Portable roller dynamometer and vehicle testing method

A vehicle chassis dynamometer system, for selectively testing vehicle wheel power output and braking, on a vehicle having at least two drive wheels, comprising:

• first and second dynamometer units for communication with said two drive wheels, each unit comprising a roller for contact with a vehicle drive wheel, a motoring and power absorption unit in communication with said roller, said roller and motoring and power absorption unit mounted on a substrate;
• a speed sensor for measuring rotary speed of each roller;
• a torque sensor associated with each motoring and power absorption unit for detecting torque between said power absorption unit and said substrate;
• a dynamometer controller linked to each dynamometer unit, said controller having a separate logic circuit associated with each dynamometer unit, each said logic circuit comprising roller speed feedback means for controlling rotary speed of each said roller independently the other of said rollers, whereby the rotary speed thereof may be set at a selected set point;
• total force calculation means for determining total vehicle braking or drive force applied to each dynamometer unit;
• and
• differential wheel power calculations means for quantitatively measuring, calculating, visually displaying and/or storing for subsequence recall, the difference between braking or vehicle drive power of right and left vehicle wheels.