Rotatable coupling

#This invention generally relates to rotatable couplings, such as those used in robotic systems for transmitting electrical power and/or signals across a continuously rotatable interface.

#Robotic systems implement devices—such as sensors and end effectors—to learn about and manipulate their environment. Some robotic systems include a coupling that serves as a mechanical joint. The coupling can provide electrical and mechanical connection between the device and the rest of the robotic system. In some cases, the coupling is configured to allow the device to rotate continuously, or at least through more than a full revolution, relative to the rest of the system. Various means of transmitting signals and/or power across such couplings have included slip rings (which feature a sliding or rolling electrical contact) and winding/unwinding coiled conductors that provide a limited range of rotation, for example.

#One aspect of the invention features a continuously rotatable coupling including an input housing rotatably coupled to an output housing by a hollow tube fixed to the output housing and on which tube the input housing rotates. The hollow tube defines a central passage. The coupling includes two cooperating magnetic flux concentrators disposed about the tube and defining therebetween an annular cavity The flux concentrators include a first flux concentrator fixed to the input housing and a second flux concentrator fixed to the output housing, such that relative rotation of the input and output housings causes relative rotation of the flux concentrators on either side of the annular cavity. The coupling includes concentric coils disposed within the annular cavity and positioned to permit electrical contact-free power transfer across the coupling. A first of the concentric coils is fixed to the input housing and a second of the concentric coils is fixed to the output housing. The coupling further includes an optical data emitter fixed to the input housing and positioned to transmit optical signals through the central passage and an optical data receiver fixed to the output housing and positioned to receive the optical signals from the input optical data emitter during the relative rotation of the input and output housings.

#FIG. 1A is a perspective view of an autonomous robot with a rotatable coupling with a sensor module navigating in a region.

#FIG. 1B is a block diagram of electromechanical systems of the autonomous robot of FIG. 1A.

#FIG. 2A is a perspective view of the coupling with the attached sensor module shown disposed on top of the autonomous robot of FIG. 1A.

#Like reference symbols in the various drawings indicate like elements.

#A robot with a power system, a drive system, a navigation system, and a sensing system navigates around a region, which can be, for example, a room in a house, a lawn, an academic institution, an office, or a wilderness area. The drive system can rotate the robot such that a forward drive direction of the robot rotates as well. One or more boundaries—for example, virtual and physical boundaries—can confine the robot to navigate within the region. The region can further contain obstacles located within the confines of the boundaries. As the robot navigates around the region, the features of the region—for example, the boundaries and the obstacles—can be located in various directions relative to the forward drive direction of the robot. The sensing system can include sensors disposed on the robot to detect features of the region, such as the boundaries or the obstacles. The object detection system using one or more sensors is disposed on a chassis of the robot. These sensors can include, for example, a camera, a wideband (WB) transceiver, a radio transceiver, an infrared (IR) laser transceiver, and/or some other radiation transceiver known in the art. The sensors, such as the laser-based sensors and the camera, can be directional (e.g., the orientation of the sensors can determine the area of the region that the sensor is sensing.). Each sensor can be coupled to a coupling that allows the sensor to rotate relative to the robot. The coupling includes both a stationary portion fixed to the robot and a rotatable portion coupled to the sensor. The coupling can orient the sensor to an angle relative to the forward direction of the robot. As described in more detail below, data and power can be transmitted to and received from the rotatable portion of the coupling while it rotates relative to the stationary portion of the coupling. Likewise, data collected from the sensor can be transmitted to the stationary portion.

#Overview of Example Robot