:
The patent applies dynamics by making the hydraulic circuit configuration adaptable rather than fixed. The control system dynamically determines which jacks to couple based on real-time external force conditions, allowing the system to switch between different coupling configurations. This enables the system to reduce complexity when forces are stable while maintaining control accuracy when forces fluctuate, resolving the contradiction between device simplicity and control reliability.
Solution Approach 2:
The patent changes the parameter of hydraulic circuit connectivity based on operating conditions. The controller monitors external forces and adjusts which jacks have their hydraulic circuits communicated together. This parameter change allows the system to optimize between reducing hydraulic device size and maintaining proper axial force control, depending on the current excavation conditions and force stability.
2Device complexity
If six thrust jacks are used for basic position and direction control, then the device structure is simplified, but the ability to resist large external forces during sharp curve excavation is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-configuring additional thrust jacks beyond the minimum six required for basic control. These extra jacks are prepared in advance and can be activated when sharp curve excavation is detected. The controller monitors excavation conditions and engages additional jacks proactively when force resistance requirements exceed what six jacks can provide, ensuring adequate strength is available before it's needed.
Solution Approach 2:
The system dynamically adjusts the number of actively controlled thrust jacks based on excavation conditions. During normal tunnel excavation, only six jacks are controlled to maintain simplicity. When sharp curves with small radii are detected, the system dynamically engages additional jacks to provide the necessary force resistance, thus adapting the device complexity to match the actual operational requirements.
3Manufacturing precision
If stroke control is performed on all six thrust jacks to maintain position and direction, then positioning accuracy is improved, but the ability to handle fluctuating external forces during sharp curve excavation is reduced
Solution Approach 1:
The patent applies local quality by applying different control strategies to different jacks based on their roles and the current operational context. During sharp curve excavation, the controller selectively applies stroke control to jacks responsible for position and direction maintenance, while applying force control to jacks that need to handle fluctuating external forces. This localized differentiation of control quality allows the system to simultaneously maintain positioning accuracy and force control capability.
Solution Approach 2:
The control strategy dynamically switches between stroke control and force control for different jacks based on real-time conditions. The controller monitors which jacks are experiencing stable loads versus fluctuating forces and adjusts the control mode accordingly. This dynamic allocation of control strategies ensures that positioning accuracy is maintained where needed while force control capability is preserved where external forces are variable.
Data Source
AI summary
A boring machine comprises a forward section, a rear section, a parallel link mechanism, stroke sensors, pressure sensors, and a controller. The parallel link mechanism includes eight thrust jacks that change the position and attitude of the forward section with respect to the rear section. The controller computes a target allocation force to be allocated to eight thrust jacks on the basis of the sensing result from the stroke sensors and the pressure sensors, and controls the thrust jacks to perform stroke control on six of the thrust jacks and perform force control on two of the thrust jacks.