The OHand may be a relatively new bionic hand, but its advanced feature set and polished engineering suggest it will be a worthy competitor going forward.
What’s On This Page?
- A Quick Look at the OHand
- Grip Patterns & Control System
- Thumb Rotation
- Proportional Speed Control
- Auto Grip
- Sensory Feedback
- Wrist Design
- Lift Capacity & Grip Strength
- Water and Dust Resistance
- Glove Options
- User Software
- Suitability for Above-the-Elbow Solutions
- Clinical Insights
- User Feedback Survey & Results
- Considerations Before Buying an OHand
- Related Information
A Quick Look at the OHand
The following is a promotional video but it does a good job of showing the OHand being used for several tasks. We especially like the Chopstick grip!
This next video caught our eye because it shows the OHand doing something that can be difficult even with a natural hand. We’re particularly impressed by the confidence that the user shows by using his OHand to perform a task that requires both high precision (separating two layers of plastic isn’t easy) and responsiveness:
Grip Patterns & Control System
The OHand offers 27 different grip patterns, of which the user can select 18 grips for use through the setup software. This means 18 different patterns of digits closing (or not closing) to form a specific grip, such as these three examples:
However, as we point out for all bionic hands, having a large number of grip patterns isn’t particularly useful. The majority of people use only a few core grips for all tasks, so the more important measure is how well a hand performs these core grips.
There is also the question of how to switch between grips. This is answered by the following video:
For clarification, the 18 available grips are divided into 3 groups of 6 each based on 3 different thumb positions. When you manually rotate the thumb into one of these positions, you are effectively selecting its group of 6 possible grips. Each group is further divided into 2 subgroups: Primary and Secondary. You can toggle the desired subgroup by clicking the Multi-function Mode Switch Button on the back of the hand.
So, the longest possible grip switching process consists of the following theoretical sequence of events:
- Move the thumb into the desired position. This selects the corresponding group of six possible grips.
- Toggle the Mode Switch Button to select either the Primary or Secondary Mode. This selects the desired subset of three possible grips.
- Use a double-open signal to rotate through the three available grips until you have selected the desired grip.
In practice, the most commonly used grips are assigned to the Primary Mode for each thumb position. Therefore, the most frequent grip switching patterns are:
- If the thumb is already in the correct position, simply rotate through the three available options until you select the desired grip.
- Otherwise, change the thumb position, then rotate through the available grip options, if necessary.
Finally, every bionic hand requires some kind of sensor-based control system. OHand can use either a traditional 2-channel myoelectric control system or an 8-channel proprietary pattern recognition system. Everything stated in this section refers to using the 2-channel system.
The OHand requires manual thumb rotation. This is not as onerous as it sounds, as users can quickly and intuitively push the thumb into position with their free hand, another body part, or even a hard surface like a table top.
Proportional Speed Control
As with most other myoelectric hands, the OHand offers proportional speed control. This means that the hand will close with a speed and force that correlates to the strength of the muscle action used to trigger the close signal.
The OHand does not offer an auto-grip feature. However, it does offer a Grip Lock/Unlock feature, which allows users to lock a grip in place so that inadvertent open or close signals do not accidentally release the grip.
To our knowledge, the OHand does not provide any sensory feedback.
The OHand currently offers a single wrist option with passive rotation of up to 175 degrees in either direction. Unfortunately, this wrist is not compatible with the Quick Disconnect Wrist (QDW) design, so quickly swapping between the hand and popular Electric Terminal Devices (ETDs), such as powered hooks, is not possible. Users would instead need a completely separate socket for their ETD.
Lift Capacity & Grip Strength
The OHand can lift 30 kgs, which is about the same as the Zeus Hand. This puts it roughly in the upper-middle tier of the industry. The maximum load per finger is 6 kg.
We have not been able to identify the OHand’s maximum grip force, as OYMotion only measures the grip force from each fingertip. Unfortunately, there is no set standard for measuring grip force in the bionic hand industry, so it is difficult to compare brands on this metric.
The OHand uses a fold-away design for its four fingers. This helps prevent breakage if too much force is applied to the fingers. Also, the hand’s main material is an aluminum alloy combined with stainless steel for some of the smaller parts. OYMotion claims that this is much stronger than plastics and should last longer. Additionally, because the aluminum alloy is molded, this significantly lowers production costs, making replacement parts less expensive.
Still, in keeping with our policy for all bionic hands, we rely mainly on the results of our User Satisfaction Survey to measure durability, and since the OHand will not enter the U.S. market until 2022, we do not expect to have reliable durability data for this device until at least 2023, if not later.
Water and Dust Resistance
The OHand is not waterproof or dustproof. The hand should only be used in clean, dry environments.
OYMotion does not offer a glove for the OHand, nor is one mentioned in any of the hand’s documentation.
The OHand offers two battery options: an internal battery and a removable battery. The internal battery lasts for 12 hours of average use, while the removable battery lasts for 6 hours.
Once drained, the batteries require three hours to fully recharge.
The OHand comes with a user application called the OHand App, which runs only on the Android platform.
The software differs depending on whether it is for the 2-Channel or the 8-Channel hand, but both versions allow users to:
- monitor the battery charge level;
- adjust the myoelectric settings;
- obtain product and debug information; and
- adjust other general settings.
The main difference between the two versions is how myoelectric signals are processed and utilized by the user control system.
In the 2-Channel version, the myoelectric settings focus on direct control of explicit muscle signals:
To better understand 2-Channel control systems, please see Finding the Right Myoelectric Control System.
In the 8-Channel version, the myoelectric settings focus on mapping hand gestures made by users to patterns of muscle movement. These are in turn translated to specific grips and actions. For example, a pinch gesture can be translated to a) switching to one of the pinch grips, and b) closing the hand, all in one action.
To better understand pattern recognition systems, please see Myoelectric Pattern Recognition for Bionic Arms and Hands.
From our standpoint, the important point here is that the OHand comes with a modern and comprehensive software application to meet end-user needs.
Suitability for Above-the-Elbow Solutions
As a component hand, the OHand is suitable for both below-the-elbow and above-the-elbow solutions.
An above-the-elbow solution requires a compatible elbow. To date, OYMotion has only worked with traditional elbow providers in China, which we don’t yet cover. Therefore, we’ll return to update this section when either a) OYMotion tests compatibility with elbows sold in western countries that we do cover, or b) we expand our elbow coverage to include bionic elbows made and distributed in China.
According to our information, the OHand will sell for between $10,000 and $20,000 US for a typical below-the-elbow solution in the U.S. market, including all prosthetist fees, for their 2-Channel hand. Their 8-Channel hand will sell for between $20,000 and $30,000 US.
For a complete list of prices for other bionic hands, please see our Bionic Hand Price List.
Currently, OYMotion is selling the OHand mainly in China, though they have shipped trial samples to Canada, Egypt, Israel, and Russia.
They plan to enter the U.S. market in 2022.
OYMotion offers a two-year limited warranty against manufacturing or parts defects for the OHand. The warranty includes general maintenance for one year.
There does not appear to be an option to extend the warranty.
The following comments are from clinicians with extensive experience with the OHand:
User Feedback Survey & Results
Are you currently using the OHand or have you used it in the past?
If so, why not help others by sharing your experiences in this quick survey:
We do not yet have a sufficient number of survey participants to publish fair and accurate results for the OHand.
As soon as we do, we’ll update this section.
Considerations Before Buying an OHand
It is difficult for us to provide much guidance on the OHand at this point, mainly because we don’t yet have enough independent user feedback.
What we will say is that we are deeply impressed by the completeness of OYMotion’s offering. Their feature set for the OHand is thorough and well-designed. And while they haven’t quite worked out all the elements of online product presentation, the core technical elements for the hand itself seem sound. Additionally, OYMotion is not a basement startup. They not only build the OHand but also several myoelectric sensor products and a bionic arm brace for rehabilitation, all of which seem highly professional.
In short, we think we’re going to see more of this company in the years ahead.
For a list of competitor devices, see All Bionic Hands.
For a comprehensive description of all current upper-limb technologies, devices, and research, see our complete guide.
If you are shopping for a bionic hand, do not miss our article on Bionic Arm & Hand Control Systems. Getting this part of your bionic system right is probably the biggest single ingredient in your long-term satisfaction.
Click here for more information on OYMotion.