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413results about How to "Reduce inertia" patented technology

Rotary servovalve and control system

An improved rotary servovalve system employs a rotary magnetic solenoid having an armature that includes at least one permanent magnet. The armature is rotatable relative to a stator formed as an electromagnet which is energizable to create alternative electromagnetic fields having opposite polarities from each other. When deenergized, the stator allows the armature to return to a neutral, null position from positions of extreme rotation in opposite angular directions due to the magnetic force of the permanent magnet of the armature. The armature is coupled to carry a movable valve element in angular rotation therewith, so that flow through the servovalve of the system can occur in alternative directions. Also, the valve element is biased toward a position in which all of the valve ports are closed when power is removed from the rotary solenoid. The control circuit employed in the rotary servovalve system expands the bandwidth of response of the solenoid actuator by compensating for frequency variations in the input command signal and in the feedback signal. This compensation is achieved utilizing a combined proportional, integral, and differential amplification circuit. Also, imbalance of fluid forces within the servovalve mechanism can be avoided by utilizing a pair of inlet orifices, a pair of outlet orifices, a pair of first fluid control orifices, and a pair of second fluid control orifices. The orifices within each pair are located on opposite sides of the valve housing from each other.
Owner:WOODWORTH RAYMOND DEXTER

Rope-driven exoskeleton type upper-limb rehabilitation robot system

The invention provides a rope-driven exoskeleton type upper-limb rehabilitation robot system, comprising a supporting seat, a control system and a driving device, wherein a shoulder rope rack adjusted and positioned above a human shoulder joint is fixedly arranged on the supporting seat; an upper arm ring and a forearm ring are respectively and fixedly arranged on a human body upper arm and a human body forearm; a forearm rope penetrates through a rope outlet hole in the shoulder rope rack, and is connected with the forearm ring; an upper arm rope penetrates through the rope outlet hole in the shoulder rope rack, and is connected with the upper arm ring; a tension pressure sensor for measuring the tension of the rope in real time is connected in series with the interior of each of the upper arm rope and the forearm rope; the control system is connected with the tension pressure sensor; the driving device is connected with the control system; the driving device is simultaneously connected with the upper arm rope and the forearm rope; the tension pressure sensor feeds back a tension signal to the control system; the control system controls the driving device to drive the upper arm rope and the forearm rope to stretch or retract according to the position feedback of the driving device and the feedback of the tension pressure sensor, so that the exercise of rehabilitating an arm is realized. According to the rope-driven exoskeleton type upper-limb rehabilitation robot system, the single-joint exercise of the human body upper arm and the human body forearm and the compound exercise of a whole upper limb can be realized; therefore the function of rehabilitation exercise is realized.
Owner:TSINGHUA UNIV

Damping for electromechanical actuators

InactiveUS7109679B2Inertia of the electric motor is substantially reducedReduce inertiaProgramme controlComputer controlOperation modeControl theory
Oscillation and other disturbance damping is provided for a system having a load driven by an electric motor, e.g., an electromagnetic actuator. Damping is achieved using feedback in an active mode, where power is supplied in a normal operation mode of the electromagnetic actuator. Feedback may be provided by measured force (or torque) transmitted between the actuator and load mass. A gear train or other mechanical advantage device may be connected between the electromagnetic actuator output and load, this combination forming an electromechanical actuator (EMA). Instead of force or torque, acceleration of the load may be used as a feedback signal. In one embodiment, active mode damping uses the motor's actual current as a feedback signal. In certain or all active damping versions of the invention, a high pass filter is preferably used to receive feedback signals and filter out low frequency feedback. Alternatively, damping is achieved in an inactive (passive) mode of motor operation, e.g., where the electric motor is not receiving power drive signals. The motor coils are shorted, e.g., using a switch. The induced motor currents act to inhibit load oscillations. Preferably, a resistance, e.g., a number of resistors, are in the short circuit to tailor the damping characteristics of the motor. In at least the active current feedback and passive modes of operation, inertia of the electric motor is substantially reduced in relation to typical motor inertia, by changing the stator to rotor diameter ratio from a typical ratio of at or about 2:1 or less, to a substantially higher ratio than 2:1.
Owner:HR TEXTRON

Double-lasso driving flexible joint used for exoskeleton robot

The invention discloses a double-lasso driving flexible joint used for an exoskeleton robot, which comprises a drive mechanism, a pre-tightening mechanism, a lasso transmission mechanism, a flexible mechanism and an exoskeleton joint. A motor drives a drilling roller to rotate; the two ends of a rope are respectively fixedly connected with the driving roller and a load roller; a driving torque is delivered to the load roller through the lasso transmission mechanism; the load roller is fixedly connected with the exoskeleton joint to drive the joint to move; a positioning hole and a positioning groove both capable of limiting the motion range of the joint are formed in the load roller; the pre-tightening mechanism adjusts a pre-tightening force of a rope by changing the screwing depth of a pre-tightening bolt so as to avoid looseness of a drive system; the flexible mechanism enables the joint to achieve flexibility and can measure an output torque based on a displacement offset of the motor and the joint. The double-lasso driving flexible joint used for the exoskeleton robot can realize separation of the motor and the exoskeleton robot, overcomes the problems of the quality of each joint of the exoskeleton and too great inertia, and can perform precise position control and force control on the drive joint.
Owner:SOUTHEAST UNIV
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