Compact and High-Power Servo Drives for Robotic Vehicles

This article details a case study of how one of Elmo’s customers, a top defense systems company, employed the Hornet servo drive for a handy, lightweight military robot application.

robotic vehicles for defense companies

Key points covered in this article may interest customers who would like to:

  • Receive MIL-STD qualification and extreme conditions ratings for products
  • Achieve up to 3.3 kW peak power using a matchbox-sized servo drive
  • Reduce development time, leading to short time-to-market
  • Place the drive virtually anywhere within the machine

Application’s Requirements

The portable robot is an advanced, two-wheeled, unmanned vehicle with a wide variety of military applications. Its most exclusive feature is the capacity of the wheels to “expand” and turn into a track with support wheels on each side of the main wheel. This enables the robot to adapt dynamically to varying surface conditions and carry on operations while overcoming hurdles. The wheel-to-track technology also allows the flexible robot to climb stairs.

An operator regulates the robot’s actions and movement via a radio-operated console and eye-piece camera as it steers through the numerous obstacles that are typical in warfare surroundings. The sturdy robot can also be used for homeland security operations, such as the skillful diffusion of a bomb in an urban cityscape.

The robot is highly versatile and can handle several different payloads, such as a camera, grenade launcher, pistol, sensors, and task-oriented tools, etc. Certain payloads can be mounted concurrently, such as a bomb disposal device and a camera.

The robot also integrates a “bridge”—two rods whose main purpose is to provide balance to the robot when it is functioning in an uneven terrain.

portable robot

Five Hornet servo drives from Elmo’s ExtrIQ series of products are integrated into the robot:

  • One in each wheel to allow the expansion into the track device
  • One for each of the two wheels
  • A fifth Hornet regulates the motion of the “bridge”, which alters position as the robot moves

The dimensions of the robot provide stealth-like features with an overall size of just 46 x 46 x 23 cm. Its small footprint is further highlighted by its weight—just 11.4 kg, excluding the variable payload. Therefore, it is possible to carry the robot in a soldier’s battle kit.

Application Challenges

The manufacturer’s key goals for the unmanned robotic vehicle were:

  • The ability to execute the wheel-to-track technology in a robotic application
  • Lightweight: The robot should be adequately light to be carried by field soldiers
  • Small footprint: The robot must be sufficiently small to fit easily into a soldier’s kit, and avoid detection by opposing soldiers

Furthermore, because of the broad range of potential battlefield environments, the robot must be able to handle extreme environmental conditions (EEC) without undermining performance. This involves working at extreme temperature, both low and high, with potentially extreme humidity.

All parts used in the unmanned ground vehicle (UGV) must endure mechanical shock and continue operating in the challenging, noisy, and volatile conditions of the modern combat zone.

The robot needs to be extremely reliable with an extended Mean Time Between Failures (MTBF) for all its various motion tasks.

As the product integrates a 360° turning base, the commands must be delivered quickly and accurately to facilitate precise motion in tough and delicate operations.

The robot’s compact size demands motion control products that can deliver high-power density within a compact unit.

Elmo’s Solution

The Hornet digital drive was selected for this application, because of its lightweight and compact size. It is PCB-mounted and can be incorporated into the robot.

The Hornet is extremely compact, measuring 55 x 15 x 46.5 mm and weighing just 50 g. It supplies up to 3.3 kW of peak power and 1.6 kW of nonstop power.

servo drives tuning / auto tuner

Composer: Servo drives tuning/auto tuner

Miniature Servo Drive

Hornet: Miniature Servo Drive 20 A/100 V, 10 A/200 V

Five drives of the type HOR-15/60 were selected to be fitted into the robot.

The Hornet belongs to Elmo’s ExtrIQ product series, engineered mainly for rugged and EEC conditions. This enables the Hornet to work in the following extended conditions:

  • Temperature shock: –40 °C to +70 °C within three minutes
  • Ambient temperature: –40 °C to +70 °C
  • Upwards of 90% relative humidity
  • Vibration: up to 2,000 Hz
  • Reduced EMI and minimal RFI
  • Mechanical shock: ±20 g; half-sine, 11 msec
  • Altitude: –400 m to 155,000 m

The five Hornets are fitted on a single PCB within the robot’s compact confines and require less cabling. The connector types and locations were selected to enhance the robot’s production and minimize maintenance. Elmo’s engineers also worked with the design team to confirm that the products were properly integrated, thus reducing the time-to-market.

Elmo offers thorough documentation and consulting services for product integration on the PCB, facilitating the most agreeable fit for the application.

The Hornet drives already have the capability to carry out advanced motion control loops for precise movement, programming capabilities, feedback inputs, and communication support. Its superior connectivity lowers time-to-market and removes the need for additional components.

Miniature Servo Drive

Solo Hornet: Miniature Servo Drive 20 A/100 V, 10 A/200 V

The Hornet drives are highly reliable and can match the challenges of the combat zone while safeguarding the lives of the soldiers who depend on the robot’s capabilities.

Elmo’s exclusive Elmo Studio software is used to program the commands for the Hornet and this allows the robot to carry out the precise tasks that require fast and accurate movement.

Why Elmo

  • The ExtrIQ product series for military and EEC applications matches the demands of combat zone applications and is equipped for extreme conditions
  • High-power density and intelligence in a small package
  • Compact, pin-based, PCB-mounted items that have a small footprint
  • Quick, precise, and efficient motion control
  • Typical communication protocols
  • High reliability in challenging military surroundings
  • Elmo’s dedicated support engineers ensure successful implementation of solutions

This information has been sourced, reviewed and adapted from materials provided by Elmo Motion Control Ltd.

For more information on this source, please visit Elmo Motion Control Ltd.

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