Abstract: A device that uses a motor may quickly and safely stop the motor using a rapid braking system. For example, the device may stop to avoid collision with an object, upon determining a failure of an internal component, upon receipt of a command, and so forth. Responsive to a signal to stop, the motor is disconnected from the battery. A braking circuit is activated that dissipates, in a controlled fashion, power produced by continuing motion of the motor. When the voltage produced by the motor's continuing motion drops below a threshold, a stop circuit shorts the terminals of the motor, causing the motor to resist further rotation. When the stop condition no longer applies the signal to stop is removed resulting in the motor being reconnected to the battery, the braking circuit being deactivated, the stop circuit opens the short between the terminals of the motor, and normal operation resumes.

Abstract: An autonomous mobile device (AMD) builds up electrostatic charges from moving and generates heat from the operation of internal components. In addition to possible user discomfort, electrostatic discharges may damage sensors and electronics. Electrostatic charges are dissipated from the AMD using an electrostatic dissipation structure and conductive wheels. A conductive path between a chassis ground, the electrostatic dissipation structure, and the conductive wheels improves the dissipation of electrostatic charges. Electrostatic charges are also dissipated from components by mounting the components using conductive materials. Sensors may be affixed to a support structure that is affected by thermal expansion. Thermal expansion may distort precise positioning of sensors, reducing accuracy of sensor data. An elastomeric foam may be used to mount sensors to a support structure, allowing for thermal expansion without distorting the positioning of the sensors.

Abstract: An autonomous mobile device may use a pair of main wheels and a caster assembly to provide mobility. The main wheels are driven by motors, providing steering and movement. Each main wheel may include a cover that conceals and protects a hub of the main wheel from the external environment. The covers may be held in place by elastomeric posts, allowing easy changeout. The caster assembly has a minimal overall height and a field replaceable caster wheel. The caster wheel may include a target that is detectable by a non-contact sensor to detect caster wheel rotation. The caster wheel may comprise an axle, caster wheel hub, and a pair of caster wheel endcaps on each end of the axle. A set of features on the caster wheel hub and each of the caster wheel endcaps provide a labyrinthian path that prevents debris from fouling around the axle.