Passive orthopedic aid in the form of a foot prosthesis or foot orthosis
View Patent ↗The invention relates to a passive orthopedic aid in the form of a foot prosthesis or foot orthosis, with a first part which is connected to a second part in a rotatable manner via a swivel joint, with a sensor arrangement for measuring parameters that provide indications of instantaneous operation requirements of the aid, with a control means which is connected to the control arrangement and is used to determine operation requirements and to generate corresponding control signals, with a controllable hydraulic damping arrangement with which a movement resistance acting on the rotation movement between the first part and the second part can be modified, and with a control means which converts the control signals of the processor arrangement and is used to control the damping arrangement.
1. Passive orthopedic aid being a foot prosthesis or foot orthosis, comprising
a first part and a second part both rotatably connected to each other by a swivel joint, so as to allow a rotation movement between the first part and the second part having a certain movement resistance,
a sensor arrangement for measuring parameters that provide indications of instantaneous operation requirements of the orthopedic aid,
a control means connected to the sensor arrangement including a processor arrangement configured to determine operation requirements and to generate control signals corresponding to the determined operation requirements,
a controllable hydraulic damping arrangement configured to modify the movement resistance of the rotation movement between the first part and the second part and being controlled by the control signals of said control means, wherein
the control of the orthopedic aid is passive,
the damping arrangement is a hydraulic cylinder with two hydraulic chambers separated from each other by a piston,
the hydraulic chambers are connected via two connection lines permitting a flow of hydraulic fluid between the hydraulic chambers in one flow direction only where the flow directions in the two connection lines are opposite to each other,
flow resistances in the two connection lines are controlled by the control arrangement separately, each connection line having an own adjustment means for adjusting different flow resistances during a gait cycle,
the processor arrangement includes an ankle moment sensor configured to detect where an ankle moment crosses zero during said gait cycle,
the processor arrangement is configured to determine a current neutral point position for each gait cycle from a zero crossing of the ankle moment detected by the ankle moment sensor, and
the control means is configured to take into account the current neutral point position determined by the processor arrangement from the zero crossing of the ankle moment for generating the control signals which control the flow resistances in the two connection lines.
2. Orthopedic aid according to claim 1 , wherein the flow resistance in at least one connection line is increasable such that the swivel joint can be locked in any desired position.
3. Orthopedic aid according to claim 2 , wherein the locked position corresponds to the neutral point position.
4. Orthopedic aid according to claim 1 , wherein the neutral point position is determinable as a function of a ground inclination.
5. Orthopedic aid according to claim 4 , wherein the neutral point position is determinable as a function of a current height of a heel of a shoe that is used with the orthopedic aid.
6. Orthopedic aid according to claim 1 , wherein the first part and the second part are mostly rigid, and wherein at least most of movement within a movement cycle is controlled by control of the flow resistances, without being influenced by material elasticities.
7. Orthopedic aid according to claim 1 , wherein the swivel joint is an ankle joint.