Powerforce. User manual - wireless edition. Powerforce User Manual. artfit/smartfitpowerforce/

Transcription

1 Powerforce User manual - wireless edition 1

2 Content Important warnings Introduction Pedal forces Force components... 5 Fr (resultant / total force)... 5 Fe (effective / tangential force)... 5 Fu (unused / radial force) Measuring Principle Technical Data Wireless edition Next Steps after unpacking components Mounting Software Installation Install NI-DAQmx Driver Install NI LabVIEW Runtime Engine Library Install IMAGO Records IMAGO Record Introduction First start and setup Load Setup-files Set, save and load calibration values Offset adjustment before every measurement Description of IMAGO Main Menu Index Tab Measurement Processing Routine Exported datasheet Description of the recorded *.bin file CyclePlotAssistent Quick buttons and contents Charts and Design Graph Selection Caption and legend Save quick button

3 Important warnings Please read the following warnings before using your Powerforce System, or else your Powerforce may be damaged, or not function properly. Do not screw on the pedals overly tight in the Powerforce System. Give some grease to the connective sites to improve reassembling of the pedals. If you open a sensor, the transmitter unit or the connection box the warranty is no longer valid. Never clean the sensor or the transmitter unit with water nor use it in wet conditions. Before each ride, ensure that sensors and pedals are fixed properly. When unplugging any connection, always pull straight down rather than sideways, or else you may damage the connector pins. Never pull on the cable itself, but rather pull on the plug. Carefully read through the full installation instructions before using the system Mounting the Powerforce System incorrectly can cause a fall or damage the system. Do not load the sensor with more than 300kg. 3

4 1.1 Pedal forces 1. Introduction In cycling, the transfer of metabolic energy into physical power or velocity of the rider-bike-system is not one-to-one. Environmental as well as mechanical and biomechanical factors affect cycling performance. The propulsion of the bike is generated by pedal forces. Therefore, the determination of pedal forces is a major prerequisite to analyze cycling performance capability from a biomechanical point of view. The question is not why to measure pedal forces but how to do it. Comparing other existing instruments whose purpose is the determination of divers mechanical parameters concerning cycling propulsion, there are some methodological or practical limitations regarding the requirements of either a biomechanical laboratory or a sports related center. The Powerforce System has the great advantage that there is no restriction to a certain pedal system. Cyclists do not have to change their pedal-shoe interface (cleats) if they want to measure their pedal forces with the Powerforce. 4

5 1.2 Force components The Powerforce System records the forces, which are performed on the pedal axis, separately for each leg. Three force components (Fe, Fu und Fr) must be differentiated. Fe Fu Fr Fr (resultant / total force) This is the total force which is generated by the athlete on the pedal. It is the vectorially sum of Fe and Fu. It is calculated, not measured. Fr tells us about the total load, the rider applies to the system the bike as well as to his own body. Joint moments and forces result from (or cause) this component. Thus, e.g. inverse dynamics are based on Fr. Fe (effective / tangential force) Fe is the component of Fr which lies in moving direction of the crank/pedal which is a circle. Therefore, the vector of Fe is always tangential to this circle or perpendicular to the crank. Fe is responsible for the propulsion, but only if it is aligned forward with the rotating direction. If it is aligned backward, e.g. if a rider does not pull up the pedal in the upstroke phase, Fe of the one side must be subtracted from the other side. Fu (unused / radial force) Fu is the component of Fr which does not generate any propulsion. It results in a very small deformation of the crank and pedal-axis. The direction of this force component is lengthwise to the crank. The highest values appear around the bottom dead center (180 crank angle) where the weight component (induced by the mass of the leg) adds to the muscular component. 1.3 Measuring Principle The pedal force measuring device is built as an own mechanical construction which is mounted between the crank and the pedal with a 12 forward rotation about the crank. The system determines the magnetic field variations (Hall-Effect) because of the angular displacement (~ 1/1000mm) of a small magnet in respect to a sensor. 5

6 Due to the specific circular construction of the force transmitting elements, the applied force can be divided into a radial and a tangential part. Positive tangential force (FT = Fe) acts in the pedaling direction. Positive radial force (FR = Fu) acts in the centrifugal direction. This principle allows every pedal system to be screwed on. new (virtuell) crank arm 12 pedal 6

7 1.4 Technical Data Wireless edition Mass of single sensor including radio: 370 g Mass of receiver: 116 g Measurement range: -500 up to 1500 N Breaking load: ~3000 N Sampling frequency pedal force: ~1000 Hz Wireless band: ISM Band: 2,4 GHz Transmission distance: Indoor: 3 5 m Outdoor: 2 3 m Battery Type: NiCd 800 mah Time for continual use: 6 8 h Resolution: 12 Bit 7

8 2. Next Steps after Unpacking First read and follow these instructions! Unpack all materials very carefully! The Powerforce System is high sensitive electronic. Handle all parts with highest care! 2.1 Components Check the content inside the suitcase: [1] 2x Powerforce sensor (left & right), with mounted transmitter units [2] 1x Base station (receiver) [3] 1x Adjustment Tool [4] 2x adjustment tool screws [5] 2x crank sensor screws [6] 2x Charger [7] 1x Serial USB cable (Base station to PC) [8] 1x USB License Dongle [9] 1x 10mm Allen Key [10] 1x 2,5mm Allen Key [11] 1x 10mm Wrench [12] 1x Calibration printout

9 2.2 Mounting For accurate measurements, it is important to fix the sensor in the correct position on the crank. Before mounting, make sure the adjustment screws are screwed out: Then, mount the sensor on the crank: Grooves for the rods of the adjustment tool Next, screw the adjustment tool onto the sensor. Make sure the adjustment tool is facing the correct direction as indicated on the label on the tool. Put the small rods of the adjustment tool in the grooves of the sensor. Be careful not to damage the wires running in the small gap between the transmitter unit and the sensor. Put the cone of the adjustment tool into the center of the bottom bracket screw: 9

10 Now, fix the adjustment tool (hand-tight) onto sensor, by using the corresponding screw for each side. Afterwards, fix the sensor using the two adjustment screws. Tighten the screws alternating: first, tighten the left screw a bit, then the right one a bit, and so on, until the screws are tight and hold the sensor in position. Make sure that the cone of the adjustment tool stays in the center of the bottom bracket screw: 10

11 After the adjustment screws hold the sensor in position, screw tight the sensor crank screw: Now, you can take off the adjustment tool. 11

12 3. Software Installation For the installation of the Powerforce software you need to download the software package on our homepage: Powerforce systems purchased in or after December 2018 please refer to the section Powerforce 2019, all other systems please refer to the section Powerforce. Make sure to follow through with the installations in the order as described below: 3.1 Install NI-DAQmx Driver Before you install the IMAGO Record-Cycle Software, you must install the NI-DAQmx-Driver. Download the setup file and click on the icon in the saved files and follow the setup instructions. The Installation will take several minutes. 3.2 Install NI LabVIEW Runtime Engine Library After installing the DAQmx Driver, you must install the NI LabVIEW Runtime Engine. This library is necessary to read out the data from IMAGO. Click on the icon and follow the setup instructions. 3.3 Install IMAGO Records After the two previous installations are finished, install IMAGO Record. To do so, open the setup.exe and follow the setup instructions. 12

13 4.1 Introduction 4. IMAGO Record IMAGO is a LabVIEW based program developed at the University of Freiburg for data acquisition and processing. Besides force measurements, further analogue channels can be recorded and displayed in IMAGO. The program also includes a processing routine. The data output from this routine is a MS Excel (2003) sheet containing the mean of all recorded channels resampled to 360 data points (1 steps). It was developed for movement analysis with the Powerforce pedal force measurement system and EMG recordings. For training and training studies the program provides an online feedback. The feature, called Cycle Plot, simplifies the data stream in a circular graph. It enables any athlete to work with live feedback without previous knowledge. As the program has many more features used at the University, which are not available in your version, there may be a few buttons and other options which have no further relevance for your pedal force measurements. If you have any further questions, please contact the Radlabor. 4.2 First start and setup Start IMAGO Records by clicking on the Icon on your desktop. Make sure, the USB-license dongle is inserted into your PC, otherwise the following error message may occur: In this case, close the program, insert the dongle and restart IMAGO Records. Your system firewall might want to block the application. You should allow the Imago record.exe to pass the firewall. The first time you start IMAGO, two windows will open: - The main record window (IMAGO record.vi) - A window displaying an overview of all channels (Wireless Cycling Instrument.vi). 13

14 4.2.1 Load Setup-files To be able to load the optimum setup file for IMAGO, find the following path in your directory: Insert the setup file called RECORD_CYCLE1.set and IMAGO that have been sent to you as shown above. Now, the optimal settings should be present in IMAGO when starting the program. Next, insert the files WirelessCyclingInstrument PF 1xx.set into the following directory: 14

15 4.2.2 Set, save and load calibration values If the calibration values, individual to your specific system are not loading automatically proceed as described below: In case your calibration values are not showing upon starting IMAGO, you can enter them manually. To enter the calibration parameters, you need the calibration protocol. The calibration protocol is delivered in the suitcase containing the Powerforce system. The calibration values contain the offset settings and the correction values that were determined by our engineers during the calibration of your system at Radlabor. Enter these values manually in the Wireless Cycling Instrument.VI window, as seen in the picture below: Note, that the gain for the power channels must be calculated with 500 N to get from the voltage in [V] to V the force in [N]. Press, the save button to save these parameters. 15

16 Follow the path described below to change the settings such that your file is loaded automatically every time you start IMAGO: Options Extras Paths Then you must load the.set files as shown in the picture: Now, IMAGO Records will load the file specific to your system automatically upon starting the program Offset adjustment before every measurement Before starting a measurement, adjust the offset of the forces Fe and Fu for both sides. After mounting the Powerforce sensors and the pedals, switch on both sensors and open the IMAGO software. The calibration values of your system should be displayed as stated in the above chapter. To adjust the offset of Fe of the left sensor, please move the left pedal such that the virtual crank arm is horizontal to the floor and facing to the front. Before you enter the calibration modus you can change the amplitude of the axis (2.). You can now choose the calibration modus in the top right corner (1.). You can zoom in to look closely at the incoming data stream by using the sliding button on the left-hand side (3.). 16

17 A red line running is now running across the screen and a black line which is being overwritten by the red line. The black line represents the measured value of the selected channel (4). If you additionally open the pedal instrument.vi (5) you can adjust the offset to match zero by entering a new value in the Offset-field (7) corresponding to the channel displayed in the main window. It is recommended to click on the small black arrows (7a) or click into the offset-numbers (7b) and change the value with the up or down key on your keyboard. To adjust Fu of the left sensor, please move the left pedal such that the virtual crank arm is facing downwards vertically, then proceed in the same manner as described above. Adjust Fe and Fu at the right side in the same way. Save the changes to the Wireless Cycling Instruments XX.set file (8.) and exit the pedal instrument.vi and the calibration modus (9.) a 7b 17

18 4.3 Description of IMAGO The following chapters describe some of the most common functions of the software IMAGO Records Main Menu IMAGO In the Imago Tab, you can select that IMAGO is always active. During the processing routine, some settings need to be confirmed. But you can also let the system confirm most of this automatically. To stop this automatism, you need to switch the Always Active option. Settings concerning the window size can be found here. The window can be printed by clicking Fenster drucken. Clicking Beenden will close IMAGO. Tools Selecting the tab Tools the Binary Export of the data is possible. This is necessary to transform your binary data in an excel readable file format, e.g. for analyzing the separated force channels or the acceleration channels. Extras Here you can select further options. If you click on it, a window appears with four different index tabs. In the tab General you can select your decimal separator as a comma or dot. This is typically set to your Excel version. This setting is dependent on your country and your MS Excel settings. Selecting Recording will allow the user to adjust settings related to the data channels being recorded. This is important when recording further analog channels (e.g. EMG) that should appear in IMAGO. Set Nr of first A/D Converter (1.) to the number of analog channels you would like to record. Then set the trigger channel to the number you just typed in + 1. If no additional channels are recorded, the numbers should be 0 and 1, respectively. 18

19 1. In Instruments, different instruments- and wireless selections of the Powerforce systems can be selected. Usually, the default selection is sufficient. The paths are already described in chapter Help The Help tab offers three selections: Kontexthilfe anzeigen which you may ignore. About IMAGO displays the version number of IMAGO that is installed. Further, the key number of your USB-license dongle is visible. Under User Manual you can call up further usage instructions for IMAGO Records. Your PC must be connected to the internet to do so Index Tab Via the Index tabs you can choose different display options of the data acquisition. Index tab Record After starting the measurement by using the Measure button you can follow the course of the data curve in the record-window. All selected channels are displayed in this window. By moving the bar on the left side of the window you can change the viewing area (1.) 19

20 1. Index tab cycle plot The cycle plot window plots the forces in a circular pattern. An additional curve shows the summation of both force signals. Above the cycle plots you see different index tabs: The power tab displays the generated power of the left and the right leg, as well as their summation. In settings, you can set the start angle, the crank length and the used data pieces. The start angle should be set to 12. Index tab Wireless Before you start the measurement, it is recommended to check the wireless-connection of your Powerforce system. fs wireless displays the arriving sampling frequency. This should be around 500 Hz (or 1000Hz depending on your system) (1). After switching on the system, it takes a few seconds until the transmitter is booted and the maximum sampling frequency is reached. Further, you see a button for manual time correction and an overview about the number of connection interrupts. 20

21 1. If you notice a high number of interrupts (>5) it may occur because of an interference of your Wi-Fi-signal or a damage on the transmitter unit. 21

22 4.4 Measurement The pedal force measurement is started by clicking the Measure button. A pop-up window will open in which filename and information about the trial can be entered. A selection which channels you want to record must be made. Select the trigger and all four force channels by clicking on the red box which will then turn green. A red line will now run across the screen writing and overwriting the recorded values in the graph. If you click on the Cycle Plot Tab and start pedaling, red circles appear on the screen. These circles display the current forces relative to a black reference circle. The black reference circle represents the zero line. The further the red line is outside the circle, the greater is the recorded force. The further the red line is inside the black line, the greater the negative force measured. The channels displayed here can be changed above the charts. The power calculations depend on the crank length, which is entered in the cycle plot window in the setting tab. To start the data recording click the RECORD button. You can pause data recording by clicking this button again and finish the trial with STOP. During recording, the RECORD button is green and a timer depicts the seconds written. As soon as you press the STOP button, the program will ask you if you want to start Online processing. If you confirm, a second window will open and ask, which data you want to include for your results. This is a control routine, which compares the length of the data pieces between two trigger signals to the average length. The tolerance interval is +/- 20% of the average signal length. If you have no accelerated movement, there should not be more than one or two signals, which vary. This is usually the last signal, because recording stops at most times less than one revolution after the last trigger signal Processing Routine There are two processing routines: 1. A processing routine for all force/acceleration channels measured by the Powerforce system (non EMG routine). 2. A processing routine to process further analog channels such as EMG data (EMG routine) A Butterworth low pass filter (non EMG routine) and a Butterworth band pass filter (EMG routine) can be applied to the data. The user can choose the cut off frequencies for these filters during the routine. The EMG routine now rectifies the data set. After this the following steps are identical for both routines. The data stream is cut at the trigger signals. To make sure that no data piece is considered which is too short (e.g. the first piece or if an interfering trigger signal divides a revolution), the length of each piece is compared to the average length and can be ignored by choice (the acceptance interval is average +/-20%). The chosen pieces are resampled to 360 pieces for one full revolution. Each channel is averaged (arithmetic mean) over all selected revolutions. As a last step, the mean of the standard deviation of the 360 data points of each channel is calculated. All calculated data is now exported to an MS Excel readable text file. EMG processing routine (labelled rectified ) Band Pass Filter rectification trigger cut length check resampling mean Non EMG processing routine (labelled not rectified ): Low Pass Filter trigger cut length check resampling mean 22

23 You can start the processing routine in two ways. The system will ask if you want to start the routine after every non remote recording or when you press the Stop button after loading the file you want to process in the View modus. The processing routine will also start automatically after every remote recording. In this case, the routine will confirm every window and save the file automatically as well, so that there is no delay until the next file is being recorded. If the system does ask you to start the routine, it is either switched off (see Fehler! Verweisquelle konnte nicht gefunden werden. ), or the hardware trigger is not giving a clear signal Exported datasheet The exported datasheet is a MS Excel readable text file. The first three columns and the first 7 rows contain file and channel information. The first matrix contains all recorded channels processed with the non EMG routine. There is one column for each channel and 360 data points from row 8 to row 367. The second matrix, containing the data resulting from the EMG (rectified) routine, is appended following the columns of the first matrix Description of the recorded *.bin file The *.bin file contains a header with all entered file information and all settings concerning the data recording. The length of the header is variable and is written to the first byte of the file. Behind this string, the measured values for all channels are written row by row into the file. The raw data displays the values in Volt. 23

24 5. Cycle Plot Assistant The Cycle Plot Assistant was developed to display the force data recorded with IMAGO Records. It is based on Excel The tool is written in Visual Basic for Applications. After opening CyclePlotAssistant.xltm, you need to activate the Macros for this Workbook. Make sure the macro files are in the same folder as the application. 24

25 After starting the CPA, you see different icons. If you click on Main_Menu you can open the menu. By clicking on the arrows above Zero circle you can change the size of the zero circle for cycle and vector plots. It has no relevance for other charts. In the box of graph size you can change between maximal amplitude for all graphs or the same proportion (standard). 5.1 Quick buttons and contents The file icon opens the *.xls files you want to display (they must be recorded with IMAGO). The white cross on the red background next to the file icon will unload the selected files. 25

26 The blue numbers are quick load buttons. Once you have created a sheet, you can save your settings and apply it to other data with these buttons. 5.2 Charts and Design Here you can select different chart types. All charts available are shown below. The sheet is divided into six areas, where charts can be plotted. There are also description fields available. If you click on Corner, Caption or Header you can arrange the header and the headline of the print sheet. The information is taken from the loaded raw data files. Multiple choices are not possible. Cycle: In this chart the data is plotted in a circle. The black circle is zero. Positive data is outside the black circle. Negative values are plotted inside the black circle. 26

27 Vector: Every ten Data Points the vector of one or two selected channels (Fe and Fu coordinate) is displayed at the according crank position. Note, that the first coordinate is always the direction of Fe, the second always that of Fu. Two different channel pairs can be shown in one graph. XY-Graph 5.3 Graph Selection Here you can see which file is represented by data1, data2, data3 and data4. The button details open the detail-window. This appears in the right part of this window and all selected graphs are shown there. To create new Quick Buttons, it might be easier to work with this view. Click on the chart position, to add graphs to the according chart. To display the same selection in one line, this button one row. applies the selected buttons to both graphs in 27

28 In the data selection, all recorded channels will be shown in the left drop down menu Up to four graphs can be plotted in one chart. 5.4 Caption and legend Comments can be added manually, which can be added to the header, label or legend (1) Similar to the overview for the graph selection an overview window for the top bar and legend labels exists. The left list represents the Top bar selection, the right one the legend selection. Multiple choices are possible. (2) By clicking on the chart position you can apply a name to the Chart in the Top bar and a description with the color of the graph in a legend underneath the chart. (3) If you want to assign the same parameters to all charts you can do this by using this button, which selects all charts 28

29 5.5 Save quick button If you click on one or more than one of the Buttons, you can use the functions of the Buttons below on the selection. These two tables correspond to the Quick Load Buttons in Main Menu You can Hide and Show the Buttons in the Main Menu. This is simply a possibility to tidy up the menu. With the Button assign settings to Button all Indices of the current selection (charts, comments, graphs, legends and header entries) are saved. Note that only the indices are saved. Meaning, that if you have selected the second recorded channel of your file the second channel of the new selected data you apply your settings to will be shown. There is no reference to the selected channel name. By clicking on New Button Name you can change the name of the button without changing the settings applied to it. 29