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When designing a robot for human-safety during direct physical interaction, one approach is to size the robot's actuators to be physically incapable of exerting damaging impulses, even during a controller failure. Merely lifting the arms against their own weight may consume the entire available torque budget, preventing the rapid and expressive movement required for anthropomorphic robots. To mitigate...
Many studies on human support robots have been carried out hitherto. Bilateral control based on 4ch bilateral controller is an efficient method for human support. Bilateral control is a method for realizing transmission of force sensation between master system and slave system. However, in the case of multi-degree of freedom system, containing vertical motion, it is difficult to distinguish reaction...
It is necessary to know the air inflow of suction cup for the designing of a new passive suction cup, which not only could easily attach and detach, but also could keep long adsorption time. This paper proposes a method to calculate the air inflow and its speed, which is easy to implement since it only requires a pressure sensor. Before calculating the air inflow, the factors affecting it should be...
Expansion Rod Capturing Nozzle Device is developed to achieve the function of capturing the non-cooperative satellite by locking the main engine nozzle. Nozzle structure is captured by the device through its throat, so the size and mass are small. The overall structure design of the device and the operating principle of the Expansion Rod mechanism are described. A method of Meshing Profile Modeling...
A variable stiffness actuator is proposed according to the human ergonomic joint actuation mechanism and applied to an elbow rehabilitation robot. The robot employs an antagonistic compliant driving actuation to ensure rehabilitation training effectiveness and the patient's safety even under the condition of spasm. The robot joint stiffness and position can be controlled simultaneously by using the...
In this paper, we study the role of soft actuation in the reduction of the energy cost for mechanical systems that perform cyclic tasks. The objective is to determine the optimal stiffness value and spring pre-load such that a given cost functional is minimized. For the analysis, we consider both fully actuated and underactuated mechanical systems using elastic actuators which, depending on how and...
It is believed that micro actuators and robots might introduce revolutionary changes in many advanced applications, such as nano manipulation and minimally invasive medicine. Many prototypes were recently developed, which could be powered either by micro organism, by onboard mechatronic systems or by remote magnetic fields. This paper presents two evolving designs, aiming at producing a micro motor...
Octopus arms, as well as elephant trunks, squid tentacles, and vertebrate tongues are termed muscular-hydrostats. In such structures, the volume of the organ remains constant during their motions, enabling diverse, complex, and highly controlled movements without the support of a skeleton. Such flexible structures show major advantages over articulated arms that have a rigid skeleton and joints. These...
This paper presents the design of a lightweight robot arm intended for safe physical human-robot interaction. The robot arm design combines tendon actuation with elasticity in the tendons to achieve a significant reduction in mass and passive compliant behavior. The use of elastic tendons in all joints in order to gain maximum safety and performance properties, however, results in a significant increase...
Robot manipulation in unstructured environments depends on understanding the geometric and physical constraints that the environment imposes on the robot. While approaches like simultaneous localization and mapping (SLAM) allow robots to understand geometric constraints, the understanding of environmental physical manipulation constraints is largely unaddressed when exploring unstructured flexible...
Low-cost but high performance robot arms are required for widespread use of service robots. Most robot arms use expensive motors and speed reducers to provide torques sufficient to support the robot mass and payload. If the gravitational torques due to the robot mass, which is usually much greater than the payload, can be compensated by some means, the robot would need much smaller torques, which...
In this paper we simultaneously optimize the parameters describing the morphology of a robot arm and the parameters of its nonlinear controller. A novel concept of a pick-and-place robot arm is considered, which is called the resonating arm (RA). It uses a nonlinear spring mechanism to generate pick-and-place motions without the need for powerful actuators. This improves energy efficiency, cost and...
We are developing an intelligent compact and modular knee-ankle-foot robot gait rehabilitation at outpatient and home settings. The robot is designed with a novel compact compliant force controllable actuator. We adopt a modular design for the knee and ankle joint so that the robot can assist patients with different conditions of gait impairments. The light-weight anthropomorphic structure designed...
This paper presents a new suction cup with a disc spring for exiting adsorption mechanisms (for example, wall-climbing robots). The center of the suction cup can be pulled up manually through the use of buckling of the disc spring. When deformation of the disc spring reaches a certain balance point, it can sufficiently generate adsorption force. However, with time, the adsorption force will gradually...
Fleas have a unique catapult mechanism with a special muscle configuration. Energy is stored in an elastic material, resilin, and the extensor muscle. Force is applied by the extensor muscle to generate a torque. Energy is released as a small triggering muscle reverses the direction of the aforementioned torque. A flea can jump 150 times its body length using this elastic catapult mechanism. In this...
In this paper, we model and characterize the thermomecahnical behavior of SMA springs based on Brinson's constitutive model of SMAs. The model developed in this paper can be used to compute the recovery length of SMA springs. We used the model to develop a temperature feedback position controller to control the joint motion of the SMA spring-actuated robot. We also implemented a position controller...
This paper presents the design and development of a novel two Degrees-Of-Freedom (DOF) safe robot manipulator. Magneto-Rheological (MR) clutches are incorporated in the design to enable antagonistic actuation at the joints. A single unidirectional motor supports bidirectional actuation of all joints. Unlike most current safe robots, high quality actuation is preserved, while the manipulator weight...
This paper considers the stable grasp in the sense of quasi-statistics, i.e., an object is grasped by a multi-fingered robot hand, where each finger is regarded as a virtual 3D linear spring. The stability analysis is to find a condition under which the equilibrium can be restored after any small perturbations of the object's position and orientation. The paper derives a necessary and sufficient condition...
This paper analyzes the effect of constraining a large deformation of elastic fingers of a structurally simple gripper on the gripping force to enhance the handling range for the purpose of developing a robot gripper for agricultural applications. The elastic fingers are modeled as a series of rigid links connected with torsional springs, and the finger deformation is analyzed based on the principle...
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