|Alcon Inc. is a world leader in the development and manufacture of surgical, pharmaceutical and consumer vision care products, and is one of few companies to produce laser surgery equipment for the eye care industry. With huge global and sales of nearly US $5 billion, Alcon is the largest specialized eye care company worldwide. With a reputation for bringing "best in class" products to market, Alcon is constantly innovating in the realm of cutting-edge, customized surgical technology.
Challenge: ENSURING A HIGH LEVEL OF PRECISION
In 2003, the company found itself facing a complex mechatronic challenge in the final stages of developing its next generation LADARVision laser eye surgical device. LADARVision allows personalized laser vision treatment to match each eye’s individual optical characteristics, delivering unmatched customized results. Despite significant investment of time and money, Alcon was unable to resolve the problem of repositioning the laser for rapid, accurate movement – a situation that requires the utmost degree of precision and reliability – for its newly designed system.
After almost a year of searching for a resolution to this challenge, and concerned about meeting its product testing and launch schedule, Alcon approached Quanser – world-renowned experts in complex mechatronics and control solutions.
The challenge faced by Quanser was complex and multi-faceted. First, the Quanser team needed to isolate the problem that had so far eluded Alcon. Then Quanser needed to provide the ability to quickly and accurately reposition the laser for a sequence of firings. The laser beam, which moves via a mirrored reflection, must move, settle and fire very rapidly before moving into a new position and repeating this process. Although speed is of great importance – the mirror is required to move at 60 hz – accuracy is paramount.
Ultimately, a control strategy and a high quality amplifier were required to send digital signals to the device in order for it to move, control the mirror and change commands quickly and precisely.
Solution: SOPHISTICATED MECHATRONIC SYSTEM
Quanser’s deep understanding of real-time control, and how it applies to sophisticated mechatronic systems, was of key significance to this project. After trouble-shooting Alcon’s laser module, Quanser was able to use WinCon*, its real-time control software, to immediately understand the problem and identify an effective path towards resolving the challenge.
Quanser designed an advanced control scheme to send command signals to the device that moves and controls the mirror, and send signals back to controller in order to change commands. In order to achieve the tight specifications required for this system, a high performance, high resolution amplifier was needed to amplify the digital signal. Quanser utilized its Linear Current Amplifier Module (LCAM), which eliminates dead-band and reduces noise issues that are common in PWM amplifiers. Quanser’s open architecture solution allowed for custom adjustments as required.
Part of the reason Quanser arrives at solutions so quickly is a willingness to put its in-house experts into one-on-one consultation with clients to fully understand and resolve their needs. Quanser collaborated very closely with Alcon to adapt the existing LCAM design and provide a control scheme that they were able to implement within their system.
Using WinCon, the team was able to calculate the motion control parameters based upon the specifications for the laser beam’s target move and settle time. A control strategy was conceptualized to improve the performance of the voice coil-actuated laser guidance stage that positions the scan mirror which, in turn, reflects the laser beam to the target.
WinCon was then utilized again to rapidly prototype the controller necessary to position the scan mirror at the high rate of 60Hz while maintaining the high positioning and performance specifications. With so many variables at play and under a compressed timeline, traditional methods of controller development would have added significant cost and time to the process, while providing poorer and inflexible final results. Within weeks, a final linear current amplifier was supplied along with an open-architecture controller to use as a design validation tool.
Results: THE NEW SYSTEM LAUNCHED ON SCHEDULE
Within a short period of time, Quanser was able to achieve the desired specifications and Alcon was able to launch its new system on schedule. Quanser’s LCAM technology is now used in Alcon’s FDA-approved LADARVision system for customized laser eye surgery and patients worldwide can rely on a safe, precise and reliable experience.
Outsourcing was an effective business solution for Alcon as the challenge required extremely specialized expertise. Although Alcon struggled with the problem for some time, Quanser was able to identify and resolve the issue quickly. Furthermore, when faced with a control issue for a new application two years later, Alcon immediately knew it could rely upon Quanser’s expertise. Quanser was once again able to jump in and resolve the problem quickly, allowing the application to perform better.
*WinCon is a predecessor of QUARC real-time rapid control prototyping software.