CN113093948B - Flexible touch type mobile robot operation input device and interaction method - Google Patents

Abstract

The invention discloses an operation input device of a flexible touch type mobile robot, and provides a stroke type interaction input method, and a method for decoding an array type force touch signal under stroke type interaction is provided, so that vector speed input of the mobile robot is obtained to control movement of the robot. The mobile touch type operation input device is an organosilicon-based capacitive sensor and comprises two shielding layers, two conductive layers and a dielectric layer, wherein the dielectric layer is partially composed of 50um PDMS, the conductive layer is composed of 0.5mm conductive silica gel, and the shielding layer is composed of 0.1mm silica gel material; the stroking type interactive input method comprises the following steps: the user touches the flexible touch sensor at different speeds along a given direction, and the speed direction and the size of the stroking action are estimated by decoding the array type force touch signals obtained by the flexible touch sensor, so that a vector v is formed as the speed control input of the mobile robot.

Description

A flexible tactile mobile robot operation input device and interaction method

Technical field

The invention relates to the field of interactive control of mobile robots, and in particular to a flexible tactile mobile robot operation input device and an interaction method.

Background technique

Tactile perception is one of the important tools for motion capture modules in many applications such as virtual reality and teleoperation. It can realize contact perception of real-world character interaction and has many applications in fields such as movies, games, sports, biomechanics, and robot control. . Traditional interactive input devices for mobile robots are mostly in the form of steering wheels, handles, etc. On the one hand, such input devices are mainly used to input the movement direction of the mobile robot. On the other hand, such devices need to be installed on a fixed base, which is inconvenient to form a wearable device. interactive device. In recent years, mobile robot operation input methods based on computer vision have also emerged, which require a certain infrastructure and cameras need to be properly installed to ensure the visibility of interactive operations, so they are mainly used in laboratory or studio environments. For scenarios where fixed cameras are not suitable, the present invention proposes a flexible tactile mobile robot input device.

Contents of the invention

In order to solve the above problems, the present invention provides a flexible tactile mobile robot operation input device and interaction method. The device can recognize an array of force tactile signals and can achieve larger bending and stretching. Based on the force tactile signal obtained by the device, a stroking interactive input method is further proposed, and a method of decoding the array force tactile signal under stroking interaction is proposed to obtain the vector speed input of the mobile robot to control the movement of the robot.

The invention provides a flexible tactile mobile robot operation input device, which includes a capacitance measurement module and a sensor module. The sensor module is a five-layer capacitance structure including two shielding layers, two conductive layers and one dielectric layer. The dielectric layer is in the middle position, the two conductive layers are separated from the two layers of the dielectric layer, and the outermost layer is wrapped by two shielding layers;

The capacitance measurement module includes a NE555 capacitance measurement circuit, a control switch circuit and a frequency measurement circuit and are connected through connecting lines.

As a further improvement of the sensor of the present invention, the dielectric layer of the sensor module is partly composed of PDMS, the conductive layer is composed of conductive silica gel, the shielding layer is composed of silica gel material, and the adhesive is composed of PMDS main agent and curing agent in a ratio of 10:1 Configured to allow for a wide range of bending and stretching.

As a further improvement of the sensor of the present invention, the dielectric layer of the sensor module is composed of 50um PDMS, the conductive layer is composed of 0.5mm conductive silica gel, and the shielding layer is composed of 0.1mm silica gel material, which can achieve higher sensitivity.

As a further improvement of the sensor of the present invention, the control switch module uses a 4053 analog switch to pass the high and low levels of the rows and columns according to certain rules to ensure that every time a capacitance measurement is performed, all capacitances with a voltage difference between the two polar plates are Parallel connection can reduce coupling problems between capacitor units.

The invention provides an interactive method for operating an input device for a flexible tactile mobile robot. The specific steps are as follows:

The user touches the flexible tactile sensor at different speeds along a given direction. By decoding the array force tactile signal obtained by the soft and stretchable capacitive sensor, the speed direction and size of the stroking action are estimated, and a vector v is formed as the speed of the mobile robot. control input;

The steps for the soft and stretchable capacitive sensor to obtain array-type force touch are as follows:

1) The outside world exerts a pressure field on the sensor, such as a finger inputting a sliding force for speed change on the sensor. This force will cause the local capacitance of the sensor to change;

2) stm32 mini controls the 4053 analog switch to pass high and low levels in rows and columns according to certain rules;

3) The Uo pin of the Ne555 capacitance measurement module outputs a square wave of a certain frequency, and the PA0 port of the stm32 mini is connected to the Uo pin for receiving the square wave;

4) Use the functional mapping relationship between the frequency f of the output square wave and the measurement capacitance Cmeasured and resistors R1 and R2 in the NE555 circuit: Determine the capacitance value of each capacitive unit of the sensor;

5) Stm32 mini frames the obtained capacitance value of the capacitor unit, and then sends the data frame to the host computer through the USB serial port for visual processing;

6) The sub-thread is used to receive serial port data, parse the data at the same time, and then send it to the main thread; after receiving the data sent by the sub-thread, the main thread will clear the window and redraw, and at the same time update and calculate the mobile robot control parameters;

The speed direction and magnitude of the stroking action are estimated, and the vector v is formed as the speed control input of the mobile robot. The specific solution method is as follows:

(1) Let the array force tactile signal obtained by the flexible tactile sensor at time t be F _t . To obtain the input speed v _t at time t, first calculate the change of the current array force tactile signal D _t =F _t -F _t-1 , and then calculate the gradient field of the change D _t of the array-type force tactile signal The gradient field G _t is a vector field defined in a two-dimensional space, which records the spatial change of the force tactile signal at each capacitive node of the flexible tactile sensor at time t;

(2) Analyze the gradient field G _t to obtain the input velocity v _t . When the calculation speed is high, directly sum the gradient vectors in Gt to obtain the input velocity v _t ;

(3) In order to eliminate the impact of noise on the results, it is proposed to use a voting strategy to determine the input speed v _t , calculate the gradient direction g _ij and gradient size r _ij at each capacitor node (i, j), and quantify the gradient direction into n Level, vote with the gradient size r _ij as the weight, count the weighted votes in n directions, select the direction with the largest weighted votes as the output speed direction, and the weighted votes are the output speed size;

(4) Finally, the scaling coefficient k can be set, and kv _t is used as the final speed control provided to the mobile robot.

As a further improvement of the method of the present invention, in step (6) of the step of acquiring array-type force tactile sensation by a soft and stretchable capacitive sensor, the direction and speed of the movement input by the external sensor can be visually displayed, specifically: real-time measurement of the sensor capacitance Scan and display the peak capacitance units sequentially in chronological order. From this, the direction of movement of the external input can be judged. At the same time, the strength of the external input force can be judged based on the size of the peak capacitance. The external input can be judged based on the time difference between the peak display of each capacitance unit. speed, and finally the python end inputs the control parameters to the subsequent robot equipment.

Compared with existing analysis methods, the characteristics and beneficial effects of the present invention are:

(1) This input device is composed of a capacitor array, which can acquire high-dimensional signals and realize multi-dimensional control of mobile robots without the need for dispersed deployment, thereby improving work efficiency. (2) This input device is made of soft silicone material that can bend and stretch to a greater extent. Compared with traditional handles, keyboards, etc., it has the advantages of being ready to use, can be placed on any curved surface, and is lightweight and small in size.

(2) The proposed new input method for mobile robot control allows the user to use stroking, and extract the speed direction and size of the stroking action as the mobile robot speed input. The interaction method is intuitive and simple.

(3) Most flexible sensor materials are manufactured based on raw materials. The manufacturing process is relatively complex and the material costs involved are high. However, the materials involved in the present invention are directly available on the market and are low-cost.

Description of drawings

Figure 1 is a schematic structural diagram of the sensor of the present invention;

Figure 2 is a schematic diagram of the capacitance measurement circuit of the present invention;

Figure 3 is a schematic diagram of the mobile robot control input flow of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments:

The invention provides a flexible tactile mobile robot operation input device, which can recognize high-dimensional force signals and achieve larger bending and stretching.

As a specific embodiment of the present invention, the present invention provides a soft and stretchable capacitive sensor, which includes a capacitive measurement module and a sensor module. The sensor module is specifically shown in Figure 1, and includes a five-layer capacitor structure with two shielding layers, two conductive layers and one dielectric layer. The dielectric layer is in the middle position, and the two conductive layers are separated from each other. The two layers of the electrical layer are wrapped by two shielding layers on the outside; the dielectric layer is made of 50unPDMS, the conductive layer is made of 0.5mm conductive silica gel, the 0.1mm shielding layer is made of silica gel material, and the adhesive is made of PMDS main agent and cured The agent is configured in a ratio of 10:1.

The capacitance measurement module is shown in Figure 2, including a Ne555 capacitance measurement circuit, a control switch circuit and a frequency measurement circuit. stm32 mini controls the 4053 analog switch to pass high and low levels in rows and columns according to certain rules. Ne555 can adjust the frequency of the output square wave according to the size of the external resistor and capacitor, that is, there is a corresponding functional mapping relationship between the frequency of the output square wave and the size of the capacitance and resistance in the Ne555 circuit. By fixing the size of the resistors (R1, R2) other than the capacitance to be measured, we can obtain the single-variable function of the capacitance to be measured and the frequency of the output square wave, so that the size of the capacitance to be measured can be obtained based on the frequency of the output square wave.

The mobile robot control input process is shown in Figure 3. Counter 2 of Stm32 mini counts the high-level duration of the input square wave at a frequency of 1MHz. When the input square wave changes from high level to low level, the counting ends. The high-level duration of the input square wave can be obtained by multiplying the count value with the period of counter 2. Since the duty cycle of the square wave output by the Ne555 capacitance measurement module is 50%, the frequency of the square wave can be calculated based on the high-level duration of the square wave, thereby calculating the primary measured capacitance value. Each measured capacitance is the sum of the capacitance values of the four capacitance units. After repeating the capacitance measurement five times, perform de-extreme average filtering and store the results into the measurement capacitance array Cm. Modify the control line of 4053 and conduct the next measurement. After measuring the nine groups of measured capacitances, the measured capacitance vector Cm can be obtained.

Denote the capacitor unit vector Cc as C _c =[C _1A ,C _2A ,C _3A ,C 1B ,C _2B ,C _3B ,C _1Γ ,C _2Γ , _{C 3Γ ]} ^T

The corresponding system of equations C _c =M×C _m can be obtained from the relationship between Cm and Cc

where M is

Solving this system of equations yields the value of each capacitor unit.

Stm32 mini frames the obtained capacitance value of the capacitor unit to facilitate subsequent data visualization processing by the host computer. Implementation:

1) Framing, formulating the format of the data frame, taking 7e02127 as an example:

0x7e(FLAG)+02(capacitor unit serial number)+127(capacitance value, decimal)

FLAG is a fixed separator. The capacitor unit serial number is used to specify the capacitor unit to which the current capacitance value belongs, in the order of 1A, 2A, 3A, 1B, 2B, 3B, 1Γ, 2Γ, 3Γ.

After sending the data frames of the nine capacitor units, a stop frame (7efffff) is sent to notify the host computer that a data transmission is completed.

2) Send, Stm32 sends the above data frame to the host computer through the USB serial port for visual processing.

The host computer data is received and visualized by using the pyserial library of python to receive the data from the USB serial port, and using matplotlib for data visualization. Implementation:

1) The main thread is used for visualization. First, define the relevant parameters of the visual image, and then create a sub-thread for receiving serial port data. Use the pipe() function for communication between threads.

2) The child thread uses the serial.Serial() function to create a serial communication object. When the serial port receiving thread receives the data frame, it first determines whether the data frame is normal. If normal, save it temporarily. After receiving the stop frame, the nine data frames are parsed and processed uniformly. Split the received string according to the delimiter (0x7e), extract the capacitance value, and store the capacitance value into the corresponding capacitance unit array element. The extracted capacitor unit array is passed to the main thread through the pipe() function.

3) After the main thread receives the capacitor unit array, it first erases the original image on the canvas, and then uses the ax.bar3d() function to visualize the received capacitor array unit to achieve an animation effect with a lower frame number. After the drawing is completed, wait for the sub-thread to send the capacitor unit array again.

Finally, after the python program decouples the capacitance value, in this example, a 3x3 array force tactile signal F is obtained, where F represents a matrix stored as 3x3. Under the stroking interactive input proposed by the present invention, assuming that the force tactile signal at time t is F _t , calculate the time change of the force tactile signal D _t =F _t -F _t-1 , and then calculate the gradient field Sum the gradient fields to get Among them/> is the gradient value at the (i,j)th capacitance node. In order to reduce the impact of noise, the plane motion direction can also be divided into n levels, for example, divided into 12 directions every 30 degrees. Calculate/> Which interval does the direction of fall into, with/> size/> Vote for the weight for that range. The direction represented by the interval with the largest number of accumulated votes is the input speed direction, and the accumulated number of votes is the speed v _t at time t extracted by the speed size setting.

Finally, the scaling coefficient k can be set, and kv _t is used as the final speed control provided to the mobile robot and input to subsequent mobile robot equipment.

The invention can acquire high-dimensional signals, realize multi-dimensional control of mobile robots, and can achieve larger bending and stretching, which can be applied and used immediately.

The above is only one of the preferred embodiments of the present invention and does not limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention still belong to the protection claimed by the present invention. scope.

Claims (2)

1. An interactive method for a flexible tactile mobile robot operation input device. The flexible tactile mobile robot operation input device includes a capacitance measurement module and a sensor module. The sensor module includes two shielding layers and two conductive layers. and a five-layer capacitor structure with one dielectric layer in the middle, two conductive layers separated by two layers of the dielectric layer, and the outermost layer is wrapped by two shielding layers; The capacitance measurement module includes a NE555 capacitance measurement circuit, a control switch circuit and a frequency measurement circuit and are connected through connecting lines; The dielectric layer of the sensor module is composed of PDMS, the conductive layer is composed of conductive silica gel, the shielding layer is composed of silica gel material, and the adhesive is composed of PMDS main agent and curing agent in a ratio of 10:1; The dielectric layer of the sensor module is composed of 50um PDMS, the conductive layer is composed of 0.5mm conductive silica gel, and the shielding layer is composed of 0.1mm silica gel material; The control switch circuit uses a 4053 analog switch to pass high and low levels to the rows and columns according to certain rules to ensure that every time a capacitance measurement is performed, all capacitors with a voltage difference between the two plates are connected in parallel. The specific steps are as follows: Characteristics are: The user touches the flexible tactile sensor at different speeds along a given direction. By decoding the array force tactile signal obtained by the soft and stretchable capacitive sensor, the speed direction and size of the stroking action are estimated, and a vector v is formed as the speed of the mobile robot. control input; The steps for the soft and stretchable capacitive sensor to obtain array-type force touch are as follows: 1) The outside world exerts a pressure field on the sensor, such as a finger inputting a sliding force for speed change on the sensor. This sliding force will cause the local capacitance of the sensor to change; 2) stm32 mini controls the 4053 analog switch to pass high and low levels in rows and columns according to certain rules; 3) The Uo pin of the Ne555 capacitance measurement module outputs a square wave of a certain frequency, and the PA0 port of the stm32 mini is connected to the Uo pin for receiving the square wave; 4) Use the functional mapping relationship between the frequency f of the output square wave and the measurement capacitance Cmeasured and resistors R1 and R2 in the NE555 circuit: Determine the capacitance value of each capacitive unit of the sensor; 5) Stm32 mini frames the obtained capacitance value of the capacitor unit, and then sends the data frame to the host computer through the USB serial port for visual processing; 6) The sub-thread is used to receive serial port data, parse the data at the same time, and then send it to the main thread; after receiving the data sent by the sub-thread, the main thread will clear the window and redraw, and at the same time update and calculate the mobile robot control parameters; The speed direction and magnitude of the stroking action are estimated, and the vector v is formed as the speed control input of the mobile robot. The specific solution method is as follows: (1) Let the array force tactile signal obtained by the flexible tactile sensor at time t be F _t . To obtain the input speed v _t at time t, first calculate the change of the current array force tactile signal D _t =F _t -F _t-1 , and then calculate the gradient field of the change D _t of the array-type force tactile signal The gradient field G _t is a vector field defined in a two-dimensional space, which records the spatial change of the force tactile signal at each capacitive node of the flexible tactile sensor at time t; (2) Analyze the gradient field G _t to obtain the input velocity v _t . When the calculation speed is high, directly sum the gradient vectors in Gt to obtain the input velocity v _t ; (3) In order to eliminate the impact of noise on the results, it is proposed to use a voting strategy to determine the input speed v _t , calculate the gradient direction g _ij and gradient size r _ij at each capacitor node (i, j), and quantify the gradient direction into n Level, vote with the gradient size rij as the weight, count the weighted votes in n directions, select the direction with the largest weighted votes as the output speed direction, and the weighted votes are the output speed size; (4) Finally set the scaling coefficient k, and use kv _t as the final speed control provided to the mobile robot. 2. An interactive method for a flexible tactile mobile robot operating input device according to claim 1, characterized in that: in step (6) of the step of acquiring array force tactile sensation by a soft and stretchable capacitive sensor, Visually display the direction and speed of the external sensor input movement, specifically: scan the sensor capacitance in real time, and display the peak capacitance units in chronological order, so that the direction of the external input movement can be judged, and at the same time, according to the peak capacitance The size determines the strength of the external input force, and the speed of the external input is determined based on the time difference between the peak display of each capacitor unit. Finally, the python end inputs the control parameters to the subsequent robot equipment.