The Feel of MEMS Barometers: Inexpensive and Easily Customized Tactile Array Sensors

Yaroslav Tenzer,Robert D Howe,Leif P Jentoft

doi:10.1109/mra.2014.2310152

Yaroslav Tenzer, Robert D Howe + Show 1 more

Open Access

https://doi.org/10.1109/mra.2014.2310152

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Abstract

This article presents a new approach to the construction of tactile array sensors based on barometric pressure sensor chips and standard printed circuit boards (PCBs). The chips include tightly integrated instrumentation amplifiers, analog-to-digital converters, pressure and temperature sensors, and control circuitry that provides excellent signal quality over standard digital bus interfaces. The resulting array electronics can be easily encapsulated with soft polymers to provide robust and compliant grasping surfaces for specific hand designs. The use of standard commercial off-the-shelf technologies means that only basic electrical and mechanical skills are required to build effective tactile sensors for new applications. The performance evaluation of prototype arrays demonstrates excellent linearity (typically <;1%) and low noise (<;0.01 N). External addressing circuitry allows multiple sensors to communicate on the same bus at more than 100 Hz per sensor element. Sensors can be mounted with as close as 3#5-mm spacing, and spatial impulse response tests show that linear solid-mechanics-based signal processing is feasible. This approach promises to make sensitive, robust, and inexpensive tactile sensing available for a wide range of robotics and human-interface applications.

Highlights

Tactile sensing is widely considered an essential capability for effective grasping and manipulation [1], [2], [3]
To experimentally characterize the performance of the proposed tactile array, three sensors were soldered in a line at 5 mm spacing to a rigid printed circuit board (PCB) (Fig. 4); this is the closest obtainable spacing for sensors mounted endto-end in the longest dimension
The rubber was a two-part room temperature curing polyurethane elastomer (VytaFlex 20, Smooth-On, Inc., Easton, USA). This inexpensive rubber has low viscosity for mixing and pouring, is compliant but mechanically robust after curing, and is compatible with shape deposition manufacturing (SDM) prototyping techniques which have proved useful for robot hand construction [12]

Summary

INTRODUCTION

Tactile sensing is widely considered an essential capability for effective grasping and manipulation [1], [2], [3]. Commercial tactile array sensors avoid the need to master exotic fabrication technologies, but they are typically costly, fragile, and cover only a limited area of a hand [4], [5], [6] Both custom-built and commercial sensors require considerable engineering effort to integrate into the contact surfaces of a new robot hand, and there are further challenges in developing the multiplexing, cabling, and digitizing to get the sensor signals down the robot arm and into the control computer. Recently-available miniature barometric sensor chips, which include a MEMS pressure sensor, temperature sensor, instrumentation amplifier, analog-to-digital converter, and standard bus interface, all for as little as US$1 per sensor These devices can be mounted on standard printed circuit boards (rigid or flexible) using standard IC surface-mount techniques. We conclude with a discussion of design considerations and the implications for robot manipulation research

Barometric Sensors

Circuitry Design and Rubber Casting

SENSOR CHARACTERIZATION METHODS

RESULTS AND DISCUSSION

CONCLUSIONS