Development of a Tow Capacity Test Device for Small Unmanned Vehicles
Unmanned ground vehicles (UGVs) will increasingly be used for tasks such as retrieving injured soldiers from a battlefield, transporting supplies, and towing other small vehicles and payloads. To date, the unmanned test community has not standardized on an apparatus or test operating procedure (TOP) specifically for evaluating the towing capacity of small unmanned ground vehicles. Draw-bar testing has been adapted by several groups to quantify small unmanned ground vehicle (SUGV) tow capacity; however, these devices are inherently limited to measuring peak static towing force. This paper describes an alternative method using a variable-resistance tow sled for quantifying the dynamic towing capacity of SUGVs. The tow sled contains a frontal skid plate and a rear axle and wheel arrangement. A weighted carriage is transferred from the rear of the sled to the front of the sled by a cable geared to the rear axle. As the sled is pulled along the ground, towing resistance increases in a controlled linear fashion. An encoder on the rear axle and a load cell in the tow chain provide motion and force data. Testing of the tow sled has been conducted on a TALON SUGV at the Southwest Research Institute (SwRI) Small Robot Test Facility and a MATILDA SUGV at the Joint Unmanned Systems Test, Experimentation, and Research (JOUSTER) site.