Overload Protection Mechanism Research Articles

Automatic Couplings With Mechanical Overload Protection for Modular Robots

This paper presents an automatic coupling mechanism with mechanical overload protection for use in modular robotic systems. The genderless coupling incorporates a novel safety mechanism that disengages two modules at a predefined torque threshold. Several key design aspects allow the minimalist coupling to contain all functionalities within a compact cylindrical space. A detailed analytical model of the overload protection mechanism is validated by testing two materials and fabrication methods. We further present a functional prototype of the coupling with a demonstration of two modular robots driving toward one another, automatically connecting and disconnecting, detecting the connection, communicating in the process, and sensing the angle between them. The coupling as well as the embedded technologies and mechanisms present essential steps toward enabling fully self-reconfigurable robots combining modular and origami features, while advancing the process of introducing modularity into a wide range of robotic systems.

English

The wheel force transducer (WFT), which measures the force or torque applied to the wheel, is an important instrument in vehicle testing field and has been extremely promoted by researchers. Since the high cost and technical secret of the commercial products may slow down the development of WFT to some extent, Southeast University has devoted to the WFT research with some prototypes. Essentially, the WFT is a multi-axis force sensor (MFS) in which an elastic-body will deform under the applied forces. However, when applying a MFS into vehicle wheel and making it to be a WFT, it may be subjected to forces/moments which exceed the measuring range under the over rated load, especially on a heavy truck WFT under loads of X or Z direction. Plastic deformation and damage may occur on the elastic-body of WFT. This paper presents a mechanical approach of the overload protection mechanism which can prevent the overload damage and guarantee the sensor performance. An intermediate flange, which is elaborately designed using Computer Aided Engineering (CAE) tools, is installed between wheel hub and the elastic body to meet the overload protection. Experiment and prototyping test are conducted on the hydraulic platform. Results show that the proposed overload protection mechanism performs well. In particular, the applied loads over ±120 kN and ±30 kNm are prevented from damage for the heavy truck WFT.   Key words: Wheel force transducer, overload protection mechanism, vehicle wheels/typres, heavy duty trucks.

A Three-Axis Force Sensor for Dual Finger Haptic Interfaces

In this work we present the design process, the characterization and testing of a novel three-axis mechanical force sensor. This sensor is optimized for use in closed-loop force control of haptic devices with three degrees of freedom. In particular the sensor has been conceived for integration with a dual finger haptic interface that aims at simulating forces that occur during grasping and surface exploration. The sensing spring structure has been purposely designed in order to match force and layout specifications for the application. In this paper the design of the sensor is presented, starting from an analytic model that describes the characteristic matrix of the sensor. A procedure for designing an optimal overload protection mechanism is proposed. In the last part of the paper the authors describe the experimental characterization and the integrated test on a haptic hand exoskeleton showing the improvements in the controller performances provided by the inclusion of the force sensor.

Wafer Level Processing of Overload-Resistant Pressure Sensors

Abstract The performance of industrial differential pressure sensors concerning the overload pressure, step response and measurement uncertainty covers wide application areas. We will present a novel approach of silicon differential pressure sensors with an integrated overload protection mechanism and measurement results of the processed glass wafer topology. Thermal treated Glass wafers are processed to develop overload protected sensors at the chip level [1,2]. By varying the process environment, the crystal growth in SCHOTT Borofloat 33 tested by x-ray crystallography and AFM analysis is reduced [3]. Without additional passivation layers the risk of chemical reactions with the glass wafer is avoided and no process steps for coating and removing are required. The glass wafers surface quality is suitable for anodic bonding.

Miniature robust five-dimensional fingertip force/torque sensor with high performance

This paper proposes an innovative design and investigation for a five-dimensional fingertip force/torque sensor with a dual annular diaphragm. This sensor can be applied to a robot hand to measure forces along the X-, Y- and Z-axes (Fx, Fy and Fz) and moments about the X- and Y-axes (Mx and My) simultaneously. Particularly, the details of the sensing principle, the structural design and the overload protection mechanism are presented. Afterward, based on the design of experiments approach provided by the software ANSYS®, a finite element analysis and an optimization design are performed. These are performed with the objective of achieving both high sensitivity and stiffness of the sensor. Furthermore, static and dynamic calibrations based on the neural network method are carried out. Finally, an application of the developed sensor on a dexterous robot hand is demonstrated. The results of calibration experiments and the application show that the developed sensor possesses high performance and robustness.

Controller design and closed-loop stability analysis for admission control in Web service systems

AbstractIT systems have to provide to their users prescribed Quality of Service (QoS) levels, usually defined in terms of application performance, which must hold irrespectively of the significantly time-varying workload. To handle system overload issues, admission control is used as an overload protection mechanism which rejects requests under peak workload conditions in order to provide QoS guarantees to the running applications. For ensuring QoS levels at design time, the performance of such mechanisms should be a priori guaranteed. To this end, this paper proposes an appropriate controller, the closed-loop stability properties pf which are formally assessed.

2A2-D06 脚部にパラレルリンク機構を用いた2足ロコモータの開発 : 第20報:足部6軸力覚センサの過負荷保護機構(脚移動ロボット)

This paper describes an overload protection mechanism for a 6-axis force/torque sensor. It can limit the load applied to the force sensor by contacting a sole part with a top plate placed on the force sensor. Specifically, compression springs are arranged between the force sensor and the top plate, and the springs are pre-compressed. When more loads than the preload are applied to the top plate, the top plate touches the sole part by compressing the springs, and it is possible to prevent the 6-axis force/torque sensor from being over-loaded. Verification of the proposed mechanism is conducted through experiments with a human-carrying biped robot, WL-16RV.

Overload-resistant pressure sensors in the nominal range of 10 mbar (1 kPa)

Differential pressure sensors with silicon diaphragms provide a nominal measuring range of 10 mbar (1 kPa) at a measurement uncertainty of ≤2⋅10−3. An additional external overload protection mechanism is required to achieve an overload reserve up to 160 bar (16 MPa). To integrate the overload protection at the wafer level, a micromechanical overload protection is needed. Such a micromechanical overload protection for differential pressure sensors can be produced from heat-treated glass. The functional principle limits the diaphragm deflection. Here, we demonstrate an overload capability reaching 50 bar (5 MPa) for a silicon diaphragm with a nominal measuring range of 10 mbar and a diaphragm thickness of 30 μm.

2A1-E04 柔軟センサ肉質外装と自動復帰可能な関節過負荷保護機構を備えたヒューマノイドの設計と開発

This paper describes development of a humanoid robot with soft thick exterior and automatic recoverable mechanical overload protection mechanism. Such features enable humanoid robots to tolerate obstacles in daily environment. The developed robot has thick soft polyurethane covers embedded with tactile sensors and mechanical torque limiters so that it tolerate impulsive and static overload. We confirmed that the developed robot can walk, carry things wearing whole-body enclosing exterior, and it can tolerate the strong contact such as falling down by dislocating the joint and recovering automatically afterwards.

Overload Protection Mechanisms for Force Detecting Beam in a Force Sensor

Overload prevention is important in force sensors to avoid fatal damage due to unexpected external impact. Until now, some mechanisms using screws or straight pins have been proposed for preventing damage to the sensor. However, nothing has been reported regarding the utility of this mechanism. The unidirectional force sensor based on an H-slit type parallel beam we proposed in previous work. This sensor structure alone can be realized for overload prevention without any other parts and can be embedded as overload protection mechanism in the structure. In this paper, we verify the utility of conventional type's mechanisms and evaluate the usefulness of the slit type one which we have developed.

1P1-A07 力検出用はりにおける過負荷防止機構(触覚と力覚)

Overload prevention is important for a force sensor in order to avoid fatal damage due to unexpected external forces. Until now, some mechanisms have been proposed which prevent damage of the sensor structure using screw and straight pin. But, there is no report regarding the utility of this mechanism. We proposed a unidirectional force sensor based on the H-slit type parallel beam structure in out previous work. This sensor structure alone can be realized for overload protection with out any other parts and can be embedded as overload protection mechanism in the structure. In this paper, we verify the utility of conventional mechanisms and evaluate the usefulness of the slit type one which we have developed.