Abstract: A chainring assembly includes a chainring carrier adapted to be coupled to a crank arm. The chainring carrier is rotatable about a rotation axis, and includes an outer periphery having carrier threads. A chainring structure includes an inner periphery having chainring threads and an outer periphery comprising a plurality of teeth. The inner periphery of the chainring structure is threadably engaged with the outer periphery of the chainring carrier. In one embodiment, a power meter device includes a body having a torque input section and a torque output section, with the torque output section including an outer periphery having threads adapted to be coupled to a chainring structure.

Abstract: A rotational speed sensor, including: a cylindrical sensor head having a measuring tip; and a tongue, which is arranged on an outer diameter of the sensor head, and which is formed to interact with a counter-contour of a fixing device as an anti-rotation lock for the rotational speed sensor. Also described are a related fixing device, a receiving device, a sensor system, and a method.

Abstract: This test system comprises: a dynamometer connected to a test piece W; an inverter for supplying electric power to the dynamometer; an encoder for generating a speed detection signal N corresponding to a rotational speed of the dynamometer; and a dynamometer control device 6 for generating a torque current command signal DYref. The dynamometer control device 6 comprises: a response model 61 that receives a higher-order speed command signal Nr and outputs a model speed command signal Nr?; a feedforward controller 62 that receives the higher-order speed command signal Nr and outputs a feedforward input uff; and a speed controller 64 that generates the torque current command signal DYref on the basis of a feedback input ufb generated on the basis of a deviation e between the model speed command signal Nr? and the speed detection signal N, and the feedforward input uff.

Abstract: A chainring assembly includes a chainring carrier adapted to be coupled to a crank arm. The chainring carrier is rotatable about a rotation axis, and includes an outer periphery having carrier threads. A chainring structure includes an inner periphery having chainring threads and an outer periphery comprising a plurality of teeth. The inner periphery of the chainring structure is threadably engaged with the outer periphery of the chainring carrier. In one embodiment, a power meter device includes a body having a torque input section and a torque output section, with the torque output section including an outer periphery having threads adapted to be coupled to a chainring structure.

Abstract: An electric vehicle includes a traction motor, an inverter that supplies the motor with an alternating current, three current sensors that respectively measure current of each phase of the alternating current output by the inverter, the alternating current being a three phase alternating current; and a controller that controls the motor through the inverter. The controller is configured to, when one of the current sensors becomes unusable, identify the unusable current sensor while controlling the motor with a d-axis voltage command value set to zero and a q-axis voltage command value set to a non-zero value.

Abstract: In an embodiment, an apparatus includes: a gearbox including: a housing having an opening; an input pinion disposed in the housing; a moving feature mechanically coupled to the input pinion, the moving feature and the input pinion being operable to convert between power and torque; and first sensors disposed on the moving feature, the first sensors having batteries, where the moving feature is operable to rotate about a common axis, each of the first sensors being exposed by the opening as the moving feature rotates about the common axis.

Abstract: A processing path generating device including an intuitive path teaching device and a controller is provided. The intuitive path teaching device is provided for gripping and moving with respect to a workpiece to create a moving path. The intuitive path teaching device has a detecting portion for detecting a surface feature of the workpiece. The controller is connected to the intuitive path teaching device. The controller generates a processing path according to the moving path of the intuitive path teaching device and the surface feature of the workpiece.

Abstract: In an exemplary embodiment, a test system is provided for testing a power steering system for a vehicle, the test system including a motor, one or more sensors, and a processor. The one or more sensors are configured to obtain sensor data pertaining to the motor. The processor is coupled to the one or more sensors and to the motor, and is configured to: determine, using the sensor data, a desired position of the motor for providing a desired amount of torque to the power steering system in order to reach one or more target behaviors: an inertia target, a spring target, a damper target, or a friction target for the power steering system; and provide instructions for the motor to move to the desired position for providing torque to the power steering system.

Abstract: A center of gravity of a robot device is estimated without utilization of a force sensor or the like. An information processing device including a center-of-gravity estimation unit that calculates, on the basis of torque applied to one or more joints included in each of a plurality of leg portions, reaction force applied from a ground contact surface to each of the plurality of leg portions, and that estimates a center of gravity of a robot device including the plurality of leg portions on the basis of the calculated reaction force on the plurality of leg portions.

Abstract: A spindle shaft device including a shaft, a first torque sensor, and a second torque sensor. The shaft extends along an axial direction and comprises a first side portion, a second side portion, and a central portion located between the first side portion and the second side portion. The central portion has a central torsional rigidity with respect to the axial direction. The first side portion has a first torsional rigidity with respect to the axial direction. The second side portion has a second torsional rigidity with respect to the axial direction. The first torsional rigidity is smaller than the central torsional rigidity. The second torsional rigidity is smaller than the central torsional rigidity. The first torque sensor is disposed on the first side portion. The second torque sensor is disposed on the second side portion.

Abstract: Resistance mechanism and method for an exercise cycle includes an adjusting bracket having magnets mounted on its inner surface and spaced from a flywheel, an adjustment shaft having a threaded rod rotatably disposed through a tubular sleeve disposed on a frame and above the adjustment bracket, a threaded member mounted on the adjustment bracket and connected the threaded rod, and a linking assembly mounting the adjustment bracket to the frame, and including a first member, a first linking member, a first sensor, and a second sensor. The first sensor is disposed on the first member adjacent to the first end of the first linking member, a second sensor is disposed on the first linking member adjacent to the first sensor. A relative position of the first sensor and the second sensor is changed with respect to the corresponding movements of the adjusting bracket.

Abstract: An exercise cycle includes a crankshaft, cranks mounted to the crankshaft, a drive mechanism including a ferromagnetic flywheel that rotates in response to rotation of the crankshaft, and a non-contact force adjustment mechanism with which a force required to rotate the flywheel can be adjusted, the force adjustment mechanism including a pivotable member to which magnets are mounted, wherein the magnets can be moved closer to the flywheel when the pivotable member is pivoted toward the flywheel to increase the force required to rotate the flywheel and can be moved farther away from the flywheel when the pivotable member is pivoted away from the flywheel to decrease the force required to rotate the flywheel.

Abstract: Provided is a threaded member tightening tool capable of returning a count value in linkage with reverse driving by the threaded member tightening tool and only when a threaded member to be removed by the reverse driving has been counted as a tightened threaded member. A computing unit of a motor-driven screwdriver is switchable between a counting mode in which the computing unit counts the number of tightened threaded members and holds the counted number as a count value and a count return mode for returning the count value to a one-preceding count value. The computing unit returns the count value to a one-preceding count value based on the fact that the engaging element fitting unit has been driven in the reverse direction when the computing unit has been switched to the count return mode.

Abstract: A power meter for a bicycle includes a body having a torque input section and a torque output section, the body configured to transmit power between the torque input section and the torque output section. The power meter also includes a printed circuit board (“PCB”) having a substrate and at least one strain measurement device which may be attached to the PCB. The power meter may be integrally constructed with a chainring construction.

Abstract: A method for correcting a compensation item of a PMSM motor, the method including: offline measuring an error data of a parameter of a PMSM motor in a control process; providing a series of current commands and calculating compensation values of the parameter corresponding to the series of current commands; establishing a lookup table with regard to the series of current commands and the compensation values of the parameter corresponding to the series of current commands; storing the lookup table in a memory of a motor controller; starting and allowing the motor to work at a normal state; and online correcting the error data of the parameter by using the lookup table.

Abstract: Step detection accuracy in mobile devices is increased by determining whether swinging is taking place. According to the invention, swinging can be detected using threshold detection, Eigen analysis, hybrid frequency analysis, and/or gyroscope-based analysis, for example. The determination that swinging is (or may be) occurring can impact how the mobile device reports detected steps for step detection. A count of missteps and/or a level of certainty, based on swing detection, can be provided with a step count.

Abstract: A method for ascertaining a torque accuracy of a torque transmitted from a belt-driven starter-generator of an internal combustion engine to the internal combustion engine, which is similar to a learning process or a calibration of the actual torque of the starter-generator with respect to a setpoint torque, includes controlling the belt-driven starter-generator to transmit a specified test torque to the internal combustion engine during a predefined test time interval during coasting down of the internal combustion engine, determining a speed variable that is dependent on a speed of the internal combustion during the test time interval, comparing the speed variable to a reference variable, and deducing the torque accuracy from this comparison.

Abstract: An input device is equipped with an operation member that is capable of performing an operation by a hand of an operator; a braking unit configured to brake a movement of the operation member; a speed determiner configured to determine a current speed of the operation member; and a controller configured to cause the braking unit to brake the movement of the operation member in response to the current speed of the operation member.

Abstract: A calibration rig (1), for calibrating a torque wrench (9), comprises a support structure (3) for supporting the torque wrench (9) during calibration. The support structure (3) comprises: a support member (7) which is free to move substantially vertically; means for applying a balance force (14, 15) to the support member (7), wherein the balance force acts counter to a force exerted by the weight of the torque wrench (9) when a handle of the torque wrench (9) is received by the support member (7); means for applying a measured torque (6) to the torque wrench (7); and means for resisting rotation (16) of the torque wrench (9) as a result of the applied torque.

Abstract: A magnetostrictive torque sensor incorporated in an electric power steering apparatus includes first through fourth detection coils, which are disposed face-to-face with a magnetostrictive film across a bobbin winding holder that is disposed around an outer circumferential surface of the magnetostrictive film. A bobbin support, which supports the bobbin winding holder, is disposed on the bobbin winding holder at a central position in the axial direction of the first through fourth detection coils.

Abstract: Provided is an actuator device used in a plurality of sites of a multi-shaft driving mechanism such as a multi-shaft manipulator, a robot arm, a leg structure and a snake-shaped robot. A torque sensor is connected to a bearing such as a cross roller bearing through a mount part. The torque sensor is driven by an outer ring relative to a stationary part case of an actuator device. An attachment surface of an output shaft frame is arranged in a position offset from the bearing on a side of the stationary part case. An entire length of the actuator device in an output shaft direction does not change also after the output shaft frame is attached and an occupied space does not increase.

Abstract: The present invention relates to a method for drilling a printed circuit board, comprising: drilling down in an initial position, and when contacting a live superficial conductive layer of a PCB, acquiring a first conductive position and acquiring a first height difference between the initial position and the first conductive position; drilling onward after the first drill bit of the driller drills through the superficial conductive layer and when contacting another conductive layer of the PCB, acquiring a second conductive position and acquiring a second height difference between the initial position and the second conductive position; calculating a difference between the second and the first height difference to obtain a third height difference; and performing back-drilling, according to the third height difference, in a position that needs back-drilling. The present invention acquires precise depth information through a test blind via and reduces Stub length of back-drilling.

Abstract: A data storage device is disclosed comprising a first disk surface comprising servo data defining servo tracks at a first radial density, a first head, and a voice coil motor (VCM) configured to actuate the first head over the first disk surface using a servo control system. A load operation is executed to load the first head over the first disk surface, and a back electromotive force (BEMF) voltage generated by the VCM during the load operation is evaluated to generate an estimated distance traveled. The servo data on the first disk surface is detected, and an initial servo track during the load operation based on the detected servo data to generate a measured distance traveled. A gain of the servo control system is configured based on the estimated distance traveled and the measured distance traveled.

Abstract: In an electric disc grinder, there is provided, between a driven gear and a spindle in a torque transmission system, a C-shaped spring member capable of elastic deformation in a diameter enlarging direction. With respect to the rotating direction, the spring member is engaged with a driving protrusion of the driven gear and a driven protrusion of a joint sleeve of the spindle; when transmitting the rotation of the driven gear to the spindle, the spring member undergoes elastic deformation in the diameter enlarging direction depending on the driven side load, thereby mitigating the starting shock. An abutment surface of the driven protrusion is formed as an inclined surface causing an end portion of the spring member contacting with the abutment surface to slide radially outwards. As a result, the spring member can easily undergo elastic deformation in the diameter enlarging direction.

Abstract: A torque sensor bearing arrangement for a shaft having first and second bearings, each with respective inner ring and outer rings with rolling elements therebetween. The bearings are located at first and second ends of the shaft. First and second sensing rings are connected to the outer rings of the bearings. First and second marking rings are connected to the inner rings, spaced apart from and aligned with the respective first and second sensing rings. The marking rings each have a wavy surface facing the respective sensing ring to form respective first and second sensors from the respective sensing ring—marking ring pairs. The sensors detect a rotational angle position of the shaft and provide a signal. A controller receives signals from the first and second sensors and calculates at least one of torque or an angular speed of the shaft based on signals from the first and second sensors.

Abstract: Two forms of load bearing or transmitting structures are disclosed wherein each uses magnetism to hold a key in one of two bodies to prevent movement therebetween. One embodiment is a clevis, wherein the clevis pin is instrumented as a load cell and a magnetic key resides in a slot in a portion of the clevis pin which protrudes outside of one of the clevis legs. In another embodiment, torque is transmitted between a shaft and a coupling by means of keys that are held in keyways by magnetism thereby to provide a torque coupling between the shaft and coupling members.

Abstract: A method for calibrating a torsion torquemeter including: placing a torsion torquemeter in a first state; performing first measurements determining first and second angular offsets, and measuring torque output by the power shaft using a reference torquemeter; placing the torsion torquemeter in a second state; performing second measurements determining the first and second angular offsets, and measuring torque output by the power shaft; placing the torquemeter in a third state; performing third measurements determining the first and second angular offsets, and measuring the torque output by the power shaft; placing the torquemeter in a fourth state; performing fourth measurements determining the first and second angular offsets, and measuring the torque output by the power shaft; calibrating the calculation unit based on the first, second, third, and fourth measurements.

Abstract: A driving unit for use in an electric assist bicycle includes a rotation detection device in addition to a torque detection device such that the detection resolution of the rotation detection device is increased. The driving unit includes a housing, a crankshaft, a torque detection device, a rotating member, and a rotation detection device. The rotating member includes a connecting shaft and an output shaft. The connecting shaft is located at one of the ends of the rotating member disposed along its axis, and is coupled with the crankshaft in the housing. The output shaft is located at the other one of the ends of the rotating member disposed along its axis. The rotation detection device includes a detected portion and a detector. The detected portion is provided on the rotating member, and located around the central axis of the crankshaft in the housing.

Abstract: Make-up speed for a tongs drive system is monitored and controlled to maintain the speed within a limited target range either throughout the make-up process or during the final portion of the make-up process, thereby improving make-up consistency and allowing for improved evaluation or torque during the make-up process. An encoder generates speed and position data during the make-up process. The speed data is compared to a target speed, which is based on rod and/or tongs characteristics. If the speed does not match the target speed or is not within a range of the target speed, a signal is transmitted to the tongs drive to adjust the speed accordingly. Furthermore, position data from the encoder, or other position sensors, provide position data for the rod during the make-up process to limit or vary the speed control parameters during different portions of the make-up process.

Abstract: An improved structure for a torque sensor assembly adapted for use in a vehicle steering system and method for producing the same. According to one embodiment, the torque sensor assembly includes a housing formed from a suitable material having a cavity; at least one flux concentrator and at least one hall effect IC disposed in the cavity of the housing; and a cover secured to the housing to close the cavity in the housing in a permanent and fluid-tight manner.

Abstract: A gobo wheel with automatic detection system that automatically detects a rotational position of the gobo. The rotational position can be detected by a magnetic marking system. Each of the gobos can be randomly placed within the holder. The position of the gobos can be automatically determined during a start up routine for example, and then those positions can be stored and used for later determination of a position.

Abstract: A ball mount for measuring tongue weight of a trailer is disclosed. The ball mount can comprise a ball portion for interfacing with a ball configured to couple with a tongue of a trailer, a hitch portion for interfacing with a hitch receiver associated with a vehicle, and a load measurement device associated with the hitch portion. The hitch portion can be configured to pivot relative to the hitch receiver about a fulcrum in response to a downward force on the ball, with the hitch receiver resisting rotation of the hitch portion about the fulcrum thereby inducing a load on the hitch portion. The load measurement device can be configured to determine a magnitude of the downward force on the ball based on the load on the hitch portion.

Abstract: Embodiments of the subject invention are directed to a method and apparatus for measuring torque applied during installation of a helical pile. Specific embodiments relate to a helical pile installation torque measuring and monitoring system for use during helical pile installation. In a specific embodiment, a load cell pin, or torque pin, is incorporated into the drive head and equipment attachment to measure the direct forces, or torque, that is being applied by the drive head as the helical pile is rotated into the ground. The direct forces, or torque, are relayed to a data capturing device, which records the data and, optionally, displays one or more of the following: the forces, the torque created by the forces, the inclination angle of installation, and the downward, or longitudinal, force applied to advance the helical pile.

Abstract: A sensor unit includes a printed circuit board, a Hall IC, a terminal member, and a capacitor. The printed circuit board has a conductive pattern. The Hall IC is disposed on the printed circuit board. The Hall IC includes an element part that detects magnetic flux. The element part is arranged in parallel with the printed circuit board and is away from the conductive pattern. The terminal member is disposed on an end portion of the printed circuit board and is configured to be electrically coupled with an external device. The capacitor is disposed on the printed circuit board.

Abstract: A torque sensing apparatus has a torque adjusting assembly and a non-contact sensing assembly. The torque adjusting assembly has a fitting unit, a regulating rod and a regulating seat. The non-contact sensing assembly has a first device and a second device. The regulating rod is rotatably mounted through the fitting unit. The regulating seat is movably mounted on the regulating rod and located outside the fixed plate of the fitting unit. The first device is mounted on the fixed plate. The second device is mounted on the regulating seat and kept from contacting the first device. The non-contact sensing assembly detects a change of the distance between the first device and the second device and generates a signal to a controller, and the controller gauges a torsional value of the torque adjusting assembly. Therefore, the non-contact sensing assembly is not abraded and increases the precision of the torque sensing apparatus.

Abstract: A system to measure the installation torque of a screw pile comprises machinery suitable to drive the screw pile into the ground, said machinery further comprising a rotary drive suspended by means of a universal joint-type coupler. A load pin, having at least one sensor, is mounted through the universal joint-type coupler as a pivot pin and is oriented within the universal joint-type coupler so that at least some of the installation torque is transmitted through said load pin and is measurable by said at least one sensor. Preferably, the load pin further comprises a pair of bores and a plurality of sensors are provided and mounted within the bores. More preferably, a differential bridge network is used to obtain a measurable signal from the plurality of sensors.

Abstract: Connection terminals are provided for electrically connecting sensor terminals and through holes provided on a control substrate, and a control unit is provided with a frame of synthetic resin for holding the control substrate. The frame of synthetic resin is provided with: a connection terminal holding portion for holding one ends of the connection terminals connected to the through holes partially insert-molded and the other ends protruding outwardly from the frame of synthetic resin; and guide openings for guiding and making the sensor terminals insert therethrough so that the sensor terminals protruding from the outer circumference of the reduction gearbox extend to the position where the sensor terminals are connectable with the other ends of the connection terminals.

Abstract: Systems and devices configured to determine misalignment of targets of a rotating shaft by monitoring axial and radial aspects of targets and the shaft. In one embodiment, a target monitoring system includes a first horizontal probe communicatively connected to at least one first horizontal target connected to the shaft, and a first axial probe located adjacent to the first horizontal probe and communicatively connected to the first horizontal target. The system also includes a second horizontal probe communicatively connected to at least one second horizontal target connected to the shaft, and a second axial probe located adjacent to the second horizontal probe and communicatively connected to the second horizontal target. The system may further include an end probe disposed proximate a first end of the shaft for monitoring axial movement of the shaft, and a computing device communicatively connected to the end probe and each horizontal and axial probe.

Abstract: A load cell structure for receiving strain gages to monitor applied torsional forces wherein the opposing force-receiving ends have a plurality of sensing beams spaced about an axis of rotation. Limit posts located between the ends each have a discontinuity therein that includes a U-shaped gap to limit relative rotation about the axis and thereby providing overload protection.

Abstract: A relative angle sensing device that senses a relative rotation angle between first and second rotary shafts includes: a rotary component that is provided on one rotary shaft out of the first rotary shaft and the second rotary shaft, and that rotates together with the one rotary shaft; a supported component that generates a magnetic field and that is supported by the rotary component through an adhesive material; and a sensor that is provided in the other rotary shaft out of the first rotary shaft and the second rotary shaft, and that outputs a value corresponding to the magnetic field generated by the supported component. A transmitting unit is provided between the rotary component and the supported component. The transmitting unit transmits rotative force of the one rotary shaft to the supported component by direct contact with each other in a case of peeling of the adhesive material.

Abstract: A torque sensing device for measuring the torque applied to a rotatable shaft, and also measuring the magnetic field noise affecting the device. The device incorporates a switching function thereby enabling the device to operate in a common signal detection mode and a differential noise detection mode. The device is capable of determining the torque applied to the rotatable shaft based upon output signals obtained from magnetic field sensors operating in both the common signal detection mode and the differential noise detection mode. The device is capable of accurately measuring a torque induced magnetic field and is capable of canceling measurement error resulting from noise induced magnetic fields.

Abstract: A stator and a rotator, which relatively rotate concentrically with a steering, are formed. A torque transmitting portion, which transmits a rotation torque of the steering to an angle detection rotating body provided in an angle detection sensor for detecting a rotation angle of the steering, is formed concentrically with the angle detection rotating body. Fitting portions for fitting to fitting allowance portions, which are formed on at least a part of a circumferential direction of the angle detection rotating body, are formed on the torque transmitting portion. Fitting abutting portions of the fitting portions, which fit and abut against the fitting allowance portions, are formed in shapes tapered toward the fitting allowance portions.

Abstract: A technique to assess or analyze cap removal or opening torque or rotational position is provided. In at least one form, a high speed, on-line machine vision system measures or determines the rotational position of a cap on a bottle, measures or determines the rotational position of the finish or neck of the same bottle, and then optionally uses such positional information to predict the opening or removal torque that will be required for a consumer to remove the bottle cap from the bottle.

Abstract: A method of accurately measuring applied torque in a hydraulic breakout machine involves using at least one sensor to measure reactive torque, and using the reactive torque measurement as an accurate indication of applied torque.

Abstract: A device for measuring the torque or force exerted by a drilling machine during a rotation, driving or lifting of a tool. The measuring device includes an engaging device with a drilling battery or with a shaft of at least a drilling equipment or rotary of the machine the engaging device is susceptible of symmetrically or axial-symmetrically locking the drilling battery or the shaft preventing the rotation and/or the axial displacement in a position in correspondence to the tool. The engaging device is associated with at least a transducer for the detection of at least a maximum torque or of at least a maximum force exerted by the machine; and the measuring device is fixedly constrained to the drilling battery or to the shaft.

Abstract: Disclosed is a rotor for a torque sensor configured to improve a mechanical coupling force with respect to a jig in a process of adjusting a torque center, thus enabling a fine adjustment, the rotor including a rotor body having a sleeve coupled to a rotating shaft and a yoke protruding from an outer circumference of the sleeve, a ring-shaped magnet coupled to an outer circumference of the yoke, and an anti-slip structure formed on the rotor body and partially coming into contact with a jig during a rotating process for adjusting a torque center, thus inhibiting slipping between the rotor body and the jig when a rotating force is transmitted, so that slipping between the jig and the rotor body is inhibited to enable precise transmission of the rotating force whereby accuracy is improved during fine adjustment of the torque center.

Abstract: Submersible pump and motor performance testing. At least some of the illustrative embodiments are methods including: coupling a torque meter between an electric motor and a pump; and submersing the torque meter, electric motor, and pump in water. During periods of time when the torque meter, electric motor and pump are submerged in the water, the method comprises: operating the pump and the electric motor; measuring pump performance; and simultaneously measuring electric motor performance.

Abstract: The invention relates to a gear mechanism comprising at least one drive shaft and at least one output shaft, which enter a gear mechanism housing through a respective opening. The drive shaft and/or the output shaft comprise a magnetically or optically coded section in the region of the respective opening. The coding in said section may be changed by the effect of a torque or a force on the drive shaft or output shaft. Moreover, at least one gear wheel connected to the drive shaft and at least one gear wheel connected to the output shaft are provided that are directly or indirectly engaged with one another. In addition, the gear mechanism according to the invention comprises at least one scanning unit for detecting the magnetic or optical coding of the drive shaft or output shaft in a contact free fashion.

Abstract: A torque sensing system can sense the torque that is flowing through a mechanical system. The torque sensing system allows for better control because the torque and horsepower of the mechanical system can be known at all times. The torque sensing system includes an input shaft and an output shaft that prompts a torque shaft to deflect onto a load cell, where the force of the deflection of the torque shaft onto the load cell may be used to determine the torque of the system.

Abstract: A pull test apparatus includes a base, a tension meter and a linkage assembly. An object is adapted to be fixed at the base. The tension meter is movably disposed at the base and adapted to connect a handle of the object. The linkage assembly includes an elastic element and a positioning element. The elastic element is connected between the base and the tension meter. When the tension meter resists the elastic force of the elastic element to move to a first position, the positioning element positions the tension meter. When the positioning element releases the tension meter, the tension meter moves toward a second position by means of the elastic force of the elastic element so as to drive the handle closed at a main body of the object to be unfolded from the main body, wherein the first position is between the object and the second position.