Autonomous Vehicle Speed Following Torque Control
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Solution Overview
Problem
Autonomous vehicles face challenges in maintaining target speed due to mechanical delays and external factors like frictional forces and wind resistance, leading to discrepancies between target and actual speeds.
Innovation Solution
A computer-implemented method calculates three torque forces: one for acceleration, one to maintain constant speed, and one to minimize speed differences, determining a throttle-brake torque force based on these calculations to control the vehicle's speed effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional speed control methods are used in autonomous vehicles, then the vehicle can operate autonomously, but mechanical delays and external factors cause speed discrepancies between target and actual speeds
Solution Approach 1:
The patent applies preliminary action by calculating and applying torque forces in advance to compensate for mechanical delays. The system predicts the required acceleration torque, maintenance torque, and speed difference torque before the speed discrepancy occurs, allowing the vehicle to proactively adjust its speed rather than reactively correcting after delays occur. This anticipatory control approach reduces the effective impact of mechanical delays on speed control accuracy.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the speed difference between target and actual speeds, then adjusting the torque forces accordingly. The speed difference torque calculation uses feedback from the measured speed discrepancy to dynamically adjust the control forces, creating a closed-loop control system that compensates for mechanical delays and external disturbances in real-time.
2Reliability
If traditional speed control methods are used, then the vehicle can maintain basic operation, but frictional forces and wind resistance cause speed deviations
Solution Approach 1:
The patent converts harmful external factors into beneficial control inputs by calculating maintenance torque that specifically compensates for frictional forces and wind resistance. Instead of treating these forces as mere disturbances to be passively endured, the system actively calculates the required torque to counteract them, transforming the problem of external resistance into a solvable control task that improves speed following accuracy.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting torque forces based on varying operating conditions. The maintenance torque and acceleration torque are continuously recalculated based on current speed, load conditions, and environmental factors, allowing the control system to adapt to changing friction and resistance characteristics throughout the vehicle's operation.
3Measurement precision
If simple throttle control is used, then the system is simple to operate, but the vehicle cannot accurately follow target speed due to mechanical delays
Solution Approach 1:
The patent applies segmentation by dividing the complex torque control problem into three distinct torque components: acceleration torque, maintenance torque, and speed difference torque. Each torque component addresses a specific aspect of speed control, allowing the system to manage complexity through modular calculation and control of separate torque elements rather than attempting to solve the entire problem with a single complex control algorithm.
Data Source
AI summary
In one embodiment, an autonomous driving vehicle (ADV) speed following system determines how much and when to apply a throttle or a brake control of an ADV to maneuver the ADV around, or to avoid, obstacles of a planned route. The speed following system calculates a first torque force to accelerate the ADV, a second torque force to counteract frictional forces and wind resistances to maintain a reference speed, and a third torque force to minimize an initial difference and external disturbances thereafter between predefined target speed and actual speed of the ADV over a planned route. The speed following system determines a throttle-brake torque force based on the first, second, and third torque forces and utilizes the throttle-brake torque force to control a subsequent speed of the ADV.