胶囊机器人与肠道准静态交互的临界滑动阻力研究

Research on the Critical Sliding Resistance on the Quasi-static Interaction between the Capsule Robot and the Small Intestine

  • 摘要: 目前,胶囊机器人从静止状态到相对运动发生的这一过程中所需要克服的阻力尚无有效数据.本文针对这一问题进行交互分析,量化影响临界滑动阻力的因素.首先基于Ciarletta 的超弹模型,分析"内力-摩擦"式和磁驱式胶囊机器人实现运动所需的临界滑动阻力.首先分别建立了包括胶囊机器人头部压力、中段摩擦力和头部摩擦力的阻力模型,并根据力的平衡关系获得临界滑动阻力的表达式.其次,构建了实验台并利用家猪的离体小肠开展了实验.随后对影响临界阻力的参数进行了分析,包括胶囊机器人外径与肠管的内径比(R/r)、肠管摩擦系数和胶囊机器人的中段长度.临界滑动阻力的理论计算结果与实验结果达到较好的吻合.R/r和肠道摩擦系数的增大都会导致临界滑动阻力增大.胶囊头部所受摩擦力在阻力中所占比例小于1%.胶囊机器人受到的阻力与其中段长度呈线性关系. 提出的模型能够准确地预测临界滑动阻力,可体现各因素的影响,其中最为主要的影响是R/r.

     

    Abstract: Currently, there are no effective results about how much resistance the capsule robot (CR) has to overcome during its start. This paper aims to obtain the critical sliding resistance (CSR), and quantify its influencing factors. Based on Ciarletta's superelasticity model, CSR is analyzed for the "internal force-static friction" CR and magnetically driven CR. Firstly, the resistance is modeled, including the pressure on the CR head and the frictions on the CR middle part and CR head, and a CSR expression is obtained from force equilibrium. Secondly, a experimental platform is built and experiments are performed with in-vitro porcine small intestine. Then, influences of three parameters on CSR are investigated, including ratio between CR's outer diameter and the small intestine's natural inner diameter (R/r), the friction coefficient and the length of the CR middle part. The theoretical value and experimental results for CSR match well with each other. Both the increasing of R/r and friction coefficient will increase the CSR. The friction force on the CR head is less than 1% of the total friction force. The CSR has a linear relationship with the length of CR middle part. The proposed model reflects the influences of various factors, and can accurately predict the CSR. The major factor affecting the resistance lies in the R/r.

     

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