针对经典直接线性变换(direct linear transformation,DLT)、EPNP(efficient perspective-n-point)等方法对目标物位姿估计存在精度不高的问题,提出一种目标物位姿估计改进方法。首先将DLT方法的计算过程进行了优化整理,使之更容易求解...针对经典直接线性变换(direct linear transformation,DLT)、EPNP(efficient perspective-n-point)等方法对目标物位姿估计存在精度不高的问题,提出一种目标物位姿估计改进方法。首先将DLT方法的计算过程进行了优化整理,使之更容易求解;然后引入非线性优化以提高精度,根据LM(Levenberg-Marquardt)优化算法的特点,提出了便于求解雅可比矩阵的代价函数,并引入李群李代数表达位姿微调矩阵,进一步方便了雅可比矩阵的求解,简化了位姿参数值的迭代估计。实验结果表明,提出的改进方法比经典DLT方法和EPNP方法精度有明显提高,也比DLT+数值LM方法精度有所提高,总体平均反投影误差为0.2690像素;提出的改进方法由于简化了雅可比矩阵计算,缩短了迭代时间,总体耗时比非线性优化的DLT+数值LM方法少,每幅图像平均耗时67.48 ms左右。提出的位姿估计方法在精度与迭代时间上有着良好的综合性能,具有较好的实际应用价值。展开更多
Shape memory alloy （SMA） materials possess completely superelasticity or pseudoelasticity above the austenite finish temperature and many unique mechanical, thermal, thermal-mechanical and electrical properties comp...Shape memory alloy （SMA） materials possess completely superelasticity or pseudoelasticity above the austenite finish temperature and many unique mechanical, thermal, thermal-mechanical and electrical properties compared with other conventional materials. Many studies have reported that the superelastic and hysteresis properties of the SMA materials can absorb energies coming from external excitations or sudden impacts. In addition, due to the special electrical properties of NiTi superelastic wires, they can also be used as strain-sensing element to monitor structural health conditions. Composite laminated specimens embedded with SMA wire sensors are fabricated and detailed testing system is designed such as multi-parameters measuring for impact and weak signal processing for SMA sensor. Low velocity impact test shows that SMA wire sensors embedded in fiber-reinforced plastic （FRP） laminate can be well used to monitor impact responses, such as the location of impact damage, impact degree, and strain distribution. Experimental results and theoretical predictions reveal almost the same. Comparing with other method, a simple, economic and reliable technique method monitoring important engineering structures on line is provided.展开更多
文摘针对经典直接线性变换(direct linear transformation,DLT)、EPNP(efficient perspective-n-point)等方法对目标物位姿估计存在精度不高的问题,提出一种目标物位姿估计改进方法。首先将DLT方法的计算过程进行了优化整理,使之更容易求解;然后引入非线性优化以提高精度,根据LM(Levenberg-Marquardt)优化算法的特点,提出了便于求解雅可比矩阵的代价函数,并引入李群李代数表达位姿微调矩阵,进一步方便了雅可比矩阵的求解,简化了位姿参数值的迭代估计。实验结果表明,提出的改进方法比经典DLT方法和EPNP方法精度有明显提高,也比DLT+数值LM方法精度有所提高,总体平均反投影误差为0.2690像素;提出的改进方法由于简化了雅可比矩阵计算,缩短了迭代时间,总体耗时比非线性优化的DLT+数值LM方法少,每幅图像平均耗时67.48 ms左右。提出的位姿估计方法在精度与迭代时间上有着良好的综合性能,具有较好的实际应用价值。
基金This project is supported by Provincial Natural Science Foundation of Jiangsu, China(No.BJ99034)Foundation of Nantong City Science and Technology Leader, China(No.2004033)
文摘Shape memory alloy （SMA） materials possess completely superelasticity or pseudoelasticity above the austenite finish temperature and many unique mechanical, thermal, thermal-mechanical and electrical properties compared with other conventional materials. Many studies have reported that the superelastic and hysteresis properties of the SMA materials can absorb energies coming from external excitations or sudden impacts. In addition, due to the special electrical properties of NiTi superelastic wires, they can also be used as strain-sensing element to monitor structural health conditions. Composite laminated specimens embedded with SMA wire sensors are fabricated and detailed testing system is designed such as multi-parameters measuring for impact and weak signal processing for SMA sensor. Low velocity impact test shows that SMA wire sensors embedded in fiber-reinforced plastic （FRP） laminate can be well used to monitor impact responses, such as the location of impact damage, impact degree, and strain distribution. Experimental results and theoretical predictions reveal almost the same. Comparing with other method, a simple, economic and reliable technique method monitoring important engineering structures on line is provided.
