In a liquid level monitor for use with a liquid container of a liquid-consuming device, a light source transmits a light beam into the liquid container at a non-normal angle of incidence respective to a wall of the liquid container. A photodetector is positioned in the path of one of (i) the light beam after passing through the liquid container when the light beam is not refracted by liquid in the liquid container and (ii) the light beam after passing through the liquid container when the light beam is refracted by liquid in the liquid container. In another approach, the sensor for detecting empty includes a vibrator and a vibration sensor, and an electronic processor is programmed to determine whether the liquid container is empty of liquid based on the detected vibration of the liquid container.

In example implementations, a powder level sensor is provided. The powder level sensor includes a capacitive sensor, a processor, and a cleaning mechanism. The processor is communicatively coupled to the capacitive sensor. The processor interprets a measurement of the capacitive sensor to detect a layer of residual build material on a surface of the powder level sensor. The cleaning mechanism may be communicatively coupled to the processor. The processor activates the cleaning mechanism to remove the layer of residual build material on the surface of the powder level sensor.

A guide robot includes a lower module includes a wheel and a motor provided inside the lower module, and an upper module disposed at an upper portion of the lower module and including a trash can assembly and a display unit. The upper module includes a body part coupled to the upper portion of the lower module and a head part rotatably coupled to an upper portion of the body part. The body part includes a front case forming a front outer appearance of the body part and including the trash can assembly provided inside the front case, and a rear case forming a rear outer appearance of the body part and including the display unit. A garbage insertion part is provided at a portion of the front case corresponding to an upper portion of the trash can assembly to insert garbage into the trash can assembly.

A fuel storage system has a tank access chamber with improved monitoring, servicing and maintenance capabilities. In particular, the chamber includes a sump monitored by a liquid sensor whose proper function can be automatically checked remotely, e.g., via an electronic controller or remote manual operation. In cases where such a check indicates a need for physical inspection of the sump sensor, the present system provides for sensor removal and installation by service personnel from a location outside the tank access chamber. Thus, the present system facilitates regular inspection and routine or unplanned maintenance without the need for a person to physically enter the tank access chamber.

In example implementations, a powder level sensor is provided. The powder level sensor includes a capacitive sensor, a processor, and a cleaning mechanism. The processor is communicatively coupled to the capacitive sensor. The processor interprets a measurement of the capacitive sensor to detect a layer of residual build material on a surface of the powder level sensor. The cleaning mechanism may be communicatively coupled to the processor. The processor activates the cleaning mechanism to remove the layer of residual build material on the surface of the powder level sensor.

A method of determining a volume of a fluid in a reservoir arranged in a vehicle includes assessing, via a controller, whether a first sensor operatively connected to the reservoir and configured to detect a predetermined level of the fluid in the reservoir has been triggered. The method also includes detecting, via a second sensor, a vehicle operative state indicative of inclination of a free surface of the fluid in the reservoir. The method additionally includes communicating, via the second sensor, the detected vehicle operative state to the electronic controller and determining a degree of inclination of the free surface of the fluid in response to the detected vehicle operative state. Furthermore, the method includes determining, via the controller, the volume of the fluid in the reservoir when the first sensor has been triggered in response to the determined degree of inclination of the free surface of the fluid.

A fuel storage system has a tank access chamber with improved monitoring, servicing and maintenance capabilities. In particular, the chamber includes a sump monitored by a liquid sensor whose proper function can be automatically checked remotely, e.g., via an electronic controller or remote manual operation. In cases where such a check indicates a need for physical inspection of the sump sensor, the present system provides for sensor removal and installation by service personnel from a location outside the tank access chamber. Thus, the present system facilitates regular inspection and routine or unplanned maintenance without the need for a person to physically enter the tank access chamber.

A liquid level sensor 1 comprises a sleeve 2 disposed so as to extend in the vertical direction, a float 3 configured so as to move along said sleeve according to fluctuation of liquid level, a resistor string 4, a plurality of grounding means 5 disposed inside the sleeve 2 and a liquid level signal output means 6 to take out an electric signal detected between a positive electrode side end part 4a and a junction part grounded by the grounding means 5 as a liquid level signal that is a signal corresponding to the liquid level, and further comprises a warning signal output means 7 to output a warning signal when the float 3 is located within a predetermined distance from a warning position that is a predetermined position within a movable range of the float 3. Thereby, a compact and reliable liquid level sensor is realized.

A system for preventing overflow of a toilet includes a sensor, a processor and an actuator. The sensor senses a parameter caused by fluid dynamics within the toilet during a flush cycle. The parameter may involve vibration, sound, pressure, fluid flow rate or other detectible characteristics of the toilet. The processor uses information regarding the parameter that is gathered by the sensor to evaluate the condition of the flush cycle to determine if an impeded flush condition exists. In the event of an impeded flush condition, the processor directs the actuator to close a valve, which may be the toilet flapper valve in some embodiments. Also disclosed are methods for preventing toilet overflow, detecting an impeded flush condition and calibrating the system.

A fuel storage system has a tank access chamber with improved monitoring, servicing and maintenance capabilities. In particular, the chamber includes a sump monitored by a liquid sensor whose proper function can be automatically checked remotely, e.g., via an electronic controller or remote manual operation. In cases where such a check indicates a need for physical inspection of the sump sensor, the present system provides for sensor removal and installation by service personnel from a location outside the tank access chamber. Thus, the present system facilitates regular inspection and routine or unplanned maintenance without the need for a person to physically enter the tank access chamber.