Use of motion sensors for autonomous monitoring of hydraulic environments

Low cost, miniaturized, commercial-off-the-shelf (COTS) motion sensors, collectively with processors, an energy source and other electronic circuitry can be packaged into very small volumes for autonomous operation. If such a system operates over short periods of time, or data acquisitions occur at a very low frequency, processor resources should be sufficient to manage offsets and errors. The paper analyzes a typical set of COTS accelerometers and gyroscopes, to indicate how best these can be used in hydraulic environments. Application examples such as river bed sediment monitoring, milk vat monitoring etc. are briefly discussed, with application oriented design approaches. Minimizing the power consumption to introduce a novel, rechargeable power supply design is briefly outlined

Implementation aspects and offline digital signal processing of a smart pebble for river bed sediment transport monitoring

Conceptualization aspects of a smart sediment particle (smart pebble) for monitoring of sediment transport in riverbeds have been documented previously [1]. However, this mixed signal approach was done only at a conceptual level and lacks complete implementation aspects such as limited PCB real estate, a miniaturized power source and adequately addressing the offset errors. A fully digital version with multiple strap-down MEMs, signal conditioning blocks, an 8-bit processor and a memory subsystem was designed and assembled within a less than 4 cm diameter sphere to allow data capture for up to 15 minutes. This compact subsystem allows exporting of output data, stored within the memory from nine sampled MEM sensors, into an offline-processing environment for further processing to generate essential motion information. Complex mathematical algorithms for axis conversion, etc, are housed within the offline-processing environment reducing the burden on the smart pebble. The total electronic subsystem embedded within the pebble together with the external processing algorithms tackle cumulative errors, gravitational compensation requirements and offset errors, while being powered by a specially designed power stage, based on a single alkaline cell

Design enhancements of the smart sediment particle for riverbed transport monitoring

This paper discusses new enhancements that are being made to the existing ‘Smart Sediment Particle’. The smart sediment particle has been designed and implemented to track its own 3-dimensional trajectory when placed in a riverbed. This device serves as a tool to detect sedimentation in rivers. The device has been developed over the years, with its size diminishing significantly down to a sphere of 2cm radius. The readings obtained from the pebble are accurate and match well with other independent motion sensor readings. Currently a novel IPT (Inductive Power Transfer) based power supply is being integrated to this device, to charge it wirelessly, when it has been extracted from the water. A new low power, miniaturized microcontroller has been introduced to minimize the power consumption and the PCB real estate of the device. The paper discusses these new enhancements in detail and also other potential enhancements such as error compensation and wireless data transfer

Low-cost autonomous 3-D monitoring systems for hydraulic engineering environments and applications with limited accuracy requirements

The details of developing autonomous 3-D motion monitoring systems based on commercial off-the-shelf (COTS) motion sensors for hydraulic environments are discussed. Possible areas of application, are river bed sediment transport monitoring and monitoring the agitation and other physical parameters inside milk vats with a mechanized agitator. Simplified calculations of inertial navigation systems (INSs) such as Euler angle method, MATLAB programs for further processing, power management systems for autonomous operation including the possibility of inductive power transfer (IPT) and use of microelectromechanical systems (MEMS) technology are discussed. Experimental results for proof of concept systems are highlighted