סמינר מחלקתי "Balancing an Inertial Wheel on a Fixed-Pivot Inverted Pendulum"

הסמינר מחלקתי "Balancing an Inertial Wheel on a Fixed-Pivot Inverted Pendulum" יתקיים ביום ג', 10.01.2017 בחדר EM302,  בין  השעות
13:45-15:40

המרצה: פרופ' אדוארד אייטלברג

תקציר:

This seminar reports on a 2005 BSc Eng final year design project at an African university.
The specification defined an inverted pendulum (shaft) with a freely rotating pivot fixed to the ground. The pendulum was to be stabilised in a vertical position by nothing else but a rotating motorised wheel at the top end of the pendulum. At first, the departmental committee refused this project proposal because – in their view – this arrangement could not make the pendulum lift itself from a non-vertical position. In the end, it was accepted because I (EE) vouched for the feasibility of this project within the scope of one semester.

All control engineers and academics that I have spoken to would intuitively design a feedback control loop to regulate the angle of the pendulum. In fact, it is possible to feed back the measured shaft angle to the hub motor of the wheel and ‘prove’ by simulation that it stabilises the pendulum in vertical position. The problem is that no angle sensor is perfect. Even an infinitesimal imperfection requires infinite speed from the wheel – which is clearly not possible.

One of the most important control engineering ideas, in this project, was to redefine the primary control task as regulating the motor speed to a given reference value. This speed loop interacts with and dominates the angle control loop in low frequency. The angle control loop operates only in some higher frequency band. The design of the two interacting feedback loops is not trivial but the student (RS) succeeded beautifully.
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