Dynamic Electric Brake for Hospital Bed Deceleration
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Solution Overview
Problem
Hospital beds are difficult to stop quickly when being moved due to their weight, as static brakes are not designed for deceleration and are typically operated by foot pedals, making it challenging for a person to control the bed's movement, especially to avoid pedestrians.
Innovation Solution
A dynamic electric braking system that includes a brake command generator, an electromachine, and a controller, allowing an operator to decelerate the bed by generating an electrical load commensurate with the brake command, using a braking effector such as a brake shoe or caliper, which can be activated through a handgrip-mounted actuator, enabling controlled deceleration and stopping of the bed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If static brakes are used to immobilize the bed when stationary, then the bed can be held in place, but the brake cannot decelerate a moving bed quickly
Solution Approach 1:
The braking system transitions from a static brake designed only for immobilization to a dynamic braking system that can both decelerate moving beds and hold stationary beds. The electromachine (motor/generator) provides dynamic braking force that can be modulated based on operational needs, enabling quick stopping during movement while maintaining holding capability when stationary.
Solution Approach 2:
The conventional mechanical foot-pedal brake system is replaced with an electromachine-based dynamic braking system. The electromachine can function as a motor during propulsion and as a generator during braking, converting mechanical energy to electrical energy. This substitution enables more precise and versatile control over the bed's motion and deceleration.
2Weight of moving object
If the bed is made heavy to support the patient, then patient support capability is improved, but the bed becomes difficult to stop quickly
Solution Approach 1:
The heavy mechanical brake system is replaced with an electromachine-based dynamic braking system. The electromachine (operating as a generator) converts the kinetic energy of the moving bed into electrical energy, providing efficient deceleration. This system can quickly dissipate the momentum of the heavy bed through electrical load, enabling rapid stopping despite the bed's substantial weight.
Solution Approach 2:
The kinetic energy that represents a hazard during stopping (the momentum of the heavy bed) is converted into useful electrical energy through the generator mode of the electromachine. This energy can be used to charge the battery or power other bed functions, turning the stopping challenge into an energy recovery opportunity.
3Ease of operation
If conventional foot-pedal brakes are used, then braking function is provided, but the brake is not accessible to the operator moving the bed
Solution Approach 1:
The electromachine serves multiple functions: it acts as a motor during bed propulsion, as a generator during braking, and interfaces with both the battery system and the control system. The handgrip-mounted actuator integrates the brake command function into the operator's existing control interface, making braking as accessible as propulsion while consolidating control functions.
Solution Approach 2:
The braking function is merged with the existing handgrip actuator that the operator uses for propulsion control. By integrating the brake command generator with the handgrip assembly, the system combines multiple control functions into a single accessible interface, eliminating the need for separate foot-pedal operation and simplifying the overall control architecture.
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
Enables safe and controlled deceleration of hospital beds, allowing operators to quickly stop or slow the bed as needed, enhancing safety by providing a user-activated braking mechanism that is integrated into the bed's mobility system.
Implementation Method 1
the electromachine is a generator having a rotary input whose source is rotary motion of the rolling element, and the rotary input is capable of being decelerated by an electrical load applied to the generator
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
An occupant support 30 includes a frame 32, at least one rolling element 44 enabling the frame to be rolled from an origin to a destination and a brake command generator 60 adapted to generate a brake command 62. An electromachine 66 produces an output 68 in response to the brake command for decelerating the rolling element.