Multiple robots can be teleoperated by a single operator to provide enhanced capacity and efficiency on accomplishing complicated tasks. The design of this kind of systems is challenging because simultaneously tele-controlling multiple robots exceeds the ability of one single operator. The intelligence and autonomy of the robots need to be integrated into the system. Besides, the communication between the operator and the multi-robot system and the communication among the multiple robots are both subject to communication constraints like time delays and packet losses. This paper designs a non-time based method to realize the single-operatormulti-robot system with random communication delay. The system is designed based on the non-time based teleoperation method and a proposed perceptive coordination method. The random delay problem and the problem of simultaneously telecontrolling multiple robots by a single operator are resolved. Experiments implemented on a multi-robot system illustrated the effectiveness of the design.

MRI compatible force sensors are important components in medical robotics as they enable force feedback in a challenging environment for surgical and assistive robots. This paper analyzes a novel MRI compatible force sensor comprised of a displacement amplifying compliant mechanism (DACM) made of polymers. Hysteresis is an inevitable problem for sensors made of polymers which reduces the precision in measurements. Displacement amplification affects both the sensitivity and hysteresis error of a sensor, yet does not ensure an improvement in either of them. Optimization methods based solely on amplification ratio or sensitivity may be ineffective on reducing the hysteresis issue and result in a design with insufficient signal-to-noise ratio (SNR). Unlike previous works that are focused on optimizing topologies with regard to a specific objective function; this work presents an analysis that accounts for both sensitivity and hysteresis. An iterative method capable of performing nonlinear analysis is established in order to monitor sensitivity and hysteresis error of the proposed sensor topology and find out how those are affected by the amplification. Optimal configurations for sensitivity and precision are deduced and the predictions made by the analysis are confirmed by experiments. This study indicated that sensitivity of a compliant mechanism could be traded for a lower hysteresis error i.e. higher precision. DACMs could be targeted to achieve a low hysteresis error rather than improving the sensitivity in a sensor. Compared to a non-amplifying, basis structure our proposed design achieved a 3-4 times higher SNR, mostly due to its higher precision.

ObjectiveThe virtual airway skills trainer (VAST) is a virtual reality simulator for training in cricothyroidotomy (CCT). The goal of the study is to test the effectiveness of training and transfer of skills of the VAST-CCT.MethodsTwo groups, control (no training) and simulation (2 weeks of proficiency-based training), participated in this study. Subjects in the control condition did not receive any training on the task whereas those in the simulation received a proficiency-based training on the task during a period of 2 weeks. Two weeks post-training, both groups performed CCT on the TraumaMan to demonstrate the transfer of skills.ResultsA total of (n=20) subjects participated in the study. The simulation group performed better than the control group at both the post-test (p<0.001) and retention test (p<0.001) on the simulator. The cumulative sum analysis showed that all subjects in the simulation group reached proficiency with acceptable failure rate within the 2 weeks of training. On the transfer test, the simulation group performed better on skin cut (p<0.001), intubation (p<0.001) and total score (p<0.001) than the control group.ConclusionsThe VAST-CCT is effective in training and skills transfer for the CCT procedure.Level of evidenceNot applicable. Simulator validation study.

Pneumatic systems have regained popularity in robotics, with the new advances in the electronic valves that have enabled precise position control of pneumatic cylinders. Recently, the use of pneumatic systems has been extended to force and impedance control. Such new applications include tele-operated medical robotic systems with pneumatic transmission lines where more advanced system modeling and control is required. Pressures of a pneumatic actuator are commonly used to improve control performance. When direct pressure measurement is not available or not desirable for cost effective implementation, actuator pressures can be estimated by a model-based observer. This paper introduces a nonlinear pressure observer based on force and displacement sensing. The proposed algorithm allows to obtain asymptotic stability of pressure estimation error with an improved convergence. The presented method does not require a transmission line model and guarantees bounded stability in the presence of disturbance in force measurements, hence it is able to provide a robust pressure estimation. The effectiveness of the proposed observer is confirmed by performing force control experiments in a tele-operated pneumatic system. Index Terms-MRI-compatibility, pressure observer, teleoperated systems.

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