Application Cases

Experiment Name: Safety Study of Tactile Feedback Wearable Hand Device

Research Direction: Aiming at the demand for haptic feedback devices in virtual reality technology, a haptic feedback wearable hand device based on electrostatic adhesion is proposed. The flexible electrodes inside the device make it lightweight, portable, and capable of providing both rigid and elastic force feedback effects.

Experiment Purpose: To build a high-resolution electrospinning 3D printing experimental platform, initially verify the correctness of the theory and numerical simulation on glass slides, and then study the impact of different process parameters (voltage, air pressure, printing speed) on the forming performance of printed silver nanowire conductive ink on PET films.

Testing Equipment: Data acquisition card, high-voltage amplifier, distance sensor, force sensor, material testing machine, etc.

Figure: Schematic Diagram of Control Method

Experiment Process:

The safety of the device mainly refers to its electrical safety. The power source used by the device is the ATA-7015 high-voltage amplifier, which receives input signals from the output end of the data acquisition card. The electrostatic adhesion brake acts as a capacitor during operation. Since the working area of the electrostatic adhesion brake remains constant, the current throughout the entire working process is zero. When using the device, the user wears a thin insulating glove, providing secondary protection for the hand. During the charging and discharging moments, the charging and discharging of the capacitor cause current in the circuit. This paper tests the relationship between current, voltage, and time at the moment of turning on and off the voltage of the electrostatic adhesion brake. The relationship between voltage, current, and time at the moment of turning on the voltage is shown in Figure 2, and the relationship at the moment of turning off the voltage is shown in Figure 3. The test results show that the charging current is 5 mA and the discharging current is 6 mA at a voltage of 300 V. Research has shown that currents below 6 mA can cause pain but do not cause harm to the human body. Even if the insulating glove is damaged, this current is within the safe range that the human body can withstand. Assuming that the electrostatic adhesion brake is punctured and the insulating glove is damaged, the power supply device in this paper has a short-circuit protection function, which will immediately reduce the voltage to 0. In summary, the working current of the capacitor itself is zero, and the protection of the insulating glove and the short-circuit protection of the power supply ensure the safety of the device through these three layers of protection.

Figure 2: Voltage and Current Changes at the Moment of Turning On the Voltage

From Figure 2, it can be seen that the electrostatic adhesion brake acts as a parallel plate capacitor at the moment the external voltage is turned on. During the voltage turn-on, the capacitor is in the charging process, with a charging time of about 1.2 ms. However, the response time of the electrostatic adhesion brake measured in this paper is about 40 ms. The large gap between the capacitor charging time and the electrostatic adhesion brake adsorption response time is due to the need to expel internal air to achieve a fully adsorbed state at the moment the electrostatic adhesion brake is turned on, which results in a brief response time for electrostatic adhesion at the moment the voltage is turned on.

Figure 3: Voltage and Current Changes at the Moment of Turning Off the Voltage

From Figure 3, it can be seen that the response time of the capacitor formed by electrostatic adhesion during discharge is 1.5 ms, while the release response time of the electrostatic adhesion brake is about 40 ms. This is because after the voltage is removed, there are van der Waals forces and residual charges between the electrostatic adhesion film electrodes, which means that the release of the electrostatic adhesion brake also requires a certain response time. However, both the turn-on and release response times are 40 ms, which does not affect the authenticity of the feedback force effect simulated by electrostatic adhesion.

Experimental Results:

The safety of the haptic feedback wearable device is demonstrated from the working principle of the electrostatic adhesion brake. The device also provides multiple protections through insulating gloves and short-circuit protection of the power supply to ensure the safety of the user.

Figure: Specification Parameters of the ATA-7015 High-Voltage Amplifier