“…The trajectory fitting estimator (TFE) is proposed first by Kutoyants (1991) as a numerically attractive alternative to the maximum likelihood estimator. The TFEs have been widely studied in stochastic processes, such as traditional OU process (Dietz, 2001; Dietz & Kutoyants, 1997; Jiang & Chen, 2016; Kutoyants, 1991), the OU process driven by ‐stable Lévy motions (Hu & Long, 2007) and the reflected OU process (Zang & Zhang, 2019). Suppose that we have the prior information of the thresholds and diffusion parameters, that is, , , and the diffusion parameter is known.…”