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93 equipment is easily accessible in the field and the battery can be swapped out,” Edwards explains. “We also wanted to maintain as much ground clearance and battery life as we reasonably could for the size of the platform.” Measuring 508 mm long, 430 mm wide and 250 mm high on its wheels, the Jackal is a welded aluminium box with a hinged aluminium lid. This simple shape was chosen to maximise the volume available for payload, convenience of mounting equipment internally and externally and ease of manufacture, Edwards explains. Its proportionately large wheels help with both ground clearance and its ability to cross rough terrain, while its aluminium fenders help keep mud off the sensors and act as carrying handles, he notes. The entry-level price of $11,000 includes a basic onboard computer, joystick controller, inertial measurement unit and GPS. “That is everything you need to start working with the Jackal in ROS and running examples of the code on your own laptop,” Edwards says. “From there you can configure different computing and network hardware, sensors and options for navigation software. Most of our Jackals leave the factory with a sensor and hardware configuration that is unique to each user.” With development completed in 2014, Clearpath considers the Jackal to be a stable and mature product, occasionally making small improvements and offering new options for hardware integration. One of the latest is a wireless charging dock based on the Wibotic system, and clients now often configure the UGV with Nvidia computing hardware such as the Jetson TX2. Edwards says the principal development challenge was combining the small form factor with a useful payload, endurance and ease of access to internal hardware. Components such as the drivetrain, microcontroller, power regulation and motor control PCB assembly are tightly packed inside, while those that users need to get to more often, such as the onboard PC and the battery, are in a fold-out tray under the lid. The lithium-ion battery pack provides a relatively large capacity for a vehicle of the Jackal’s size, he notes. Power and comms breakouts are easily accessible inside the chassis, he says, and can be routed to the outside through either of the payload hatches. Staying on budget while providing a rugged and reliable system was another challenge, given that high-quality gear motors, lithium batteries and computing hardware are expensive. “Most of our clients appreciate this trade-off, as the cost of downtime while working in the field or even the lab, with multiple researchers on standby, can be even more expensive,” Edwards says. Also, Clearpath prefers to make its platforms from metal because it survives the rigours of outdoor operations and university research labs while being easier to work with when integrating new hardware, although it is not always a low- cost option. “We’ve found that welded or fastened formed sheet-metal is about the right compromise in terms of price-to- performance ratio,” he explains. Systems and software architecture, however, were more straightforward, as the Jackal’s are similar to those used Clearpath Robotics Jackal | Digest Unmanned Systems Technology | April/May 2020 The Jackal has a chassis consisting of an aluminium alloy box protected by a powder coating and with a battery- electric four-wheel-drive system (Images courtesy of Clearpath Robotics) The fold-out tray under the hinged lid houses the battery – not installed here – and the mini-ITX format computer, positioned for easy access to a range of data connection ports