(257 days)
SOLO+, SOLO and SERVO turn a manually propelled wheelchair into a powered wheelchair. They are intended for medical purposes to provide a means for a disabled person to take over the propulsion of the wheelchair and increase mobility and flexibility.
The subject devices SOLO, SOLO+ and SERVO are power-wheelchair-conversion-kits that add powered propulsion to a manual wheelchair, thereby, turning a manual wheelchair into a powered wheelchair. They consist of two powered wheels (each incorporating an electrical motor) a control unit with its bracket and a battery pack. A battery charger and a bag for the battery pack are included in the delivery as well. The powered wheels substitute the conventional manual wheels from selected wheelchairs. The battery-pack and the controller-unit can easily be attached to the wheelchair. Speed, acceleration and deceleration are microprocessor-controlled. A preselection of the maximum speed can be done with buttons on the control unit. The wheelchair will accelerate or drive with steady speed when the joystick (SOLO and SOLO+) or the hand-rims (SERVO) are pushed into the travel-direction. The motors will steadily reduce the driving force until the wheelchair stops if no driving-signal (deflection of the joystick or the rim) is provided. The safety-brakes lock automatically when the wheelchair stopped (SOLO, SOLO+). The manual parking brakes can also be used to prevent unintended movement. After ten minutes of non-use the device turns off automatically. The powered wheels can be disengaged if the user wants to drive with manual propulsion, only.
The provided document describes the Food and Drug Administration's (FDA) substantial equivalence determination for the AAT Alber Antriebstechnik GmbH's SOLO+, SOLO, and SERVO powered wheelchair conversion kits (K142770). It specifies the devices, their intended use, and a comparison to a predicate device. The document details the non-clinical tests performed to demonstrate substantial equivalence to legally marketed predicate devices, focusing on various ISO standards.
Here's an analysis of the acceptance criteria and study data based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly present a table of "acceptance criteria" with specific pass/fail values. Instead, it refers to performing non-clinical tests according to recognized standards. The "reported device performance" is generally stated as meeting these standards or being similar to the predicate device, implying compliance with the standards' requirements.
However, a comparison table and a discussion of differences between the subject device (SOLO / SOLO+ / SERVO) and the predicate device (e-motion, K003449) are provided, which indirectly indicate performance attributes.
| Feature | Predicate device (e-motion K003449) | Subject devices (SOLO / SOLO+ / SERVO) | Discussion and Indication of Performance |
|---|---|---|---|
| Technical Data | |||
| Wheels | 22" / 24" | 24" | "The subject and the predicate devices are available with 24-inch wheels. The predicate device is also available with smaller 22-inch wheels... However, the wheel-size has no influence on the safety of the powered propulsion." (Indicates safety equivalence despite size difference). |
| Weight | 22 kg | 22.9kg / 22.9kg / 24.8kg | "The weight differences occur from design details. The subject devices are able to carry a higher max. load while the basic material is the same. Therefore, the design is reinforced, more rigged and consequently a bit heavier. The weight differences have no negative influence on the safety of the subject devices." (Implies safety performance is maintained despite weight difference). |
| Max. user weight | 130 kg | 160kg / 200kg / 150kg | "The subject devices are designed to carry a higher user-weight. This is actually an advantage. It lowers the risk of unintended overloading the wheelchair. All mechanical and driving characteristics are well approved to ensure a safe use under the max. load. The differences have no negative influence on the safety." (Improved performance in terms of max load, safety maintained). |
| Total weight approved | 180 kg | 210kg / 250kg / 200kg | "The total weight of the subject devices is consequently higher because of the higher product-weight and max. user-weight. The differences have no negative influence on the safety." (Safety maintained despite higher total weight). |
| Braking technologies | Electro-magnetic spring loaded drum brakes. | Electro-magnetic spring loaded drum brakes. | "same" (Equivalent performance). Non-clinical tests were performed according to ISO 7176-3: Determination of effectiveness of brakes. (Indicates meeting this standard). |
| Speed, acceleration, deceleration | Preselected max-speed, microprocessor-controlled speed, acceleration and deceleration. | Preselected max-speed, microprocessor-controlled speed, acceleration and deceleration. The user controls these parameter with the joystick or rim-propulsion. | "same" (Equivalent performance). Non-clinical tests were performed according to ISO 7176-6: Determination of maximum speed, acceleration and deceleration of electric wheelchairs. (Indicates meeting this standard). |
| User Interface | same as SERVO | Joystick (SOLO, SOLO+) / rim with hall-sensor (SERVO) | "The SOLO and SOLO+ have a Joystick to steer the wheelchair... This opportunity has no negative influence on the safety of the device. It expands the range of users." (Indicates safety maintained, expanded usability). |
| Driving force | Approx. 10N to push or pull the joystick or rim. | Approx. 10N to push or pull the joystick or rim. Rim-sensor-sensitivity is adjustable. | "same as SERVO" (Equivalent performance). |
| Forward/backward movement | same as SERVO | Joystick (SOLO, SOLO+)/ rim with hall-sensor (SERVO) | "same as SERVO" (Equivalent performance). |
| Locks to prevent unintended movement | manual parking brake (SERVO) | manual parking brake (SERVO); SOLO, SOLO+ have an electro-magnetic spring loaded drum brakes in addition | "same as SERVO" plus additional brakes on SOLO/SOLO+ (Potentially improved safety/redundancy, but not explicitly stated as an "acceptance criteria" improvement over predicate in this section). Performance implicitly meets ISO 7176-3. |
| Foldable wheelchair still foldable? | Foldable, after detaching the battery | Foldable, after detaching the battery | "same" (Equivalent performance). |
| Performance | |||
| Range (ISO 7176-14) | up to 15.5 mil | up to 22mil / 9.3mil / 34mil | "The theoretical driving distance from our subject devices differ from the predicate device because of different weight capacities and the possibility to choose different batteries. This difference has no influence on the safety of the devices. It only has an influence on the comfort of the devices." (Performance difference, but safety maintained). Non-clinical tests according to ISO 7176-4: Energy consumption of electric wheelchairs... for determination of theoretical distance. |
| Speed: forward/backward | 3.8 mil/h / 1.9 mil/h | 3.8 mil/h / 1.9 mil/h | "same" (Equivalent performance). Non-clinical tests were performed according to ISO 7176-6. |
| Electrical data | |||
| battery | 25.2V, 6.0 Ah (Li-Ion) | 28.8V, 16Ah (Pb) / 24V, 8.5 Ah (Li-Ion) | "The user of the SOLO, SOLO+ and SERVO can choose between Pb-batteries and Li-lon batteries... The differences have no influence on the safety of the devices." and "Both battery types are approved and have their advantages." (Different options, safety maintained). Non-clinical tests according to ISO 7176-14. |
| motor | 25.2V; DC; 60W | 24-28.8V; DC, 150W/70W (microprocessor controlled adaption to the power source (PB or LI-Ion)) | "While the material and design is similar, the electrical data differ. The motor-characteristics may have little influence on driving characteristics but they don't result it any safety differences." (Different characteristics, but no safety impact). Non-clinical tests according to ISO 7176-14. |
Acceptance Criteria (Implied by Standards Met):
The device is deemed to meet acceptance criteria by conforming to the following recognized standards:
- Static stability: ISO 7176-1: Determination of static stability.
- Dynamic stability: ISO 7176-2: Determination of dynamic stability.
- Brake effectiveness: ISO 7176-3: Determination of effectiveness of brakes.
- Power system effectiveness (range): ISO 7176-4: Energy consumption of electric wheelchairs and scooters for determination of theoretical distance.
- Speed, acceleration, deceleration: ISO 7176-6: Determination of maximum speed, acceleration and deceleration of electric wheelchairs.
- Measurement comparability: ISO 7176-7 and ANSI / RESNA WC-1:2009 section 7: method of measurement of seating and wheel dimensions.
- Mechanical strength and durability: ISO 7176-8 Wheelchairs - Part 8: Requirements and test methods for static, impact and fatigue strengths.
- Climatic tests: ISO 7176-9 Wheelchairs - Part 9: Climatic tests for electric wheelchairs.
- Load tests comparability: ISO 7176-11 Wheelchairs - Part 11: Test Dummies.
- Driving and braking tests comparability: ISO 7176-13 Wheelchairs – Part 13 Determination Of Coefficient Of Friction Of Test Surfaces.
- Electrical safety, software-validation and performance: ISO 7176-14 Wheelchairs - Part 14: Power and control systems for electrically powered wheelchairs and scooters -Requirements and test methods.
- Electromagnetic compatibility: ANSI/RESNA wc/ vol.2 and ISO 7176-21 Wheelchairs - Part 21: Requirements and test methods for electromagnetic compatibility of electrically powered wheelchairs and scooters, and battery chargers.
- Biocompatibility: ISO 10993-5: Biological evaluation of medical devices – Part 5: Tests for in vitro cytotoxicity.
The document states that the devices are "as safe, as effective and perform as well as the predicate device" based on these non-clinical tests, implying that the performance meets the necessary standards for substantial equivalence.
2. Sample size used for the test set and the data provenance
The document explicitly states that non-clinical tests were performed. These types of tests typically involve testing the physical devices themselves (e.g., a sample of the SOLO, SOLO+, and SERVO models) under controlled laboratory conditions, rather than a "test set" of patient data as might be relevant for AI or diagnostic devices.
The document does not specify the sample size for the devices tested (e.g., number of units of each model).
The data provenance is not explicitly stated as country of origin or retrospective/prospective. However, given that it's a submission to the U.S. FDA by AAT Alber Antriebstechnik GmbH (Germany-based company), the tests were likely performed either in Germany or by a certified testing facility relevant to international standards (ISO). The testing is prospective in the sense that the tests were conducted for the purpose of this submission to demonstrate compliance and substantial equivalence before commercial distribution. It is not retrospective data from real-world usage.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
This information is not applicable to this type of device and submission. The tests performed are non-clinical, mechanical, electrical, and materials-based assessments against recognized engineering and medical device standards (ISO). There is no "ground truth" derived from expert interpretation of clinical data in the way one would for an AI diagnostic device. The "ground truth" here is the physical performance of the device measured against the established parameters and limits of the ISO standards.
4. Adjudication method for the test set
This information is not applicable for the same reasons as point 3. "Adjudication" typically refers to resolving discrepancies in expert interpretations or clinical outcomes. In non-clinical engineering tests, the results are quantitative measurements against predefined criteria in the standards.
5. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
This information is not applicable. An MRMC study is relevant for diagnostic devices, particularly those involving human interpretation (e.g., radiologists reading images) where AI assistance might improve their performance. The SOLO+, SOLO, and SERVO are powered mobility devices, not diagnostic or AI-powered devices, and therefore an MRMC study would be irrelevant.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
This information is not applicable. These devices are not AI algorithms. They are electromechanical devices with microprocessors controlling speed, acceleration, and deceleration, but this is embedded control logic, not a "standalone algorithm" in the context of an AI device. The phrase "algorithm only without human-in-the-loop performance" specifically refers to AI models making decisions independently, which is not what these devices do. They assist a human user in propelling a wheelchair.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)
As discussed in point 3, for these non-clinical tests, the "ground truth" is established by the definitions and quantitative limits within the referenced ISO and ANSI/RESNA standards. For example:
- For static stability (ISO 7176-1), the ground truth is whether the device remains stable at specified angles.
- For brake effectiveness (ISO 7176-3), the ground truth is whether the brakes can stop the device within specified distances or hold it on a specified incline.
- For biocompatibility (ISO 10993-5), the ground truth is the chemical and biological response of materials.
There is no expert consensus on clinical findings, pathology, or outcomes data involved in these specific tests for this device.
8. The sample size for the training set
This information is not applicable. These are not machine learning or AI devices that require a "training set" of data.
9. How the ground truth for the training set was established
This information is not applicable as there is no training set.
§ 890.3860 Powered wheelchair.
(a)
Identification. A powered wheelchair is a battery-operated device with wheels that is intended for medical purposes to provide mobility to persons restricted to a sitting position.(b)
Classification. Class II (performance standards).