Biomedical Engineering, Vol. 36, No. 1, 2002, pp. 37-38. Translated from Meditsinskaya Tekhnika, Vol. 36, No. 1, 2002, pp. 32-33. Original article submitted June 26, 2001.
An Electronic Hand-Training Dynamometer A. V. Gornaev and E. A. Khlynov
Physical fitness is provided both by the innate abilities of a given individual and by the abilities acquired by exercise. Both physical and psychological factors, such as volition and intellect, have an effect on the development of various physical characteristics [2]. The capacity for work is determined to a significant extent by the degree of physical fitness. One of the most important tasks of physical training is the recovery of motor performance in traumatized patients. There are various methods of strength training [1]. If a constant load is applied to a muscle, the muscular contraction is performed under isotonic conditions. An exercise performed under isokinetic conditions involves movement of limbs at a constant rate. Under static conditions, an effort does not change the length of the muscle. Physical endurance is determined by the ability for performing a given physical exercise for a considerable length of time. Physical endurance can be both static and dynamic. Recently, considerable attention has been given to a special type of physical fitness, the ability for switching from one type of muscular activity to another without reducing the physical effort. Development of this ability requires special training. Strength-training devices are very useful for training dynamic and static physical endurance. Various dynamometers are used for measuring the strength of muscles. Combined electronic devices providing both training and measurement of strength are especially useful. The goal of this work was to consider one of such devices, an electronic hand-training dynamometer. An electronic hand-training dynamometer should meet the following requirements: possibility of application and measurement of a short-duration dynamic load; possibility of application and measurement of a long-duration static load;
counting of the efforts exceeding a given threshold; counting of the total effort; possibility of fast switching from one type of muscular activity to another; autonomous power supply, small size and weight, and ergonomic shape. Characteristics of several hand-training dynamometers available from different manufacturers are given in Table 1 [3, 4]. These dynamometers have the following disadvantages. 1. None of these models can be used for measuring the dynamic effort. 2. None of these models can be used for monitoring the static effort. 3. None of these models can be used for counting the total effort. 4. The interface is either absent or insufficiently convenient. The main advantage of these dynamometers is their good ergonomic characteristics. An electronic hand-training dynamometer meeting all requirements listed above was developed at Radkon, Ltd. The dynamometer provides: measurement of the dynamic effort up to 75 kg with an accuracy of ± 5%; counting of efforts at a maximum rate of 2 efforts per sec; TABLE 1. Performance of Hand-Training Dynamometers λ-shaped, Lind & Ponack
Ball, VaCoRu
Effort is not measured
Effort is not measured
Up to 90 kg
Counting of the efforts exceeding given threshold
Yes
Yes
No
Counting of the total effort
No
No
No
Characteristic Maximum effort measured
Monitoring of static load Dimensions, mm
Moscow Institute of Electronic Engineering. Radkon, Ltd., Moscow, Russia; E-mail:
[email protected]
Weight, kg
No 150 × 100 × 30 0.15
No 60 × 60 × 60 0.30
Mechanical dynamometer
No 110 × 50 × 15 0.2
37 0006-3398/02/3601-0037$27.00 2002 Plenum Publishing Corporation
Gornaev and Khlynov
38
counting of the efforts exceeding the threshold specified by user; counting of the total effort; measurement and control of the long-duration static effort within the range up to 75 kg with an accuracy of ± 5%; autonomous power supply for at least 6 months. A schematic diagram of the electronic hand-training dynamometer is shown in Fig. 1. A MSP430F1121 microcontroller (16-bit RISC microcontroller, Texas Instruments) [5] is used as the control element of the dynamometer. The microcontroller is operated from a CR-2032 lithium battery (3 V). The program memory of the microcontroller is 4 kb; RAM, 256 bytes; reprogrammable data memory, 256 bytes. The microcontroller has a 16-bit timer-counter, a watchdog timer, and a comparator. The power consumption of the microcontroller is very low, so that the current consumption of the dynamometer operating in the energy-efficient mode does not exceed several microamperes. The signal generated by a forcefrequency converter (FFC) is applied to the complementing input of the microcontroller. The dynamometer has a userfriendly interface consisting of a 5-character liquid-crystal display (LCD) and two buttons for selecting the operation mode. The interface is operated by an HT1621B driver (Holtek). The input data are processed using special algorithms. The accuracy of measurement of the effort is 2%. The performance of the microcontroller is sufficiently high to provide rapid data processing. The LCD driver circuit is used in the device because the microcontroller has only 13 input/output ports. In addition, the LCD driver circuit provides audible indication. The hand-training dynamometer provides control of both static and dynamic loading. Besides, it allows some integral characteristics to be determined. The device combines the elasticity of a hand-training device and the rigidity of a dynamometer. The dynamometer is covered with rubber. Its dimensions are 120 × 75 × 15 mm. The dynamometer can operate in the following modes: measurement of the maximum effort within the range from 5 to 75 kg with indication of the results of measurement (measurement accuracy, 2%);
Fig. 1. Schematic diagram of the electronic hand-training dynamometer.
counting and indication of the number of efforts exceeding a threshold specified by user (number of efforts counted can be as much as 65,536); measurement and indication of the total effort (up to 655,360 kgf); the static H erotmode, in which the user can monitor his static efforts for 99 sec; the mode of semiautomatic calibration used for determining the coefficients of linearization of the effort frequency curve (this mode is inaccessible for user); the clock mode with electronic correction of the clock operation. In general, the developed hand-training dynamometer meets all requirements for devices of this type. The user-friendly interface makes it especially useful. The dynamometer can be used for rehabilitation of patients with traumas of various severity. REFERENCES 1. 2. 3. 4. 5.
S. A. Dumanin, E. A. Petrova, and L. Ya. Ivashchenko, Self-Control of Physical Fitness [in Russian], Kiev (1980). I. I. Shmalgauzen, Human Body as a Whole in the Individual and Historical Process [in Russian], Moscow (1982). Cho Myung Ho, Federhantel ausgebildeten Handgriff, Deutches Patentamt A63B 5/20 No. DE3304973C2 (1995). Taan K. Chin, Gripping-and-Compressing Type Exerciser with Adjustable Compressive Resistance, US Patent A63B 23/16 No. 5529551 (1996). MSP430xlxx Family Users Guide: www.ti.com/ microcontrollers/msp430/slau49.pdf.
