Method of braking automated guided vehicle, and automated guided vehicle

A method of braking an automated guided vehicle, the automated guided vehicle comprising a support structure and at least three drive units connected to the support structure, wherein each drive unit comprises:

• a wheel rotatable about a wheel axis and about a steering axis perpendicular to the wheel axis;
• an electric wheel motor arranged to drive the wheel about the wheel axis;
• a wheel sensor device arranged to determine a first rotational position of the wheel about the wheel axis;
• an electric steering motor arranged to drive the wheel about the steering axis;
• and
• a steering sensor device arranged to determine a second rotational position of the wheel about the steering axis;
• wherein the method comprises:
• positioning two wheels of the drive units on two non-coincident wheel lines;
• position controlling each wheel of the drive units to hold a target position about the respective steering axis;
• position controlling each of the two wheels to hold a target position about the respective wheel axis;
• and
• velocity controlling each of the remaining wheels of the drive units about the respective wheel axis based on a zero velocity.

A method of braking an automated guided vehicle, the automated guided vehicle comprising a support structure, and at least two drive units connected to the support structure, wherein each drive unit comprises:

• a wheel rotatable about a wheel axis and about a steering axis perpendicular to the wheel axis;
• an electric wheel motor arranged to drive the wheel about the wheel axis;
• a wheel sensor device arranged to determine a rotational position of the wheel about the wheel axis;
• an electric steering motor arranged to drive the wheel about the steering axis;
• and
• a steering sensor device arranged to determine a rotational position of the wheel about the steering axis;
• wherein the method comprises:
• electrically powering the wheel motors and the steering motors of the drive units by a primary power supply in a primary power mode;
• velocity controlling each wheel of the drive units about the respective wheel axis based on non-zero target wheel velocities;
• and
• emergency braking the automated guided vehicle upon a voltage drop or a power loss in the primary power supply, the voltage drop or the power loss being detected as an emergency;
• wherein the emergency braking comprises:
• braking each wheel about the respective wheel axis;
• electrically powering the steering motors in a secondary power mode;
• and
• controlling each wheel about the respective steering axis based on a target valid configuration of the wheels.