Omnidirectional Platform Research Articles

Omnidirectional robot for the diagnosis of the attention deficit

Attention Deficit Hyperactivity Disorder (ADHD) occurs in 16% of the Colombian student population and estimates that between 30-70% of these children continue to show symptoms in adulthood. Thus, a tool is proposed for the professional to support his diagnosis according to the criteria offered by the Diagnostic and Statistical Manual of Mental Disorders (DMS). An omnidirectional platform is implemented, striking for its design, for children, adolescents and that becomes a concentration challenge for adults.With an Electroencephalography (EEG) helmet a brain wave reading is made; with the help of a Computer Brain Interface (BCI) you can have the reading of facial gestures, having said reading is implemented to control the omnidirectional platform, with the same BCI you also have the reading of concentration, stress, excitation, etc. of individuals; Thus, the professional in the area can support his diagnosis according to several factors, such as: EEG interpretation, emotional data (concentration, stress, excitement ...), and the observation of the individual. The evaluation of the patient makes the health professional, generating some challenges to overcome the platform and interpreting the different data according to their professional criteria.

A Comprehensive Performance Evaluation of Different Mobile Manipulators Used as Displaceable 3D Printers of Building Elements for the Construction Industry

The construction industry is currently technologically challenged to incorporate new developments for enhancing the process, such as the use of 3D printing for complex building structures, which is the aim of this brief. To do so, we show a systematic study regarding the usability and performance of mobile manipulators as displaceable 3D printing machinery in construction sites, with emphasis on the three main different existing mobile platforms: the car-like, the unicycle and the omnidirectional (mecanum wheeled), with an UR5 manipulator on them. To evaluate its performance, we propose the printing of the following building elements: helical, square, circular and mesh, with different sizes. As metrics, we consider the total control effort observed in the robots and the total tracking error associated with the energy consumed in the activity to get a more sustainable process. In addition, to further test our work, we constrained the robot workspace thus resembling real life construction sites. In general, the statistical results show that the omnidirectional platform presents the best results –lowest tracking error and lowest control effort– for circular, helicoidal and mesh building elements; and car-like platform shows the best results for square-like building element. Then, an innovative performance analysis is achieved for the printing of building elements, with a contribution to the reduction of energy consumption.

Adaptive Single Neuron Anti-Windup PID Controller Based on the Extended Kalman Filter Algorithm

In this paper, an adaptive single neuron Proportional–Integral–Derivative (PID) controller based on the extended Kalman filter (EKF) training algorithm is proposed. The use of EKF training allows online training with faster learning and convergence speeds than backpropagation training method. Moreover, the propose adaptive PID approach includes a back-calculation anti-windup scheme to deal with windup effects, which is a common problem in PID controllers. The performance of the proposed approach is shown by presenting both simulation and experimental tests, giving results that are comparable to similar and more complex implementations. Tests are performed for a four wheeled omnidirectional mobile robot. Tests show the superiority of the proposed adaptive PID controller over the conventional PID and other adaptive neural PID approaches. Experimental tests are performed on a KUKA® Youbot® omnidirectional platform.

An Omnidirectional Assistive Platform Integrated With Functional Electrical Stimulation for Gait Rehabilitation: A Case Study.

This paper presents a novel omnidirectional platform for gait rehabilitation of people with hemiparesis after stroke. The mobile platform, henceforth the "walker", allows unobstructed pelvic motion during walking, helps the user maintain balance and prevents falls. The system aids mobility actively by combining three types of therapeutic intervention: forward propulsion of the pelvis, controlled body weight support, and functional electrical stimulation (FES) for compensation of deficits in angular motion of the joints. FES is controlled using gait data extracted from a set of inertial measurement units (IMUs) worn by the user. The resulting closed-loop FES system synchronizes stimulation with the gait cycle phases and automatically adapts to the variations in muscle activation caused by changes in residual muscle activity and spasticity. A pilot study was conducted to determine the potential outcomes of the different interventions. One chronic stroke survivor underwent five sessions of gait training, each one involving a total of 30 minutes using the walker and FES system. The patient initially exhibited severe anomalies in joint angle trajectories on both the paretic and the non-paretic side. With training, the patient showed progressive increase in cadence and self-selected gait speed, along with consistent decrease in double-support time. FES helped correct the paretic foot angle during swing phase, and likely was a factor in observed improvements in temporal gait symmetry. Although the experiments showed favorable changes in the paretic trajectories, they also highlighted the need for intervention on the non-paretic side.

An omnidirectional WPT platform for distributed fully implanted neural recording systems

Recent progress on human brain science requires developing advanced neural recording system to capture the activity of large neural populations accurately, across a large area of the brain, and over extended periods. Recently proposed distributed neural recording systems with numerous implanted devices require reliably energizing them wirelessly. Random distribution of these mm-sized implants and brain motion place them at different positions and orientations with respect to the power transmitter. Therefore, traditional wireless power transfer techniques fall short of reaching sufficient power for all implants simultaneously, rendering some implants nonfunctional. In this paper, a three-layer power transmitting array with three-phase coil excitation current is introduced, which is capable of producing omnidirectional and homogeneous magnetic field across the volume where the Rx coils are located. The individual coil dimensions in the array is optimized to improve the worst-case scenario in terms of homogeneity, which is further verified by the measurements using a scaled-up prototype system. The measurement results show that the minimum received voltages is improved from 0.34 V for 10-mm side-length hexagonal transmitting coil array to 0.83 V for the optimal case, i.e., 35 mm side-length hexagonal transmitting coil array.

Research on the Dynamics of an Omnidirectional Platform Taking into Account Real Design of Mecanum Wheels (as Exemplified by KUKA youBot)

Research on the Dynamics of an Omnidirectional Platform Taking into Account Real Design of Mecanum Wheels (as Exemplified by KUKA youBot)

High mobility control of an omnidirectional platform for gait rehabilitation after stroke.

We present a novel control method for an omnidirectional robotic platform for gait training. This mobile platform or "walker" provides trunk support and allows unrestricted motion of the pelvis simultaneously. In addition to helping the user maintain balance and preventing falls, the walker combines two types of therapeutic intervention: forward propulsion of the trunk and partial body weight support (BWS). The core of the walker's control is an admittance controller that maximizes the platform's horizontal mobility by optimizing the virtual mass of the admittance model. Said mass represents the best tradeoff between a low-frequency oscillation mode that becomes more damped as the virtual mass decreases, and a high-frequency mode that becomes less damped simultaneously and hence could destabilize the system. Forward propulsion of the trunk is aided by a horizontal force that is modulated with the patient's gait speed and turning rate to ensure easy adaptation. BWS is provided by a second, independent admittance controller that generates a spring-like upward force. In an initial study, a stroke patient was able to walk stably in the platform, as evidenced by the absence of oscillations associated with an excessively low virtual mass. A progressive increase in the patient's self-selected speed, along with greater uniformity in the instantaneous velocity, suggest that forward propulsion was effective in compensating the patient's own propulsion deficit.

Omni-Directional Conveyor Platform

Omni-Directional Conveyor Platform

General Model of an Omnidirectional Mobile Robot Suitable for Uneven Ground

Mecanum wheels are used when omnidirectional movability of a vehicle is desired. For achieving the movability it is important to have a model of this omni-directional platform. In order to apply the omni-directional vehicle with four Mecanum wheels both to plane ground and to uneven ground, this paper presents a general model. Firstly the kinematics and the dynamics of the model on plane ground are presented. Then it is presented that there are mainly four types of uneven ground and four classes of touch states between the Mecanum wheels and the uneven ground in common buildings. A kinematical model which is suitable for the uneven ground is illustrated. It is proved that this model is also suitable for plane ground. A mobile robot control system was established by using Simulink module of MATLAB.

Instantaneous centre of rotation based motion control for omnidirectional mobile robots with sidewards off-centred wheels

AZIMUT-3 is a nonholonomic omnidirectional platform design using sidewards off-centred compliant wheels. This design makes it possible to experiment with the use of the chassis’ instantaneous centre of rotation (ICR) for motion control. Research on ICR-based motion controllers has focused on handling structural singularities and misses a more general consideration of the chassis’ kinematic and physical constraints like steering, velocity and acceleration constraints. This paper presents the design of an ICR-based motion controller for AZIMUT-3. Leveraging a new parametrization of the motion state space and the associated representation in R3 (collectively referred to as the H representation) and adapting a time scaling principle initially developed for manipulator trajectories, the designed motion controller is able to handle actuators coordination and their physical limits, as well as structural singularities. Results of tests done with the platform are presented, demonstrating the applicability of the proposed motion controller in efficiently handling these issues.

Motion Improvement of Four-Wheeled Omnidirectional Mobile Robots for Indoor Terrain

The four-wheeled omnidirectional platform is great to use for an indoor mobile robot. It can increasingly move and change heading directions. However, the robot is easy to slip when it is moving. One or more wheels are sometimes not touching the ground. This paper approaches to solving these problems by computational simulation in locomotion. The mathematical models simulate the robot movement. The robot struggles to go to the target with randomly simulated slips and untouched ground circumstances. The robot can estimate the positions using the Kalman filter and readjust itself to the planned path. Consequently, this paper demonstrates the motion improvement and compares the results of decreasing errors.

PCA-based selection of distinctive stability criteria and classification of post-stroke pathological postural behaviour

In this paper, we study the postural behaviour of two categories of people: Post-CVA subjects suffering from cerebrovascular accident syndromes and healthy individuals under several levels of anterior-posterior and medial-lateral sinusoidal disturbances (0.1-0.5 Hz). These perturbations were produced from an omnidirectional platform called Isiskate. Afterwards, we have quantified seventy postural parameters, they were combined of linear stabilometric parameters and non-linear time dependent stochastic parameters using stabilogram diffusion analysis and some spectral attributes using power spectral density. The aim of our analysis is to reduce data dimensionality using principal component analysis (PCA). Furthermore, we proposed a new PCA-related criterion named: criterion of contribution in order to evaluate the contribution of every variable in the resulted system structure, and thus to eliminate the redundant postural characteristics. Afterwards, we highlighted some interesting distinctive parameters. The selected parameters were used thereafter in comparison between the studied groups. Finally, we created a classification model using support vector machines to distinguish stroke patients. Our proposed techniques help in understanding the human postural dynamics and facilitate the diagnosis of pathologies related to equilibrium which can be used to improve the rehabilitation services.

Omnidirectional Aerial Vehicles With Unidirectional Thrusters: Theory, Optimal Design, and Control

This paper presents a theoretical study on omni-directional aerial vehicles with body-frame fixed unidirectional thrusters. Omniplus multi-rotor designs are defined as the ones that allow to exert a total wrench in any direction using positive-only lift force and drag moment (i.e., positive rotational speed) for each rotor blade. Algebraic conditions for a design to be omniplus are derived, a simple necessary condition being the fact that at least seven propellers have to be used. An energy optimal design strategy is then defined as the one minimizing the maximum norm of the input set needed to span a certain wrench ellipsoid for the adopted input allocation strategy. Two corresponding major design criteria are then introduced: firstly, a minimum allocation-matrix condition number aims at an equal sharing of the effort needed to generate wrenches in any direction; secondly, imposing a balanced design guarantees an equal sharing of the extra effort needed to keep the input in the non-negative orthant. We propose a numerical algorithm to solve such optimal design problem and a control algorithm to control any omnidirectional platform. The work is concluded with informative simulation results in non-ideal conditions.

Development of a Dexterous Dual-Arm Omnidirectional Mobile Manipulator

Abstract This paper presents an experimental mobile manipulator composed of a dual-arm torso with a human-like structure assembled on an omnidirectional platform. The dual-arm system integrates several commercial devices: two arms UR5 with 6 degrees of freedom, each one equipped with an Allegro Hand with four fingers and a total of 16 degrees of freedom, and each fingertip provided with a tactile sensor. The omnidirectional platform has a circular shape and three wheels, with an original special design, whose coordinated movements allow omnidirectional displacements of the platform. It is equipped with laser-range sensors, a radio positioning system and an RGB-D camera to detect potential obstacles and navigate safely. The paper describes the main aspects of the mechanical structure of the mobile manipulator and the software framework developed to control the whole device.

Stereotactic EEG via multiple single-path omnidirectional trajectories within a single platform: institutional experience with a novel technique.

OBJECTIVEStereotactic electroencephalography (SEEG) is being used with increasing frequency to interrogate subcortical, cortical, and multifocal epileptic foci. The authors describe a novel technique for SEEG in patients with suspected epileptic foci refractory to medical management.METHODSIn the authors' technique, standard epilepsy evaluation and neuroimaging are used to create a hypothesis-driven SEEG plan, which informs the 3D printing of a novel single-path, multiple-trajectory, omnidirectional platform. Following skull-anchor platform fixation, electrodes are sequentially inserted according to the preoperative plan. The authors describe their surgical experience and technique based on a review of all cases, adult and pediatric, in which patients underwent invasive epilepsy monitoring via SEEG during an 18-month period at Vanderbilt University Medical Center. Platform and anatomical variables influencing localization error were evaluated using multivariate linear regression.RESULTSUsing this novel technology, 137 electrodes were inserted in 15 patients with focal epilepsy with favorable recording results and no clinical complications. The mean entry point localization error was 1.42 mm (SD 0.98 mm), and the mean target point localization error was 3.36 mm (SD 2.68 mm). Platform distance, electrode trajectory angle, and intracranial distance, but not skull thickness, were independently associated with localization error.CONCLUSIONSThe multiple-trajectory, single-path, omnidirectional platform offers satisfactory accuracy and favorable clinical results, while avoiding cumbersome frames and prohibitive up-front costs associated with other SEEG technologies.

A multi objective genetic algorithm approach to a design parameter generation for a robot platform on three omnidirectional wheels

Superior mobility while ensuring maximum stability is a key requirement for most mobile robots. These requirements are fulfilled if the robot has a well-designed robotic platform that serves as a physical interface between its body and the floor. Although there are different design and development approaches for car-like robotic platforms, there is little design guidance for robot platform on three omnidirectional wheels. Hence, a method for generating optimal design parameters of such robotic platforms is proposed in this work. An objective function relevant to platform stability, the robot mass, and driving torque is formulated to form a min–max optimization problem. Finally, a trade-off between the design variables of the robotic platform is carried out from the result of Multi Objective Genetic Algorithm in Matlab. An omnidirectional wheeled robotic platform is developed to study the stability and mobility analysis of this robotic platform for various maneuver modes. This approach is seen to be effective for generating design variables of omnidirectional three wheels robotic platform that has maximal stability and minimal driving torque while traversing across inclined and flat floors. As a result, this optimization approach can be used to yield better design analysis with reduced reworking cost and manufacturing time.

A Low-Cost and Lightweight Alternative to Rehabilitation Robots: Omnidirectional Interactive Mobile Robot for Arm Rehabilitation

Robotic rehabilitation is a growing field. Robots facilitate repetitive therapies, which have positive effects on the rehabilitation of patients who lack arm control because of central nervous system lesions. However, the use of such rehabilitation robots is rare due to high costs and low acceptance among patients. Therefore, this study is focused on the development and control of a novel low-cost omnidirectional interactive mobile robotic platform with force feedback to assist and guide a patient’s hand during therapy. The primary goals for such a mobile robot are to minimize its weight and dimensions, which are significant factors in patient acceptance. Position-based stiffness control was employed with a proportional derivative controller to control the position of the robot and to assist the patient during motion. A user interface with given tasks was built to manage tasks, obtain test results and set control variables. Test results showed that the developed experimental mobile robot successfully assisted and guided the user during the test period.

Sensor Integration for Autonomous Docking of a Mobile Robot with Omnidirectional Platform

Docking of mobile robots requires precise rawpose estimation relative to the docking platform to accomplish the task successfully. Besides, sensors data acquisitions in an indoor environment should be accurate enough for localization and navigation toward the docking platform. However, the sensors are entitled to errors due to the measurement uncertainty. In this paper, sensor integration is exploited to decrease the measurement ambiguity and increase the accuracy of the docking.

Global navigation approach for assistant robot

Contexto: En este trabajo se muestra un enfoque de navegación novedoso basado en imágenes para un robot asistente híbrido compuesto por un humanoide y una plataforma omnidireccional.Método: Este enfoque presenta un análisis del espacio complejo, usando el principio de atracción y repulsión de polos y ceros. Para desarrollar el algoritmo se desarrolla un sistema integrado, el cual incluye: una cámara externa (para tomar la vista de la superficie global de navegación), el robot asistente, y los algunos dispositivos de comunicación. La navegación está soportada por algoritmos de procesamiento digital de imágenes y llevada a cabo usando la técnica de localización de raíces.Resultados: Se obtuvo un sistema integrado de navegación global con sensórica externa para el robot híbrido propuesto.Conclusiones: Algunas simulaciones y pruebas experimentales se discuten con el fin de validar esta propuesta y el sistema entero. También se dan sugerencias para trabajos futuros.

Design Process of a Master Controller for Electric Omnidirectional Platforms

The need vehicles able to move or park easily in narrow or cluttered halls, along with the progress in matter of motors, batteries and controllers applied to electric vehicles has supported the development of electric omnidirectional vehicles, in robotics, industrial and health fields.The solutions currently found in the market generally integrate all the electrical/mechanical components and do not offer an option of a master controller compatible with different omnidirectional platforms.A master controller for electric omnidirectional platforms adaptable to a wide range of usage conditions and mechanical power requirements, would be an interesting component for design purposes at academic level, where engineering students could understand how design variables are related to the component selection.This article presents the design process of a master controller for this kind of vehicles and the procedure for determining its parameters and the specifications for electric motors required on different platforms that will have different mechanical power requirements and use conditions. First, specific characteristic for a general platform have been defined, the kinematic behavior has been characterized and next, a simulation model has been configured and tested with a real platform in order to identify the real behavior or the master controller.