Posted on Leave a comment

Application of Stepper Motors in Medical Electronics

1. Introduction
Currently, major therapeutic methods in the treatment of open, complicated and unstable fractures in traumatology, orthopaedics and surgery (limbs, joints, the pelvis, jaws, etc.) include external fixators. This therapeutic method provides the advantage of simple application of the external fixator with perfect stabilisation of the fracture,allowing for timely rehabilitation of the patient. External fixators can also be used to extend limbs or to correct axial deformities. However, no fixator has been made until now that would provide motor control of joint movement – advisable and desired for therapy associated with rehabilitation in unconscious patients or patients with complicated joint fractures. VSB-TU Ostrava has gained practical experience in this field in cooperation with University Hospital in Ostrava; fixator prototypes which are equipped with an electric stepper motor to control joint bending in patients exist.There are currently two solution variants that can be considered for the electric actuation, in principle.

Application of Stepper Motors in Medical Electronics

1.1 Hybrid Actuators with Stepper Motors
Hybrid linear actuator stepper motor transfer the rotation movement of the stepper to the movement of a linear screw with the help of a special patented nut. The actuator contains a hybrid stepper motor, which utilizes both the advantages of a reluctance motor and a motor with permanent magnets. The construction is based on a reluctance motor and ensures a small step angle (up to 0.9°) and fine resolution. The use of permanent magnets on the other hand increases the turning moment and provides a stronger motor. The composition of these two technologies together with the movement nut into a single case creates an affordable compact linear drive  a hybrid stepper actuator.

Hybrid actuators represent an affordable solution for all application requiring small and exact control of a linear movement. Actuators create large forces in small spaces.The actuator contains a standard stepper motor, which may be simply controlled in the same way as stepper motors. The core of the hybrid actuator is an exact trapezoidal movement screw and nut shaped for the corresponding load. Integration of the movement screw in the motor provides a compact and precise drive unit which simplifies the construction of the resulting machine. Actuators find applications in medicine, measuring technology, handling technology and in other areas.

1.2 Stepper Motor Combined with a Linear Lead
The other possibility is offered by using a linear lead in connection with a standard two-phase stepper motor. The Kuroda linear lead used to convert rotational linearmovement can be mentioned as an example.The lead is equipped with a ball screw for positioning medium- up to heavy-weight
loads. The lead converts rotational movement of the stepper motor to the linear movement of the positioned load. An optimum configuration of the linear drive is obtained by combining the stepper motor and linear lead.

Which is Better for Cnc? Servo or Stepper Motors?

Torque and Speed Considerations Of Stepper Motor
Posted on Leave a comment

Advantages, Applications & Control of Brushless DC Motor

A brushless DC motor consists of a rotor in form of a permanent magnet and stator in form of polyphase armature windings. It differs from conventional dc motor in such that it doesn’t contains brushes and the commutation is done using electrically, using a electronic drive to feed the stator windings.

Advantages, Applications & Control of Brushless DC Motor

4 Pole 2 Phase Motor Operation
The brushless DC motor is driven by an electronic drive which switches the supply voltage between the stator windings as the rotor turns. The rotor position is monitored by the transducer (optical or magnetic) which supplies information to the electronic controller and based on this position, the stator winding to be energized is determined. This electronic drive consists of transistors (2 for each phase) which are operated via a microprocessor.

7 Advantages of Brushless DC Motors
Better speed versus torque characteristics
High dynamic response
High efficiency
Long operating life due to a lack of electrical and friction losses
Noiseless operation
Higher speed ranges

The cost of the Brushless DC Motor for sale has declined since its presentation, because of progressions in materials and design. This decrease in cost, coupled with the numerous focal points it has over the Brush DC Motor, makes the Brushless DC Motor a popular component in numerous distinctive applications. Applications that use the BLDC Motor include, yet are not constrained to:

Consumer electronics
Heating and ventilation
Industrial engineering
Model engineering
Principle of Working

The principles for the working of a BLDC motors are the same as for a brushed DC motor, i.e., the internal shaft position feedback. In case of a brushed DC motor, feedback is implemented using a mechanical commutator and brushes. Within BLDC motor, it is achieved using multiple feedback sensors. In BLDC motors we mostly use Hall-effect sensor, whenever rotor magnetic poles pass near the hall sensor, they generate a HIGH or LOW level signal, which can be used to determine the position of the shaft. If the direction of the magnetic field is reversed, the voltage developed will reverse too.

What are Brushless DC Motors Used For?

Brush DC Motor VS Brushless DC Motor