Adaptive Self-triggered Control for Remote Operation of Wifi Linked Robots

Abstract

Abstract. We consider the problem of remotely operating an autonomous robot through a wireless communication channel. Our goal is to achieve a satisfactory tracking performance while reducing network usage. To attain this objective we implement a self-triggered strategy that adjusts the triggering condition to the observed tracking error. After the theoretical justification we present experimental results from the application of this adaptive self-triggered approach on a P3-DX mobile robot remotely controlled. The experiments show a relevant reduction on the generated network traffic compared to a periodic implementation and to a non-adaptive self-triggered approach, while the tracking performance is barely degraded.

Aperiodic Linear Networked Control Considering Variable Channel Delays: Application to Robots Coordination

“…Table 4 also highlights the benefits of the authors' proposal with respect to the conservative approach [ 27 ], where only the maximum channel delay is considered to tackle with a self-triggered control solution. The performance requirements of the conservative approaches are highly restrictive, mainly when the maximum delay is large.…”

“…This is because the t min obtained through the σ value has to be greater than the maximum channel delay ( τ MAX ) to guarantee the stability. To replicate the controller designed in [ 27 ], we took into account that the τ MAX with four robotics units was 150 ms; this is why we worked with σ = 0.1 ( t min = 154.5 ms) when | x ( t ) − x eq | > 0.1 and σ = 0.05 (t min = 164.2 ms) when | x ( t ) − x eq | ≤ 0.1.…”

“…The proposed strategy is an extension of the one described in [ 27 ] dealing with variable delays. Basically, to compensate the channel delay, it is required to transmit a measurement at the time: being τ̂ the time that guarantees the signal reception before t k .…”

“…Working over the maximum delay as in [ 27 ] leads to a clear conservative solution, because it is the worst case scenario. In this case, the τ MAX is restricting the performance due to the t min value obtained through the performance function S ( t ) having to be greater than this delay in order to guarantee stability.…”

“…In the context of robotics cooperation and tele-operation, it is of foremost importance to minimize the computational load of the on-board electronics system [ 15 , 25 , 26 ], as well as to reduce the communications burden. In a previous work [ 27 ], a conservative design dealing with the maximum delay was evaluated and implemented. That solution achieves a significant reduction in the network traffic when only a robot is remotely controlled.…”