Showing papers on "Torsion spring published in 2009"

Control of Rotary Series Elastic Actuator for Ideal Force-Mode Actuation in Human–Robot Interaction Applications

Abstract: To realize ideal force control of robots that interact with a human, a very precise actuating system with zero impedance is desired. For such applications, a rotary series elastic actuator (RSEA) has been introduced recently. This paper presents the design of RSEA and the associated control algorithms. To generate joint torque as desired, a torsional spring is installed between a motor and a human joint, and the motor is controlled to produce a proper spring deflection for torque generation. When the desired torque is zero, the motor must follow the human joint motion, which requires that the friction and the inertia of the motor be compensated. The human joint and the body part impose the load on the RSEA. They interact with uncertain environments and their physical properties vary with time. In this paper, the disturbance observer (DOB) method is applied to make the RSEA precisely generate the desired torque under such time-varying conditions. Based on the nominal model preserved by the DOB, feedback and feedforward controllers are optimally designed for the desired performance, i.e., the RSEA: (1) exhibits very low impedance and (2) generates the desired torque precisely while interacting with a human. The effectiveness of the proposed design is verified by experiments.

A low-voltage three-axis electromagnetically actuated micromirror for fine alignment among optical devices

Abstract: In this paper, a new three-axis electromagnetically actuated micromirror structure has been proposed and fabricated. It is electromagnetically actuated at low voltage using an external magnetic field. The main purpose of this work was to obtain a three-axis actuated micromirror in a mechanically robust structure with large static angular and vertical displacement at low actuation voltage for fine alignment among optical components in an active alignment module as well as conventional optical systems. The mirror plate and torsion bars are made of bulk silicon using a SOI wafer, and the actuation coils are made of electroplated Au. The maximum static deflection angles were measured as ±4.2 ◦ for x-axis actuation and ±9.2 ◦ for y-axis actuation, respectively. The maximum static vertical displacement was measured as ±42 μm for z-axis actuation. The actuation voltages were below 3 V for all actuation. The simulated resonant frequencies are several kHz, and these imply that the fabricated micromirror can be operated in sub-millisecond order. The measured radius of curvature (ROC) of the fabricated micromirror is 7.72 cm, and the surface roughness of the reflector is below 1.29 nm which ensure high optical performance such as high directionality and reflectivity. The fabricated micromirror has demonstrated large actuated displacement at low actuation voltage, and it enables us to compensate a larger misalignment value when it is used in an active alignment module. The robust torsion bar and lifting bar structure formed by bulk silicon allowed the proposed micromirror to have greater operating stability. The additional degree of freedom with z-axis actuation can decrease the difficulty in the assembly of optical components and increase the coupling efficiency between optical components. (Some figures in this article are in colour only in the electronic version)

A Unidirectional Series-Elastic Actuator Design Using a Spiral Torsion Spring

Abstract: This paper presents a novel series-elastic actuator (SEA) design that uses a spiral torsion spring to achieve drivetrain compliance in a compact and efficient mechanism. The SEA utilizes electromechanical actuation and is designed for use in the experimental biped robot KURMET for investigating dynamic maneuvers. Similar to helical torsion springs, spiral torsion springs are particularly applicable for legged robots because they preserve the rotational motion inherent in electric motors and articulated leg joints, but with less drivetrain backlash and unwanted coil interaction under load than helical torsion springs. The general spiral torsion spring design equations are presented in a form convenient for robot design, along with a detailed discussion of the mechanism surrounding the spring. Also, the SEA mechanism has a set of unidirectional hardstops that further improves the position control by allowing series-elasticity in only one rotational direction.

Counterbalanced motorized shade roll system and method

Abstract: In a window covering system with a shade roll, a counterbalanced motorized shade roll system includes a shade roll with a hollow interior connected with a window covering system. A motor is located within the hollow interior. A torsion spring is also located within the hollow interior of the shade roll and the torsion spring is connected with the motor on one end and with the hollow interior on another end. Batteries are also located within the hollow interior of the shade roll opposite from the motor and after the connection of the torsion spring with the hollow interior of the shade roll such that the torsion spring does not surround the batteries.

Tortionally stiff, thermally isolating shaft coupling with multiple degrees of freedom to accommodate misalignment

Abstract: A coupling arrangement coupling and thermally isolating a continuously variable electrical actuator rotationally coupled to and from a butterfly valve is provided. The valve may be used to modulate high temperature exhaust gas flow through an engine turbocharger. The actuator provides a continuously variable control of the valve. The coupling arrangement provides a thermal block to reduce heat transfer and vibration insulation between the actuator and the valve. The coupling arrangement generally includes a coupling shaft rotationally coupled at opposite ends to the input and output shafts by torsion spring mechanisms. The torsion spring mechanisms include yokes rotationally locking the coupling shaft to the input and output shafts. The torsion spring mechanisms allow a limited range of axial and pivotal translation between the coupling shaft and the input and output shafts and are preloaded to prevent rotational hysteresis in the valve.

High fill-factor micromirror array using a self-aligned vertical comb drive actuator with two rotational axes

Abstract: We present a two-axis micromirror array with high fill-factor, using a new fabrication procedure on the full wafer scale. The micromirror comprises a self-aligned vertical comb drive actuator with a mirror plate mounted on it and electrical lines on a bottom substrate. A high-aspect-ratio vertical comb drive was built using a bulk micromachining technique on a silicon-on-insulator (SOI) wafer. The thickness of the torsion spring was adjusted using multiple silicon etching steps to enhance the static angular deflection of the mirrors. To address the array, electrical lines were fabricated on a glass substrate and combined with the comb actuators using an anodic bonding process. The silicon mirror plate was fabricated together with the actuator using a wafer bonding process and segmented at the final release step. The actuator and addressing lines were hidden behind the mirror plate, resulting in a high fill-factor of 84% in an 8 × 8 array of micromirrors, each 340 µm × 340 µm. The fabricated mirror plate has a high-quality optical surface with an average surface roughness (Ra) of 4 nm and a curvature radius of 0.9 m. The static and dynamic responses of the micromirror were characterized by comparing the measured results with the calculated values. The maximum static optical deflection for the outer axis is 4.32° at 60 V, and the maximum inner axis tilting angle is 2.82° at 96 V bias. The torsion resonance frequencies along the outer and inner axes were 1.94 kHz and 0.95 kHz, respectively.

Flexible two-wheel self-balance robot system and motion control method thereof

Abstract: The invention discloses a flexible two-wheel self-balance robot system and a motion control method thereof; wherein the flexible two-wheel self-balance robot system comprises a main controller (1), a motion controller (2), an auxiliary controller (3), a servo drive (4), a sensor, an input/output device, a direct current motor (5) and a power supply system; a trunk top plate (11) is provided with a camera (12); a trunk (6) and a bottom disc (8) are respectively provided with an inclinometer and a gyro; the trunk (6) and the bottom disc (8) are connected by a flexible joint (7) which is provided with a double-arm torsion spring (25) and a cylindrical spring (26); the main controller (1) is connected with the motion controller (2), the auxiliary controller (3) and the input/output device. The user instruction of the main controller (1) is an immediate instruction or a prestored instruction; the main controller (1) operates a motion behavior decision algorithm, the motion controller (2) operates a motion balance control algorithm and the servo drive (4) controls the torque of the motor(5), thus realizing plane walking and remote control of the robot.

Adjustable Spring Assist for Window Coverings and Awnings

Abstract: There is provided a spring assisted electric motor driven lifting mechanism for lifting and lowering a blind which permits the quick and easy matching of the spring assist pre-rotation to the torque output of the electric motor. The device includes an elongated cylinder coupled to the blind such that rotating the cylinder about its axis lifts and lowers the blind. Coupled to the elongated cylinder is an electric motor which is configured to rotate the elongated cylinder about its axis. A torsion spring is coupled to the cylinder for biasing the elongated cylinder to at least partially neutralize the weight of the blind. The torsion spring is in turn coupled to a spring preload adjuster which is configured to adjust the tension on the torsion spring by moving an adjustment member. The spring preload adjuster is further configured such that the adjustment member extends perpendicularly away from the axis of the elongated cylinder.

Downhole adjustable bent-angle mechanism for use with a motor for directional drilling

Abstract: A housing including longitudinally extending tubular members interconnected to allow controlled relative bending thereof, during a drilling operation, a rotary drive transmitting torsion bar extending generally longitudinally within the housing to controllably bend in response to relative bending of said members, a rotary drill bit operatively connected to said torsion bar to be rotated as the bar rotates, a rotary drive operatively connected to the torsion bar to rotate the bar, means for controlling relative bending of the said members during torsion bar rotation and as a function of such rotation.

Simultaneous Realization of Stabilized Temperature Characteristics and Low-Voltage Driving of a Micromirror Using the Thin-Film Torsion Bar of Tensile Poly-Si

Abstract: The tense thin-film torsion bar of polycrystalline (poly-) Si has been recently introduced into a micromirror. A tensile stress is obtained by the crystallization of amorphous Si. The poly-Si has almost the same coefficient of thermal expansion as that of Si substrate. An electrical connection is obtained with doping without the use of metal overlayer. The thin-film torsion bar of poly-Si is fabricated with a revised process so as to protect against the crystalline Si etching. Considering the earlier advantages and techniques, the stabilized temperature characteristics and the low-voltage driving are simultaneously realized.

Experiment table for detecting dynamic characteristics of harmonic reducers

Abstract: The invention discloses an experiment table for detecting dynamic characteristics of harmonic reducers, which comprises an X guide rail arranged on a bottom plate, as well as a first servo motor, wherein the first servo motor is fixed on the X guide rail and is axially connected with a follow-up harmonic reducer; the follow-up harmonic reducer is fixed on the X guide rail and is axially connected with a first torque sensor through a first torsion bar; the first torsion bar sensor is axially connected with a first angle measuring device; the first angle measuring device is connected with a first connecting shaft; and a detected harmonic reducer is arranged on the X guide rail through a mounting bracket and a positioning piece. The experiment table is characterized in that a Y guide rail perpendicular to the X guide rail is arranged on the bottom plate; when the detected harmonic reducer is a right-angled reducer, a second angle measuring device is arranged on the Y guide rail and is axially connected with a second torque sensor; and the second torque sensor is axially connected with a second servo motor. The experiment table has the advantages of good universality and capability of completing the task of testing the dynamic characteristics of a plurality of detected harmonic reducers on one experimental device.

A Mechanical Model of the Human Ankle in the Transverse Plane During Straight Walking: Implications for Prosthetic Design

Abstract: In order to protect sensitive residual limb soft tissues, lower limb prostheses need to control torsional loads during gait. To assist with the design of a torsional prosthesis, this paper used simple mechanical elements to model the behavior of the human ankle in the transverse plane during straight walking. Motion capture data were collected from ten able-bodied subjects walking straight ahead at self selected walking speeds. Gait cycle data were separated into four distinct states, and passive torsional springs and dampers were chosen to model the behavior in each state. Since prosthetic design is facilitated by simplicity, it was desirable to investigate if elastic behavior could account for the physiological ankle moment and include viscous behavior only if necessary to account for the inadequacies of the spring model. In all four states, a springlike behavior was able to account for most of the physiological ankle moments, rendering the use of a damper un-necessary. In State 1, a quadratic torsional spring was chosen to model the behavior, while linear torsional springs were chosen for States 2-4. A prosthetic system that actively changes stiffness could be able to replicate the physiological behavior of the human ankle in the transverse plane. The results of this study will contribute to the mechanical design and control of a biomimetic torsional prosthesis for lower limb amputees.

Arrangement of a stabilizer on a wheel suspension for motor vehicles

Abstract: The invention relates to an arrangement of a stabilizer (44), which is configured in two parts, on a wheel suspension for a motor vehicle, characterized in that the stabilizer parts (43) thereof can be co-rotated in the same or opposite direction by means of an associated engine/transmission unit (46). Each stabilizer part (43) comprises a hollow-cylindrical outer torsion bar (49) whose end on the transmission side (45) is connected to a transmission output (50a) and whose end lying away from the transmission is connected for drive purposes to an inner torsion bar (47) which is led through the hollow-cylindrical outer torsion bar (49) and out of the end (45) on the transmission side of the hollow-cylindrical outer torsion bar. The inner torsion bar (47) is directly or indirectly connected to an output lever (41) which is articulated on a wheel suspension element (16). According to the invention, the transmission (50) of the engine/transmission unit is disposed with its transmission output (50a) between the servomotor (48) and the output lever (41) in the transverse direction of the vehicle (y).

Rubber bushing torsion test apparatus

Abstract: The invention relates to a rubber lining torsion test device used in rubber lining endurance test, which comprises a pedestal, a torsion shaft disposed on the pedestal and capable of rotating thereon, and a jig for fixing the rubber lining; one end of the torsion shaft is fixedly connected with a swing rod; the other end of the torsion shaft is fixedly connected with a torsion bar which passes through the rubber lining; the swinging of the swing rod drives the torsion bar to rotate to apply a torsional force onto the rubber lining. the rubber lining torsion test device in the invention realizes the multiple output modes needed in test, and achieves the advantages of simple appearance, low manufacturing difficulty, low cost, convenient installation and long service life.

Compact tensioner with sustainable damping

Abstract: A tensioner assembly that includes a base, an arm, an opening spring (i.e., a torsion spring that opens or radially expands with increasing torque applied thereto), a spring reaction member, and a pivot bushing. The tensioner assembly is configured to orient various loads in predetermined directions. For example, a spring load can be oriented to counteract a hub load to reduce a bushing load that acts on the pivot bushing. As another example, a spring reaction force exerted by the spring reaction member can be employed by a damping mechanism to generate a grounding force that is parallel to the spring reaction force and is directed to intersect an axis about which the arm pivots relative to the base. A tensioner assembly having improved assembly characteristics is also provided.

Tensioner with hub load balancing feature

Abstract: A tensioner assembly with a drive member, a tensioner arm, a shaft, a pivot bushing, a torsion spring and a load balancing element. The tensioner arm has a hub portion, a drive member mount and an arm disposed therebetween. The drive member is coupled to the drive member mount. The shaft is mounted coaxially within the hub portion. The pivot bushing has a frustoconical bearing surface, which engages a corresponding frustoconical surface in the hub portion, and is slidably mounted on the shaft. The torsion spring is received between the shaft and an outer wall of the hub portion and biases the tensioner arm about the shaft in a predetermined rotational direction. The load balancing element is received between and abuts the outer wall and the torsion spring to transmit a radially outwardly directed force generated by the torsion spring to the outer wall at a predetermined location.

Improving the sensitivity of a torsion pendulum by using an optical spring method

Abstract: We present a scheme aiming at improving the sensitivity of a torsion pendulum by means of radiation-pressure-induced optical spring. Two partial-reflective mirrors are installed on the opposite sides of a torsion pendulum, and one high-reflective mirror is mounted at the end of the torsion beam so that two identical Fabry-Perot cavities can be formed and aligned in series. Due to the antisymmetric radiation pressures acting on the opposite sides of the torsion beam, a negative restoring coefficient can be generated within a certain dynamic range, such that both the resultant torsional rigidity and the resonant frequency of the torsion pendulum are reduced, and the minimum detectable response torque in high-frequency region can be reduced accordingly.

Spring assist for multi band roller shade

Abstract: A spring assist for use with multi banded roller blinds includes a plurality of torsion springs coupled between a roller tube and a shaft. Each of the torsion springs is capable of applying an individual torsion force to the roller tube relative to the shaft. Each of the torsion springs have a first and second end, the first end of each torsion spring being coupled to the shaft and the second end of each torsion spring being coupled to the roller tube. The torsion springs are coaxially aligned and each torsion spring is coupled to the shaft and to the roller tube such that the individual torsion forces of the torsion springs are applied to the roller tube in parallel and the sum total of the torsion applied to the roller tube is equal to the sum of the individual torsion forces.

Prediction of vibrating forces on meshing gears for a gear rattle using a new multi-body dynamic model

Abstract: An efficient multibody dynamic model was developed to predict the vibrating transmitted gear forces of loaded and unloaded pairs of helical gears simultaneously at all speeds. The model can also calculate the bearing forces of a manual transmission that, in turn, may be converted to rattling noises. The bending of meshing gear teeth and torsional flexibility of transmission shafts were considered and embodied effectively in the multibody dynamic model by calculating the tooth bending stiffness and adding a torsion spring on a shaft section between two gears, respectively. The reactive forces on teeth and bearings were calculated and compared using three different models that were developed for this study — an equivalent model, a rigid-body model, and a frequency-based model. The equivalent model took only 58% computation time, compared to the frequency-based method, even though the two showed very similar results.

Variable Joint Elasticities in Running

Abstract: In this paper we investigate how spring-like leg behavior in human running is represented at joint level. We assume linear torsion springs in the joints and between the knee and the ankle joint. Using experimental data of the leg dynamics we compute how the spring parameters (stiffness and rest angles) change during gait cycle. We found that during contact the joints reveal elasticity with strongly changing parameters and compare the changes of different parameters for different spring arrangements. The results may help to design and improve biologically inspired spring mechanisms with adjustable parameters.

High-speed motor train set bogies

Abstract: The utility model relates to a motor train bogie of a high-speed motor train unit, which comprises wheel pairs, axle boxes, a spiral spring assembly, a bogie frame, air springs, an anti-rolling torsion bar, anti-yaw dampers, a central retractor, a wheel disc basic brake and a swing bolster; a longitudinal beam assembly between two beam steel tubes adopts an integrated design; both sides of the longitudinal beam are motor suspension mounting bases, and the middle of the longitudinal beam is a transversal damper base; a transversal side beam connecting base adopts a forging and various section design; one end of the transversal side beam connecting base is in butt joint and assembly welding with the beam steel tubes; the other end of the transversal side beam connecting base is in assembly welding with the upper cover plates and the lower cover plates of side beams into a box structure; rubber springs with low rigidity are arranged under the spiral spring assembly; and the axle boxes are connected with the bogie frame through axle box rubber nodes. The modules of the utility model are reasonably arranged and assembled so that the motor train bogie has enough fatigue intensity and enough bearing capability; the bogie has good vertical comfort and transversal comfort on straight routes and curved routes, has favorable stability in running at high speed, and meanwhile, decreases the acting force of a track.

Numerical Path Following as an Analysis Method for Electrostatic MEMS

Abstract: This paper aims to find all static states, including stable and unstable states, of electrostatically actuated microelectromechanical systems (MEMS) device models. We apply the numerical path-following technique to solve for the curve connecting the static states. We demonstrate that device models with 2 DOF can already exhibit symmetry-breaking bifurcations in the curve of static states and can have multiple disjoint solution paths. These features are also found in a finite-element method (FEM) model for a flexible beam suspended by a torsion spring. We have observed multiple hysteresis loops in measurements of a capacitive RF-MEMS device and have captured the qualitative features of these measurements in a model with 5 DOF. Numerical procedures for determining stability of solutions and finding bifurcation points are provided. Numerical path following is shown to be an efficient technique to find the curve of static states both in low-dimensional models and in FEM models.

Hinge assembly and mobile terminal having the same

Abstract: A hinge assembly and a mobile terminal are disclosed. The hinge assembly can include: a torsion spring; a shaft, which penetrates through the torsion spring; a bushing, coupled to one end of the torsion spring and to one side of the shaft; a holder, which is coupled to the other end of the torsion spring, and which the shaft penetrates through; a sliding cam, which is coupled to the other side of the shaft, and which may move in linkage with the shaft; a fixed cam, which engages the sliding cam; a compression spring, which is positioned between the holder and the sliding cam, and which may place the sliding cam in close contact with the fixed cam; and a housing coupled to the holder and the fixed cam. Thus, the mobile terminal can be unfolded automatically using just a few number of parts without requiring energy consumption.

Rack shaft support device and torsion amount adjustment method for torsion spring used therein

Abstract: A rack shaft support device includes: a rack shaft support member that slidably supports a rack shaft; a sealing member fixed to an inlet port of a retention hole formed in a housing; an intermediate member that is interposed between the rack shaft support member and the sealing member; a torsion spring that couples the intermediate member so that torque is transmitted to the intermediate member; a torsion amount adjusting member that is attached to the sealing member in such a manner that a position of the torsion amount adjusting member with respect to the sealing member is adjustable and adjusts a torsion amount of the torsion spring; and a cam mechanism that converts a rotation force of the intermediate member induced by untwisting of the torsion spring into a force by which the intermediate member pushes the rack shaft support member.

Stabilizer for a utility vehicle

Abstract: The invention relates to a stabilizer for a utility vehicle, having an elongate torsion spring (5), having two link arms (6, 7) which are fixedly connected to and extend away from the torsion spring (5) and between which the torsion spring (5) extends, and having an actuator (12) which is connected in parallel with the torsion spring (5) and which is connected to the torsion spring (5) or to the link arms (6, 7) with the interposition of hinge joints (23, 25) or leaf springs (17, 19).

Combination limb and abdominal exerciser

Abstract: The combination limb and abdominal exerciser of the present invention has a first torsional spring coupled between two rods of a set of pivotally connected rod members, such that the expansion or compression of the first torsional spring provides an exercise resistance when the two rods are moved outward away from or moved inward closer to each other by an external force, and the two rods return by the resilience of the first torsional spring when the external force is released, so as to help a user to exercise the upper limbs or exercise the lower limbs. Furthermore, a handle can be axially disposed at the end of each of the two rods, and a second torsional spring is disposed between each handle and the corresponding rod. The user can hold the handles and make the rods to rotate with respect to each other for wrist exercise.

Sliding mode tracking for actuators comprising pneumatic muscle and torsion spring

Abstract: In this study, the sliding mode approach is applied to the tracking control problem of a planar arm manipulator system driven by a new type of actuator, which comprises a pneumatic muscle (PM) and a torsion spring. Unlike the traditional agonist/antagonist pneumatic muscle actuator, the PM is arranged in place of bicep and the torsion spring provides opposing torque in the presented actuator. The dynamic model is derived for this system and a sliding mode controller is designed to make the joint angle track a desired trajectory within a guaranteed accuracy even there are modeling uncertainties. A selection method is also proposed to obtain appropriate spring coefficient, which plays an important role in the tracking control task. The effectiveness of the proposed method is confirmed by simulations. The differences between the control results of using our new actuator and that of using the traditional pneumatic muscle actuator in opposing pair configuration are also compared.

Gravity gradiometer with torsion flexure pivots

Abstract: A quadrupole responder for an OQR-type gravity gradiometer comprises a housing, and a mass quadrupole positioned within the housing. The mass quadrupole has a pair of sides, and also has a center of mass between the sides. The quadruple responder further comprises at least two torsion spring flexures. The torsion spring flexures are provided by pins connecting each side of the mass quadrupole to the housing. The torsion spring flexures provide an axis of rotation which passes through the center of mass of the mass quadrupole and through both torsion spring flexures.

A torsional parametric oscillator based on carbon nanotubes

Abstract: Parametric oscillations are observed in torsional electromechanical oscillators based on carbon nanotubes via molecular dynamics simulations. The stretch of nanotube torsion springs due to the vertical translational-electrostatic force acting on the paddle makes possible the parametric oscillations. The electrostatic force can provide control over nanotube stretching that allows it to parametrically modulate the torsional spring constant at twice the resonance frequency. This reveals potential building blocks for a variety of applications of the devices.