Method of determining impact severity and adaptive impact attenuation
An adaptive energy absorption system for a vehicle seat is disclosed, utilizing an adaptive energy absorber or variable profile energy absorber (VPEA) for mitigating occupant injury due to extreme vehicle movement (e.g., during a vehicle shock event), and/or for mitigating vibration experienced by an occupant of the vehicle seat during normal vehicle operating conditions. The adaptive energy absorption system achieves the aforementioned objectives for a wide range of occupant weights and load levels. An alternate configuration of a dual-goal energy absorption system is also disclosed that enables both shock mitigation and vibration isolation.
1. An adaptive energy absorption system comprising:
a variable profile energy absorber connected between a payload and a supporting structure;
one or more sensors for determining impact velocity of said payload;
a controller comprising memory storing predetermined acceleration pulse profile characteristics including at least shape of an anticipated shock pulse associated with shock events for a particular application, and for storing software by which said controller electronically adjusts a force level of said variable profile energy absorber based upon determined impact velocity, a known payload mass, and said predetermined acceleration pulse profile characteristics.
2. An adaptive energy absorption system of claim 1 , wherein the predetermined acceleration pulse profile characteristics include shape and duration of an anticipated shock pulse associated with shock events for a particular application.
3. An adaptive energy absorption system of claim 2 , wherein the predetermined acceleration pulse profile characteristics include shape, duration and peak amplitude of an anticipated shock pulse associated with shock events for a particular application.
4. An adaptive energy absorption system of claim 1 , wherein the predetermined acceleration pulse profile characteristics include shape and peak amplitude of an anticipated shock pulse associated with shock events for a particular application.
5. An adaptive energy absorption system of claim 1 , wherein the variable profile energy absorber is a linear magnetorheological fluid damper.
6. An adaptive energy absorption system of claim 1 , wherein the variable profile energy absorber is a rotary magnetorheological fluid brake or clutch.
7. An adaptive energy absorption system of claim 1 , wherein the variable profile energy absorber is an electronically adjustable friction device selected from the group consisting of a piezo friction damper and magnetically controlled friction damper.
8. An adaptive energy absorption system of claim 1 , wherein the variable profile energy absorber is an electronically adjustable hydraulic damper with an orifice adjusted by electromechanical actuator.
9. An adaptive energy absorption system of claim 1 , further comprising a predetermined shock acceleration profile stored in said controller memory.
10. An adaptive energy absorption system of claim 9 , further comprising a library of different predetermined shock acceleration profiles stored in said controller memory.
11. An adaptive energy absorption system of claim 10 , wherein said controller selects one predetermined shock acceleration profile from said library based on a position of a manual switch.
12. An adaptive energy absorption system of claim 10 , wherein said controller selects one predetermined shock acceleration profile from said library based on a measurement from said one or more sensors.
13. An adaptive energy absorption system of claim 1 , further comprising a payload mass/weight sensor.
14. An adaptive energy absorption system of claim 13 , wherein the payload mass/weight sensor is a force transducer.
15. An adaptive energy absorption system of claim 13 , wherein the payload mass/weight sensor is a strain gauge.
16. An adaptive energy absorption system of claim 13 , wherein the payload mass/weight sensor is a pressure sensor.
17. An adaptive energy absorption system of claim 13 , wherein a mass value is periodically measured by said payload mass/weight sensor to update a stored payload mass value in the controller.
18. An adaptive energy absorption system of claim 13 , wherein the payload mass/weight is continuously monitored at said payload mass/weight sensor by said controller.
19. An adaptive energy absorption system of claim 18 , wherein the monitored payload mass/weight is filtered to remove undesirable oscillations.
20. An adaptive energy absorption system of claim 1 , further comprising
a. a spring;
b. a sensor for measuring relative displacement of the payload with respect to a supporting structure.
21. An adaptive energy absorption system of claim 20 , wherein the payload mass is derived from a displacement signal and known spring stiffness.
22. An adaptive energy absorption system of claim 20 , wherein the payload mass is derived from relative static displacement of the spring due to gravitational acceleration.
23. An adaptive energy absorption system of claim 22 , wherein the relative static displacement is derived by filtering a real-time displacement signal from said sensor for measuring relative displacement of the payload with respect to the supporting structure to remove undesirable oscillations in said real-time displacement signal.
24. An adaptive energy absorption system of claim 20 , wherein the controller determines that a free-fall is occurring by a displacement sensor measurement and multiplies an expected constant free-fall acceleration by the amount of time in free-fall to determine impact velocity.
25. An adaptive energy absorption system of claim 20 , wherein a free fall event is determined by the controller comparing a real-time measured displacement with a known static displacement value.
26. An adaptive energy absorption system of claim 1 , wherein the known payload mass/weight is predetermined and stored in said controller memory.
27. An adaptive energy absorption system of claim 1 , wherein at least one of said one or more sensors for determining impact velocity comprises an existing vehicle instrumentation component from among the group consisting of a tachometer, speedometer, altimeter, and air speed indicator.
28. An adaptive energy absorption system of claim 27 , wherein the controller multiplies expected constant free-fall acceleration by the amount of time in free-fall to determine impact velocity.
29. An adaptive energy absorption system of claim 1 , wherein one or more of said sensors are mounted to the payload for determining impact velocity.
30. An adaptive energy absorption system of claim 29 , wherein one or more of said payload mounted sensors are accelerometers.
31. An adaptive energy absorption system of claim 30 , wherein the controller determines that a free-fall is occurring by a displacement sensor measurement and integrates an accelerometer measurement with respect to time to determine impact velocity.
32. An adaptive energy absorption system of claim 31 , wherein the controller periodically resets the integration to remove drift due to noise and or bias.
33. An adaptive energy absorption system of claim 31 , wherein the controller interrupts periodic resetting of said integration during a free fall event.
34. An adaptive energy absorption system of claim 31 , wherein the controller interrupts periodic resetting of the integrator when a logical threshold from among displacement, velocity, and/or acceleration thresholds are exceeded.
35. An adaptive energy absorption system of claim 30 , wherein a free fall event is determined by the controller evaluating accelerometer measurements.
36. An adaptive energy absorption system of claim 27 , wherein the controller determines that a free-fall event is occurring by integrating a measurements of said accelerometers with respect to time to determine impact velocity.
37. An adaptive energy absorption system of claim 1 , wherein the controller pre-adjusts the variable profile energy absorber to an appropriate value prior to an impact based upon known mass value, real-time impact velocity determination, and knowledge of the predetermined acceleration pulse profile characteristics of said impact.
38. An adaptive energy absorption system of claim 1 , wherein the controller adjusts the variable profile energy absorber in real-time to a value that is proportional to a mathematical function of payload mass/weight and the real-time payload velocity measurement.
39. An adaptive energy absorption system of claim 38 , wherein the controller adjusts the variable profile energy absorber in real-time to a value that is proportional to payload mass/weight and an nth order polynomial function of the real-time payload velocity measurement.
40. A method of controlling a variable profile energy absorber with a controller to minimize acceleration of a payload during a shock event, said controller comprising a microprocessor operatively connected to memory in which is stored a predetermined shock acceleration profile library, the method comprising the steps of:
inputting a mass of said payload and communicating said mass to said microprocessor;
measuring velocity of said payload prior to a shock event and communicating said velocity to said microprocessor;
selecting from said memory a predetermined shock acceleration profile by said microprocessor;
calculating by said microprocessor a priori expected shock impulse levels during said shock event based on said inputted mass, monitored velocity, and selected predetermined shock acceleration profile;
calculating by said microprocessor a required oppositional force to be applied said payload to mitigate said expected shock impulse levels during said shock event;
signaling a variable profile energy absorber to apply said calculated required oppositional force to said payload.
41. A method of controlling a variable profile energy absorber with a controller to mitigate acceleration of a payload during a shock event, said controller comprising a microprocessor operatively connected to memory in which is stored a predetermined shock acceleration profile library, the method comprising the steps of:
weighing said payload by a weight sensor to determine a weight and communicating said determined payload weight to said microprocessor;
monitoring impact velocity of said payload prior to a shock event and communicating said velocity to said microprocessor;
selecting from said memory a predetermined shock acceleration profile by said microprocessor;
calculating by said microprocessor a priori expected shock impulse levels during said shock event based on said payload weight, monitored velocity, and selected predetermined shock acceleration profile;
calculating by said microprocessor a required oppositional force to be applied to said payload to mitigate said expected shock impulse levels during said shock event;
signaling a variable profile energy absorber to apply said calculated required oppositional force to said payload.