An elastic path controller (EPC) is developed in this paper to add "elasticity" to a path following controller and enable dynamic modification of the guiding path for assistive devices based on path guidance. This permits the users to compensate for changes in the environment such as obstacles or error in position sensing. The EPC is demonstrated both on the Scooter cobot and on the collaborative wheelchair assistant (CWA). Simulation results and psychophysical experiments performed with the Scooter suggest that this novel tool is efficient and can help human operators to adapt to environment changes