Low Cost Inverse Servo
Unique concept for super fast and high precision CNC control with steppermotors

The unique Sensa HDM48000 concept is now also available for
the low-cost market. Experience the unique features of the revolutionary change in CNC-design yourself. The LCIS project allows CNC designers to implement this advanced technology in their own designs for outstanding performance improvement. No chips needed to translate phase and steps or microsteps. The PC takes real-time full control of the dynamic motor position by calculating the winding currents directly. The software calculates first all speeds, accelerations and decelerations and then outputs a huge stream of motor current data to the USB port.  

How is it done?
A special transconductance amplifier controls the motor current in 4 quadrants. Some of the base principle is described at http://focus.ti.com/lit/an/slua073/slua073.pdf
Sensa's software determines the motor currents in the PC at 48000 positions per sec.

The result?

• 10x better performance of steppermotors
• High accelerations
• Still 90% of the holding torque at 1500 rpm.
• High accuracy resulting in smooth surface quality
• fine X-Y contour (radius 1..3 mm) with high speed 

The LCIS concept:

The LCIS is a small version of the professional HDM48000 control based on a complete and tested USB2.0 with drivers
Other modules such as amplifiers, power supply and I/O are available as components kits. The schematics of these modules wil soon be published on this page.

A complete set
Each amplifier requires its own 6A power supply (in general 3x)
A system consists of 1x USB, 1x I/O and 3x Amp+power.
Casing, connectors, cabling not included.

The characteristics and behaviour of the motor is known by the software. The PC looks ahead by calculating the exact currents required to reach certain positions. A special current amplifier maintains the maximum possible current, even at high rpm and will reverse the current for breaking. This results in a torque close to the holding torque even at high speeds i.e. 50 Circles of 3mm can be made in one second! The only limitation is the mechanical strenght of the construction.

Kit Euro 90 . Sensa four quadrant current amplifier.
6A Kit Euro 80. Voltage by rpm regulated Power Supply, 6 Amp. constant current

6A Smart power supply

The power requirements for a dynamic stepper motor control are exceptional.
At holding torque or very low speed, the internal resistance of stepper motors is typically less than 1 ohm which requires a very low voltage with high current. At high speeds a stepper motor may require up to 60 Volt to maintain substantial torque.
In fact, a continuous current source maintaining 6 Amps from 4 V. to 60V. is required. Constant current amplifiers can do the job but at holding torque when powered with 60V. the amplifier will need to dissipate 56V. at 6 Amp., which is 336 Watt of just heat.
Sensa developed a unique controlled switched power supply providing constant current from shortcut up to 60V. without high dissipation losses.
The weight of Sensa's smart  power supply is only 250 gram