Shared Control Method Research Articles

An FDES-Based Shared Control Method for Asynchronous Brain-Actuated Robot.

The asynchronous brain-computer interface (BCI) offers more natural human-machine interaction. However, it is still considered insufficient to control rapid and complex sequences of movements for a robot without any advanced control method. This paper proposes a new shared controller based on the supervisory theory of fuzzy discrete event system (FDES) for brain-actuated robot control. The developed supervisory theory allows the more reliable control mode to play a dominant role in the robot control which is beneficial to reduce misoperation and improve the robustness of the system. The experimental procedures consist of real-time direct manual control and BCI control tests from ten volunteers. Both tests have shown that the proposed method significantly improves the performance and robustness of the robotic control. In an online BCI experiment, eight of the participants successfully controlled the robot to circumnavigate obstacles and reached the target with a three mental states asynchronous BCI while the other two participants failed in all the BCI control sessions. Furthermore, the FDES-based shared control method also helps to reduce the workload. It can be stated that the asynchronous BCI, in combination with FDES-based shared controller, is feasible for the real-time and robust control of robotics.

Adapted Control Methods for Cerebral Palsy Users of an Intelligent Wheelchair

The development of an intelligent wheel chair (IW) platform that may be easily adapted to any commercial electric powered wheelchair and aid any person with special mobility needs is the main objective of the IntellWheels project. To be able to achieve this main objective, three distinct control methods were implemented in the IW: manual, shared and automatic. Several algorithms were developed for each of these control methods. This paper presents three of the most significant of those algorithms with emphasis on the shared control method. Experiments were performed by users suffering from cerebral palsy, using a realistic simulator, in order to validate the approach. The experiments revealed the importance of using shared (aided) controls for users with severe disabilities. The patients still felt having complete control over the wheelchair movement when using a shared control at a 50 % level and thus this control type was very well accepted. Thus it may be used in intelligent wheelchairs since it is able to correct the direction in case of involuntary movements of the user but still gives him a sense of complete control over the IW movement.

Brain–machine interface control of a manipulator using small-world neural network and shared control strategy

The improvement of the resolution of brain signal and the ability to control external device has been the most important goal in BMI research field. This paper describes a non-invasive brain-actuated manipulator experiment, which defined a paradigm for the motion control of a serial manipulator based on motor imagery and shared control. The techniques of component selection, spatial filtering and classification of motor imagery were involved. Small-world neural network (SWNN) was used to classify five brain states. To verify the effectiveness of the proposed classifier, we replace the SWNN classifier by a radial basis function (RBF) networks neural network, a standard multi-layered feed-forward backpropagation network (SMN) and a multi-SVM classifier, with the same features for the classification. The results also indicate that the proposed classifier achieves a 3.83% improvement over the best results of other classifiers. We proposed a shared control method consisting of two control patterns to expand the control of BMI from the software angle. The job of path building for reaching the ‘end’ point was designated as an assessment task. We recorded all paths contributed by subjects and picked up relevant parameters as evaluation coefficients. With the assistance of two control patterns and series of machine learning algorithms, the proposed BMI originally achieved the motion control of a manipulator in the whole workspace. According to experimental results, we confirmed the feasibility of the proposed BMI method for 3D motion control of a manipulator using EEG during motor imagery.

Shared Compliant Control of Teleoperation Based on Stiffness Feedback

In teleoperation tasks, communication delays between master and slave sides negatively affect the stability and transparency of closed loop system, and make it difficult to maintain a desired contact force. In order to improve the performance of contact force control in teleoperation under large time delays, a shared compliant control method is proposed in this paper. On the master side, the operator issues a desired contact force command according to the feedback of the contact stiffness identified on line besides motion commands. And on the slave side, a local contact force controller is designed using an adaptive Smith predictor, so as to shares control load with the operator. Experimental results show that this method can improve the force control performance, lower the difficulty of operation, and help the operator complete contact tasks with proper forces.In teleoperation tasks, communication delays between master and slave sides negatively affect the stability and transparency of closed loop system, and make it difficult to maintain a desired contact force. In order to improve the performance of contact force control in teleoperation under large time delays, a shared compliant control method is proposed in this paper. On the master side, the operator issues a desired contact force command according to the feedback of the contact stiffness identified on line besides motion commands. And on the slave side, a local contact force controller is designed using an adaptive Smith predictor, so as to shares control load with the operator. Experimental results show that this method can improve the force control performance, lower the difficulty of operation, and help the operator complete contact tasks with proper forces.