Abstract: For control of systems that vary in space, there is generally choice in the type of actuator and sensors used and also their locations.   Performance depends on the location of controller hardware, the sensors and actuators. The best locations may be different from those chosen based on physical intuition. Since it is often difficult to move hardware, and trial-and-error may not be effective when there are multiple sensors and actuators, analysis is crucial. A mechatronic approach, where controller design is integrated with actuator location, can lead to better performance without increased controller cost. Similarly, better estimation can be obtained with carefully placed sensors.  Proper placement when there are disturbances present is in general different from that appropriate for reducing the response to an initial condition, and both are quite different from locations based on optimizing controllability or observability. The choice of actuator and sensor and modelling of the control hardware are also factors in controller design. The models for these systems will be coupled ordinary/partial differential equations (PDE's). Approximations to the governing equations, often of very high order, are required and this complicates both controller design and optimization of the hardware locations. Numerical algorithms and issues will be briefly discussed.