WO2008058959A1

WO2008058959A1 - A method and a system of managing remote devices placed on objects

Info

Publication number: WO2008058959A1
Application number: PCT/EP2007/062270
Authority: WO
Inventors: Baldur Thorgilsson
Original assignee: Kine Ehf
Priority date: 2006-11-13
Filing date: 2007-11-13
Publication date: 2008-05-22
Also published as: EP2086394A1

Abstract

This invention relates to a system and a method for managing remote devices adapted for placement on one or more objects, where at least one of the remote devices is adapted to measure at least one or exert at least one object characteristic. A command initiates an action command to be executed simultaneously at the remote devices, and a transmitter for transmitting the action command to a master base device, which forwards the action commands to the remote devices. The remote devices comprise receivers tuned to a single and common frequency channel, and the forwarding to the remote devices is performed via the single common frequency channel.

Description

A METHOD AND A SYSTEM OF MANAGING REMOTE DEVICES PLACED ON OBJECTS

FIELD OF THE INVENTION

The present invention relates to a system and a method for managing remote devices adapted for placement on one or more objects, where at least one of the remote devices is adapted to measure at least one object characteristic. The present invention further relates to a communication protocol to be implemented in the system for communicating from the system.

BACKGROUND OF THE INVENTION

In movement analysis of humans, animals and machines (e.g. robots), many types of measuring systems are available. Measuring movements can be roughly divided into three categories: kinematics (the position and movement of body in space), kinetics (internal, external and contra acting forces and pressures) and physiological signals (most typical electromyography, EMG, electrical potentials inside muscles or at the surface of the skin above the muscle in question. Other examples are EEG, ECG, breathing and temperature).

Current use of movement analysis includes computer games, animation, rehabilitation, sports, ergonomics, behavioral and psychological analysis, orthosis and prosthetics fitting and machine -observation, -alarms, -training (e.g. robots). Movement analysis is conducted for scientific purposes (e.g. development of new products or investigation of movement patterns), or as a clinical routine (e.g. gait analysis or biofeedback). Because of the nature of movement it is very beneficial if the measurement of the movement is not effecting the movement.

Current systems for kinematics include optical systems, ultrasound systems and magnetic systems. Some of these systems demand special markers, e.g. small object with optical properties to detect in camera images, magnetic sensors or sound sensors/emitters, to be but on the object. Some even demand wires connected sensors on the object. Kinematics can also be measured with accelerometers, gyroscopes, magnetic direction sensors or with goniometers.

Kinetics is measured by force platforms in one or more dimensions on the ground or measuring planes under the foot of the object (in some cases traveling with the object in the form of a measuring shoe insole), but can also be measured as force or pressure with special force transducers.

Electromyography is divided into two categories: surface EMG and invasive EMG (needles or fine wire). In both cases it is still today very common to measure by wired electrodes that tether the object to a stationary device in the laboratory. Other so-called wireless EMG systems are constructed of a central remote device attached to the body (e.g. to the waist with belt or kept in a back-sack) with wires to the muscle in question (often 0.5 - Im long wires).

Various kinds of signals are used to influence the human body in form of information, biological effect or treatment. Audio and visual stimulus is common in epilepsy research. Visual display and sounds are used in biofeedback to inform about a movement. Vibrators are used in cellular phones to get attention of a single person in a crowd. Electrical stimulation is used to restore or change a function or as training. These signals could be referred to as out-signals in contrast to the previous described signals that could be referred to as in-signals

In the following, a combination of zero or more in-signal and out-signal devices on the object is referred to as remote device (being remotely together with the object of interest and not necessary close to the signal managing system) where as the complimentary part in a input-output-system is referred to as base device (being close to the signal managing system).

Few of the today's EMG devices are wireless, digital, and intelligent with no central remote device and a dimension of a small box (about the size or a match box) snapped on to electrodes that are glued to the skin of the muscle in question. The benefit of such a system using EMG devices is among others less time spent on preparing measurement and less noise in signal. Also this construction introduces the new possibility of measuring on more than one object at the same (e.g. like reaction times between objects).

Most of the today's systems remote devices, EMG wireless devices, are operated via protocols like Bluetooth, Zigbee and Wi-Fi. In the Bluetooth protocol a three- bit MAC address is used, where the "master" can only communicate with up to 7 active remote devices playing the role of the "slave". Such a network of group of up to 8 remote devices (the master and the 7 slaves) is called a piconet, i.e. a wireless network where the Bluetooth technology protocols allows the master device to interconnect with up to the seven slaves. Within such a piconet each individual device and the master "rotate" between different frequencies, i.e. at any instant of time the devices within the piconet have different frequencies, in order to prevent a possible overlap with each other or other ambient remote devices or networks. This is of particular advantage for some applications in wireless local area network, e.g. coexistence.

In the scenarios where the number of devices is more than 8, e.g. up to several hundred or even thousands, there is a need for multiple piconets that form a scatternet, with some devices acting as a bridge by simultaneously playing the master role in one piconet, and slave role in another piconet. Within each piconet the master and the devices within each respective piconet "rotate" between different frequencies. Similar principle applies for Zigbee and Wi-Fi protocols. One difference between Zigbee and the Bluetooth protocol consists in that Zigbee can communicate with up to 32 active remote devices.

Although the above mentioned protocols are especially well suited for wireless local area networks comprising e.g. computers, mobile phones, PDA's and the like, when implementing the protocols in applications where time synchronization between the network devices is an essential factor such as in measuring reaction times between objects, these protocols fail. Just the fact that each individual device and the master "rotate" between different frequencies and sub-nets causes a significant time delay when initiating a simultaneous action command in the devices, e.g. beginning with recording biosignal data.

This time delay increases with increasing number of remote devices, since the piconets must additionally communicate with each other, i.e. the master devices must communicate with each other prior to forwarding the action command to the remote devices.

In praxis, in the case of the blue tooth protocol the time synchronization is not based on round-trip but on the Bluetooth clock offsets reported by the Bluetooth module. The maximal error is then the sum of the max error reading the clock on sender and receiver plus the per-hop error. Reading from the clock is around +/- 1 ms on average and up to 5 ms. The per-hop error should in theory be below 1.25 ms but is praxis the upper limit of this error is 2.5 ms. Accordingly, for 7-hop network, this means that the maximum error is 5+5+17.5=27.5 ms.

Also, the Bluetooth protocol operates in the industrial, scientific and medical (ISM) radio band 2.4 GHz, whereas Zigbee operates in the following ISM radio bands: 868 MHz in Europe, 915 MHz in the USA and Australia, and 2.4 GHz in most jurisdictions worldwide. This large frequency range is at the price of the range of these protocols, which is up to only few meters.

WO 2006/006159 discloses a system, device and method for monitoring parameters, comprising a wireless mobile monitoring device including an array of sensors, which may include one or more physiological sensors and/or one or more environmental sensors, and a medical center server enabled to remotely reconfigure the functioning of the monitoring device. This device is based on monitoring parameters and further discloses a remote reconfiguration by e.g. transmitting software updates, commands and/or instructions from the medical center server to the device using e.g. Global System for Mobile Communications (GSM) or Time Division Multiple Access (TDMA). The operation via GSM or TDMA (which is currently only a theoretical solution) is always done via a telephone exchange or an intermediate server, where there is always a large delay factor plus frequently a queue. This will obviously causes huge delay factor and be impossible to implement in techniques where time synchronization between remote devices is an essential factor, especially where a delay around 1-2 ms can be tolerated, but not more than that.

BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to overcome the above mentioned drawbacks by providing a system and a method for managing biosignal measurements and exertion of biosignal remote devices where time synchronization between the remote devices is an important factor. The object of the present invention further relates to providing a communication protocol for optimizing time synchronization of such remote devices. According to one aspect the present invention relates to a system for managing remote devices adapted for placement on one or more objects, where at least one of the remote devices is adapted to measure or exert at least one object characteristic, the system comprising : • a signal managing system comprising : o a command initiator for initiating an action command to be executed simultaneously at the remote devices, and o a transmitter for transmitting the action command,

• one or more base devices including a master base device, the master base device comprising : o a transceiver for receiving and forwarding the action command to the remote devices, wherein the remote devices comprise receivers tuned to a single and common frequency channel at any instant of time, the forwarding to the remote devices being performed via the single common frequency channel.

Thereby, the time delay for executing the action command at the remote devices simultaneously due to the frequency "rotation" at both the remote device side as well as at the base device is eliminated. Thus, since the action command is transmitted to the remote devices at the single frequency channel the time difference in reception of the action command at the various remote devices is equal or less than lmilli second. This provides very effective time synchronization between the remote devices, i.e. the transmitted command will be received at the remote devices with an extreme low time delay, or less than lmilli second. Such synchronization is as an example very relevant when e.g. measuring neural conductance where two remote devices that are started simultaneously, one at the shoulder that stimulates and the other at the wrist that measures the electroneurogram or electromyogram where it is required that in order that the measurements are reliable tolerates maximum l-2milli seconds. Thus, by implementing prior art protocols where the delay becomes much higher, it will be impossible to conduct such measurement. Also, the system provides almost unlimited number of remote devices within the same network, e.g. up to 65536 devices or 2¹⁶ devices.

In one embodiment, the remote devices further comprise: • a memory having pre-stored data uniquely identifying the devices and their measuring characteristics, and

• a transmitter for transmitting the pre-stored data uniquely identifying the devices to the signal managing system via the one or more base devices.

Thus, the managing system becomes aware of the presence of the devices which allows e.g. an automatic update. New remote devices can be introduced to the system that e.g. automatically updates the signal managing system with its abilities without any manual intervention. E.g. a user has bought an EMG system including 4 EMG devices. Later the user decides to add a force measuring capability. The introduction of a force-remote-device is automatically recognized in the signal managing system and the signal is displayed in newtons in stead of volts. Also, a built in calibration may be provided. Thus, no calibration of the remote device is needed since measuring characteristics may contain the calibration constants that were entered to it during factory calibration. Thus, the delivered data are calibrated to newtons. It follows that each measuring device is very well defined. Also, by adding/removing a remote device, such a change will be identified by the managing system, which makes the system more intelligent. For signals that need frequent recalibration (e.g. pH or drifting sensors) a calibration function is supplied. Also, since the system is particularly suitable to be implemented on more than one object, it is possible to measure e.g. reaction times between the objects.

In one embodiment, the measuring characteristics comprise the measuring mode the remote devices are in.

In one embodiment, the memory is further adapted to store measured data.

Thereby, in case that the communication between the remote devices and the managing system get lost, it is ensured that the measured data will not get lost. This further allows measurements over larger volume than the radio range possible. Also, the signal managing system is capable of, after a recording, to recollect missing data with the help of the memory on board on the remote units.

In one embodiment, the action command comprises commands instructing the remote devices to be in high-power alert state or low power battery saving state.

Thus, an energy saving feature is provided for the remote devices.

In one embodiment, the action command comprises a command instructing the remote devices to start recording data or exerting a physical out signal from or to the at least one object.

In one embodiment, the data measured by the remote devices are transmitted as a data packages from the remote devices to the managing system, the data being subsequently processed for determining at least one object characteristic value.

In one embodiment, the data uniquely identifying the remote devices is associated with the data package transmitted from the remote devices.

Thus, the data package can very easily be linked to the correct remote device. It is therefore ensured that the transmitted data packages will not be mixed when received by the managing system.

In one embodiment, each respective remote device or a group of remote devise is associated with a single base device that communicates with the signal managing system through a communication channel such that the transmitted data package are transmitted to the signal managing system via the associated base devices.

In one embodiment, the determined object characteristic value is subsequently transmitted back to the at least one remote device.

The single remote device may be such that it has an in-signal and out-signal and a downloadable rule for deciding when to apply the out-signal according to the in signal.

Thus, the devices do not require being "intelligent" since the processing is performed on the signal managing system side. The values can be represented to the objects, or to be used as input values for e.g. initiating a warning if the exceed a threshold value. In one embodiment, the remote devices further comprise at least one remote device adapted to alert the object when the object characteristic value reach or exceed a pre-defined threshold value.

In one embodiment, the result of the data processing is subsequently transmitted back to the at least one remote device adapted to alert the object, the least one remote device being pre-programmed to initiate an alert signal if the result of the data processing reaches the threshold value.

Thus, a kind of warning signal can be issued by one of the remote devices, e.g. in a form of light, acoustic sound, vibration, electrical current and the like. Thus, the object can be warned in due time to e.g. stop a certain training program etc.

In one embodiment, the remote devices comprise at least one remote device selected from the group of:

• wireless digital Electromyography (EMG) devices,

• wireless digital accelerometer device

• wirelsess digital gyroscope device

• wireles digital magnetometer device • wireless digital measuring device measuring other physiological data

• a remote device comprising two or more measuring channels for measuring one or more signals simultaneously,

• a remote device comprising a measuring module for switching between two or more different measuring modes, • a remote device comprising a transceiver and is adapted to receive and transmit signals simultaneously,

• a remote device comprising an alert unit for initiating an alert signal, and

• a combination thereof.

In one embodiment, the managing system further comprises a user programming interface.

This allows an advanced user with programming skills to easily make his own application program that e.g. shows all the available remote devices, the base units, signals on a computer screen etc. In one embodiment, the managing system further comprises a user interface and a display for visualizing the real time and/or pre-stored data uniquely identifying the devices and their measuring characteristics graphically on the display.

Thereby, a very user friendly interface is provided that enables the user to see the remote devices that are present.

In one embodiment, the user interface is further provided with a selection function for selecting between the various remote devices displayed on the display.

This allows the user in a user friendly way to select the remote devices that are to participate a session (measurements for in-signals, exertion for out-signals). In one embodiment, the user application interface is further provided with a recollection or retransmission function

In one embodiment, the user application interface is further provided with a function collecting headers to discover the properties of a remote unit

In one embodiment the signal managing system contains a model to interpret and combine signal data relating them to a certain movement. This e.g. makes it possible to make a decision that would be impossible to make based on a single signal. Thus the signal managing system takes the intelligence to a higher level by combining multiple signals into a decision making model.

In one embodiment, the object's characteristics comprises is selected from the group of:

• kinematics,

• kinetics, and

• electromyography, • physiological related signals.

With the term kinematics is meant position and movement of body in space, with the term kinetics is meant internal, external and contra acting forces and pressures, with the term electromyography is meant EMG, electrical potentials inside muscles or at the surface of the skin above the muscles in question. In one embodiment, the remote devices operate in the industrial, scientific and medical (ISM) radio band of 433MHz or 868MHz.

Due to the high bandwidth of Bluetooth, it can only operate on the 2,4GHz ISM band. Zigbee has an option to work on 868 or 902 MHz ISM bands, but only with one channel. Zigbee is only really effective on the 2,4GHz ISM band. These two radio protocols are forced to work on this high ISM band resulting in more attenuation to the signal and shorter radio range. By operating these remote devices on 433MHz ISM band gives radio range up to several hundred meters and has bandwidth matched to the signal giving much higher density of channels than Zigbee and Bluetooth. Being able to work at 433MHz ISM band this invention can cover communications for a whole football pitch at less than 1OmW witch is impossible with Bluetooth and ZigBee. Another example is home monitoring. A 1OmW 433MHz device is more likely to cover a whole flat than a 1OmW 2,4GHz device e.g. due to less attenuation in walls

In one embodiment, the remote devices are operated at the power range between ImW-IOmW.

According to another aspect, the present invention relates to a communication protocol to be implemented in the system for managing the communication from the signal managing system comprising a processor and a transmitter to the remote devices via the master base device, wherein the protocol is adapted to instruct the processor to transmit an action command initiated at the managing system side to the master base device such that the action command becomes forwarded to the remote devices via the single frequency channel being common with the receipt frequency channel of the remote devices.

For comparison with other communication protocols, Bluetooth uses frequency hopping to avoid coilision with other traffic. Rotating between a set of frequencies minimises the chance of lack of communication because of occupied frequency. Zigbee uses another scheme to fight compeating data traffic. Pseudo random code is added before transmission and same code is used in reception. This does fight the noise but also increases the bandwidth and thus reduces the number of channels available for same radio channel. In Zigbee at 2,4GHz ISM band there are 16 available frequency channels. For each of the frequency channels several pseudocode can be used making several logical channels on same carrier frequency.

The advantage of said communication protocol is that it does not need these spreading or hopping schemes, which makes the frequency band usage more effective and allowing more signal channels.

According to yet another aspect, the present invention relates to a method of managing remote devices adapted for placement on one or more objects, where at least one of the remote devices is adapted to measure or exert at least one object characteristic, the method comprising: • initiating an action command to be executed simultaneously at the remote devices, • transmitting the action command to the remote devices via a master base device comprising a transceiver for receiving and forwarding the action command to the remote devices, wherein the remote devices comprise receivers tuned to a single and common frequency channel at any instant of time, the forwarding to the remote devices being performed via the single common frequency channel.

According to yet another aspect, the present invention further relates to a computer program product for instructing a processing device to execute the above mentioned method steps when the product is run on a computer.

The aspects of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which

Figures 1 and 2 show a system according to the present invention for managing remote devices, Figure 3 shows one embodiment of the system 1 shown in Figs. 1 and 2,

Figure 4 shows one embodiment of a remote device shown in Figs. 1-3,

Figure 5 shown one embodiment of a base device,

Figure 6 shows a system according to the present invention is configured of N remote devices and N base devices (Ia) and also shows another system configuration where there is only one base for multiple (M) remote units (Ib). Figure 6 also describe a possible coexistence demand for two systems of the type of present invention in the same radio space witch is solved by net numbers.

Figure 7 shows an example of a system according to the present invention consisting of three remote devices and three base devices and a signal managing system, which is a PC computer, and

Figure 8 shows a flow chart of a method according to the present invention of managing remote devices adapted for placement on one or more objects.

DESCRIPTION OF EMBODIMENTS

Figure 1 shows a system 1 according to the present invention for managing remote devices 2-6 adapted for placement on one or more objects 7-11, where at least one of the remote devices is adapted to measure or apply at least one object characteristic. The object may according to the present invention be human beings, patients, athletes, any kind of biological species or a machine. The remote devices 2-6 may be selected from the group of:

• wireless digital Electromyography (EMG) devices,

• wireless digital accelerometer device

• wirelsess digital gyroscope device • wireles digital magnetometer device

• wireless digital measuring device measuring other physiological data

• a combination thereof.

The object characteristics may comprise data relating to kinematics, e.g. position and movement of body in space, kinetics, e.g. internal, external and contra acting forces and pressures, and electromyography, e.g. EMG, electrical potentials inside muscles or at the surface of the skin above the muscles in question or other physiological signals for living objects or sensors for machines.

The system comprises a signal managing system 12 comprising a command initiator (C_I) 30 for initiating an action command 19 to be executed simultaneously at the remote devices or data for out signals, and a transmitter (T) 31. The term simultaneously means according to the present invention an extremely short time difference in reception of the command at the various remote devices, typically around 1 ms or less. As shown here, the signal managing system 12 may be selected from a group of: a computer system such as a PC computer, a microcomputer, PDA's, intelligent mobile phones and the like, comprising the transmitter and the command initiator. In one embodiment, the command initiator (C_I) 30 typically comprises a processor which initiates the action command 19 based on e.g. a selection request made by an operator of the system, e.g. via a selection function provided on a graphical display wherein by selecting one of the selection functions, e.g. via a mouse command, the action command is issued. Other kinds of command initiators are also possible, such as an automatic command initiator where the system 1 is pre-programmed to issue an action command automatically, or a command initiator comprising an external signal from other systems; or a command initiator comprising a speech recognition system where the operator of the system 1 instructs the system via a speech command to issue the action command.

The system further comprises one or more base devices 13-18 including a master base device 13 comprising a transceiver. Since this embodiment disclosed "oneway" communication from the managing system 12 to the remote devices 2-6 the use of only the master base device 13 would in principle work. However, as will be discussed in Fig. 2, it is preferred when implementing the system as "two-way" system, to use the base devices 14-18 acting as "slaves" for the master base device 13.

As shown here, the master base device 13 acts as an intermediate agent between 5 the signal managing system 12 and the remote devices 2-6, so that all communications from the signal managing system 12 to the remote devices 2-6 goes via the master base device 13 that receives the action command 19 from the signal managing system 12 and forwards it to the devices 2-6.

10 The remote devices 2-6 are provided with receivers adapted to be tuned to a single and common frequency channel, wherein the forwarding of the action commands 19 to the remote devices 2-6 is being performed via this single common frequency channel. Thus, the remote devices 2-6 "listen" to the master base device 13 at a single frequency channel. As soon as the master base device

15 13 receives an action command from the signal managing system 12 it will be forward it to all the remote devices 2-6 via this single frequency channel and thus received simultaneously at the remote devices 2-6. Thus, a very good time synchronization of the remote devices 2-6 is provided, i.e. the time difference in reception of the command at the various remote devices 2-6 is around 1 ms or

20 less. In certain cases, a larger difference may be acceptable, e.g. up to 2 ms or even more, depending on the measurement/exertion being measured/performed.

As illustrated in this embodiment, the communication between the signal managing system 12 and the master base device 13, and between the master

25 base device 13 and the remote devices 2-6 is wireless. However, a wired connection between the signal managing system 12 and the master base device 13 may just as well be used. It is however preferred, but not necessarily, that at least the communication between the master base device 13 and the remote devices 2-6 is wireless such that the objects are not tethered down.

30

Each remote device may be adapted to measure a single of multiple object characteristics, e.g. the one and the same remote device may e.g. be adapted to measure distance, speed and acceleration of the object wearing the remote device. Thus, the result provided by each respective remote device may be a kind

35 of a vector where each vector element is e.g. a distance, a speed/velocity and the acceleration.

In the embodiment in Fig. 2, the signal managing system further comprises a receiver 32 for receiving data 20-25 transmitted by the remote devices 2-6 via the base devices 13-18. Accordingly, the remote devices 2-6 are further provided with a transmitter for transmitting the data. In one embodiment, the transmitted data are transmitted as data packages 20-25 comprising e.g. data relating to measurement performed by at least some of the remote devices 2-6. It is namely so that some of the remote devices 2-6 can be adapted to measured data, e.g. biosignal data from the objects, whereas other remote devices 2-6 may be adapted as "output devices" meaning that they may be provided with means for initiating an alert signal, e.g. via a light (e.g. a red light), vibration, voice commands, and the like.

In one embodiment, the measured data may be transmitted over to the signal managing system 12 where they are used as input values for determining one or more output values indicating one or more object related characteristics. If e.g. the values exceed a particular pre-defined threshold value, the signal managing system 12 could be adapted to send a warning signal to the alert devices, which accordingly would initiate an alert signal.

An example is a system that overlooks execution of a defined exercise for rehabilitation. Different EMG units report to the signal managing system when certain muscles are active. Different acceleration units report to the signal managing system the position of the body. The signal managing system combines this information and sends vibration commands and data to one of the emg/vibration units indicating that it is performing badly according to the exercise planned.

In one embodiment, the measured data might just as well be processed at the remote device side, meaning that the devices would be more "intelligent" and adapted to communicate directly with each other, or via the signal managing system 12 as disclosed here above. Thus, if the result of the processing would indicate that the determined object related characteristics exceed the threshold value, the device could inform the alert devices. In one embodiment, the devices 2-6 are further provided with a memory for e.g. storing all measured data, output data and data that uniquely identify the devices and their measuring characteristics, e.g. the units the devices are set up to measure. The devices may be adapted to frequently send these data to the signal managing system 12 and preferably to attach at least a part of these data to the data packages send by the devices to the signal managing system 12 so that the data package can be linked to the remote device that sent the package. It is therefore ensured that the transmitted data packages will not be mixed when received by the managing system. As an example, if particular data package was measured and transmitted by a remote device ID20697, where this ID data might be attached to the data package. By frequently sending the data that uniquely identify the devices and their measuring characteristics to the signal managing system 12 it will be aware of the presence of the devices which allows e.g. an automatic update of the devices. New remote devices can be introduced to the system that e.g. automatically updates the signal managing system with its abilities without any manual intervention. E.g. a user has bought an EMG system including 4 EMG devices. Later the user decides to add a force measuring capability. The introduction of a force-remote-device is automatically recognized in the signal managing system and the signal is displayed in newtons in stead of volts. Also, a built in calibration may be provided. Thus, no calibration of the remote device is needed since measuring characteristics may contain the calibration constants that were entered to it during factory calibration. Thus, the delivered is calibrated to newtons. It follows that each measuring device is very well defined. Also, by adding/removing a remote device, such a change will be identified by the managing system, which makes the system more intelligent. Also, since the system is particularly suitable to be implemented on more than one object, it is possible to measure e.g. reaction times between the objects.

Table 1 depicts graphically a comparison of various wireless communication protocols, the Bluetooth, Wi-Fi, Zigbee and WUSB protocols with the protocol according to the present invention. As shown here, Wi-Fi and WUSB are not intended as low power consuming protocols, but are meant for extremely high throughput data transfer with little or any emphasis on low power consumption.

Table 1

In one embodiment, the communication to the remote devices 2-6 is done using 433 Mhz frequency band; Industrial, Scientific and Medical band (ISM), where the range is at least 40 meters on 1 mW sending power. Since with each transmission only takes in the order of seconds the power consumption becomes very low. The throughput may be tunable, but only a very moderate data rate is required for each channel Because of the nature of the data being transmitted no special security is required. The redundancy is a more important factor, and each message may be CRC encoded. In one embodiment, if a message gets lost during transmission said receiver may request it being resent after the transmission. Thus, it is possible to measure out of transmission range, just if the measurement started within the range. In one embodiment, each remote device 2-6 is provided with 2MB storage onboard. Thus, an EMG signal can be accumulated for about 7 minutes without transmitting and losing data.

Table 2

Table 2 depicts the functioning of the protocol according to the present invention. MU stands for Measuring Unit or a remote device (MU) and BU stands for Base Unit. The Bus may receive the data and display it on a computer they are connected to, while the MUs are typically wireless measuring and transmitting units. Of all the base units BU 1 is the only one that the MU list to, and hence acts as a master. The MU wait for this master to send the synchronization signal, and then they all start sampling and transmitting data to their corresponding base units. All the MUs have to start their sampling/measuring at the exact same time, or with as little delay as possible. Currently, the protocol can achieve less than 1 ms delay between starting times of the units. The receivers are extremely sensitive, - 103 dBm (5OfW) for a compressed signal as an EMG, down to -

112DBm (6fW) for slower signals. Trying to put that into perspective, this may be converted into range. Approximated for the maximum theoretical range, derived form a Friis model ("J. A. Gutierrez, E. H. Callaway, and R. L. Barret. Low-Rate Wireless Personal Ares Networks. Standard Information Network IEEE Press, New York, 2003") hereby incorporated by reference,

L_B (dB)=32.44+20logiof_MHz+20logiod_km

with L_B the past loss in dB. For an EMG signal (-103 dBm receiver sensitivity), and with the maximum rated power of the transmitter at 10 dBm (1OmW), the path loss is 113 dB through ideal perfect medium. This translates into theoretical maximum range of over 24 km. For 0 dBm output power this number falls to less than 8 km, but that is still extraordinary. The same value for Zigbee and Bluetooth is however around few hundred meters.

Figure 3 shows one embodiment of the system 1 shown in Figs. 1 and 2, comprising N base devices from Fig. 1 and 2 13, 104, and N remote devices 2, 106. Each of the remote devices can be of various types as discussed previously, and can communicate to one or more of the base devices 13, 104, and vice verse, the two base devices 13, 104 can communicate to one or more of the remote devices 2, 106. In this embodiment, the communications paths 110, 111, 112 and 113 for this 2 channel system are wireless. N is the order of the system and can be 1,2,...65536 or more. The base devices can be attached to base units for charging, programming and data transfer.

The base devices 13, 104 relay data from and to the signal managing system 12, which can e.g. be a microcomputer 107, via communication lines 121 and 122 (for this 2nd order system). These communication paths may be selected from RS232, RS485 USB, FireWire, Ethernet or similar serial protocols. This can be done via serial lines, USB hubs, Ethernet hubs or any similar common equipment.

A Unit Interface 102 then translates the data packages to calibrated numbers based on data acquired from the remote units.

All description of data and calibration is kept in the remote devices. A software program (101) or programming interface(102) is provided allowing commands and data to be sent and reception of data from the remote devices 2, 106 to the signal managing system 12 in a calibrated form and further allows adjusting the remote devices into e.g. different measuring modes and other functions.

In one embodiment, the managing system 12 further comprises a documented user programming interface.

This allows an advanced user with programming skills to easily make his own user interface (application program) that e.g. shows all the available remote devices, the base units, executing recording etc. without knowing the underlying mechanism in details.

In one embodiment, the managing system further comprises an application program (user interface) 101 that the operator/user interacts with. A display may further be provided for visualizing the pre-stored data uniquely identifying the devices and their measuring characteristics graphically on the display. Thereby, a very user friendly interface is provided that enables the user to see the remote devices that are present. In one embodiment, the user interface is further provided with a selection function for selecting between the various remote devices displayed on the display. In one embodiment the user interface provides methods for viewing recorded data and/or viewing and selection of data to send as output signal.

Figure 4 shows one embodiment of a remote device 2-6 shown in Figs. 1-3, where the device 2-6 comprises a power source 212 e.g. in form of a chemical battery, solar cell, power generator or similar, a receiver 218 for receiving said action command 19 and in an embodiment a transmitter 219. The power is managed by a power management part 213 that keeps the power stable and supplies it to the other part of the device. The power management part can power up and down specified sections of the units in order to save energy. It might also take part in charging the power source via external connectors 216 or wirelessly.

The remote device 2-6 can comprise signal sensor or multiple signal sensors 202. In case of multiple sensors it might be an assembly of several types of sensors. As an example of single sensor is temperature or connectors for EMG electrodes (where the electrodes them self's are outside of unit but connected to the unit). An example of multiple signal type is an assembly of 3-axis accelerometer, 3 axis gyro meters, 3 axis magnetic direction sensors.

Depending on the sensor type and quantity, the sensor interface 203 and an analog/digital converter 204 connect the sensor to the microcontroller/microprocessor 205. In some cases the sensors are digitally connected to the processor, in other cases the signal needs to be amplified and A/D converted. Some sensors or theirs signals processing needs power or adjustments. This is performed via this interface.

The microcontroller 205 is adapted to process the signal and store it in a memory 208, and to send or receive data or program code via radio 207, serial line 206 or programming interface 211 and keep track of time 214 and keep track of current operating mode. The device can be controlled by inputs 209 and can show output via outputs 210. Buttons are examples of inputs, light emitting diodes and LCD displays and electrical stimulation are examples of output. The microcontroller runs a firmware that sends and receives commands, data and code via radio or serial lines in packages. It stores constants that describe the device, its capabilities, amongst other its signals. The radio 207 may be adapted to be connected to antenna and related circuit 215 for two way communications.

Each remote unit 2-6 can have one or more signal modes. The same device could thus e.g. be both EMG and Acceleration unit; one, the other or both at the same time (multiple signal units)

The actuator 217 can apply physical quantities (e.g. light, sound, vibration, electrical current, heat) to the body for functional or cognitive reasons (e.g. as an indication). Measured values can be translated to actuator values (output signal) and applied by the device with or without a decision rule (on board intelligence). Also, the actuator can be controlled according to received data, preprogrammed data and timed events.

In an embodiment, the remote devices 2-6 have several power modes. In the alert mode the device is ready to receive the start command and immediately start recording. In power down mode the unit wakes up every few seconds and checks if measurement is to be done. If so the unit is put in alert mode. The deep sleep mode is used for pacifying the unit or maximum power preservation. This more can only be exited by manual interaction with the unit.

Figure 5 shown one embodiment of a base device 13-18 comprising a transceiver 313 for e.g. transmitting packages to and receiving packages from remote devices. The device typically runs on external power but can also operate on internal power. In one embodiment, the base device 13-18 is adapted to supply charging power to the remote units 2-6 via e.g. external connectors 312 or wirelessly.

5 It can receive and send packages via e.g. radio 305 and serial communication 302. Data packages received by the serial communication may be relayed to the radio and data received by the radio may be relayed to the serial communication. The serial communication paths 302, 110-113 can be TTL, RS232, RS485 USB, FireWire, Ethernet or similar serial protocols.

10

The microcontroller 301 controls the data flow and state of the unit. The settings for the base device are kept in memory 303, which can also buffer data in either way. The microcontroller can be programmed by programming interface 309 such that it keeps track of time with the timing circuit 311. Inputs 307 and outputs 308

15 are comprised in the base device 13-18 for e.g. synchronization with other systems and controlling modes.

Figure 6 shows a system according to the present invention Ia is configured of N remote devices 410, 411 and N base devices 412, 413 connected via e.g. a hub

20 505 to a pc computer 414. As an example this could be four USB connections from four bases to a USB hub that connects to a single USB connector in the PC. Each remote device 410, 411 has a unique identifier 415, 416; each base device 412, 413 has a unique identifier 417, 418, and the PC application has a unique identifier 419. When communicating with the measurement units the PC

25 application sends commands and data packages via a communication protocol, serial line, hub, base to the remote units. The remote units send data packages back the other way around.

If another system Ib is in the same radio range 402 it will not influence the data 30 communication since the data packages are identified by specific net number not accepted in the first system Ia.

The systems can according to the present invention either be multiple base type 401 or single base type 402. In multiple base types the radio channels are 35 frequency multiplexed, that is one frequency for each channel or all units. Still each measuring unit listens to the same frequency to ensure time synchronization. Data are streamed back on different channels. In single base type systems the channels are time multiplexed, that is all units send and receive on same frequency but at different times. In both cases the frequencies can be changing in order to optimize the communication .

The communication settings for the system may be net ID, channel ID, remote unit ID, base ID and communication frequencies can be pre-programmed or automatically obtained in an initialization process.

Synchronized recording can be performed by two methods: direct initiating and indirect initiating. Direct initiating is performed when all units are activated at the same time . Indirect initiating is when a common time sync command is sent with information about when to initiate a session and when to quit.

The procedure of recording:

In one embodiment the starting up the application software it starts to collect information of communication channels to bases.

Then base units are queried for their capabilities, the remote units are queried for their capabilities and signal description. This is referred to as collecting headers and might involve power management like taking remote units from power down mode to power up mode. Then the system is ready for recording. Typically a common signal starts the recording including the max time for recording. The system can or can not be stopped before this time has elapsed. During recording data are streamed to the PC in numbered packages. After the time has passed or the stop command has been issued the PC can check the units for maximum package recorded and compare to the packages received. If packages are missing the application can acquire for the missing data. This is referred to as recollection. When all data is received the remote units can be set to power down mode.

During long recording times, good communication environment and slow data generation, packages are sent to base with handshaking methods, that is base has to send acknowledge for each received package. In this case the remote unit does not have to save data and can delete data that it has received acknowledge for (retransmission and no recollection is needed). In more time constrained recordings and under poor communication conditions data can be saved to memory and sent to the base at the same time without checking in real time for the successful reception on the base side. After the recording base can require for lost data (recollect). Programming Interface 102:

The functions that can be performed via the interface are in one embodiment: Initialize (string connection Type)

- This function sets up a session using a specified connection Type and is preferably called before anything else. - The main connection type to use is "serial" which uses COM ports to interact with units.

GetHeaders(bool complete)

- This function communicates with all available units to try and get their headers. - If complete is true, then this function will throw a error if any unit is unreachable, f.ex. if they don't have battery, are asleep or out of range.

- If complete is false, then any unit that does not respond is disabled and will be ignored in any following actions.

StopGetHeaders()

- Because GetHeaders is a time-consuming operation, it may be desireable to cancel it. This function will not immediately cancel the operation as that could leave some threads left open, instead, it will signal the GetHeaders function to stop. And it should be stopped in, at most, half a second.

GetHeadersAsync(bool complete)

- Because GetHeaders is a time-consuming operation, it may be desirable to perform it without causing the primary thread to stall. This function starts GetHeaders on a secondary thread. To know when it finishes, use the FinishedGetHeaders event.

WakeupO

- Tries to wake up all sleeping units. This is a time-consuming operation (somewhere around 5 seconds). WakeupAsyncO

- Same as above, but async, that is, running on a secondary thread. Use OnWakeupFinished event to know when it is finished.

SleepO

- Puts all available units to sleep. In sleep-mode, the units consume less power.

DeepSleepO - Puts all available units into deep-sleep mode. In this mode they can not be operated on until they are manually powered on again.

RecordingPrepareO

- Prepares units for a recording. This function must be called if you wish to recover any data that gets lost during recording.

RecordingPrepareAsyncO

- Same as above, but on a secondary thread.

RecordingStart(float time)

- Starts a recording over a specified time duration. During this time, data will pour in from each unit and can either be accessed real-time using events or afterwards by accessing the Unit objects.

RecordingStartAsync(float time)

- Same as above, but on a secondary thread

GetRecordingStatsO

- This function should be called after a recording to find out how much data was recorded. These information allows you to see how much data was lost, and if you need to recollect lost data.

RecordingRecollectO

- This function should be called after a recording to recollect any lost data from it. For this operation to work, the recording must have been prepared, and it is recommended to call GetRecordingStats before calling this function for it to better know which data is missing.

RecordingRecollectAsyncO - Same as above, but on a secondary thread.

Scan()

- Read network number, scan for available measuring units and read their signal properties.

Actuate(value)

- excert a value to a remote unit

Logical description of measurement channels:

Each remote unit can have one or more signals. Each signal is described with the following information shown in table 3 that is stored in the units and is acquired by the application program when collecting headers.

Table 3

The name of the signal is the default name that is displayed to the user. Name could e.g. be EMG-I and later be changed by the user to Tibialis anterior. Unit is the physical unit of data like V (for volts) or N (for newtons). The sampling frequency is the frequency of which the signal is sampled. It is given as two long integers and the ratio between them is the sampling frequency. The data is sent to the PC as integers. The offset (long integer) and multiplier (floating point value) are used for linear translation of bit values to a physical unit. Calibrating a unit involves changing these values. Y=(x-o)*m, where Y is calibrated value, x is the integers transmitted, o is the offset and m is the multiplier.

Type is a three byte value indicating witch type of signal this is. Examples of types are electro physical, force, pressure, acceleration, direction.

Each unit may have the channel settings:

• Unit-ID

• Ass. Unit-ID

• Net-ID • Unit Tx frequency channel

• Unit Rx frequency channel

• NumChannels

Each unit has the following parameters: • Current time

• Current mode

Each unit may have the following functions:

• Start sampling • Stop sampling

• send package

• receive package

• Power down

• Power up • Set parameters

• Get parameters

Data and command packages:

The data and command packages are built up like this

The sync byte is an 8 bit value that all packages start with.

The header bytes include source address, destination address, network ID, size of data in package and size or check sum.

Data bytes are the actual data transferred. Check sum is a common cyclic redundancy check, 8, 16 or 32 bits.

Lost data:

Data are sent to PC in packages with check sums (CRC) for error detection. If the data in the package does not fit with the check sum, the package is discarded. In other cases due to poor data communication condition a package never arrives. This means lost data. In order to over come this problem there are two modes of operation: recollection mode and retransmission mode. In the retransmission mode the base must acknowledge correct received data before unit sends next package. In recollection mode all transmitted data is also stored in local memory, no immediate check is done on if the data is received on the other end. After recording the number of package generated can be read by the application and the lost packages can be recollected (read from the on board memory).

Example:

Let's take an example of a 3 channel system where the configuration is shown in Fig. 7, i.e. three remote devices 701-703, three base devices 704-706 and a signal managing system, which is a PC computer with software 707.

The base device 704 is master in the sense that all outgoing traffic from PC to any of the remote units is routed through it. All the remote units are listening to base device 704 but are sending to each respective base device, i.e. remote device 701 sends via base device (the master base device) 704, remote device 702 sends via base device 705 and remote device 703 send via base device 706. Each base device is connected to the PC with e.g. a serial connection that appears as virtual comport on the PC.

The channels of communication are on different frequencies, but this requirement is in general not essential. A channel number refers to a specific frequency. In this case 3 channels are defined : ch-1, ch-2 and ch-3. The transmission (Tx) and Receiving (Rx) frequencies are thus set as in table 4.

All units are on the same net but have separate ID number.

Table 4

When the application program starts up, it first checks for available base devices. Either the user has chosen coml-com3, 708-710, as the comport to use or they are found by auto scan. When the available base devices are found they are acquired for their remote unit and its capabilities. This process is referred to as collecting headers. After collecting headers and if all units are in alert state, the system is ready for e.g. recording.

A single recording command for unit 0 is sent to the master base device 704. All remote units will start as 0 is the broadcast address. That is, all remote devices 701-703 act on their address (Unit ID = 1, 2 or 3) and address 0. All the devices 701-703 will now start to record, send data to PC (ID=7) and store data in memory at the same time. The data are sent from each remote unit to its respective base (remotel to base 1, remote 2 to base 2 and so on). At the PC end a software program (programming interface or user application) is provided and pre-programmed to receive the packages and compare each package content to its check sum. If the sum is not matching, the package is discarded.

When recording is over, each remote device is acquired for how many packages it sent to its base. The software on the PC will now compare these numbers to the number of correct received packages. If any packages are missing, the software sends a message to the remote devices 701-703 describing which data is needed must be resent. The remote units looks up the data in the on-board memory and re-transmit this to PC. Some iteration might be needed to complete this procedure, referred to as recollecting. If all goes well the data is complete at the PC end.

In case of the subject going out of the radio field after the record command was issued and is not back when recollection starts, the measurement interface tries several times and then asks the user if he wants to continue with the data gotten so far or if he wants to continue to recollect. In the latter case the user would wait until the subject is back again and then issue recollect. After a successful recording the remote units are put in power down mode to conserve power (happens automatically by KMUI or specificity issued by application software).

Figure 8 shows a flow chart of a method according to the present invention of managing remote devices adapted for placement on one or more objects, where at least one of the remote devices is adapted to measure at least one object characteristic.

In the first step (Sl) 801 an action command is initiated, where the command is to executed simultaneously at the remote devices. The action command may e.g. comprises a command instructing the remote devices to start recording data from the at least one object.

In a second step (S2) 803 the command is transmitted to the remote devices via a master base device comprising a transceiver for receiving and forwarding the action commands to the remote devices, wherein the remote devices comprise receivers tuned to a single and common frequency channel, the forwarding to the remote devices being performed via the single common frequency channel.

In one embodiment, the data measured by the remote devices are transmitted as a data package from the remote devices to the managing system (S3) 805, where the data are subsequently processed for determining at least one object characteristic value. These values can e.g. include values relating to kinematics (the position and movement of body in space), kinetics (internal, external and contra acting forces and pressures) and physiology ( e.g. electromyography: EMG, electrical potentials inside muscles or at the surface of the skin above the muscle in question).

In one embodiment, the data object characteristic value are transmitted back to the remote devices (S4) 807, wherein if the values exceed pre-defined threshold values the remote devices are used for generating an alert signal.

In one embodiment, the data uniquely identifying the remote devices is associated with the data package transmitted from the remote devices (S5) 809 so that the transmitted data packages can be linked to the device.

Certain specific details of the disclosed embodiment are set forth for purposes of explanation rather than limitation, so as to provide a clear and thorough understanding of the present invention. However, it should be understood by those skilled in this art, that the present invention might be practiced in other embodiments that do not conform exactly to the details set forth herein, without departing significantly from the spirit and scope of this disclosure. Further, in this context, and for the purposes of brevity and clarity, detailed descriptions of well- known apparatuses, circuits and methodologies have been omitted so as to avoid unnecessary detail and possible confusion.

Reference signs are included in the claims, however the inclusion of the reference signs is only for clarity reasons and should not be construed as limiting the scope of the claims.

Claims

1. A system (1) for managing remote devices (2-6) adapted for placement on one or more objects (7-11), where at least one of the remote devices is adapted to measure or exert at least one object characteristic, the system comprising:

• a signal managing system (12) comprising: o a command initiator (30) for initiating an action command (19) to be executed simultaneously at the remote devices (2-6), and o a transmitter (31) for transmitting the action command (19), • one or more base devices (13-18) including a master base device (13), the master base device comprising: o a transceiver (313) for receiving and forwarding the action command

(19) to the remote devices (2-6), wherein the remote devices comprise receivers (218) tuned to a single and common frequency channel at any instant of time, the forwarding to the remote devices being performed via the single common frequency channel.

2. A system as claimed in claim 1, wherein the remote devices further comprise:

• a memory (208) having pre-stored data uniquely identifying the devices and their measuring characteristics, and

• a transmitter (219) for transmitting the pre-stored data uniquely identifying the devices to the signal managing system via the one or more base devices.

3. A system as claimed in claim 1 or 2, wherein the measuring characteristics comprise the measuring mode the remote devices (2-6) are in.

4. A system as claimed in claim 2, wherein the memory (208) is further adapted to store measured data.

5. A system according to any of the preceding claims, wherein the action command (19) comprises commands instructing the remote devices to be in high- power alert state or low power battery saving state

6. A system as claimed in any of the preceding claims, wherein the action command (19) comprises a command instructing the remote devices (2-6) to start recording data or exerting a physical out signal from or to the at least one object (7-11).

7. A system as claimed in any of the preceding claims, wherein the data measured by the remote devices (2-6) are transmitted as a data package (20-25) from the remote devices to the signal managing system (12), the data being subsequently processed for determining at least one object characteristic value.

8. A system as claimed in claim 7, wherein the data uniquely identifying the remote devices (2-6) is associated with the data packages (20-25) transmitted from the remote devices.

9. A system as claimed in claims 7 or 8, wherein each respective remote device (2-6) or a group of remote devise is associated with a single base device that communicates with the signal managing system (12) through a communication channel (110-113) such that the transmitted data package are transmitted to the signal managing system (12) via the associated base devices.

10. A system as claimed in claim 7, wherein the determined object characteristic value is subsequently transmitted back to the at least one remote device (2-6).

11. A system as claimed in claim 1 or 10, wherein the remote devices (2-6) further comprise at least one remote device adapted to alert the object when the object (7-11) characteristic value reach or exceed a pre-defined threshold value.

12. A system according to any of the preceding claims, wherein the remote devices (2-6) comprise at least one remote device selected from the group of:

• wireless digital Electromyography (EMG) devices,

• wireless digital accelerometer device • wirelsess digital gyroscope device

• wireles digital magnetometer device

• wireless digital measuring device measuring other physiological data

• a remote device comprising two or more measuring channels for measuring one or more signals simultaneously, • a remote device comprising a measuring module for switching between two or more different measuring modes,

• a remote device comprising a transceiver and is adapted to receive and transmit signals simultaneously,

• a remote device comprising an alert unit for initiating an alert signal, and 5 • a combination thereof.

13. A system according to any of the preceding claims, wherein the signal managing system (12) further comprises a user programming interface (102).

10 14. A system according to any of the preceding claims, wherein the signal managing system (12) further comprises a model of the data for integrating information, decision-making and alarming.

15. A system according to any of the preceding claims, wherein the signal

15 managing system (12) further comprises a user interface (102) and a display for visualizing the real time and/or pre-stored data uniquely identifying the devices and their measuring characteristics graphically on the display.

16. A system according to any of the preceding claims, wherein user application 20 interface (102) is further provided with a selection function for selecting between the various remote devices displayed on the display.

17. A system according to claim 16, wherein the user application interface (102) is further provided with a recollection or retransmission function

25

18. A system according to claim 16 or 17, wherein the user application interface (102) is further provided with a function collecting headers to discover the properties of a remote unit

30 19. A system according to any of the preceding claims, wherein the objects characteristics comprises at least one object characteristic selected from the group of:

• kinematics,

• kinetics, and

35 • physiological related signals.

20. A communication protocol to be implemented in a system as claimed in claims 1-19 for managing the communication from the signal managing system (12) comprising a processor and a transmitter to the remote devices (2-6) via the

5 master base device (13), wherein the protocol is adapted to instruct the processor to transmit an action command (19) initiated at the managing system (12) side to the master base device (13) such that the action command becomes forwarded to the remote devices (2-6) via the single frequency channel being common with the receipt frequency channel of the remote devices. 10

21. A system according to any of the preceding claims, wherein the remote devices operate in the industrial, scientific and medical (ISM) radio band of 433MHz or 868MHz.

15 22. A system according to any of the preceding claims, wherein the remote devices are operated at the power range between ImW-IOmW.

23. A method of managing remote devices adapted for placement on one or more objects, where at least one of the remote devices is adapted to measure or exert 20 at least one object characteristic, the method comprising :

• initiating an action command (801) to be executed simultaneously at the remote devices,

• transmitting the action command (803) to the remote devices via a master base device comprising a transceiver for receiving and forwarding the action

25 command to the remote devices, wherein the remote devices comprise receivers tuned to a single and common frequency channel at any instant of time, the forwarding to the remote devices being performed via the single common frequency channel.

30 24 A computer program product for instructing a processing device to execute the method step of claim 232 when the product is run on a computer.