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In this paper a new ground contact model (GCM) for the calculation of foot-ground reaction forces (GRF) is presented. The model is appropriate for the simulation of walking, running and jumping of human and biped robots. To ensure this capability, some criteria of a proper GCM are introduced and it is shown that the new GCM passes all these criteria. Finally, the GCM is used for the simulation of...
In this paper, we propose a leg compliance method and strategies for ZMP-based bipedal walking robot on continuous uneven terrain without gyro sensor by combining soft joint, impedance, force and position control. We divide biped robot into support leg and swing leg to apply different control methods, and distinguish period of swing leg into four procedures, which adopt different strategies. By this...
Falls are one of the main causes of decreased quality of life and activities of daily living among the elderly individuals. Because tripping is the most common cause of falls, some types of recovery motions have been reported after tripping induced by a flat plate or block. Common recovery strategies observed under these conditions included elevating and lowering strategies. Especially, in case that...
We present the MIT Super Mini Cheetah, a small (sub-10kg) and low-cost (sub-10k$) quadrupedal robot for dynamic locomotion. The robot can control vertical and horizontal force and impedance at each foot and performs dynamically stable walking, jumping, pronking, turning and braking using simple force and impedance trajectories. We present design specifications for dynamic legs which were used to guide...
The work presents the development and evaluation of a novel foot sole for humanoid robots. For humanoid locomotion the foot sole is important for absorbing impacts. In contrast to the simple planar rubber pad foot sole that is conventionally used in humanoid robots this paper introduces a new foot sole design in which the dissipation of energy during collision is done effectively using a viscous air...
This paper addresses the frequency content of Vertical Ground Reaction force (VGRF) signals. Signal processing of such data is crucial in order to characterize the gait itself. The outcome processing can be used to show the presence of disease, to track the rehabilitation or even to detect the possibility of falling. In order to come up with the correct processing, it is important to set up the rules...
An important aspect of gait analysis is the measurement and interpretation of the Ground Reaction Force (GRF) characteristics. These measurements are important for the calculation and analysis of joint moments and forces, in addition to its assistance in natural and artificial walk control. Usually, a force platform, requiring a large space, is used to obtain these measurements but only few steps...
In situations where humanoid robots with constrained posture walk through a narrow space (e.g. manufacturing plants and kitchens), shuffling motions that are stepless and possess wide foot supporting area are effective. One of the difficulties of humanoid's shuffle translations is the load distribution between both feet. If sole loads are not distributed appropriately, the humanoid robot cannot maintain...
In this paper, we propose a new kind of tripedal locomotion—namely, robotic walking with three legs. We develop a prototype robot, which we call Martian III, having three stretchable legs fixed to each other at the center of the body. Therefore the coxa (the hip joint) is completely fixed in this robot, and the only control we have are the linear actuators to stretch the three legs in the radial directions...
This paper describes a novel foot for biped robots designed to provide a reliable and low-cost solution for sensing the Center of Pressure (CoP) on flat and uneven surfaces. The foot uses a new method for detecting contact forces based on measuring the deflection of three flexural toes using Hall-effect magnetic field sensors. We experimentally compare five mathematical models for calculating the...
This paper introduces a novel Balance Feedback Interface (BFI) that addresses the problem of bilateral feedback for teleoperation of humanoid robots. With this new device we expect to enhance robot's high force manipulation performance to a level comparable to humans by dynamically synchronizing master and slave. Through this Human-Machine Interface (HMI) we aim to achieve two goals: (i) have the...
This paper investigates the ability of dynamically walking bipeds to adapt their motion to persistent exogenous forcing. Applications that involve physical interactions between a bipedal robot and other robots (or humans), require that the robot adjust its stepping pattern in response to externally applied force signals. In our setting, an underactuated bipedal robot model walks under the influence...
Weight and power consumption of variable stiffness actuation mechanism are critical for its implementation in a portable assistive device combined with an actuator, gearhead, elastic element, and batteries. Therefore, we present a portable stiffness modulation mechanism for an Ankle Foot Orthosis (AFO) utilizing pneumatic stiffness. The mechanism consists of two units: a driving unit that controls...
This research presents the design and development of a new strategy for an ankle rehabilitation system. The developed ankle rehabilitation system can be used as Continuous Passive Motion (CPM) device and strength endurance training device for early stage functional rehabilitation. The designed mechanism can allow desired maximum and minimum Range of Motion (ROM) for dorsiflexion and plantar flexion...
This paper describes the initial design, control system development and preliminary testing of a robotic gait training device which aims to help teach and/or improve the gait patterns of children affected by cerebral palsy (CP). An H-frame, timing-belt driven, 2 degree-of-freedom stage has been designed and built to guide a child's leg through a gait pattern during over-ground training. The end-effector...
This paper illustrates the dynamic effects of using a kinetic shape as a crutch tip on swing through crutch walking (non-weight bearing). The overground crutch walking of four participants was measured to examine the effect of a Kinetic Crutch Tip (KCT) on step length and swing time using a ProtoKinetics®Zeno Walkway System. Changes in ground reaction forces during the crutch gait cycle were examined...
Measurements of multi-axial Ground Reaction Force (GRF) can provides quite useful information for monitoring abnormalities of gait during Activities in Daily Living (ADL). Measuring multi-axial GRF using ambulatory GRF sensing systems is difficult due to the height of sensor and the number of sensors used. Therefore, we developed a wireless GRF sensing system having the low height (12 mm) and the...
A novel device, named ‘Walk-Even’, was developed to measure human gait and provide real-time feedback to correct gait asymmetry. Gait asymmetry is usually exhibited in patients with stroke or with certain neurological disorders. Our device can measure the weight pressure distribution that the patient exerts on each foot, in addition to the gait time, swing time, and stance time of each leg while walking...
This work presents a comparison between two optimization methods used to compute the muscle activation levels and corresponding forces that drives a set of generalized coordinates towards a set of desired trajectories. To improve the performance of musculoskeletal optimizations a supplemental set of actuators is often included in addition to the modeled muscles. Given a dynamic musculoskeletal model...
Mobility assistance robots can provide physical and balance support in order to prevent falls of elderly or patients. In this paper we propose a fall prevention approach for a mobility assistance robot equipped with a pair of actuated arms. The algorithm evaluates the user's Extrapolated Center of Mass (XCOM) and determines required supportive forces to be provided to the user in order to prevent...
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