servomotor - FAULHABER - DC Motors & Micro Drive Systems
electronic actuator was developed to complement the micromotor. The new Motion Controller MCBL 05002 makes servomotor servomotor - FAULHABER - DC Motors & Micro Drive Systems it possible to set all the motor parameters individually, as is state of the art Servomotor with larger drives. Not only can rotary speed and torque settings
be made, speed profiles with acceleration and
deceleration ramps can also be selected. The servomotor accuracy achieved is comparable with that of precision stepping motors. It became possible
because of a sinusoidal actuator matched to the properties of the micromotor. ... and the secret of sinusoidal
actuation
In the micrometer range, pulse width modulation – which is
often used on larger motors for regulating
purposes – servomotor leads to substantial inaccuracies and speed fluctuations, especially in the low speed range. The reason for this is the low inertia
of the rotor. If, instead, one selects actuation via servomotor a sinusoidal signal with three analog sine waves, smooth running is guaranteed even at low speeds and low levels of servomotor inertia. (Fig. 2)
The rotor can follow the continuous, sinusoidal current characteristic without any accelerating torque or indexing torque. By monitored control of sine-wave voltage a resolution of 256 steps per servomotor revolution is achieved. (Fig. 3)
The amplitude of the sine-wave voltage increases automatically as rotary speed rises and compensates for armature reaction. Torque thus remains constant over the entire speed range. Position input is performed by an open-loop actuator without feedback. This technique has proved extremely successful with stepping motor positioning controls.
Via a serial port (RS232 or RS422) to set the parameters, all the control inputs of the application can be programmed accordingly. A powerful 24 MHz microcontroller then processes the control inputs internally. That way the user can adapt the properties to specific requirements, for example, step size for stepping motor operation, the input of set velocity, or a pointer instrument input, where the rotor is steered out of the home position in proportion to an analog voltage.
In practice
To support the user in operation and configuration, there is control-compatible software available called "Motion Manager 2" (free download at www.faulhaber.de). The compact control board is smaller than a matchbox and can easily be integrated into other electronic assemblies with a DIL28-IC socket (Fig. 4 ). This board can also be found in a starter kit, which is available in addition and is comprised of a small control box – ready for plug-and-play operation.
The user-friendly design of the motion control system makes it possible to develop new processes and applications specially designed for microtechnology. An ultrasound catheter and a micro-positioner are just a few examples of the numerous potential applications.
Examples of applications
Non-invasive medicine goes easy on the patient and enables rapid, low-cost diagnosis. One example of such an application is ultrasound diagnostics. In a miniaturized form, e.g. as a catheter, the sites to be examined can thus be reached by a targeted approach via cavities, like arteries or the ureter. Such an ultrasound catheter is essentially comprised of a catheter head with an ultrasound transducer on the motor/gearhead unit as well as a catheter tube for the power supply and data line. The supply of power and data to and from the transmit/receive head is provided via slip
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