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Aperiodic linear networked control considering variable channel delays: application to robots coordination.

Santos C, Espinosa F, Santiso E, Mazo M - Sensors (Basel) (2015)

Bottom Line: One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance.This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources.Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included.

View Article: PubMed Central - PubMed

Affiliation: Electronics Department, Polytechnics School, University of Alcala, Campus Universitario, Ctra. Madrid-Barcelona, Km. 33,600, 28871. Alcalá de Henares, Madrid, Spain. carlos.santos@depeca.uah.es.

ABSTRACT
One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is the design of a remote control solution based on an aperiodic and adaptive triggering mechanism considering the current network delay of multiple robotics units. Working with the actual network delay instead of the maximum one leads to abandoning this conservative assumption, since the triggering condition is fixed depending on the current state of the network. This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources. The communication standard under study is the widespread IEEE 802.11g, whose channel delay is clearly uncertain. First, the adaptive self-triggered control is validated through the TrueTime simulation tool configured for the mentioned WiFi standard. Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included. Both of them demonstrate the advantage of this solution in terms of network accessing and control performance with respect to periodic and non-adaptive self-triggered alternatives.

No MeSH data available.


Linear velocity registered (red line) when a reference (blue line) is applied to one of the robots. Results from different implementations: periodic sampling (Upper Left Corner), fixed high value of the sigma parameter (Upper Right Corner), fixed low value of the sigma parameter (Lower Left Corner) and adaptive solution proposed by the authors (Lower Right Corner).
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f7-sensors-15-12454: Linear velocity registered (red line) when a reference (blue line) is applied to one of the robots. Results from different implementations: periodic sampling (Upper Left Corner), fixed high value of the sigma parameter (Upper Right Corner), fixed low value of the sigma parameter (Lower Left Corner) and adaptive solution proposed by the authors (Lower Right Corner).

Mentions: Figure 7 shows the linear velocity that is the first component of the output vector y(t) from one of the four tested P3-DX robots. The top-left picture corresponds to a fixed sampling time of 10 ms, which shows good tracking performance. The top-right figure displays a high-performance self-triggered implementation (σ = 0.9). The bottom-left illustration depicts a low-performance self-triggered implementation (σ = 0.05). The bottom-right picture describes the adaptive self-triggered solution. It can be appreciated that the higher the value of cr, the better the servo control performance. Nevertheless, the adaptive self-triggering solution presents a balanced solution with a lower number of channel access and an acceptable control performance. The same behavior is observed for the tracking of the angular velocity that is the second component of the output vector y(t), which for the sake of space, is omitted from the paper.


Aperiodic linear networked control considering variable channel delays: application to robots coordination.

Santos C, Espinosa F, Santiso E, Mazo M - Sensors (Basel) (2015)

Linear velocity registered (red line) when a reference (blue line) is applied to one of the robots. Results from different implementations: periodic sampling (Upper Left Corner), fixed high value of the sigma parameter (Upper Right Corner), fixed low value of the sigma parameter (Lower Left Corner) and adaptive solution proposed by the authors (Lower Right Corner).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507601&req=5

f7-sensors-15-12454: Linear velocity registered (red line) when a reference (blue line) is applied to one of the robots. Results from different implementations: periodic sampling (Upper Left Corner), fixed high value of the sigma parameter (Upper Right Corner), fixed low value of the sigma parameter (Lower Left Corner) and adaptive solution proposed by the authors (Lower Right Corner).
Mentions: Figure 7 shows the linear velocity that is the first component of the output vector y(t) from one of the four tested P3-DX robots. The top-left picture corresponds to a fixed sampling time of 10 ms, which shows good tracking performance. The top-right figure displays a high-performance self-triggered implementation (σ = 0.9). The bottom-left illustration depicts a low-performance self-triggered implementation (σ = 0.05). The bottom-right picture describes the adaptive self-triggered solution. It can be appreciated that the higher the value of cr, the better the servo control performance. Nevertheless, the adaptive self-triggering solution presents a balanced solution with a lower number of channel access and an acceptable control performance. The same behavior is observed for the tracking of the angular velocity that is the second component of the output vector y(t), which for the sake of space, is omitted from the paper.

Bottom Line: One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance.This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources.Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included.

View Article: PubMed Central - PubMed

Affiliation: Electronics Department, Polytechnics School, University of Alcala, Campus Universitario, Ctra. Madrid-Barcelona, Km. 33,600, 28871. Alcalá de Henares, Madrid, Spain. carlos.santos@depeca.uah.es.

ABSTRACT
One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is the design of a remote control solution based on an aperiodic and adaptive triggering mechanism considering the current network delay of multiple robotics units. Working with the actual network delay instead of the maximum one leads to abandoning this conservative assumption, since the triggering condition is fixed depending on the current state of the network. This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources. The communication standard under study is the widespread IEEE 802.11g, whose channel delay is clearly uncertain. First, the adaptive self-triggered control is validated through the TrueTime simulation tool configured for the mentioned WiFi standard. Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included. Both of them demonstrate the advantage of this solution in terms of network accessing and control performance with respect to periodic and non-adaptive self-triggered alternatives.

No MeSH data available.