A Hardware Trojan is a malicious hardware modification of an integrated circuit. It could be inserted at different design steps but also during the process fabrication of the target. Due to the damages that can be caused, detection of these alterations has become a major concern. In this paper, we propose a new resilient method to detect Hardware Trojan based on path delay measurements. First, an accurate path delay model is defined. Then, path delay measurements are compared in a way that theoretically eliminate process and experimental variations effects. Finally, this proposed detection method is experimentally validated using different FPGA boards with substantial process variations. Both small sized sequential and combinatorial Hardware Trojans are implemented and successfully detected.