Tomorrow’s driverless convoy on the road today

Unmanned tactical wheeled vehicles for logistics and route clearance missions provide a significant force protection advantage — removing personnel from targeted vehicles, extending standoff distance from explosives, and empowering a single operator to simultaneously supervise multiple unmanned assets in convoy. This article discusses some of the enabling technologies and the motivations behind them, for safer and more efficient logistics and route clearance operations in a tactical environment.

By John Beck

Unmanned ground vehicles (UGVs) that can semi-autonomously operate over complex terrain represent a promising technological enabler for effective logistics supply and route clearance functions.

Oshkosh Defense has developed autonomous systems for tactical wheeled vehicles (TWVs), working closely with government agencies on autonomous appliqué systems with developed tactics, techniques and procedures that together offer a more efficient and less perilous means to perform critical missions in theater.

The system is designed to be unobtrusive, so that the host platform retains its original mobility, payload capacity, survivability (minimal impact to armor) and manual operation. By upgrading existing fleet vehicles with the capability for unmanned operation, the TerraMax UGV technology can economically and innovatively deliver force protection and force multiplication advantages.

MOTIVATION

Improvised explosive devices (IEDs) pose one of the greatest threats to today’s ground forces carrying out logistics missions in hostile environments. While the up-armoring of tactical vehicles has been effective in reducing casualties, the warfighter remains at risk to the ever-increasing net explosive weights. By fielding UGVs, militaries will be able to remove personnel from TWVs and mitigate the danger of armor overmatch.

To increase efficiency of a reduced force structure, UGVs will serve as force multipliers, enabling a warfighter in a protected vehicle to supervise the coordinated operation of multiple UGVs from a safe standoff distance. These UGVs will be able to operate for extended periods of time, during day and night, and through dust and adverse weather conditions without fatigue or loss of awareness. UGVs will precisely maintain vehicle separation, enabling greater security, improved efficiency and fewer collisions.

Environment Drives Design. To be sustainable in theater, unmanned TWVs must equal their manned counterparts in performance, reliability and mobility in austere tactical environments. For the purposes of overcoming complex terrain, prevailing TWVs are engineered to be capable of feats such as fording 1.5 meters of water and traversing 60% gradients and 30% side slopes.

In addition, these vehicles are expected to operate across broad temperature extremes in dusty, sandy or muddy environments, enduring all manner of precipitation, vegetation and weather conditions. The stringent operational requirements of expeditionary forces influence both individual component selection and overall system design for manned vehicles; the same is true for an unmanned appliqué complement, which must be capable of interpreting and operating in these harsh and complex environments.

ENABLING FULL MOBILITY

TerraMax UGVs are actuated by a tightly integrated drive-by-wire system enabling precise vehicle control using MIL-STD system components to ensure reliability and durability in a tactical environment. It is a safety-critical system that integrates with relevant vehicle components, including steering, engine, brakes, transmission and auxiliary driving functions (such as the central tire inflation system, drive line locks and engine braking), preserving the broad mobility characteristics of the host platform.

The drive-by-wire system both enables higher level robotic control functionality and provides independent benefits in the form of advanced driver assistance system (ADAS) features to benefit manual driving, reducing accidents and collisions.

To facilitate detecting errors absent in an in-vehicle driver’s intuition, the drive-by-wire system communicates with core vehicle diagnostic sensors. It also utilizes add-on sensors that enable monitoring of vehicle and auxiliary subsystem attributes such as hydraulic and pneumatic pressures, ambient and local temperatures, fuel and fluid levels, battery charges and power usage.

All of this data is accessible from the control interface. In addition, threshold values are configured for each monitored sensor such that an operator will be advised if any components exceed warning or critical levels. This ensures that severe conditions do not go unnoticed by an operator, who could be at a distance beyond direct line of sight and may be preoccupied or otherwise unable to dedicate full attention to monitoring multiple UGVs downrange.

Perception Sensors. The TerraMax UGV sensor suite (Figure 1) uses multiple sensor modalities to provide robust sensing capability. The primary sensor for analyzing terrain and obstacles is the high-definition (HD) laser detection and ranging (LADAR), with 64 scanning lasers sweeping 360 degrees.

Figure 1. Sensor suite aboard TerraMax UGV.

In addition, radars are positioned around the vehicle to detect moving obstacles such as other vehicles. Wide-angle cameras are also positioned around the periphery to give a remote operator the ability to visually check vehicle surroundings.

A navigation solution using GPS and an inertial navigation system (INS) supports the ability to drive accurately even with limited GPS signal availability. On the roof facing forward are two cameras used for teleoperation of the vehicle: a wide dynamic range (WDR) camera for daytime use and a short wavelength infrared (SWIR) camera for night operations.

Perception Software. The TerraMax UGV perception software leverages a multi-sensor suite that compensates for the weaknesses of one sensing modality with the strengths of another; for example, relying upon the dust-penetrating ability of automotive radar when LADAR and visible-spectrum camera feeds are obscured.

The perception software uses several modules to interpret the world around it: terrain detection, which assesses roughness of the nearby terrain and informs the selection of appropriate speeds; terrain classification, which distinguishes among foliage, dust or other airborne obscurants and obstacles (Figure 2) and enables traversability appraisals of the surrounding area; and dynamic obstacle detection, which tracks vehicles and dismounts and allows the UGV to exhibit defensive driving behaviors. This software also affords situational awareness and a means for remote supervision of the vehicle by providing processed output for display at the operator control unit.

Figure 2. Perception system display in the TerraMax UGV.

In addition, fused sensor data are combined using novel registration techniques that couple the vehicle’s perception of its surroundings with ground-truth geospatial mapping data to correct for errors in GPS position estimates. This allows the system to be enhanced by, rather than dependent upon, GPS and vehicle-to-vehicle data. Government testing has demonstrated the ability of the TerraMax UGV system to endure complete GPS blackout for more than 19 kilometers with no noticeable impact on mission performance.

Key features of the perception system are:

• operable in all environments under all weather and lighting conditions;
• installed inconspicuously on the base vehicle and capable of covert modes of operation;
• able to deliver reliable system performance under extreme GPS degradation or denial.

Motion-Planning Software. This onboard software takes in an operator’s objectives regarding routing, speed and inter-vehicle spacing as entered during mission planning or on-the-fly. It consequently observes processed sensor data from the perception system and calculates and executes speed and steering commands that guide the vehicle along an optimal path. The motion planning software has been developed with machine learning techniques to emulate smooth human driving behaviors such as avoidance of obstacles and terrain hazards while maintaining appropriate vehicle speed on various terrains.

Key features of the motion planning system are:

• intelligent speed and path selection in all terrain, including secondary roads and trails;
• capability of sustaining high platform mobility (for example, handling fording and grade climbs);
• ability to support high operational tempo (OPTEMPO).

Modes of Operation. When enabled for unmanned operation, a TerraMax UGV can be placed in one of three different modes: semi-autonomous, follower,or tele-operation. The mode selection for each vehicle is controlled from the primary OCU that can be installed in any other tactical or combat vehicle.

In semi-autonomous mode, basic waypoint navigation via GPS coordinates is supported. In addition, mission plans can be created that include information such as check-points, intended vehicle separation distances, speed limits by region, and exclusion zones. These missions are planned from the OCU on a route map that is produced from standard geospatial vector data and predefines the roads on which the UGVs may travel.

This feature, illustrated in Figure 3, allows for on-the-fly mission planning and route changes by selecting “via points” on the road network (similar to a Google Maps functionality) that are automatically connected into a full route plan.

Figure 3. Waypoint navigation.

This requires significantly less effort than manually selecting each individual waypoint for each unmanned vehicle. Once a route has been established, the UGVs traverse the assigned road using their fused global position estimates (leveraging GPS signals as well as the sensor-enhanced map registration to stay on the road) and take advantage of the data link between the vehicles to ensure they maintain prescribed leading and following distances.

In follower mode, no predetermined mission plan is required; a manned vehicle such as the command and control vehicle (C2V) is simply designated as the leader by the operator, and the unmanned vehicles will follow anywhere on the roadway (while still performing intelligent road-keeping and obstacle detection). Two modes of leader tracking are supported: coordinate-based and direct observation.

In the primary mode of coordinate-based following, the lead vehicle transmits its GPS-based position to the follower via the radio data link. The follower vehicle correlates this position to the route map and subsequently appends a waypoint to its upcoming path that would bring the follower to a position on the road directly behind the leader.

In tele-operation mode, an operator assumes remote control of a single UGV and directly commands vehicle speed, steering and other functions via a rugged handheld controller. The operator has a selection of either live video feeds, or an augmented reality view supported by perception data overlaid on aerial imagery, displayed on the OCU display.

OPERATOR CONTROL UNIT

The operator control unit (OCU)hardware and software (Figure 4) are designed to be installed in any other tactical vehicle, along with a low-cost GPS receiver and radio data link that enables communication with multiple TerraMax UGVs from up to 1 kilometer. The OCU allows a single operator to manage coordinated mission command and control of mixed convoys comprised of manned and unmanned vehicles. Route information and convoy behaviors can be pre-planned, saved, loaded and modified as needed during operations.

Figure 4. TerraMax UGV operator control unit.

Touchscreen and function keys allow rapid input using relevant and contextual menus including configurable preset values. Live position and status of each vehicle is displayed on a zoom-able overhead map, and camera feeds from any of the UGVs may be displayed in a familiar picture-in-picture format.

A distilled version of the perception information can be selectively overlaid, aiding the operator’s situational awareness of the vehicles’ surroundings. Remote control and tele-operation is supported using a ruggedized game-style controller for situations when the operator wants direct control of steering and throttle.

TRAINING

Because pre-deployment training opportunities may be limited and any near-term requirement for highly specialized troops is untenable, ease of skill acquisition is critical. In two warfighter experiments for the U.S. Marine Corps Warfighting Lab’s recent Cargo UGV project, the TerraMax system was demonstrated to be operable by veteran motor transport operators after a three-day training course comprising classroom instruction, a realistic desktop simulation environment, and hands-on exercises with the vehicles.

The capstone experiment integrated two TerraMax UGVs into a manned logistics convoy, which was then subjected to a variety of realistic operational scenarios including unexpected road blocks, simulated IED strikes and night operations. Results showed the novice users were able to successfully complete mission objectives using the unmanned systems.

At the conclusion of each of the warfighter experiments for the Cargo UGV project, operators believed they could comfortably control three to five UGVs from a single user interface without suffering cognitive overload.

CONCLUSION

With onboard sensing and decision-making, these unmanned TWVs can provide a force multiplier by empowering a single operator to simultaneously supervise several unmanned assets traveling in convoy, operating semi-autonomously for extended-duration movements. This advantage is significant because it permits more efficient completion of missions by lowering both risk to, and demand for, ground forces.

The procurement, operations and maintenance costs for a robotic capability on TWVs will also be minimized by modernizing existing fleet vehicles with an appliqué kit, but to become viable in theater operations, unmanned TWVs must be able to contend with the same performance, reliability, and mobility in the austere tactical environments as their manned equivalents.

TerraMax UGV technology can be applied to any tactical vehicle and has already been prototyped on the Medium Tactical Vehicle Replacement (MTVR), Palletized Loading System (PLS), Family of Medium Tactical Vehicles (FMTV) and the Mine Resistant Ambush Protected (MRAP) All-Terrain Vehicle (M-ATV).

TERRAMAX HISTORY

Oshkosh has been developing and fully autonomous UGVs since 2003. Among its several generations:

In the 2005 Defense Advanced Research Project Agency (DARPA) Grand Challenge, TerraMax was one of only five vehicles to complete the entire 132-mile course.

In 2007, the TerraMax vehicle was one of 11 qualifiers at the DARPA Urban Challenge.

In 2012, a second unmanned MTVR was built to evaluate multiple UGVs supervised by a single operator.

In 2013, TerraMax UGV M-ATV  demonstrated capabilities for route-clearance missions. (Featured on the June 2016 cover.)

ACKNOWLEDGMENT

This article is based on a technical presentation given at AUVSI xPONENTIAL, May 2016 in New Orleans.

John Beck is chief engineer, Unmanned Systems, at Oshkosh Corporation.