To easily calculate center of gravity of a vehicle, check the following link:
Calculating the centre of gravity (CoG) of a vehicle is very important in automotive engineering. There are several methods, but the basic principle is the same:
The CoG is the point where the entire weight of the vehicle can be considered to act.
Also Read: Why is center of gravity important in cars?
🔹 Methods to Calculate Centre of Gravity of a Vehicle
1. Longitudinal Position of CoG (front to back)
This tells you how weight is distributed between the front and rear axles.
Where:
- Lcg = distance of CoG from the front axle
- Wrear = weight on the rear axle
- Wtotal = total vehicle weight
- L= wheelbase (distance between front and rear axles)
👉 This is usually measured by putting the vehicle on two weighing scales (one under each axle).
2. Lateral Position of CoG (side to side)
If the car is symmetric, the CoG will be on the centerline.
If it’s not (e.g., race car with driver on one side), you measure:
Where:
- Ycg = distance of CoG from left wheel track
- Wright= weight on right wheels
- T= track width (distance between left and right wheels)
3. Vertical Position of CoG (height above ground)
This is trickier to measure. One common method is the tilt method:
- Put the car on a set of scales and measure axle loads normally.
- Then tilt the whole vehicle to a known angle (θ) and re-measure axle loads.
- Use geometry to solve for CoG height:
Where:
- hcg = height of CoG above ground
- Wshift = change in weight distribution due to tilting
- θ = tilt angle
👉 Automotive labs often use a hydraulic tilt table to do this.
4. Mathematical Approach (for design stage)
If the vehicle is still in CAD design, CoG can be found using:
Where:
- mim_i = mass of each component (engine, seats, chassis, etc.)
- xi,yi,zix_i, y_i, z_i = position of each component’s CoG
This gives a very accurate result if you know the weight and position of every part.
Summary
- Axle weights + wheelbase → longitudinal CoG
- Side weights + track width → lateral CoG
- Tilt test (or CAD) → vertical CoG
Other courses:
