CN101305939B - An electric stimulator for sensory feedback of humanoid myoelectric prosthetic hand - Google Patents

Abstract

An electrical stimulator for sensory feedback of a humanoid myoelectric prosthetic hand, which is a sensory feedback stimulation device for the electrical control system of a myoelectric prosthetic hand, to solve the problem of poor accuracy and versatility of sensory sensory feedback and time delay Longer, indistinguishable stimulus intensity questions. The power terminal and inductor of the main control chip of the power module are connected to the power supply, the inductor and the rectifier diode are connected to the driving terminal of the main control chip of the power module, and the first and second configuration resistors are connected to the driving terminal of the main control chip of the power module. Both the first configuration resistor and the rectifier diode are connected to the drive terminal of the stimulation drive circuit; the power supply terminal of the main control chip of the stimulation drive circuit is connected to the power supply terminal of the power module circuit, and the output terminal of the frequency signal generation circuit is connected to the main control chip of the stimulation drive circuit. The signal terminal is connected, the detection resistor is connected to the detection terminal of the main control chip of the stimulation driving circuit and the power ground, and the off-time configuration circuit is connected to the shutdown control terminal of the main control chip of the stimulation driving circuit and the power ground.

Description

An electric stimulator for sensory feedback of humanoid myoelectric prosthetic hand

technical field

The invention relates to a sensory feedback electrical stimulation device for a multi-degree-of-freedom myoelectric prosthetic hand electrical control system, belonging to the technical field of Biomechatronics.

Background technique

Research on prosthetic hands is very important for disabled people to carry out daily life and better integrate into society. In recent years, the number of physically disabled people caused by work-related injuries and car accidents has been increasing year by year. Data from the Second National Survey on Disabled Persons shows that in the nearly 20 years from 1987 to 2006, the number of disabled people in my country has increased from 51.64 million to 82.96 million, while the number of physically disabled people has increased from more than 8 million to the present. 24.12 million, has become the largest group of disabled people in my country, accounting for 29.07% of the total number of disabled people. People with physical disabilities also need to be well integrated into society, so countries around the world have conducted targeted research, including the development and application of prosthetic hands for physically disabled people.

A prosthetic hand should have the same shape and size as a human hand, be light in weight, and have the functions of grasping and dexterous manipulation, thereby functionally replacing a human hand. However, most of the more mature commercial prosthetic hands on the market are single-degree-of-freedom. In recent years, multi-freedom prosthetic hands with multiple fingers and joints have become a relatively active research direction. In the field of multi-freedom prosthetic hand research, more attention is paid to the prosthetic hand based on the principle of underactuation. This design reduces the weight of the fingers and increases the grip stability. However, in the training and daily use of prosthetic hand wearers, it is found that people with physical disabilities cannot feel the prosthetic hand well. In some prosthetic hands equipped with tactile sensors, users have improved sensory awareness, but due to time delays, objects often fall, etc., and this tactile sensation is fed back to the processor, not the disabled's own nervous system . In order to allow the wearer to use the prosthetic hand better, it is necessary to carry out research and application of sensory feedback, so that it can truly produce the feeling of "phantom limb". The so-called sensory feedback means that after training, the mechanical grasping force of the prosthetic hand corresponds to the stimulation intensity of the system equipment on the human skin, so that the wearer can better perceive the feeling similar to the real hand and avoid false actions or errors. At present, there is no mature sensory feedback system applied to prosthetic hands on the market.

Ordinary prosthetic hands do not have the same sense of force, temperature, sliding, etc. as normal hands, and without the help of vision, they cannot even perceive the relative position of the prosthetic hand and the body. Research institutions at home and abroad often distribute some sensors on the palm and fingers for sensory feedback in the research of prosthetic hands. However, the technology of this mode is complicated, the reliability is poor, and there is also delay. The feedback systems are self-designed and cannot be used interchangeably with each other.

Contents of the invention

In order to solve the problems of poor sensory feedback accuracy, time delay, inability to distinguish stimulation intensity and poor versatility in the myoelectric prosthetic hand using sensors as sensory feedback, the present invention proposes a humanoid myoelectric prosthetic hand Electrical stimulators for sensory feedback. The present invention is composed of a power supply module circuit and a stimulation drive circuit. The drive power output end of the power supply module circuit is connected to the drive power input end of the stimulation drive circuit. The power supply module circuit includes: an inductor, a rectifier diode, a first configuration resistor, a second configuration The resistance and the main control chip of the power module, the power input end of the main control chip of the power module and the first end of the inductor are connected to the 7.2V power supply, the second end of the inductor and the anode of the rectifier diode are connected to the driving power of the main control chip of the power module The input end is connected, the first end of the first configuration resistor and the first end of the second configuration resistor are connected to the drive power output end of the main control chip of the power module, and the second end of the first configuration resistor and the cathode of the rectifier diode are connected to each other. The driving power input terminal of the stimulating drive circuit is connected; the stimulating driving circuit includes an off-time configuration circuit, a detection resistor, a frequency signal generating circuit and a main control chip of the stimulating driving circuit, and the driving power input terminal of the main controlling chip of the stimulating driving circuit is connected to the power supply. The power supply output terminal of the module circuit is connected, the signal output terminal of the frequency signal generation circuit is connected with the PWM signal input terminal of the main control chip of the stimulation drive circuit, and the two ends of the detection resistor are connected with the detection power output terminal of the main control chip of the stimulation drive circuit and the power supply respectively. The two ends of the off-time configuration circuit are respectively connected to the off-time control terminal of the main control chip of the stimulation driving circuit and the power ground.

Beneficial effects: the electric stimulator of the present invention is simple and reliable, and the driving electrodes work stably after being activated. The delay of the humanoid myoelectric prosthetic hand is about 50ms, and the user will not feel the delay, and the wearer of the humanoid myoelectric prosthetic hand will not feel the delay after training. According to the stimulation degree of the electric stimulator electrodes on the skin surface, six levels of stimulation levels with different intensities can be distinguished, which can be used to correspond to the six levels of grasping force of the prosthetic hand, so as to reduce the misoperation of the humanoid myoelectric prosthetic hand , the six levels of intensity can also be easily changed in the software program, so it has good versatility for wearers of prosthetic hands with different sensitivities; in addition, the maximum operating voltage of the electric stimulation circuit is the human body safety voltage lower than 36V, After the electrodes are placed on the skin, the stimulation current flowing through the human skin under normal operation is 8mA, which will not cause harm to the human body.

Description of drawings

Fig. 1 is a schematic diagram of the circuit structure of the present invention; Fig. 2 is a schematic diagram of the structure of the present invention working in an electrical control system.

Detailed ways

Specific embodiment one: Referring to Fig. 1 and Fig. 2, the electric stimulator 7 for sensory feedback of the present embodiment is made up of power supply module circuit A and stimulation driving circuit B, and the driving power output end of power supply module circuit A is connected to stimulation driving circuit B Drive power input terminal, power module circuit A includes: inductor L5, rectifier diode D1, first configuration resistor R59, second configuration resistor R63 and power module main control chip 7-1, power input of power module main control chip 7-1 end and the first end of the inductance L5 are connected to the 7.2V power supply, the second end of the inductance L5 and the anode of the rectifier diode D1 are connected to the drive power input end of the main control chip 7-1 of the power module, and the first configuration resistor R59 Both the first end and the first end of the second configuration resistor R63 are connected to the drive power output end of the main control chip 7-1 of the power module, and the second end of the first configuration resistor R59 and the cathode of the rectifier diode D1 are connected to the stimulation drive circuit The drive power input terminal of B is connected; the stimulation drive circuit B includes an off-time configuration circuit RC, a detection resistor R64, a frequency signal generation circuit PWM and a stimulation drive circuit main control chip 7-2, and the stimulation drive circuit main control chip 7-2 The drive power input terminal is connected to the power output terminal of the power module circuit A, the signal output terminal of the frequency signal generation circuit PWM is connected to the PWM signal input terminal of the main control chip 7-2 of the stimulation drive circuit, and the two ends of the detection resistor R64 are respectively connected to the stimulus The detection power output terminal of the main control chip 7-2 of the driving circuit is connected to the power ground, and the two ends of the off-time configuration circuit RC are respectively connected to the off-time control terminal of the main control chip 7-2 of the stimulation driving circuit and the power ground.

The main control chip 7-1 of the power module in this embodiment can adopt the LM2577 chip, and the packaging form is 5Lead TO-263, which is a mature DC-DC voltage regulator chip produced by National Semiconductor; the main control chip of the stimulation drive circuit Chip 7-2 can use LMD18245 chip, the package form is 15Lead TO-220, and it is also a product of National Semiconductor. It is a DMOS full-bridge driver chip with a maximum withstand current of 3A and a maximum withstand voltage of 55V. It integrates over-current protection inside. It is relatively safe and reliable to use. The 7.2V inlet voltage of the power module circuit A is provided by two lithium-ion polymer batteries, which can be filtered by capacitor C31 (0.1uF, the two ends of capacitor C31 are respectively connected to the 7.2V power supply and the power ground) and then enter the 5 pin of the LM2577 chip At the same time, the filtered voltage is connected to pin 4 of the LM2577 chip (that is, the collector terminal of the NPN transistor inside the LM2577 chip) through the inductor L5, which is used as the switching voltage of the main control chip 7-1 of the power module; pin 4 of the LM2577 chip is then passed through Fast recovery rectifier diode D1 (IN4934) and electrolytic capacitor C32 (1000uF/70V/1206), under the action of the first configuration resistor R59 (100K) and the second configuration resistor R63 (4K), configure the stimulus drive circuit B. 30~33V DC voltage, the calculation formula is V _out = 1.23×(R59/R63+1), in addition, the third configuration resistor R58 (2.4K) and configuration capacitor C30 (4.7uF) can be added, the third configuration resistor R58 The first terminal of the third configuration resistor R58 is connected to the first configuration power supply terminal of the main control chip 7-1 of the power module, the second terminal of the third configuration resistor R58 is connected to the first terminal of the configuration capacitor C30, and the second terminal of the configuration capacitor C30 is connected to the power module The second configuration power terminal connection of the main control chip 7-1 can be freely configured according to the required output voltage by referring to the data sheet of the LM2577 chip; Eliminate the surge current on the drive power line, and then eliminate the pulse voltage on the drive power line through the ceramic capacitor C33 (1uF) (the two ends of the aluminum electrolytic capacitor C35 are respectively connected to the power output terminal of the power module circuit A and the power ground, The two ends of the ceramic capacitor C33 are respectively connected to the power supply output terminal of the power supply module circuit A and the power ground), and then connected to the 9 pins of the LMD18245 chip of the stimulation drive circuit B, as the driving voltage of the part circuit of the stimulation drive circuit B, the LMD18245 chip 14 pins, 4, 6, 7, and 8 pins are all connected to 3.3V digital voltage. This input voltage comes from the main DSP circuit 1 of the humanoid myoelectric prosthetic hand electrical control system, of which 14 pins provide reference voltage for the LMD18245 chip, and 4 , 6, 7, and 8 pins are used to configure the maximum current threshold value of the load that can be driven on the drive bridge (in this embodiment, these four pins are all pulled high, so that there is a larger drive current output at a lower voltage); The 10-pin of the LMD18245 chip is grounded (the emergency braking function is not used, and it can be set according to the actual application), and the off-time configuration circuit RC (composed of RC resistor R65 and RC capacitor C36) is connected to the 3-pin of the LMD18245 chip. It is used to configure the turn-off time of the H-bridge inside the chip. The calculation formula is T _off-on = 1.1RC. The detection resistor R64 connected in series between pin 13 of the LMD18245 chip and the ground is used to obtain the voltage signal for current detection as an internal current ratio The input of the comparator is compared with the converted output analog signal, and then the PWM (pulse width modulation) signal is obtained through the monostable state, and the output current of the H-bridge circuit is controlled by chopping.

The electrical stimulator for sensory feedback of the present embodiment is arranged on a main DSP circuit 1, a buzzer circuit 2, a power management circuit 3, a temperature sensor 4, an EMG channel circuit 5, a vibration motor circuit 6, an electric stimulation circuit 7, and a bluetooth circuit. 8. From the electrical control system of the humanoid myoelectric prosthetic hand (see Fig. 2) that DSP circuit 9, a plurality of torque sensors 10, CPLD circuit 11, a plurality of motor drive circuits 12 and a plurality of motors M form, when the humanoid After the type myoelectric prosthetic hand starts to work, the myoelectric electrode picks up the myoelectric signal of the wearer of the prosthetic hand. After the signal is processed, it is sent to the main DSP circuit 1 for classification and identification. The continuous movement of the prosthetic hand body, the force and torque sensors detect the grasping force of the prosthetic hand in real time and return it to the main DSP circuit 1, the main DSP circuit 1 selects the electric stimulation intensity according to the force, and then controls the slave DSP circuit 9 to drive the electric stimulation circuit 7 , the electrical stimulation circuit 7 provides corresponding stimulation intensity according to the instruction, and applies the corresponding electrical stimulation sensation to the skin of the human body through the stimulation electrodes. In this embodiment, the prosthetic hand itself does not have a sensing function through the sensor, but the information of the grasping force of the prosthetic hand is fed back to the brain of the wearer of the prosthetic hand by means of the electric stimulation circuit 7, so that after a period of training, the grasping force of the prosthetic hand can be established. Corresponding relationship between force condition and electrical stimulation intensity. Using an electric stimulator to convert the grasping force of the prosthetic hand into skin stimulation caused by electric current that feels comfortable to the human body. Since the entire skin surface has sensory nerves, sensory information can be fed back to the brain without being directly connected to the nerves. According to the stimulation degree of the electric stimulator electrodes on the skin surface, six levels of stimulation levels with different intensities can be distinguished, which can be used to correspond to the six levels of grasping force of the prosthetic hand, so as to reduce the misoperation of the humanoid myoelectric prosthetic hand , the six-level intensity setting of the electric stimulator is realized by the frequency of current stimulation and the duty cycle of PWM wave, see the table below for details:

Stimulus level one two three Four five six Stimulation frequency Hz (duty cycle) 2 (0.46%) 10 (2.3%) 20 (4.6%) 40 (9.2%) 80 (18.4%) 400 (92%)

Claims (4)

1. An electric stimulator for sensory feedback of humanoid myoelectric prosthetic hand is characterized in that it is made up of power module circuit (A) and stimulation driving circuit (B), and the driving power output terminal of power module circuit (A) Connect the drive power input end of the stimulation drive circuit (B), the power module circuit (A) includes: an inductor (L5), a rectifier diode (D1), a first configuration resistor (R59), a second configuration resistor (R63) and The main control chip (7-1) of the power module, the power input terminal of the main control chip (7-1) of the power module and the first end of the inductor (L5) are connected to the 7.2V power supply, and the second end of the inductor (L5) is connected to the The anodes of the rectifier diodes (D1) are all connected to the drive power input terminals of the main control chip (7-1) of the power module, and the first ends of the first configuration resistor (R59) and the second configuration resistor (R63) are connected to each other. Connect with the drive power output end of the main control chip (7-1) of the power module, the second end of the first configuration resistor (R59) and the cathode of the rectifier diode (D1) are connected with the drive power input end of the stimulation drive circuit (B) Connect; the stimulation drive circuit (B) includes an off-time configuration circuit (RC), a detection resistor (R64), a frequency signal generation circuit and a stimulation drive circuit main control chip (7-2), and the stimulation drive circuit main control chip (7-2) 7-2) the driving power input end is connected with the power output end of the power supply module circuit (A), the signal output end of the frequency signal generation circuit is connected with the PWM signal input end of the main control chip (7-2) of the stimulation drive circuit, and the detection The two ends of the resistance (R64) are respectively connected to the detection power output terminal and the power ground of the main control chip (7-2) of the stimulation drive circuit, and the two ends of the off-time configuration circuit (RC) are connected to the main control chip (7-2) of the stimulation drive circuit respectively. 7-2) The off-time control terminal is connected to the power ground. 2. A kind of electric stimulator for sensory feedback of humanoid myoelectric prosthetic hand according to claim 1, it is characterized in that described power supply module circuit (A) also comprises electric capacity (C31), two electric stimulators of electric capacity (C31) The terminals are respectively connected to the 7.2V power supply and the power supply ground. 3. A kind of electrical stimulator for sensory feedback of humanoid myoelectric prosthetic hand according to claim 1, it is characterized in that described power supply module circuit (A) also comprises the 3rd configuration resistance (R58) and configuration capacitance ( C30), the first end of the third configuration resistor (R58) is connected to the first configuration power supply end of the main control chip (7-1) of the power module, and the second end of the third configuration resistor (R58) is connected to the configuration capacitor (C30) The first end of the configuration capacitor (C30) is connected to the second end of the configuration capacitor (C30) and the second configuration power supply end of the main control chip (7-1) of the power module. 4. A kind of electrical stimulator for sensory feedback of humanoid myoelectric prosthetic hand according to claim 1, is characterized in that described stimulation driving circuit (B) also comprises aluminum electrolytic capacitor (C35) and ceramic capacitor (C33 ), the aluminum electrolytic capacitor (C35) and the ceramic capacitor (C33) are first connected in parallel and then both ends are respectively connected to the power output terminal of the power module circuit (A) and the power ground.

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