Hybrid Braking System for Autonomous Delivery Vehicles
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Solution Overview
Problem
Delivery autonomous ground vehicles (AGVs) face challenges in effectively braking at low speeds, especially in emergency situations, as existing dynamic braking systems are less effective at lower speeds and can cause motor damage, while mechanical brakes are not always sufficient to immobilize the vehicle quickly.
Innovation Solution
A hybrid braking system combining an emergency electrical brake that short-circuits motor terminals to dissipate energy as heat and a mechanical parking brake, which is spring-biased for engagement and held out of engagement by an electric actuator, allowing for rapid speed reduction and immobilization of the AGV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic braking is used to stop the AGV, then the motor can be stopped by ramping down power, but the braking system is less effective at low speeds and can cause motor damage
Solution Approach 1:
The braking system is segmented into two independent components: an electrical brake for high-speed stopping and a mechanical brake for low-speed stopping. This segmentation allows each brake type to operate in its optimal speed range, preventing motor damage while maintaining braking effectiveness at all speeds.
Solution Approach 2:
The patent combines electrical braking and mechanical braking systems into a hybrid braking system. The electrical brake handles high-speed deceleration by dissipating energy through motor resistance, while the mechanical brake takes over at low speeds to provide sufficient stopping force without causing motor damage.
2Speed
If mechanical brakes are used to immobilize the AGV, then stopping force can be provided at low speeds, but the brakes may not be sufficient to quickly immobilize the vehicle in emergency situations
Solution Approach 1:
The braking system dynamically switches between electrical and mechanical braking based on vehicle speed. At high speeds, the electrical brake provides rapid deceleration; as speed decreases, the system transitions to mechanical braking for reliable immobilization. This dynamic operation ensures both rapid speed reduction and reliable immobilization capability.
3Loss of time
If power is rapidly reduced to the motor for emergency stopping, then the AGV can stop quickly, but the motor may be damaged from the sudden power change
Solution Approach 1:
The electrical brake converts the motor into a generator during deceleration, transforming the motor's kinetic energy into electrical energy that is dissipated as heat through motor resistance. This process provides rapid stopping while protecting the motor from damage by avoiding sudden power cuts and using the motor's electromagnetic properties beneficially.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The hybrid braking system enables safe and reliable stopping of AGVs at low speeds, reducing the risk of motor damage and ensuring the vehicle can be immobilized until inspected or retrieved, even in emergency situations.
Implementation Method 1
an electrical brake, which includes electrical means for shorting across the motor terminals to dissipate energy as heat
Implementation Method 2
a mechanical brake, including a braking element engageable with the wheel to prevent rotation of the wheel
Data Source
AI summary
A delivery AGV has a hybrid braking system. An emergency electrical brake shorts between motor contacts to stop the AGV quickly, but it doesn't work well to keep the AGV stopped, such as when on a hill. A mechanical parking brake is electrically actuated to lock the wheels. Both systems can be used at once for stopping the AGV.