A Robotic Hand with a Gentle Touch
A student applies pressure to an egg with a glove.Copyright 2014 RET-ENET Program, Electrical Engineering Department, The University of Texas-Pan American
Students groups act as NASA/GM engineers challenged to design, build and test robotic hands, which are tactile feedback systems made from cloth gloves and force sensor circuits. Student groups construct force sensor circuits using electric components and FlexiForce sensors to which resistance changes based on the applied force. They conduct experiments to find the mathematical relationship between the force applied to the sensor and the output voltages of the circuit. They take several measurements—force vs. resistance, force vs. voltage—and use the data to find the best fit curve models for the sensor. Different weights applied to the sensor are used as a scalable force. Students use traditional methods and current technology (calculators) to plot the collected data and define the curve equations. Students test their gloves and use a line of best fit to determine the minimum force required to crack an egg held between the index finger and thumb. A PowerPoint® file and many student handouts are included.
Curve fitting plays an important role in all STEM fields. Studying models helps to provide a better understanding of the behavior and relationships among variables. Often, models are an effective and efficient way to simulate solutions to real-world problems. For example, the design of robots by biomedical and electrical engineers involves looking at curve models that relate voltages, resistance and forces applied on load sensors. In fact, all devices that output resistance require a circuit to convert the resistance to voltage range. The curve models used to calibrate sensors serve as a tool to improve robotic tactile feedback systems for surgical and manufacturing applications. In this activity scenario, students act as real-world engineers challenged to discover the correct model that best fits voltage data collected from an applied force to a sensor. To test their models, students create tactile feedback systems using gloves and apply pressure to a fragile object.
After this activity, students should be able to:
- Identify and use simple engineering curve models.
- Collect and plot data using two variables.
- Graph linear functions on the coordinate plane.
- Estimate solutions by writing, with and without the assistance of technology, linear functions that provide a reasonable fit to data.
- Use and apply force sensors.