Design Con 2015

Rethinking PID use in the age of MEMS

August 02, 2012

Bernard Cole-August 02, 2012

After reading “A stepwise method for tuning PI controllers using ITAE criteria“ recently I was inspired to take a look at the current uses of PID (Proportional/Integral/Derivative) algorithms, long a building block for virtually every embedded motor control design.

What I found surprised me. The use of PID algorithms is now appearing in support of Micro-electro-mechanical systems (MEMS) in a new generation of motor control apps in the industrial automation, robotics (both civilian and mil/aero) and automotive markets. In addition, developers are looking at the use of PID algorithms in MEMS-based mechatronics designs in embedded consumer apps (games) and next generation smartphones where motion sensors and micro-machines based on MEMS are becoming common. A few of the notable papers that I came across include:

Modeling and control of hard disk drives in mobile applications (PDF)
Design and construction of a control system for a ball-shaped robot(PDF)
Tuning algorithms for PID control using soft computing techniques(PDF)
Development of a Self Balanced Robot & its Controller(PDF)
Visual tracking and hovering flight control with an MCU (PDF)

For most of Embedded.com's 20 year history an effort has been made to cover design activity involving PID algorithms extensively. In addition to Tim Wescott's  still popular "PID without a Phd," published in 2000, some other notable and still relevant articles, webinars and white papers on this topic include:

Case study of PID control in an FPGA
Make a PI controller on an 8-bit micro
The basics of doing PID design
Quick and Efficient PID Control Design
Using block diagrams as a control system design "language"
Automatic Level Controller for Speech Signals Using PID

But the extremely small size of the MEMS-based motor control designs in consumer and mobile apps may also mean that the PID algorithms as they are traditionally used may have to be re-evaluated and adapted to these new environments.

Their limitations in the design of many embedded applications which require precise power management may also require that the algorithm be re-evaluated, extended or replaced. I look forward to hearing from you about your experiences in the use of PID algorithms, both in traditional apps and new ones.

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