Electronic differential - Sharp turns - no problem!

Input torque is applied to the ring gear, which turns the entire carrier (all blue), providing torque to both side gears (red and yellow), which in turn may drive the left and right wheels. If the resistance at both wheels is equal, the planet gear (green) does not rotate, and both wheels turn at the same rate.
If the left side gear (red) encounters resistance, the planet gear (green) rotates about the left side gear, in turn applying extra rotation to the right side gear (yellow).

Please note that the pictures above shows how a mechanical differential looks like.

The main purpose of the Electronic differential is to substitute the mechanical differential in multi-drive systems providing the demanded torque for each driving wheel and allowing different wheel speeds. When turning at a corner the inner and outer wheels rotate at different speeds. This happens because the inner wheel describes a smaller turning radius. The electronic differential uses the steering wheel command signal to control each wheel speed in order to smoothly perform the turning.

These driving schemes with one motor per driving wheel need an additional top level controller which is responsible to perform the same task as the mechanical differential. Named electronic differential, it is capable of substituting its mechanical counterpart with significant advantages.

• simplicity, it avoids additional mechanical parts like gearboxes or clutch;

• independent torque for each wheel allows auxiliary functionalities (e.g., traction control, stability control);
• reconfigurable, it is reprogrammable in order to include new features or tuned according to the driver’s preferences;
• allows distributed regenerative braking;
• does not have the mechanical differential limitation where the torque limited by the lesser traction wheel.

Moreover, a multi-drive traction system with distributed electric motors have advantages over the traditional solutions^[1]:

1. faster response times;
2. accurate knowledge of traction torque per wheel.

Difference between Mechanical differential and Electrical differential.

A mechanical differential has a set of gears arranged along a common axle in a way which is receptive to forces acting on the tires.

An Electrical differential has motors fixed to each individual tire and is independent of either of the tires. Motors are programmed to effect different rotation speed of the tires.

Posted by: Raja Babu Dwivedy.
ID: 4810750499.
Reference:http://en.wikipedia.org/wiki/Differential_%28mechanical_device%29