Problem Description: Getting accurate location data for the NIMS node Problem Description: Getting accurate location data for the NIMS node Proposed Solution: Separate encoder module Proposed Solution: Separate encoder module Introduction: Networked Infomechanical Systems (NIMS) Introduction: Networked Infomechanical Systems (NIMS) What is NIMS? NIMS is a sensor network which is composed of both mobile nodes and static nodes Designed to access remote environments which are inaccessible by conventional means NIMS contains various data sensors which monitor the surrounding environment on a 24 hour basis Different sensors include temperature sensors, light sensors, humidity sensors, and a camera. Importance of Accurate Position Readings Collision Avoidance –If the position of an obstacle is known, the node must be able to avoid collision with the obstacle. Reproducible movements –Environmental experiments require the node to repeatedly collect data at the same location at different times. Autonomous movement of the node –Ability to run algorithms without human assistance Previous Method Proved Unreliable Encoder moduleEncoder Software Architecture Center for Embedded Networked Sensing UCLA – UCR – Caltech – USC – CSU – JPL – UC Merced Roja Bandari, Wendy Gwo, Rachel Scollans, Richard Pon, and Professor William Kaiser NIMS Reliable Actuation for Networked Infomechanical Systems Position obtained from motor –Motor uses resolver feedback to monitor position. Slipping of drive wheels on the cable –The actual distance traveled by the node was different from the data reported by the motor because of the slipping. Pendulum movement –Stacking modules vertically under the main node causes undesirable oscillation and slippage Addition of an encoder module –The accurate position data is acquired by an optical encoder –The encoder is enclosed in a separate module –The module is dragged or pushed by the main node on the cable. –The module runs on idler wheels connected to the encoder pulley –This setup makes a train-like structure to reduce the pendulum movement The Encoder –Optical encoder –IP67 splash rating The Design –Stainless steel idler wheels connected to the encoder via timing belt –Tension wheels to increase friction and reduce slipping –Thinner walls to reduce overall weight of node NIMS Applications Allows for complex algorithm development including image processing, collision detection and avoidance, and sensing uncertainty Allows for long term observation of various natural environmental conditions Enhances educational programs in the scientific community Coordination of Encoder and Current Motor System Reliable Actuation Motor Driver Encoder Driver Feedback: absolute position Sends move commands: currently not using motor feedback Functionality Absolute movement Relative movement xy movement movement in both steps and meters boundary checking Features Dual Channel Quadrature Encoder RS-232 Compact On board network address switch Programmable counting directions Idler Wheel Tension Wheel Encoder Timing Belt Pulley The Module