A robotic inspection platform (“GeoRover”) is proposed for real-time and remote evaluation of highway culverts, drainage pipes, hillslopes, and other structures or features within a highway maintenance setting. The GeoRover is constructed of low-cost and readily available components for customized inspection purposes which are tailored to typical and specific highway maintenance needs; no expensive machining or elaborate construction and assembly is required, although control software must be written as this is not an off-the-shelf product. The GeoRover and selected onboard devices may be controlled using a standard hobby-grade 6-channel radio controlled (R/C) transmitter/receiver system, with the ability to operate in semi-autonomous mode if so programmed.
The intended applications include: visual inspection of culvert and pipe interiors with a wireless camera for assessment of structural and drainage conditions; indication of culvert or pipe height/collapse/pinch points using a sonar sensor; measurement of hillslope or pipe tilt/angle/grade using a MEMS-based dual-axis accelerometer; and evaluation of environmental parameters such as humidity, temperature, or potential gas presence within culverts or pipes such as propane, carbon monoxide, or methane using modular sensors as desired.
Distances into culverts or pipes may be measured using an attached 100-foot (or other suitable length) tape measure rather than dead-reckoning or electronic odometry to keep costs low and provide useful information.
The controller is based on a Parallax Inc. Propeller® P8X32A microcontroller with eight parallel-processing cores and 32 I/O pins. This multicore processor allows for complex programs that are not dependent upon conventional interrupts, permitting multiple tasks to be performed simultaneously. Rechargeable NiMH battery packs are used to power six brushed DC gearmotors that are mounted onto a rigid chassis fashioned from 0.08 inch thick sheet aluminum (signage scrap material). An upper level panel made from 0.04 inch thick sheet aluminum (also scrap) is separated from the lower chassis panel with standoffs and provides mounting locations for the electronics, camera, and other components.
Off-road R/C vehicle-type of wheels and tires will allow for increased traction on varying terrain and surface conditions, and the suspension is such that the motor/wheel assemblies will flex a considerable amount to allow for adequate clearance and navigation over small obstructions such as accumulated debris, rocks, ditches, and concrete curbs. The GeoRover will be steered by differential steering.
Three gearmotor assemblies are placed along the left and right sides of the GeoRover, and are affixed to the chassis using a “captive spring-and-pin hinge” arrangement. Each gearmotor is installed within a short length of one-inch diameter Schedule 40 PVC pipe that is suspended from the chassis and is attached with a pin that runs through the pipe, allowing the gearmotor/wheel assembly to readily travel up and down. The chassis itself serves as a limit stop and the travel motion is tempered by a spring connected from the distal end of the assembly to the chassis.
The price point for the GeoRover should allow multiple units to be constructed and placed into service, at a cost that is substantially lower than the price of a comparable commercial inspection rover.