Abstract: Four-wheel alignment parameters are closely related to the suspension system. The suspension is crucial for vehicle performance, safety, and comfort. DTAS 3D provides tolerance simulation analysis methods for various types of suspensions.

Keywords: DTAS 3D, front and rear suspension, tolerance simulation analysis, motion coupling

I. Overview of Suspension Tolerance Analysis

The suspension—the connection between the chassis and wheels—is a vital component in vehicle safety, handling, and comfort. It buffers road shocks, maintains tire contact, and stabilizes the vehicle during cornering, braking, and acceleration.

The primary goal of suspension tolerance analysis is to evaluate how manufacturing tolerances affect four‑wheel alignment parameters, including:

•Camber 

•Toe‑in

•Kingpin inclination (front wheels only)

Through simulation, we assess the impact of these tolerances on vehicle performance and ensure alignment remains within functional specifications.

DTAS 3D supports two approaches for chassis suspension tolerance simulation:

1. Static Assembly Modeling
   Builds a virtual assembly for the chassis (e.g., multi‑constraint or rotational assemblies), integrating tolerance analysis with motion studies. 

2. Kinematic Pair Modeling
   Creates various kinematic pairs and drivers to simulate suspension articulation.

   Both methods differ in modeling but deliver equivalent analytical accuracy and results.

Suspension Types Supported
DTAS 3D can analyze:

•MacPherson strut 

•Double wishbone 

•Three‑link (“chopstick”) 

•Four‑link (trailing arm)

•Five‑link 

•H‑arm

This article focuses on modeling double‑wishbone front suspension and five‑link rear suspension—two widely used designs that balance performance, handling, and structural complexity.

II. Tolerance Analysis of Double Wishbone Front Suspension and Five-Link Rear Suspension

Modeling Approach: The double wishbone front suspension mainly establishes the following kinematic pairs, including two drive pairs: one for wheel hopping and the other for steering drive.

The five-link rear suspension has five links, resulting in ten ball joints with the chassis and steering knuckle. Shock absorbers, etc., can be modeled as slider joints, ball joints, etc. Wheel hopping drive is established on the steering knuckle.

Multi‑Constraint Assembly as an Alternative

The five‑link rear suspension can also be modeled using multi‑constraint assembly, as shown below. This method controls the distance between the steering knuckle and subframe mounting points, ultimately defining the knuckle's final position.

Multi‑constraint assembly applies to various front and rear suspension types and offers faster computation and simpler setup than kinematic‑pair modeling.

Virtual Measurement: DTAS 3D allows for the creation of various virtual measurements, including toe angle, camber angle, front wheel kingpin inclination, caster angle, and the difference or sum of the left and right toe angles.

Simulation Results: Motion trajectory analysis, analyzing the trajectory of the wheel under different states, such as steering angle and wheel bounce height.

Fluctuation of Four-Wheel Parameters: Contribution and transfer coefficient analysis, showing the sensitivity and contribution of each tolerance to the four-wheel parameters, providing direction for subsequent optimization.

Simulation Animations: Double Wishbone Suspension, Five-Link Suspension, Tolerance Simulation Animations for Other Suspensions: MacPherson Front Suspension, Split Double Wishbone Suspension, Three-Link Suspension, H-Arm Suspension.

III. Conclusion & Outlook

DTAS 3D enables tolerance simulation for all major automotive suspension types, with both static and kinematic modeling approaches, supporting full validation of handling and comfort performance.

A central challenge—and future direction—remains the integrated simulation of mechanism motion, tolerance effects, and flexible bushings in suspension systems.