I have found some interesting concepts. However, I would only take partial parts of these elements to put together my design

- robotic arm mounted on the front middle of the cart; arm with predetermined elevation and depression magnitude; rotatable

- tracks instead of wheels for better grip and maneuverability. made of plastic in order to avoid damage to the ground; made to support more weight; 

- storage constructed in a U shape; spring to allow bendable and flexible movements from the plaform

- shopping cart with computer, allowing both research of products and payment on the spot