Double inverted pendulum

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University of New Brunswick


The goal of this project was to design a Double Inverted Pendulum (DIP) for non-linear control algorithm testing in the Intelligent Control Laboratory (ICL). It was designed to be within two meters long, less than one meter of total arm length, and of durable and modular construction in order to function. The system is operated through a data acquisition system with algorithm compiled in the Microsoft Visual Studio development environment. The design includes safety considerations and came to a total cost of $1131.79. This report includes information on the background research for the driving motor and the encoders, and on the mechanical design of the track and cart system. A Gantt chart is present to detail the project plan throughout the year. The method for deriving the system state-space model using Lagrangian mechanics is implemented. This model is used to test the system in an open-loop fashion to see how the assembly will move. A preliminary design for a Linear Quadratic Regulator (LQR) controller is also implemented in order to observe how the system can be controlled, and to obtain torque and speed curves for the motor, to help with motor selection. Description of the mechanical design is given to explain how the different components fit together in the assembly and the reasoning for the design choices. With system components specified, mechanical calculations are performed, and the resulting data tabulated to view the shear and bending stresses present in the various components of the system in a worst case scenario analysis. Also included is a section on the electrical design, including a process flow diagram for the entire system and electrical schematic. A description of the software environment and control flow diagram is given. Finally, a list of the all the purchased parts along with associated costs is provided, followed by a brief description of the different manufacturing methods used for custom part production.