EP0108398A2
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Control system in a tractor
Assignee: Valmet Technologies Oy
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Filing: 1983-11-03
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Granted: —
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Expires: 2003-11-03
Abstract
Abstract An analog/digital control system for a tractor. In the system is performed the measurement of a factor, or factors, dominating the work performance of the tractor's lifting attachment or of the actuator of a work implement. In this way is formed the actual value signal of the control system and its set-point signal (a), and the signal (e) stating their difference, on the basis of the latter being governed an analog/digital control unit, which governs the control means of the actuator, such as a solenoid valve (16,22,23). The control deviation signal in analog form is transformed into digital form by the sampling in order to establish a so-called dead range in the time dimension. The digital signal is processed in comparator members (9,12), in which have been set the limit values (Ty,Ta) defining the dead range. When in the sampling procedure the pulse amplitudes fall once or several times outside the dead range (Ty-Ta), such influence is exerted on the sampling means that transition is made to continuous following of the control deviation and in this manner the requisite control measures are carried out. When a value (e 2 ) derived from the control deviation falls in the dead range (Ty-Ta), transition is made back to the sampling procedure.
Inventors
- 👤 Hannu Hannukainen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 08:24
CPC Classifications
G; G05; G05D; G05D3/00; G05D3/12; G05D3/20; A; A01; A01B; A01B63/00; A01B63/02; A01B63/10; A01B63/111; A01B63/1117
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
266 words
In a tractor, a control system of which the electronic part has been carried out by analog/digital technique and wherein is performed the measurement of a factor or factors dominating the performance of the actuator of the tractor's lifting means or equivalent work implement and on the basis of this, or of these, a signal representing the actual value (b) of the control system is formed and a signal (a) representing the set point value is established, and a signal (e) representing the difference between above values (a-b), i.e., the control deviation, on the basis of which the analog/digital control unit is governed, said unit governing the control means of the actuator, such as a solenoid valve (16,22,23), characterized in that the signal in analog form representing the control deviation (e) is converted into digital form by a sampling principle (with sampling frequency f ), or by another equivalent procedure, to the o purpose of establishing a so-called dead range in the time dimension, that said digital signal is processed in comparator members (9,12) in which have been set the limit values (Ty,Ta) defining the dead range, and that when the amplitude of the pulses established by said sampling procedure or equivalent falls one or more times outside said dead range (Ty-Ta), the sampling means is acted upon in a way causing transition to continuous following of the control deviation, on the basis of which requisite control measures are carried out, and that when the value (e 2 ) derived from said control deviation falls into said dead range (Ty-Ta), said sampling procedure is again adopted.
Claim 2
Dependent Claim
266 words
In a tractor, a control system of which the electronic part has been carried out by analog/digital technique and wherein is performed the measurement of a factor or factors dominating the performance of the actuator of the tractor's lifting means or equivalent work implement and on the basis of this, or of these, a signal representing the actual value (b) of the control system is formed and a signal (a) representing the set point value is established, and a signal (e) representing the difference between above values (a-b), i.e., the control deviation, on the basis of which the analog/digital control unit is governed, said unit governing the control means of the actuator, such as a solenoid valve (16,22,23), characterized in that the signal in analog form representing the control deviation (e) is converted into digital form by a sampling principle (with sampling frequency f ), or by another equivalent procedure, to the o purpose of establishing a so-called dead range in the time dimension, that said digital signal is processed in comparator members (9,12) in which have been set the limit values (Ty,Ta) defining the dead range, and that when the amplitude of the pulses established by said sampling procedure or equivalent falls one or more times outside said dead range (Ty-Ta), the sampling means is acted upon in a way causing transition to continuous following of the control deviation, on the basis of which requisite control measures are carried out, and that when the value (e 2 ) derived from said control deviation falls into said dead range (Ty-Ta), said sampling procedure is again adopted.
Claim 3
Dependent Claim
51 words
Control system according to claim 1, characterized in that in the forward leading branch of the control system information is at first transferred in analog form, and that in connection with realizing the first dead range which is in the time dimension, transition is made to digital information transfer and processing.
Claim 4
Dependent Claim
159 words
Control system according to claim 1 or 2, intended for controlling the ploughing depth or traction resistance of a work implement, such as ploughs attached to the three-point linkage of an agricultural tractor, characterized in that in the system is measured by the aid of pick-ups (1,2) both the position of the lifting arms, which represents the ploughing depth or another equivalent working depth, and the traction resistance acting on the tractor from the work implement, and the signals (c 1 ,c 2 ) from the pick-ups (1,2) mentioned are carried to a ratio member (3) which can be acted upon by a control means (19) for setting the relative weight coefficients of the said two different signals, and that the said signal (b) obtained from the ratio member (3), which represents both the ploughing or other equivalent working depth and the traction resistance with appropriate relative weight factors, is used for actual value signal in the control system.
Claim 5
Dependent Claim
36 words
Control system according to any one of claims 1 to 3, characterized in that the governing means of the control system is a magnetic valve with at least two control solenoids (22,23), preferably a so-called mini-valve.
Claim 6
Dependent Claim
72 words
Control system according to any one of claims 1 to 4, characterized in that the system comprises in the forward branch of the control circuit after said comparator member (9,12) a digital electronic block (13), to which has been carried a compilation of data, e.g. switch data (k ...k ), on the basis of which the decision is made whether the control measure suggested by the control system can be carried out.
Claim 7
Dependent Claim
49 words
Control system according to any one of claims 1 to 5, characterized in that to said digital/electronic block (13) has been carried a connection from suitable external means, it being possible on the basis of this connection to cover the automatics at appropriate times, e .g. in transport situations.
Claim 8
Dependent Claim
83 words
Control system according to any one of claims 1 to 6, characterized in that in the system has been provided control of the compensation for leakage of the lifting cylinder (27) of the lifting means (25) in that the position during transport (c 1 ') of the lifting arms and the changes taking place therein are observed by the aid of a particular block (17), and that a compensating lifting correction is applied through said digital/electronic block (13), by-passing the control branch proper.
Claim 9
Dependent Claim
32 words
Control system according to any one of claims 1 to 7, characterized in that the sampling frequency (f ) is on the order of o 1...100 Hz, preferably about 10 ...20 Hz.
Claim 10
Dependent Claim
45 words
Control system according to any one of claims 1 to 8, characterized in that said comparator unit (9,12) comprises a sensitivity setting unit (9), in which by the aid of a particular control member (21) can be set the limits (Ty,Ta) of said dead range.
Claim 11
Dependent Claim
54 words
Control system according to any one of claims 1 to 9, characterized in that the pulses picked up by said sampling means are stored in a memory (8), which preferably is accomplished by analog technique, the error value (e 2 ) therein stored being processed in said comparator block (9,12) as to its amplitude.
References Cited (Backward Citations)
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