Vehicle Step Trajectory Control via Multi-Arm Linkage
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Solution Overview
Problem
Existing vehicle-step apparatuses with four-link mechanisms have restricted step member travel, making it difficult to control the motion trajectory, limiting mounting positions and causing interference with the vehicle chassis and ground.
Innovation Solution
A vehicle-step apparatus with a mounting bracket, step bracket, and a trajectory-control assembly that connects arms to control the motion trajectory of the step member, allowing for longer travel and precise control, enabling mounting at various positions on the chassis without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a four-link mechanism is used for the vehicle-step apparatus, then the structure is simple, but the step bracket travel is short and the motion trajectory of the step member is difficult to control
Solution Approach 1:
The mechanism is divided into multiple arms (first arm, second arm, third arm) with distinct functions. The first arm provides pivotal connection to the mounting bracket, the second arm connects to the third arm, and the third arm connects to the step bracket. This segmentation allows independent control of each arm's motion, enabling precise trajectory control of the step member while maintaining structural simplicity.
Solution Approach 2:
The second arm acts as an intermediary component between the first arm and the third arm. By introducing this intermediate element, the system gains an additional degree of freedom and control point, allowing the trajectory-control assembly to precisely manage the motion path of the step bracket without complicating the overall structure.
2Length of moving object
If the step bracket has short travel, then the structure is compact, but the mounting position is limited and interference with ground and chassis occurs
Solution Approach 1:
The mechanism transitions from a static, fixed-travel four-link structure to a dynamic multi-arm system where the step bracket travel distance can be adjusted by changing the pivot points and arm lengths. This dynamic configuration allows the same apparatus to be mounted at various positions on the chassis while achieving the required travel distance without ground or chassis interference.
Solution Approach 2:
The motion path of the step bracket is extended from a simple linear or arc trajectory in the four-link mechanism to a more complex multi-dimensional path enabled by the three-arm configuration. This dimensional expansion of the motion space allows the step bracket to achieve longer travel distance while avoiding obstacles and adapting to different mounting positions.
3Device complexity
If the step member trajectory is difficult to control, then the mechanism is simple, but the mounting position is restricted near the door edge
Solution Approach 1:
The trajectory-control assembly serves multiple functions: it controls the motion trajectory of the step member, enables mounting at various positions on the chassis, and prevents interference with ground and chassis components. By designing the mechanism with this multi-functional capability, the system achieves both trajectory control and mounting flexibility without proportionally increasing complexity.
4Length of moving object
If the step bracket travel is extended, then the mounting position flexibility improves, but the mechanism complexity increases
Solution Approach 1:
The first arm, second arm, and third arm are integrated into a single coordinated mechanism system driven by one motor. The trajectory-control assembly merges the motion control of all three arms into a unified control structure, allowing the step bracket to achieve extended travel distance while the overall mechanism complexity remains manageable through integrated design.
Data Source
AI summary
An extending and retracting device for a vehicle-step apparatus includes a mounting bracket and step bracket. A first arm defines a first end pivotally connected to the mounting bracket and a second end pivotally connected to the step bracket. A second arm defines a first end pivotally connected to the mounting bracket and a second end. A third arm defines a first end pivotally connected to the second end of the second arm and a second end pivotally connected to the step bracket. A trajectory-control assembly is configured to connect the first arm to the second arm and/or third arm to control a “motion” trajectory of the step bracket. A vehicle-step apparatus includes a step member, the extending and retracting device, and a driving device driving the first arm and/or second arm to move the extending and retracting device between an extended position and a retracted position.