Case Study: Unlocking Precision Prototyping in MedTech with Epson Force Guide

Project Scope: Optimizing Force Measurement for an Iterative R&D Process 

An R&D team working on medical devices was struggling with measurement inconsistencies and inefficiencies while using a force measurement system of load cells and serial communications. While load cells are an easy and cost-effective solution for measuring force, they require frequent calibration to ensure accuracy and typically only provide readings in one axis. Furthermore, serial communications lack the speed to provide reasonably responsive feedback times. The team needed a better way to measure force for their real-time pressing application, one that could better support the highly iterative nature of their work. 

Solution Design: Epson Force Guide Integration

As the R&D team was already using Epson robots, IRH opted to reconfigure the existing system using Epson Force Guide – a high-precision, rigid force sensor solution that only requires an I/F card installed in the robot controller and the accompanying Epson software. The connection of the I/F card to the processing in the robot controller enables Force Guide to capture force readings in six axes and at a much higher rate than serial communications, increasing the accuracy of the achieved target force. Force Guide is easily installed into an existing system, requiring few, if any modifications, and does not require calibration. 

At the outset, IRH retrofit one prototype robot on which the Force Guide system was installed for code development and testing prior to system-wide deployment. Code was developed by IRH engineers in Epson’s SPEL programming language using the RC+ programming environment. During this phase, existing motions were modified to execute a pressing tool path that required a tightly controlled rate of descent so as not to over influence adhesion. Once the target contact force was achieved, within a 1% margin of force, the tool would lift away and proceed to the next part. Parameters of tool speed and rate of descent, both of which determine contact force exerted by the machine, were rigorously tested and adjusted to achieve desired output frequency and improved accuracy for the Client’s application. 

The project was designed for a single robot-system configuration, thereby streamlining code development, debugging, deployment, and ongoing maintenance. Once code was debugged and running cleanly on the prototype machine, all robots were refitted and the code was deployed system-wide. Site acceptance tests (SATs) were conducted on each of the robots to ensure repeatability and to identify and correct small variances within unique robot cells. Upon successful completion of SATs, robots were approved for production use.

Results: Prolific Production and Amplified Accuracy 

Originally designed with an 8-week implementation timeline, IRH successfully executed the Force Guide integration in just 3 weeks to meet the Customer’s accelerated deadline. The project ultimately retrofitted 9 machines and commissioned 5 new robots.

The implementation of Force Guide increased production speeds while also enhancing accuracy and precision. Production output increased by up to 200% and rate of deviation from target force decreased from 10-15% under the old system to 3% under Force Guide. The deployment of the Force Guide system also reduced production disruption caused by prolonged downtime for robot maintenance.