The goal of Psiaki's research is to enhance the performance of existing systems through the use of estimation and control theory, dynamic system theory, optimization, and system modeling. A modest amount of theoretical research is being conducted to develop new algorithms or solutions for state and parameter estimation problems and for optimal guidance and control problems. The bulk of Psiaki's research is applied. It involves the use of advanced techniques to solve state-estimation, system-identification, guidance, or control problems for specific systems. Applications of interest include satellite navigation, satellite attitude determination and control, GPS-based position, attitude, and acceleration determination, and aerospace vehicle guidance.

After completing his undergraduate studies in physics, Psiaki worked for three years for RCA Astro-Electronics doing mechanical design and testing. While a graduate student at Princeton, he was a National Science Foundation Fellow, a Guggenheim Honorary Fellow, and a Lothrop Honorific Fellow. Psiaki joined the Cornell faculty in 1986. In 1994 he received a Lady Davis fellowship, and under this award he spent a sabbatical leave with the aerospace engineering faculty at the Technion in Haifa, Israel. He is an associate fellow of the American Institute of Aeronautics and Astronautics and served on its Guidance, Navigation, and Control technical committee from 1992 through 1995. He is the recipient of two best paper awards, one for the 1997 AIAA Guidance Navigation and Control Conf. and the other for the 1998 AIAA/AAS Astrodynamics Specialist Conf.