Alejandro González

• PhD
• Professor at Tecnológico de Monterrey

Soft pneumatic actuators are ideal for interacting with fragile objects, food, and humans due to their inherent compliance. Modulating stiffness and deformation is crucial for adapting to diverse applications. However, achieving non-uniform stiffness and deformation remains challenging, as most methods provide only uniform stiffness or limited defo...

Functionally graded metamaterials represent a cutting-edge approach to designing structures with cellular materials. By manipulating parameters in specific regions, a customized mechanical response is achieved, optimizing material utilization. Despite various proposed methods to generate functionally graded structures, the challenge of high computa...

Human–robot collaboration has gained attention in the field of manufacturing and assembly tasks, necessitating the development of adaptable and user-friendly forms of interaction. To address this demand, collaborative robots (cobots) have emerged as a viable solution. Deep Learning has played a pivotal role in enhancing robot capabilities and facil...

The rising demand for adaptable and user-friendly forms of interaction in the field of manufacturing and assembly tasks has led to increased attention on human-robot collaboration. Collaborative robots (cobots) have emerged as a promising solution to address this demand. In this study, we propose the integration and application of cobots along with...

In this paper, a control approach for reconfigurable parallel robots is designed. Based on it, controls in the vision-sensor, 3D and joint spaces are designed and implemented in target tracking tasks in a novel reconfigurable delta-type parallel robot. No a priori information about the target trajectory is required. Robot reconfiguration can be use...

A pendulum with two segments can be used to study the behavior of a human-like system which considers motion at the ankles and hips. Stability of such a system can be achieved by means of joints’ torques provided by the muscles, but this approach may be energetically taxing. Other methods have been suggested to act concurrently and take advantage o...

It is a challenging task to track objects moving along an unknown trajectory. Conventional model-based controllers require detailed knowledge of a robot’s kinematics and the target’s trajectory. Tracking precision heavily relies on kinematics to infer the trajectory. Control implementation in parallel robots is especially difficult due to their com...

A Kapitza's pendulum shows that it is possible to stabilize an inverted pendulum by making its base oscillate vertically. This action seems to introduce an inertial effect which will produce an attractor about the upright vertical position. This work shows that the upright posture of the trunk achieved while walking can be explained using a combina...

One of the most common injuries in athletes is that of the Anterior Cruciate Ligament (ACL). This type of injury is commonly analyzed by observing the dynamics of the body in the sagittal plane. ACL injury can be indicated by a the small knee flexion angle and a small angular position of the trunk at start of leg-landing task. In this article a 4 D...

The kinematic design and navigation control of a new autonomous mobile manipulator for uneven terrain is presented in this work. An innovative suspension system's design is based on the kinematic synthesis of an adaptable, passive mechanism that compensates for irregularities in the terrain and facilitate the control of the robotic platform using c...

Background Tracking the whole body center of mass (CoM) trajectory of balance-impaired individuals with a personalized model is useful in the development of customized fall prevention strategies. A personalized CoM estimate can be obtained using the statically equivalent serial chain (SESC) method, but the subject has to perform an identification p...

At a point in the future there may be few physical therapists for the number of patients who need treatment. To address the problem, we have created a device that can rehabilitate the wrist movements like flexion/extension and abduction/adduction, in addition to being able to fit either the left or right wrist. This paper presents the design and de...

Background: Balance control deteriorates with age and nearly 30% of the elderly population in the United States reports stability problems. Postural stability is an integral task to daily living reliant upon the control of the ankle and hip. To this end, the estimation of joint parameters can be a useful tool when analyzing compensatory actions ai...

The estimation of the human ankle's mechanical impedance is an important tool for modeling human balance. This work presents the implementation of a parameter-estimation approach based on the State-Augmented Extended Kalman Filter (AEKF) to infer the human ankle's mechanical impedance during quiet standing. However, the AEKF Filter is sensitive to...

When we face a super-aging society, there is a drastically increased need for efficient systems in terms of time and cost that can improve rehabilitation standards for the elderly people and other motor-impaired subjects. Human balance ability depends largely on the control of the full body center of mass (CoM), fall risks can be evaluated by estim...

Purpose The purpose of this paper is to present a new vision-based control method, which enables delta-type parallel robots to track and manipulate objects moving in arbitrary trajectories. This constitutes an enhanced variant of the linear camera model-camera space manipulation (LCM-CSM). Design/methodology/approach After obtaining the LCM-CSM vi...

Balance control deteriorates naturally with age and is reliant upon the control of the ankle and hip joints. To this end, the estimation of ankle and hip parameters in quiet standing can be a useful tool when analyzing compensatory actions aimed at maintaining postural stability. This work presents an experimental study of a theoretical approach bu...

Parallel robots have a growing range of applications due to their appealing characteristics (high speed and acceleration, increased rigidity, etc.). However, several open problems make it difficult to model and control them. Low computational-cost algorithms are needed for high speed tasks where high accelerations are required. This article develop...

Postural stability is important in everyday life as falls can cause severe injuries. Risk of injuries is higher in the elderly whose balance is often impaired. Modeling postural stability and the parameters that govern it is important to understand the balance mechanism and allow for the development of fall prevention strategies. Several mathematic...

Balance control naturally deteriorates with age, so it comes as no surprise that nearly 30% of the elderly population in the United States report stability problems that lead to difficulty performing daily activities or even falling. Postural stability is an integral task to daily living which is reliant upon the control of the ankle and hip. To th...

En este artículo se presenta un estudio orientado a la validación del movimiento de la muñeca de una persona sana, usando el enfoque de control óptimo. Se pretende validar que, en condiciones ontroladas y después de un proceso de entrenamiento, el movimiento descrito por una extremidad humana, en este caso la muñeca de una persona sana, puede ser m...

About 30% of the elderly population of the USA exhibits a motor impairment that inhibits daily activities and increases the probability of a fall. The ability of these individuals to maintain proper balance is largely dependent on their control over their hip and ankle joints. Studying the mechanical behaviour of these joints is important for the a...

Debido a la creciente demanda de sistemas automatizados para la recolección de cultivos, se ha planteado el desarrollo de un sistema de visión que pueda guiar a un robot manipulador en la recolección de hortalizas bajo la metodología de control conocida como manipulación de espacio de cámara (CSM por sus siglas en inglés). Una característica de est...

Poststroke hemiplegic patients often show altered weight distribution with balance disorders, increasing their risk of fall. Conventional balance training, though powerful, suffers from scarcity of trained therapists, frequent visits to clinics to get therapy, one-on-one therapy sessions, and monotony of repetitive exercise tasks. Thus, technology-...

Se investiga el posible uso de la posición personalizada del centro de masa (CoM) obtenida mediante el método Statically Equivalent Serial Chain (SESC) para evaluar el equilibrio de un sujeto en el contexto clínico. Se calculó la velocidad del CoM para cuatro tareas de posturografía: doble apoyo con ojos abiertos, doble apoyo con ojos cerrados, apo...

As the world population continues to age, there is an increased need for efficient systems that can improve rehabilitation standards for the elderly and other motor-impaired subjects. A self-training system that takes into account subject-specific differences would contribute in a positive way to personalized home rehabilitation protocols. Since hu...

Knowledge of the mass and inertial parameters of a humanoid robot or a human being is crucial for the development of model-based control, as well as for monitoring the rehabilitation process. These parameters are also important for obtaining realistic simulations in the field of motion planning and human motor control. For robots, they are often pr...

This paper presents a center of mass (CoM) estimation technique that uses the statically equivalent serial chain(SESC). A SESC is a representation of any multilink branched chain whose end-effector locates the CoM. Locating the CoM is useful for modeling humans and humanoid robots. The method starts with an experimental phase involving a force plat...

Accurate and real time balance estimation can be used to improve home based rehabilitation systems. We developed a personalized balance measurement, making use of the subject-specific center of mass (CoM) estimate offered by the statically equivalent serial chain (SESC) method and the zero rate of change of angular momentum (ZRAM) concept to evalua...

As the center of mass (CoM) position can be used to determine stability, current rehabilitation standards may be improved by tracking it. A personalized CoM estimate can be obtained using the statically equivalent serial chain (SESC) once the model parameters are identified. The identification phase can be completed using low-cost sensors (Kinect a...

he trajectory of the whole body center of mass (CoM) is useful as a reliable metric of postural stability. If the evaluation of a subject-specific CoM were available outside of the laboratory environment, it would improve the assessment of the effects of physical rehabilitation. This paper develops a method that enables tracking CoM position using...

This study investigates the possibility of using the so-called Statically Equivalent Serial Chain approach to estimate the subject-specific 3D whole body centre of mass (CoM) location. This approach is based on a compact formulation of the 3D whole body CoM position associated with a least squares identification process. This process requires a cal...

The present study aims at designing and evaluating a low-cost, simple and portable system for arm joint angle estimation during grasping-like motions. The system is based on a single RGB-D camera and three customized markers. The automatically detected and tracked marker positions were used as inputs to an offline inverse kinematic process based on...

Center of mass (CoM) estimation can be used to evaluate human stability during rehabilitation. A personalized estimation can be obtained using the serial equivalent static chain (SESC) method, calibrated using a series of static postures. The estimation accuracy is dependent on the number and quality of poses used during calibration. Currently, thi...

A human's center of mass (CoM) trajectory is useful to evaluate the dynamic stability during daily life activities such as walking and standing up. To estimate the subject-specific CoM position in the home environment, we make use of a statically equivalent serial chain (SESC) developed with a portable measurement system. In this paper we implement...

An increasingly aging society creates the need for a reliable evaluation of postural stability, specially for rehabilitation. Estimation of a subject’s center of mass (CoM) is important for the assessment of unsupported, stable standing. A portable, in-home estimation of CoM can be used as a rehabilitation tool and could be achieved using a Microso...

Center of mass (CoM) trajectory is important during standing and walking since it can be used as an index for stability and fall prediction. Unfortunately current methods for CoM estimation require the use of specialized equipment (such as motion capture and force platforms) in controlled environments. This paper aims at applying the statically equ...

We develop and present a portable tool intended for real time estimation of the center of mass (CoM) in human subjects. Using the statically equivalent serial chain (SESC) method we can account for subject specificity after identification of the model's parameters. CoM position estimates are then available from measurements of the subject's limbs o...

This article presents a study on the postural equili-brium conditions for biped robots. Criteria for dynamic walking, such as ZMP and CoP are introduced and their similarities discussed. We also introduce the effects of a compliant foot and take them into consideration during the evaluation of the criteria. A model of a planar biped is used to imit...