About 1 billion passenger cars are on the roads worldwide today, a number that’s expected to double by 2040. The cars need to park, but the rising cost and decreasing availability of land make parking a major challenge for developers, architects, and urban planners.

Serva Transport Systems addressed the problem with Ray, an automated guided vehicle (AGV) system that can potentially increase the packing density of vehicles by up to 60%. Ray is capable of lifting automobiles weighing as much as three tons and placing them with an accuracy measured in millimeters. Ray’s four wheels are powered by brushless DC servo motors and are capable of rotating 360°. The robot can travel at a speed of up to 3 m/s with acceleration of approximately ±0.4 m/s2.

Read this case study to learn about:

  • Preventing an inertia mismatch stemming from undersized motors and drives
  • Enabling a long duty cycle between battery recharges with a servo drive that delivers over 99% efficiency
  • Achieving high speeds and high acceleration rates with small, high-power servo drives
  • Reaching 15 kW of continuous output power from a package weighing just 700 g
  • Optimal servo drives for operating in wide voltage change rates
  • Built-in, TUV-certified safety functionality with safe torque off (STO)

Tired of looking for parking? Get a robot to park for you

Don’t you hate circling a full parking lot, waiting for a space? It’s set to get worse as populations grow denser. Taking on the parking challenge, Serva Transport Systems developed an automated guided vehicle (AGV) system that can increase the density of parked vehicles by up to 60%. For this, they needed a safe, high power motion control solution. Read how Elmo delivered it.

Machine requirements

To minimize the amount of parking area used per vehicle, the Ray robot had to be as compact as possible. Therefore, the motors and drives had to be small but still generate enough torque to control the heavy load. The combined weight of the robot and maximum load capacity is 5.5 tons. At those weights, an inertia mismatch stemming from undersized motors and drives could be disastrous.

Ray’s wheels needed to both move the vehicles and maintain safe operation during complex maneuvers. Therefore, it was critical that the robots avoid contact with people, the structure, other vehicles, or even other robots. In addition, as with all portable systems, motor and drive efficiency was vital to keeping recharging time to a minimum.

The Elmo Motion control solution included:

The Serva team chose Elmo’s 150 A/100 V Gold Drum to meet its motion control requirements. The drive delivers 15 kW of continuous output power from a package weighing just 700 g.  Elmo drives operate with >99% efficiency, enabling the Ray to operate for up to eight hours between charges.

Power quality varies over the discharge cycle of a battery, so the minimum supply voltage of a drive is just as important as the maximum. Elmo’s Gold Drum drive can handle a variation in source voltage ranging from 14-95 VDC, enabling the drives to be effective throughout the charge lifetime.

To navigate to a planned destination, Ray uses optical sensors and retro reflectors to communicate wirelessly with the central controller an average of 6000 times in a single trip. The Gold Drum drives communicate with the sensors and feedback devices over an EtherCAT network.

Elmo’s Gold Drum drives are equipped with safety functionality  in the form of safe torque off (STO). Ray scans the surroundings 100 times per second to maintain situational awareness and check for obstacles and personnel. If one of the sensors detects an obstacle, it sends an alert to the drive over the EtherCAT network, which operates with a cycle time of 100 µs or better. The Gold Drum drive then invokes STO, immediately preventing the motor from generating torque and an external brake stops the vehicle. The drive remains energized to streamline restart.

The outcome

Elmo’s Gold Drum drives enable the Ray AVG to operate effectively and efficiently. High power-density minimizes the space required for the drives, while their high efficiency maximizes operating lifetime per charge. The drives also offer compatible connectivity and built-in safety functionality to keep individuals, vehicles, and infrastructure from harm.

With Elmo Motion Control, Serva found a supplier for whom product quality and service go hand in hand. “This philosophy fits exactly with our own”, said Leopold Meirer, CEO of Serva Transport Systems.

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