Robots with force and touch sensitivity

High-speed automation is a hallmark of the manufacturing industry. But some production processes are still carried out by hand because operations require touch sensitivity and force control. Grinding and polishing rough surfaces are but two examples.

The work is done manually because sensing the pressure applied by a moving machine or robot and precisely adjusting it in real time is a complicated and vexing problem. As a result, the few autonomous, force-sensitive tools on the market are either prohibitively expensive, require complex software, or give unsatisfactory performance.

The Active Contact Flange (ACF) from FerRobotics Technology GmbH in Linz, Austria, reportedly overcomes these limitations. The pneumatically powered, controlled-contact device mounts to a robot arm, and tools such as a sanding pad bolt on with a standard flange. In essence, it gives common industrial robots a sense of touch.

Controlling force
The ACF combines a pneumatic actuator, force and position sensors, and closed-loop controls that let it maintain a preset force on a work surface. Its proprietary pneumatic actuator is actually an actuator and force sensor in one, fully integrated into the flange. It was developed together with the Mechatronics Engineering Department and Institute for Robotics at the Johannes Kepler University Linz.

In practice, an operator or technician sets the intended force to be applied to the work face, say for a grinding head. Then, as the tool contacts the surface, the ACF senses the applied force, and servopneumatics quickly adjusts the actuator stroke and force to increase or decrease contact pressure as necessary to maintain the preset conditions.

The ACF works in tandem with a standard industrial controller. Standard I/Os link the self-regulated adapter to the overall robot-control program, but the internal ACF controls let it operate independently within its predefined range. Because the Active Contact Flange itself controls force output and motion, meticulous and costly programming of every tool movement in the higher-level robot-control system is unnecessary.