Mand.ro Hand Mark 7
Introduction
Mand.ro Hand Mark 7 is a robotic prosthetic hand designed for people with upper-limb disabilities. It consists of 5 fingers, and each finger operates with a new micro (10mm) brushless DC motor with embedded sensors and a reducer, making it suitable for both partial hand and most upper-limb amputees.
The beauty of this product lies not only in its robust (long-lasting) individual finger design, which ensures a longer lifetime thanks to the brushless DC motor, but also in its significantly (10-times) lower cost compared to existing solutions in the market. As a result, it will be much more affordable for amputees.
As of July 2023, we have tested our Mark 7 hands with 10+ actual upper-limb amputees as part of clinical trials, and we will be ready to ship this hand as a finished product by the end of the year 2023 (early 2024) in most countries.
Engineering :
Self-contained Robotic Finger with a motor, sensor, reducer, control board, mechanical structure, flexible cable, and a customizable design to meet different user requirements.
1. On-demand, customizable brushless DC motor: We utilize a spiral coil structure with a flexible substrate like an FPCB, making it very easy to redesign and produce on-demand.
2. Sensor and micro control board: We employ multiple hall-effect sensors and a micro-scale (24mm x 8mm x 1.2mm) control board for the brushless DC motor, positioned right next to the motor (inside the finger). This enables precise and extremely low-latency control for its movement and stall-torque.
3. Customizable two-stage reducers for the entire finger structure: We have divided the reducers into two stages within the finger unit, allowing better utilization of the limited space within each finger. Additionally, it facilitates easier customization of the reduction ratio, which significantly affects the force and speed of the fingers.
4. Customizable finger design for various cases: Thanks to the features mentioned above (motor, reducers), we can customize the length and shape of each finger, accommodating different requirements from actual amputees."
Design :
Mand.ro Hand Mark 7 introduces a "customizable and anatomically correct design" for finger phalanges through its engineered design approach.
Typically, a reduction ratio of 2000:1 ~ 4000:1 is required to achieve sufficient finger-tip force (approximately 1~2kgf.cm) from a micro brushless (or brushed) DC motor. However, reducing this ratio in one stage would impact the finger phalanges' proportions due to the volume and length of the reducer.
To address this issue, we divided the reducers into two-stage trains, allowing for optimal space utilization within the finger phalanges.
The first stage is assembled together with a motor and is positioned between the finger-tip and PIP joint. It functions with fast, lower force reduction and efficiently transmits force and speed to the second stage reducer.
The second stage is situated between the PIP and MCP joint, operating with slow but high force, generating significant force for the entire finger movement.
The first stage reducer can be customized using 10mm planetary reducers available in the market, while the second stage reducer can be reconfigured based on specific length and shape requirements.
The result is a highly adaptable robotic hand that takes into account the anatomical needs of each user. By employing a two-stage reducer system, Mand.ro Hand Mark 7 ensures optimal performance and user comfort.
Innovation:
Mand.ro Hand Mark 7 will significantly improve the lives of most upper-limb amputees, including those with partial hand amputations.
In many countries, partial hand amputations are the most common cases. For instance, in South Korea, 84.2% of the 147,000 upper-limb amputees surveyed in 2017 had partial-hand amputations, according to a report from the Ministry of Health.
Regrettably, existing solutions in the market for partial hand amputees are extremely expensive due to their complexity and technical difficulty. A single finger assembly unit costs approximately USD 10,000, while a myoelectric prosthetic hand with four fingers ranges from USD 40,000 to USD 70,000, making it unaffordable for many amputees.
In response to this challenge, we initiated this project in late 2020 to create an affordable solution. Our robotic finger prosthesis features a better anatomical design and will be available at just 5-10% of the cost of legacy solutions in the market. Our robotic finger unit will be priced between USD 500 and USD 1,000, significantly improving affordability for most upper-limb amputees.