Chee Leong Teo

A Brain Controlled Wheelchair to Navigate in Familiar Environments

While brain-computer interfaces (BCIs) can provide communication to people who are locked-in, they suffer from a very low information transfer rate. Further, using a BCI requires a concentration effort and using it continuously can be tiring. The brain controlled wheelchair (BCW) described in this paper aims at providing mobility to BCI users despite these limitations, in a safe and efficient way. Using a slow but reliable P300 based BCI, the user selects a destination amongst a list of predefined locations. While the wheelchair moves on virtual guiding paths ensuring smooth, safe, and predictable trajectories, the user can stop the wheelchair by using a faster BCI. Experiments with nondisabled subjects demonstrated the efficiency of this strategy. Brain control was not affected when the wheelchair was in motion, and the BCW enabled the users to move to various locations in less time and with significantly less control effort than other control strategies proposed in the literature.

A Haptic Knob for Rehabilitation of Hand Function

This paper describes a novel two-degree-of-freedom robotic interface to train opening/closing of the hand and knob manipulation. The mechanical design, based on two parallelogram structures holding an exchangeable button, offers the possibility to adapt the interface to various hand sizes and finger orientations, as well as to right-handed or left-handed subjects. The interaction with the subject is measured by means of position encoders and four force sensors located close to the output measuring grasping and insertion forces. Various knobs can be mounted on the interface, including a cone mechanism to train a complete opening movement from a strongly contracted and closed hand to a large opened position. We describe the design based on measured biomechanics, the redundant safety mechanisms as well as the actuation and control architecture. Preliminary experiments show the performance of this interface and some of the possibilities it offers for the rehabilitation of hand function.

A robotic teacher of Chinese handwriting

We introduce a virtual teaching system for Chinese ideograms that guides movements by haptic and visual means. A powerful 6-DOF haptic interface and reflection of the image ensure transparent virtual manipulation with undistorted hand-eye coordination. The guidance mode and assistance levels can be adapted to the user and optimized for learning. The users performance and progress are quantitatively evaluated. Initial experiments with six subjects showed how the students improve their skills.

A Brain-Controlled Wheelchair Based on P300 and Path Guidance

This paper presents the first working prototype of a brain controlled wheelchair able to navigate inside a typical office or hospital environment. This brain controlled wheelchair (BCW) is based on a slow but safe P300 interface. To circumvent the problem caused by the low information rate of the EEG signal, we propose a motion guidance strategy providing safe and efficient control without complex sensors or sensor processing. Experiments demonstrated that healthy subjects could safely control the wheelchair in an office like environment, without any training

A Collaborative Wheelchair System

This paper describes a novel robotic wheelchair, and reports experiments to evaluate its efficiency and understand how human operators use it. The concept at the heart of the collaborative wheelchair assistant (CWA) is to rely on the users motion planning skills while assisting the maneuvering with flexible path guidance. The user decides where to go and controls the speed (including start and stop), while the system guides the wheelchair along software-defined guide paths. An intuitive path editor allows the user to avoid dangers or obstacles online and to modify the guide paths at will. By using the human sensory and planning systems, no complex sensor processing or artificial decision system is needed, making the system safe, simple, and low-cost. We investigated the performance of the CWA on its interaction with able-bodied subjects and motion efficiency. The results show that path guidance drastically simplifies the control. Using the CWA, the wheelchair user needs little effort from the first trial, while moving efficiently with a conventional wheelchair requires adaptation.

Effects of a robot-assisted training of grasp and pronation/supination in chronic stroke: a pilot study

BackgroundRehabilitation of hand function is challenging, and only few studies have investigated robot-assisted rehabilitation focusing on distal joints of the upper limb. This paper investigates the feasibility of using the HapticKnob, a table-top end-effector device, for robot-assisted rehabilitation of grasping and forearm pronation/supination, two important functions for activities of daily living involving the hand, and which are often impaired in chronic stroke patients. It evaluates the effectiveness of this device for improving hand function and the transfer of improvement to arm function.MethodsA single group of fifteen chronic stroke patients with impaired arm and hand functions (Fugl-Meyer motor assessment scale (FM) 10-45/66) participated in a 6-week 3-hours/week rehabilitation program with the HapticKnob. Outcome measures consisted primarily of the FM and Motricity Index (MI) and their respective subsections related to distal and proximal arm function, and were assessed at the beginning, end of treatment and in a 6-weeks follow-up.ResultsThirteen subjects successfully completed robot-assisted therapy, with significantly improved hand and arm motor functions, demonstrated by an average 3.00 points increase on the FM and 4.55 on the MI at the completion of the therapy (4.85 FM and 6.84 MI six weeks post-therapy). Improvements were observed both in distal and proximal components of the clinical scales at the completion of the study (2.00 FM wrist/hand, 2.55 FM shoulder/elbow, 2.23 MI hand and 4.23 MI shoulder/elbow). In addition, improvements in hand function were observed, as measured by the Motor Assessment Scale, grip force, and a decrease in arm muscle spasticity. These results were confirmed by motion data collected by the robot.ConclusionsThe results of this study show the feasibility of this robot-assisted therapy with patients presenting a large range of impairment levels. A significant homogeneous improvement in both hand and arm function was observed, which was maintained 6 weeks after end of the therapy.

Controlling a wheelchair using a BCI with low information transfer rate

This paper describes a control hierarchy to drive a wheelchair using an interface with asynchronous and very low information transfer rate signal. Path guiding assistance allows the user to bring his or her wheelchair in a building environment, from one destination to the next destination. The user can stop the wheelchair voluntarily during movement, or through a reflex elicited by sensors. Decisions are simplified by presenting only the possible selections on the GUI, in a context dependent menu. This system is implemented on a conventional wheelchair with a P300 Brain Machine Interface. Tests with healthy subjects show that this system can move the wheelchair in a typical building environment according to the wishes of its user, and that the brain control is not disturbed by the movement.

A Haptic Knob for Rehabilitation of Stroke Patients

The strong impairment of motor functions in stroke survivors affects daily activities such as eating, manipulating objects or writing. Our goal is to induce long lasting improvements in such tasks by having patients perform systematic exercises using haptic interfaces. This paper describes a novel two-degrees-of-freedom interface which we have developed to help stroke patients gradually recover the ability to open and close the hand and manipulate knobs. Different solutions are studied and a design consisting of two parallelogram structures interacting with the fingers is proposed. The mechanical design offers the possibility to adapt the interface to various hand sizes and finger orientations, and to right or left-handed subjects. Design kinematics as well as actuation and system control are described. Several knobs are proposed to interact with patients, especially a cone mechanism to train a complete opening movement from a strongly contracted and closed hand to a large opened position. The interaction force with the subject is measured over four force sensors located close to the output of the interface. A preliminary study has been performed to evaluate the performances of the haptic interface

Dynamic thread for real-time knot-tying

Real-time simulation of knot-tying with visual and force feedback is essential to VR surgery training. We present a physics-based simulator that enables realistic knot tying at haptic speed. The virtual thread obeys Newtons laws and behaves naturally. The model covers mechanical properties of real thread such as stretching, compressing, bending and twisting, contact forces with self and the environment, and gravity. Its structure has essential advantages over geometrically based approaches.

Haptics in computer-mediated simulation: training in vertebroplasty surgery

Surgical simulators and computer games share the enabling technologies in the human-machine interface. With appropriate design and development, the computer-game-like medical training simulator could be used in surgical training. The authors describe a PC-based system for the simulation of the vertebroplasty procedure. In vertebroplasty, the surgeon or radiologist relies on sight and feel to properly insert the bone needle through various tissue types and densities and monitor the injection and reflux of the polymethylmethacrylate (PMMA), or cement, into the vertebra. This article focuses on the provision of a near-realistic haptic feel in bone needle insertion and manual PMMA injection. This involves an efficient biomechanical modeling of bone needle insertion and PMMA flow in bone for haptic rendering, as well as reliable delivery of forces via haptic devices. The authors show that with virtual reality gaming technologies, the surgical simulator can become a virtual trainer for a potentially risky spinal interventional procedure.