The standard of care for PD patients is the use of oral levodopa to manage their motor symptoms. However, in advanced PD, the efficacy of levodopa can decline and fluctuate throughout the day switching between ON and OFF medication periods. As these motor fluctuations occur, patients are prescribed more pills and need to regularly monitor their dosage during the day, significantly impacting their quality of life. After 5 years of oral levodopa treatment, more than half of all patients develop levodopa-related complications, such as motor fluctuation and dyskinesias. Our motor fluctuation study uses motion sensors that measure motor symptoms such as walking, tremor, dyskinesia, bradykinesia, postural instability, slowness and walking difficulties that occur during periods of motor disturbances. The studies focus on characterizing individual patients patterns of predictable and unpredictable motor fluctuations and using this data to build biomechanical models of mobility. This information will be then used to assist movement disorder clinicians in determining which late stage PD therapy option will be most beneficial for each patient.