CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/SG2018/050590, filed Dec. 3, 2018, which claims priority to Singapore Patent Application No. 102017100415, filed Dec. 4, 2017, the disclosures of which are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to a sensor-based communication apparatus, a sensor-based communication method, and a communication medium.

BACKGROUND

Artificial somatosensory perception typically requires sensor arrays that can capture and process rapidly varying contact stimuli over non-uniform surfaces. Electronic skins (e-skins) are electronic devices that are arrayed to facilitate the sensing of human-machine-environment interactions with applications in advanced collaborative anthropomorphic robots and neuro-prosthetics. Although much progress has been made in developing compliant e-skin sensors with high sensitivity, known signal communication arrangements of such e-skin sensors have numerous disadvantages.

One known arrangement of the sensors relies on conventional Time Division Multiple Access (TDMA) architectures for signal communications, in which the sensors are sampled at a predetermined frequency or predetermined time slots. TDMA based sensor systems are known to have poor scalability because sequential data acquisition leads to a greater transmission latency in larger arrays. Further, the conventional row-column wiring for addressing individual sensors is prone to damage. In addition, highly localized and transient contact stimuli, such as a needle prick or an object slip, may be missed if the sensor sampling frequency is too low.

Another arrangement relies on Code Divisional Multiple Access (CDMA) techniques for wireless signal communications. CDMA is more complex due to the need for signal modulation from an intermediate frequency to a carrier frequency. Additional modules for power regulation are also required. Moreover, CDMA uses level shifted codes, which are relatively susceptible to low frequency interferences (e.g., AC power noises). Further, CDMA typically requires expensive high resolution ADCs. CDMA is also known to have a low capacity.

Another known arrangement involves Address Event Representations (AER). AER relies on asynchronous hand-shakes to time-multiplex data packets on a first-come-first-served basis. AER requires an implementation of arbitration logic in order to determine which packet to transmit first in the event of a packet collision, which results in a more complex network.

Optical CDMA is another known signal communication arrangement, known to use unipolar pulses and hence requiring additional synchronization signals and protocols. Dedicated electro-optical components are also required.

Yet another arrangement uses Ethernet. It does not support simultaneous packet transmission from a plurality of nodes. Further, transmission overheads (such as Carrier Sense Multiple Access) are needed to prevent packet collision, and multiple, separate conductors are needed to implement the protocols.

It is desirable to provide a sensor-based communication apparatus, a sensor-based communication method, and a communication medium, which address at least one of the drawbacks of the prior art and/or to provide the public with a useful choice.

SUMMARY

According to a first aspect, there is provided a sensor-based communication apparatus comprising: a plurality of sensor nodes associated with respective unique pulse signatures and adapted to communicate with respective sensors with each sensor configured to generate a sensory signal in response to a respective stimulus, wherein each sensor node is triggered, upon receipt of the corresponding sensory signal, to transmit the associated unique pulse signature independently and asynchronously through a transmission medium shared by the sensor nodes, the unique pulse signatures transmitted by the sensor nodes being a representation of a stimulus event associated with the stimuli detected by the corresponding sensors.

The described embodiment is particularly advantageous. For example, since the sensor nodes are configured to transmit the respective pulse signatures independently with each trigger, i.e. on receipt of the stimulus, a highly efficient signalling scheme may be achieved. Since the described embodiment includes using event-based sensing elements responding to a single stimulus event, a resultant pattern in space and time may be used to represent the stimulus event.

Preferably, each inter-pulse interval of the unique pulse signature of each of the sensor nodes may have a unique duration. Such an arrangement is useful in reducing the probability of collision of pulses transmitted by the sensor nodes.

The unique pulse signature may have eight or ten pulses, or any number of pulses. An optimal performance of Signal to Interference and Noise Ratio (SINR) can be achieved when the number of pulses fall within or is close to this range or the alternative range of 8 to 14 pulses.

Alternatively, the unique pulse signature of one of the sensor nodes may have a first number of pulses and the unique pulse signature of another of the sensor nodes may have a second number of pulses different from the first number. This arrangement allows the numbers of pulses to be flexibly determined, for example, based on the types and numbers of associated sensors.

Preferably, the unique pulse signature has a signature duration of 1 ms (millisecond). This allows the sensor nodes to mimic the transmission performance of the biological counterparts. The signature duration may also be adjusted to meet various capacity needs.

Alternatively, the unique pulse signature of one of the sensor nodes may have a first signature duration and the unique pulse signature of another of the sensor nodes may have a second signature duration different from the first signature duration. This arrangement allows the signature durations to be flexibly determined, for example, based on the types and numbers of associated sensors.

Preferably, the unique pulse signature may have a pulse duration of 60 ns (nanoseconds). This allows the sensor nodes to mimic the transmission performance of the biological counterparts. More preferably, the unique pulse signature may have a pulse duration shorter than 60 ns (nanoseconds) which may maximise capacity and minimise error rates.

Alternatively, the unique pulse signature of one of the sensor nodes may have a first pulse duration and the unique pulse signature of another of the sensor nodes may have a second pulse duration different from the first pulse duration. This arrangement allows the pulse durations to be flexibly determined, for example, based on the types and numbers of associated sensors.

Preferably, the apparatus further comprises the sensors. The apparatus may be manufactured so that each sensor node is integrated with or otherwise associated with a corresponding sensor. Where the apparatus does not comprise the sensors, the sensor nodes of the apparatus may be adapted to be associated with external sensors. The sensors may include tactile sensors of different sensitivities. By mixing sensors of different sensitivities, a more accurate, comprehensive representation of the stimulus event can be obtained. Further, the sensors may include temperature sensors. Other types of sensors may also be included such as electro-magnetic, humidity, surface texture, vibration, acceleration and/or optical sensors etc.

Preferably, each sensor node may be triggered, upon receiving a current value in the corresponding sensory signal, to transmit a current one of the associated unique pulse signature to indicate the current value by an interval between the current one of the associated unique pulse signature and a previous one of the associated unique pulse signature. This arrangement is useful when the sensor node is associated with a sensor which generates a sensory signal representing a current value of detection by the sensor. For example, the sensory signal may have a state representing the current value. A slow adapting (SA) sensor (or a piezoresistive resistive element configured to be a slow adapting sensor) is one such sensor.

The sensor nodes may be adapted to be associated with one of a robot, a human and a vehicle, or a robot may comprise such a sensor-based communication apparatus.

Preferably, the sensor nodes may harvest power from an external energy source. Such a source may be a source of electromagnetic waves, mechanical motions, solar energy, chemical substances, or the likes.

The apparatus may further comprise: a receiver configured to receive through the transmission medium an incoming signal relating to the transmitted unique pulse signatures, to correlate the associated unique pulse signature of each sensor node with an intermediate signal relating to the incoming signal, and to provide indication signals indicating respective times of triggering of the sensor nodes based on a result of correlation for representation of the stimulus event. The receiver may be locally or remotely located with respect to the sensor nodes.

Preferably, the receiver includes a plurality of filters each activated, upon detection of an edge in the incoming signal by the receiver, to correlate the intermediate signal with a corresponding one of the unique pulse signatures. This arrangement allows the filters to be activated to correlate the intermediate signal with the signatures in parallel when the edge is detected in the incoming signal. That is, the filters may remain deactivated to save power when no signature is transmitted (thus no edge). Other components (e.g., correlation threshold circuits) associated with the filters may be activated and deactivated correspondingly.

The transmission medium may include a conductive medium, and the sensor nodes may be distributed along the conductive medium and electrically coupled to one another through the conductive medium. Preferably, the sensor nodes are arranged on a surface of the conductive medium. Preferably, the sensor nodes are embedded in the conductive medium. Preferably, the conductive medium is made of polymer. Preferably, the conductive medium is elastic and flexible. Preferably, the conductive medium is mesh or planar in form. With one or more of such arrangements, signal communication via the conductive medium is resistant to damages such as tears. Communication between two portions of the conductive medium remains unaffected unless one portion is completely torn or otherwise removed from the other portion.

The conductive medium may include at least one of a conductive fabric, a conductive bulk conductor, a conductive substrate, a conductive solid, a conductive gel, and a conductive fluid. For example, when the conductive medium is implemented in the form of a fabric or substrate may be suitable for electronic skin applications. For the avoidance of doubt, “fluid” can include, but is not limited to, “liquid”.

It is envisaged that each sensor node may be associated with one or more unique pulse signatures. Preferably, each sensor node may be further associated with a further (or another) unique pulse signature. This arrangement is useful when the sensory signal of each sensor has two states. Each sensor node may be triggered, upon receipt of the corresponding sensory signal in a first state, to transmit the associated unique pulse signature, and upon receipt of the corresponding sensory signal in a second state, to transmit the associated further unique pulse signature independently through the transmission medium. The unique pulse signatures associated to each sensor node may correspond to or exceed the number of states in the corresponding sensory signal.

Each sensor node may be configured to transmit the associated further unique pulse signature independently through the transmission medium to indicate an internal state of the respective sensor node. This arrangement reduces the need for another communication path or channel for indicating the internal state.

Further, the unique pulse signatures of each sensor node may have different pulse polarities. For example, two signatures assigned to a sensor node may have the same pulse positions and opposite pulse polarities, where a pulse polarity is a positive or negative voltage potential. Further, two signatures of a sensor node may be otherwise different, either partially or wholly.

Advantageous, the representation of the stimulus event may be a spatiotemporal representation.

In a second aspect, there is provided a sensor-based communication method comprising: receiving a sensory signal generated by a corresponding sensor in response to a respective stimulus, and upon receipt of the sensory signal, triggering respective ones of a plurality of sensor nodes to transmit an associated unique pulse signature independently and asynchronously through a transmission medium shared by the sensor nodes, the unique pulse signatures transmitted by the sensor nodes being a representation of a stimulus event associated with the stimuli detected by the corresponding sensors.

In a third aspect, there is provided a communication medium comprising: a conductive medium; and a plurality of sensor nodes distributed along the conductive medium and electrically coupled to one another through the conductive medium.

The conductive medium of the described embodiment provides a high degree of flexibility in sensor node placement, and provides robust signal conducting paths for the sensor nodes.

It is envisaged that features relating to one aspect may be applicable to the other aspects.

