The ATR1 can position itself precisely in confined spaces thanks to sideways movements known as strafing. © Tractonomy Robotics

The movement system must be able to tow a heavy weight and therefore generate sufficient torque to set a payload of several hundred kilograms in motion from a standing position. To enable it to be operated in confined spaces, its first AMR design was only 70 centimetres long and 50 centimetres wide. A compact motor that took up very little space was therefore essential. After several tests, the decision was made in favor of a brushless Maxon DC flat motor, the EC 60 flat. With four motors per robot - one per wheel - the design also had to be cost-effective for series production, especially as the motors also require integrated, high-resolution encoders.

Robots for heavy loads

"We tested these engines in the ATR1 prototype and they were really impressive. They could pull a car with the extra weight of three people. And they are really tiny motors, only 60 millimeters wide," Chintamani points out. With the concept confirmation of the initial design, an autonomous towing robot called ATR1 (Autonomous Towing Robot), Tractonomy Robotics was born. The ATR1 can tow trolleys of any design weighing up to 400 kg at speeds of more than 1 m/s. With the support of a special navigation module, the robot docks quickly and can even recognize free parking spaces and park trolleys autonomously. The navigation system uses cameras and computer vision feedback. The control accuracy is based on the reaction speed of the motors.

With the concept confirmation of the initial design, an autonomous tugger robot called ATR1, Tractonomy Robotics was born. © Tractonomy Robotics

"The ATR1 can dock precisely and reliably onto trolleys in under 20 seconds and, thanks to sideways movements known as strafing, can position itself precisely in confined spaces by making the smallest of adjustments," says Chintamani. After further trials with ATR1, Tractonomy Robotics received requests for towing larger payloads, such as metal sheets weighing 800 kg and more. This led to a radical redesign, the ATR2, with a unique, adaptive double-arm docking system. This enables the robot to handle a whole range of different trolley sizes. Tractonomy plans to produce the ATR2 in a standard torque version as well as a high torque version. The tensile loads will be 600 and 800 kg respectively, with speeds of 1.8 to 2.5 m/s - equivalent to 6.5 to 9 km/h - being achieved.

Flexibility in material handling

With dimensions of 90 x 64 cm, the ATR2 is larger than its predecessor in order to make room for additional batteries and new electronics. However, in order to be able to transport the higher payload while maintaining a compact size, significantly higher torque motors were required. "After consulting with Maxon engineers, it became apparent that we could use a lower voltage motor suitable for the overall system that could still produce the peak motor speeds and torques required by the higher load while maintaining thermal limits," explains Chintamani. "Thanks to this significant recommendation, we offer a single platform suitable for a range of cars and payloads using just two motor types."

When pulling heavy loads at high speeds, braking power becomes all the more important. This is why the ATR2 is equipped with integrated brakes and a 360-degree safety system that prevents collisions. Component failure safety also plays a key role in round-the-clock operation. "These machines cover at least 15 to 20 kilometers a day under variable conditions. Downtime reduces productivity. A reliable motion solution is therefore particularly important," says Chintamani.

Maxcon flat motors are particularly suitable for limited space conditions. © Maxon

ATR2 is currently entering the operational validation phase. Tractonomy is now focusing on series production. The AMR is primarily aimed at the manufacturing industry and distribution logistics that rely on material handling technologies - such as factories, warehouses of large supermarkets and postal service providers. The robots can also be used to load and unload trolleys into trucks, replacing conventional tugger trains and conveyors and providing a safer and automated alternative to forklift trucks. Chintamani continues: "We are seeing an increasing demand for a single machine that can be used for a variety of material handling applications. This reduces costs and administration for the end user. Tractonomy offers exactly this flexibility with just one robot that can be used for a wide range of material handling functions."

Flat motors as a solution for limited space

Maxon flat motors are particularly suitable for limited space conditions. The brushless motors are designed as internal and external rotors and achieve speeds of up to 20,000 revolutions per minute. The EC flat motors are optionally available with Hall sensors, sensorless or with integrated electronics. They can also be combined with gearboxes and encoders.