Patent ID: 6871715
Filing Date: 2005-03-29
Classification: B60L,B62B,Y02T

Abstract:
1. A system for controlled operation of a device propelled by electric motors, said system having: at least a first and a second drive wheel mounted in an axially opposed manner, each of said first and second drive wheels for propelling the device forward and backward; at least a first independent electric motor for propelling the first drive wheel and a second independent electric motor for propelling the second drive wheel; a first and a second push and pull element; at least a first independent control means for the first independent control means for the first independent electric motor and a second independent control means for the second independent electric motor, each control means having: a plurality of sensor means; an independent power amplifier; the sensor means: detecting the mechanical force of pushing and pulling applied to the push and pull elements by a user standing on a floor; transforming said mechanical force into signals indicating degree and direction of the mechanical force; capable of being operated separately so as to power each drive wheel selectively; the independent power amplifier: amplifying the electric signals produced by the sensor means; supplying electric power to the electric motor; the electrical signals being amplified in accordance with an amplification factor as a function of the device weight; each drive wheel being propelled in accordance with a torque corresponding to movement ordered by the sensor means; wherein: each power amplifier is provided with a feedback circuit that measures a true value of an electric motor current said motor current being proportional to a torque of the electric motor, the feedback circuit comprising: a comparator means for comparing said true value with a pre-established nominal value of an electric current needed to achieve movement of each drive wheel, a detecting means for detecting differences detected between the true value and the pre-established value, a transforming means for transforming said differences into error signals; an altering means for altering the electric input signals to the power amplifier on the basis of said error signals, so as to make said power amplifier supply the necessary power to the electric motor so that torque needed for producing movement ordered by the sensor means is generated by the electric motor.