Toward smart composites: Small-scale, untethered prediction and control for soft sensor/actuator systems
Abstract
We present formulation and open-source tools to achieve in-material model predictive control of sensor/actuator systems using learned forward kinematics and on-device computation. Microcontroller units that compute the prediction and control task while colocated with the sensors and actuators enable in-material untethered behaviors. In this approach, small parameter size neural network models learn forward kinematics offline. Our open-source compiler, nn4mc, generates code to offload these predictions onto MCUs. A Newton-Raphson solver then computes the control input in real time. We first benchmark this nonlinear control approach against a PID controller on a mass-spring-damper simulation. We then study experimental results on two experimental rigs with different sensing, actuation and computational hardware: a tendon-based platform with embedded LightLace sensors and a HASEL-based platform with magnetic sensors. Experimental results indicate effective high-bandwidth tracking of reference paths (≥120 Hz) with a small memory footprint (≤6.4% of flash memory). The measured path following error does not exceed 2mm in the tendon-based platform. The simulated path following error does not exceed 1mm in the HASEL-based platform. The mean power consumption of this approach in an ARM Cortex-M4f device is 45.4 mW. This control approach is also compatible with Tensorflow Lite models and equivalent on-device code. In-material intelligence enables a new class of composites that infuse autonomy into structures and systems with refined artificial proprioception.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 03, 2022
- Source ID
- 10.1177/00219983221129691
Entities
People
- Khoi Ly
- Mark E Rentschler
- Nikolaus Correll
- Patricia Xu
- Robert F Shepherd
- Sarah Aguasvivas Manzano
- Vani Sundaram
Organizations
- Air Force Office of Scientific Research
- Cornell University
- University of Colorado