E09 – Cart push

General description. A customer decides to pay a visit to the shopping mall to do some shopping. S/he likes to visit shops, but hates to bring around her/his purchases. Fortunately, the mall has some new robot shopping helpers. In fact, as soon as the customer arrives at the mall, one of the “robot helpers” is assigned to her/him. The robot will take care of pushing the shopping cart, following the customer through the corridors and shops of the mall while keeping a safe distance; however, whenever the customer needs to put something in the cart or pull something out, s/he only has to ask the robot to “Come here” and the robot will park the cart next to her/him, waiting for the “Let’s go!” command before resuming movements. A final “Park the cart” command tells the robot to park the cart and stop.

Platforms allowed. Any platform possessing actuators capable of physically interacting with the cart’s handle (which is a standard bar of the type used by human shopping cart users), and of receiving vocal commands.

Setting. A small area of the shopping mall comprising part of a corridor and two shops opening on it. The environment includes a section of a wall, against which the shopping cart is parked at the start and at the end. In the area are present fixed obstacles (benches, columns, trash bins, …).

Procedure. Before the start of the episode, a customer reaches the robot at its starting position. The episode starts, and the robot (without need for commands from the customer) collects the shopping cart that is parked in a nearby space against a wall. Then the shopping begins: the customer visits 2 different shops, one very open and one where the customer has to navigate through obstacles (dress stands). The robot must avoid losing the customer, even when a person dressed with perfectly matched colors walks between the robot and the customer. In general, other customers and obstacles of different types are present in the area. During the episode, two times the customer commands the robot to “Come here” and then gives the “Let’s go” command, each time after visiting one of the shops. When the customer and the robot are back in the shopping cart parking area, s/he tells the robot to “Park the cart”. The episode ends when the cart is back in its parking position. During the episode, the robot should never be more than 5 m from the customer. If the robot perceives that its distance from her/him is more than 3m, it can ask the customer (vocally) “Wait for me”. In this case, the customer stops and gives the robot some time to catch up with her/him (i.e. get their distance below 3m).

DH interaction. None.

Main functionality(ies). The main functionalities tested are Robot Control under external forces.

Auxiliary functionalities. Other required functionalities are Localization and Navigation, Speech Understanding and Grasping (of the cart’s handle).


  • The robot correctly retrieves the shopping cart from its parking space.
  • The robot correctly reacts to the first “Come here” command.
  • The robot correctly reacts to the first “Let’s go” command.
  • The robot does not lose the customer when the similarly-dressed person walks behind them.
  • The robot correctly reacts to the second “Come here” command.
  • The robot correctly reacts to the second “Let’s go” command.
  • The robot correctly reacts to the “Park the cart” command.
  • The robot correctly parks the shopping cart in its parking space.

Penalising behaviors.

  • The robot lightly touches a person with its body or the shopping cart.
  • The robot hits an obstacle with its body or the shopping cart.
  • Acceleration (linear or rotational) of the shopping cart exceeds predefined values.
  • Velocity (linear or rotational) of the shopping cart exceeds predefined values.
  • The robot requires repetition of a command to execute it.
  • The distance between the customer and the robot goes over 5m (applied every time this occurs, and, for each occurrence, applied again every 30s from previous application).
  • The robot asks the customer to “Wait for it” (first request is not penalised, each subsequent requests is).
  • The robot hits a person with its body or the shopping cart.
  • The robot damages the shopping cart.
  • The robot damages the shopping mall.

We were delighted to support the @SciRocChallenge event, focused around the theme of Smart Inclusion in Smart Cities, including challenges such as delivering coffee shop orders, and sign language interpretation. Learn more about the event in our blog: https://blog.pal-robotics.com/sciroc-challenge-robotics-in-smart-cities-plus-tiago/

One week ago... the #SciRoc2021 final took place! 🤖 Missed out on any of the action? Find our winning teams, highlights from the event and all competition streams at: http://www.sciroc.org

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