Ankle Ergometer With 3D Force Sensor and Open Chain Configuration
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Solution Overview
Problem
Existing ankle-type ergometers overestimate force measurements by involving muscles from other joints, such as the knee or hip, and fail to accurately measure forces in three dimensions, particularly during plantar and dorsiflexion movements, due to their design and use of unidirectional sensors, which limits their precision and functionality, especially in assessing orthostatic posture and rehabilitation.
Innovation Solution
A compact ankle ergometer with a splint-type first part and a boot-like second part, featuring a rigid plate with a 3D force sensor between the plate and a counter-support element, allowing precise measurement of forces exerted by ankle flexion muscles without involving other joint muscles, and an open chain configuration to minimize friction and ensure accurate three-dimensional force measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing ankle-type ergometers use unidirectional force sensors to measure ankle joint forces, then the device structure is simple, but the measurement precision is insufficient because they cannot accurately measure forces in three dimensions during plantar and dorsiflexion movements
Solution Approach 1:
The patent transitions from unidirectional force sensors to a 3D force sensor that measures forces in three dimensions (Fx, Fy, Fz). This dimensional expansion allows accurate measurement of forces during plantar and dorsiflexion movements, resolving the limitation of previous bidirectional or unidirectional sensors that could not capture the full complexity of ankle joint force vectors.
2Ease of operation
If existing ergometers allow knee or hip muscles to be involved in the measurement, then the device is easier to operate, but the measurement precision deteriorates because forces from other joints are included in the measurement
Solution Approach 1:
The patent extracts and eliminates the confounding influence of knee and hip muscles from the measurement system. By using a boot-like structure that secures the lower limb and a specialized force sensor configuration, the system isolates ankle joint forces, ensuring that only the forces generated by ankle muscles (tibialis anterior, gastrocnemius, soleus) are measured, while excluding contributions from proximal joints.
3Reliability
If existing ergometers use a closed chain configuration with friction, then the device structure is stable, but the measurement precision worsens due to friction interference in force measurement
Solution Approach 1:
The patent replaces the traditional closed chain mechanical configuration with an open chain configuration. This substitution eliminates friction-induced measurement errors by allowing the lower limb to move freely through its range of motion without mechanical constraints that generate friction, while still maintaining measurement reliability through the boot-like structure and force sensor system.
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 ergometer provides precise and reliable measurements of ankle joint forces, limiting the influence of other joint muscles and enabling accurate assessment of ankle strength, facilitating rehabilitation and orthostatic posture evaluation while being portable and easy to use.
Implementation Method 1
a force sensor interposed between said plate and said counter-support element, said sensor being configured to measure the force exerted by the foot on the support plate
Data Source
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AI summary
The present invention concerns an ankle ergometer (100) for measuring a force exerted on the ankle joint (C) of a user (U) by the muscles involved in the mobility of said ankle (C), said ergometer (100) comprising: - a first splint part (10) capable of receiving said lower member when the knee of said user (U) is extended, and comprising immobilisation means (11) configured to immobilise said lower member with the leg (J) extended, and - a second part (20) comprising: a) a main body (21) fixed to the first part (10), b) a counter-bearing element (22) rigidly connected to said main body (21), c) a rigid plate (23) forming a bearing surface for the lower surface of said foot, said rigid plate (23) being substantially static relative to said counter-bearing element (22), d) a force sensor (24) interposed between said plate (23) and said counter-bearing element (22), said plate (23) not being rigidly connected to said main body (21), in such a way that said sensor (24) is capable of measuring the force exerted on the bearing surface of the plate (23) by the muscles involved in the mobility of said ankle (C), said force being transmitted from the plate (23) to the counter-bearing element (22).