Low cost stabilized gimbal retrofit

Low cost stabilized gimbal retrofit

A major surveillance video solutions supplier with a low-cost indirect drive pan-tilt product line asked IJK Controls to analyze the feasibility of retrofitting stabilization for improved on-the-move performance. The pan-tilt was to be converted to a two-axis stabilized gimbal.

IJK Controls reviewed the mechanical, electrical and software details of the design and presented the customer a trade matrix comparing the disturbance rejection performance and design impacts of various options and configurations of the proposed two-axis stabilized gimbal.

The solution required understanding the control limitations imposed by the drive configuration along with the mechanical and electrical design space. The new stabilization software would have to run on an existing low-cost 8 bit microcontroller that was already responsible for a suite of other features. A quick system simulation was created to help understand fundamental limitations and trade-offs.

After selecting a system architecture with the customer’s input, IJK Controls was asked to prototype the new system. IJK Controls designed a custom board to house the gyroscopes and other sensors and provide communication to the existing control board. IJK Controls completely re-designed the control software, applying a “stabilization loop” paradigm instead of a “motion control” paradigm. Further, all control math (including gyro bias estimation) was optimized to run fast with integer arithmetic, no costly floating point operations. The structure of the hardware interrupts was re-designed and optimized. Monitor and control features were re-written to reduce processor load.

The solution allowed the customer to offer a gyro stabilized gimbal at an affordable price, with no impact to the existing electronics and without sacrificing a great user experience. IJK Controls delivered a custom sensor board design and all new embedded software, backing up high-level controls consulting with detailed engineering effort.

Keywords: low-cost stabilization, gyro stabilized gimbal design, gyro bias estimation