A Flight into the Future with MapleSim - User Case Studies - Maplesoft

User Case Study: A Flight into the Future with MapleSim

Dr. Richard Gran is well placed to appreciate the benefits modern technology has brought to modeling and simulation. As a key member of the NASA team that designed the digital flight control system for the Apollo Lunar Module in the 1960s, he spent many months developing a FORTRAN simulation on an IBM 7090 to verify the design. Now the president and CEO of The Mathematical Analysis Company, he uses MapleSim™ to reduce the time it takes to develop physical models and prototype control systems.



His career has spanned five decades, and has included projects such as Princeton’s Tokamak Fusion Test Reactor, the X-29 Forward Swept Wing aircraft, and magnetically levitated trains for the US Department of Transportation. He has seen the growth of computing power from slide rules and mainframes in the 1960s to the powerful, yet very affordable, multiple-core PC workstations available today. This evolution now enables engineers, like Dr. Gran, to exploit software technology that automates the time-consuming processes of creating high-fidelity physical models, generate high-speed C-code for real-time applications, and document designs in a math-aware environment.

To try MapleSim, Dr. Gran developed a model of an eight-room house to investigate a new home heating system controller. MapleSim’s remarkably intuitive drag-and-drop physical modeling environment allowed him to rapidly develop the model while also learning to use Maplesim. The model uses a hierarchy of eight simple room subsystems (see the figure above right) as the building blocks. Each room subsystem consists of a thermal capacitance that accounts for the heat stored in the air volume of the room. Heat in the room is conducted to adjacent rooms, to the spaces above and below, and to the outside. In addition, convection and radiation elements model the heat flow from the room heaters. Eight of these building block subsystems create the house model (see the figure left). Connections at this top level of the hierarchy provide the thermal sink to the outside air temperatures, the furnace heat inputs (from the Heating Controller), and the PID controllers that regulate the temperature of each of the two heating zones in the house. This exercise shows that continuous heating controllers provide energy savings by circulating the heat from the heating source to the rooms at lower absolute temperatures. This reduces the conductive heat loss from the ducts or plumbing that circulates the heat to the rooms.

Dr. Gran had created a simpler version of this system for a book he wrote. This simpler model had only two rooms and two heat exchangers. The derivation and simulation of the equations for the book took over three days to create. This eight-room model, the control system design, and the simulation to verify the results took less than eight hours. He remarked, “The original model was about 1/10 the complexity of the MapleSim model but took me days to develop. MapleSim saved me many hours of work because the model maps onto the topology of the physical system and the dynamic equations do not have to be developed by hand. This also enables very complex multi-disciplinary system models to be built and analyzed by a single person. MapleSim converts a painstaking and laborious process into one that is simple and enjoyable.”

The figure at the right shows the first floor zone’s temperature over a forty-eight-hour period. The results of the MapleSim simulation demonstrated that a continuous form of heating control is more efficient than a controller that uses a bi-metal thermostat.