June 14, 2015
June 14, 2015
June 17, 2015
26.63.1 - 26.63.13
A low cost and flexible open source inverted pendulum for feedback control laboratory coursesThis paper presents the complete design and build of a low-cost, open source inverted pendulum(IP) platform to support control systems engineering and technology laboratory instruction. Inthis standard IP system, a linear actuator consisting of a belt drive and stepper motor is used tostabilize the vertical angular position of an inverted pendulum connected to a cart. The noveltyof the presented system is the open-source approach, which achieves both low-cost and permitsindividual customization. The linear actuator and cart were designed in SolidWorks andmanufactured using a MakerBot Replicator 2X, with the design files published onThingiVerse.com. Linear motion is achieved via a standard NEMA17 size stepper motor drivenby an Arduino Uno microcontroller development platform and an open source stepper motordriver circuit that can either be purchased or built in-house. Angle conversion of the IP isperformed using a low cost rotary encoder and the analog to digital convertor of the ArduinoUno. Additionally, a digital PID control algorithm is presented that addresses the issues ofsample time, derivative kick, on-the-fly tuning, reset windup, and bumpless transfer. The code isdocumented to explain these phenomenon and to enable tuning using standard practices such asZiegler-Nichols tuning. Through the use of 3D printing technology and open-source electronicsand computer code, the material cost of the system was kept under $100 per unit, making this anideal student project for an undergraduate controls curriculum. Additionally, through openaccess to the design files, control systems educators and students have the flexibility tocustomize the project to their individual needs. Student feedback is also presented supportingthe efficacy of the system as an active learning tool.
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